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Lunar Exploration Definition Team

Lunar Exploration Objectives and Requirements Definition

LERD_issue1_revision_1

Prepared by James Carpenter, Richard Fisackerly, Sylvie Espinasse and the Lunar Exploration Definition Team Reference LL-ESA-ORD-413 Issue 1 Revision 0 Date of Issue 1 February 2010 Status Approved/Applicable Document Type RP Distribution

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Title Lunar Exploration Objectives and Requirements DefinitionLunar Exploration Definition Team

Lunar Exploration Objectives and Requirements Definition Issue 1 Revision 0 Author James Carpenter, Richard Fisackerly, Sylvie Date 1 February 2010 Espinasse and the Lunar Exploration Definition Team Approved by Date Alain Pradier 1 February 2010

Reason for change Issue Revision Date Updates made to requirements following Topical Team 1 1 12 August 2010 consultations Correction made to requirement reference in 1 1 23 February 2010 panoramic camera section

Issue 1 Revision 0 Reason for change Date Pages Paragraph(s)

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Table of contents:

List of Figures...... 6 List of Tables ...... 7 List of Acronyms...... 10 1 Introduction ...... 12 2 The Context for Lunar Exploration ...... 14 3 ESA’s First Lunar Lander ...... 17 4 Landing ...... 18 4.1 Navigation ...... 19 4.2 Guidance ...... 20 4.3 Control ...... 20 5 Human health ...... 21 5.1 Radiation Risks to Human Health ...... 21 5.1.1 Lunar radiation environment ...... 21 5.1.1.1 Solar radiation ...... 21 5.1.1.2 Galactic cosmic rays ...... 24 5.1.1.3 Secondary radiation ...... 26 5.1.2 Effects on human physiology ...... 27 5.1.3 Health effects of radiation - potential objectives ...... 28 5.1.3.1 Improve current space weather forecast from the Moon to improve early warning systems for crews ...... 29 5.1.3.2 Quantify the radiation risks to human lunar exploration due to GCRs ...... 30 5.1.3.3 Improve current understanding of the response of biological systems to radiation damage in the integrated lunar environment such that risks assessment for humans can be improved...... 30 5.1.3.4 Determine the radiation shielding properties of lunar regolith ...... 31 5.2 Health Risks of Lunar Dust ...... 31 5.2.1 Health effects of dust - potential objectives ...... 33 5.2.1.1 Quantify the health risks to human exploration posed by lunar dust unrepresented in sample collections ...... 34 6 Habitation ...... 36 6.1 The Suitability of a Potential Future Landing Site for Human Exploration ...... 36 6.1.1.1 Characterise the suitability of a potential future landing site for future exploration ...... 37 6.2 Lunar Dust and Effects on Habitation ...... 37 6.2.1 Dust and soil effects on habitation - potential objectives ...... 40 6.2.1.1 Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities ...... 40 6.2.1.2 Determine thermal and heat flow properties of the regolith ...... 41 6.3 Impact Risks for Habitation ...... 41 6.3.1 Impact risk for habitation - potential objectives ...... 43 6.3.1.1 Quantify the risk to human exploration posed by impacts ...... 44 6.4 Seismic Risks for Human Habitation ...... 44 6.4.1 Seismic risks for habitation - potential objectives...... 45 6.4.1.1 Determine the seismic risk to future human exploration activities ...... 45 6.5 Enabling Research for Habitation Technologies ...... 45 6.5.1 Enabling research for habitation technologies – potential objectives ...... 46 6.5.1.1 Understand the effects of reduced gravity on multiphasic properties critical in habitation technologies ...... 46 6.5.1.2 Understand the impact of the lunar environment on biological processes important for life support technologies 47 6.5.1.3 Demonstrate advanced power storage technologies ...... 47

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7 Resources ...... 48 7.1 In Situ Resources and their Utilisation ...... 48 7.1.1 In situ resources - potential objectives ...... 48 7.1.1.1 Identify the presence or otherwise of water ice in permanently shadowed craters ...... 49 7.1.1.2 Identify the abundance and distribution of ilmenite ...... 50 7.1.1.3 Improve our understanding of the potential use of highlands regolith as a resource ...... 51 7.1.1.4 Improve our understanding of the potential use of mare regolith as a resource ...... 51 7.1.1.5 Provide ground truth to support orbital observations, by other missions, of potential in situ resources ...... 51 7.1.1.6 Determine the abundance as a function of depth and distribution of H2O, OH and hydrated minerals in the regolith. 52 7.1.1.7 Determine the abundance and distribution of solar wind implanted volatiles in a non Apollo locality ...... 53 7.1.1.8 Perform "proof of concept" in-situ resource extraction based on SWIP volatiles ...... 53 7.1.1.9 Perform "proof of concept" in-situ resource extraction based on water/OH in the regolith ...... 53 7.1.1.10 Perform "proof of concept" in-situ resource extraction based on ilmenite reduction, carbothermal reduction or molten silicate electrolysis...... 54 8 Robotics and Mobility ...... 55 8.1 Challenges for Robotics and Mobility ...... 55 8.1.1 Robotics and mobility - potential objectives ...... 55 8.1.1.1 Characterise the key environmental parameters having a major impact on robotics and mobility elements ...... 56 8.1.1.2 Investigate environmental effects on communications (surface - surface) ...... 56 9 Human Activities ...... 58 9.1 The Research Activities of Future Human Explorers ...... 58 9.1.1 Potential objectives ...... 60 9.1.1.1 Inventory the variety, distribution, and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return ...... 61 9.1.1.2 Determine the density, composition, and time variability of the fragile lunar exosphere at the landing site before it is perturbed by further human activity...... 61 9.1.1.3 Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar exploration...... 61 9.1.1.4 Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar-based astronomy...... 62 9.1.1.5 Determine the regional thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and global scales ...... 62 9.1.1.6 Demonstrate the suitability of the lunar surface as a platform for low frequency radio astronomy ...... 62 9.1.1.7 Piggy back science ...... 64 10 Public Engagement ...... 66 11 Prioritisation of Objectives ...... 67 11.1 High Priority Objectives...... 67 11.2 Medium Priority Objectives ...... 68 11.3 Low Priority Objectives ...... 69 11.4 Piggy Back Science Objectives ...... 70 12 Requirements ...... 71 12.1 Requirements to Meet High Priority Objectives ...... 71 12.2 Requirements to Meet Medium Priority Objectives ...... 81 12.3 Requirements to Meet Low Priority Objectives ...... 85 13 Potential Instrumentation and Techniques ...... 88 13.1 Stereo Panoramic Cameras ...... 88 13.2 Radiation Monitor ...... 88 13.3 Radiation Biology Experiment ...... 89

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13.4 High Resolution Camera ...... 91 13.5 Wet Chemistry Station ...... 92 13.6 Dust Effects on Microorganisms Experiment ...... 92 13.7 Dust Trajectory Sensor ...... 92 13.8 Langmuir Probes ...... 93 13.9 Optical Microscope ...... 94 13.10 Atomic Force Microscope ...... 94 13.11 X-ray Spectrometer ...... 94 13.12 X-ray Diffractometer ...... 96 13.13 Laser Ionisation Breakdown Spectrometer ...... 96 13.14 Mössbauer Spectrometer ...... 97 13.15 Raman Spectrometer ...... 97 13.16 IR spectrometer ...... 98 13.17 Gamma Ray Spectrometer ...... 99 13.18 Neutral and Ion Spectrometer ...... 99 13.19 Broad Band Seismometer ...... 100 13.20 Short Period Seismometer ...... 100 13.21 Mole and Heat Flow Experiment...... 101 13.22 Radio Antenna ...... 101 13.23 Patch Plates ...... 102 13.24 Quartz Crystal Microbalance ...... 102 13.25 Micrometeoroid Impact Detector ...... 102 13.26 High Definition Video ...... 103 13.27 Subsurface Mass Spectrometer ...... 103 13.28 Subsurface Imaging Infrared Spectrometer ...... 103 13.29 Gas Analysis Package ...... 104 13.30 Rock abrasion tool / corer grinder ...... 104 13.31 X-ray and Particle measuring Solar Monitor ...... 105 13.32 Subsurface dosimeter ...... 105 14 Mission Scenario and Implications for Achievable Objectives ...... 106 14.1 Mission duration ...... 107 14.2 Night operations ...... 108 14.3 Landing site ...... 108 14.4 Mobility ...... 108 References ...... 109 Appendix I ...... 116 SELENE (Selenological and Engineering Explorer) – Kaguya (JAXA) ...... 116 Chang’e 1 (CNSA)...... 117 Chandrayaan 1 (ISRO) ...... 117 Lunar Reconnaissance Orbiter - LRO (NASA) ...... 118 Lunar CRater Observation and Sensing Satellite - LCROSS (NASA) ...... 118 Gravity Recovery and Interior Laboratory – GRAIL (NASA) ...... 118 Lunar Dust - LADEE (NASA) ...... 119 Planned missions ...... 120

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LIST OF FIGURES

Figure 4.1. Descent and landing trajectory for soft precision landing at the lunar South Pole...... 19 Figure 5.1. Proton Flux in four energy bands at 1AU measured during a typical SEP event by the proton monitor on the NOAA GOES-11 geostationary spacecraft in the period between 00:00 on 19 November 2005 to 23:00 on 23 November 2005. Data shown are hourly averages...... 22 Figure 5.2. Polynomial approximations to the solar X-ray spectrum in M1, C1and B1 flare states together with measured solar X-ray spectra from the X-ray Solar Monitor (XSM) instrument on SMART 1. Also shown is the predicted magnitude of the diffuse X-ray back ground (DXB) measured by XSM between 3 and 7keV (from RD 7)...... 24 Figure 5.3. Galactic cosmic ray proton fluxes at 1 AU during solar minimum and solar maximum, modelled using the FLUX subroutine implemented in the CREME96 model [RD 11]...... 26 Figure 5.4. Composition of typical lunar soils in lunar Maria (Apollo 17 soil 71060) and lunar highlands (Apollo 16 soils 67700). Data taken from RD 33...... 32 Figure 6.1. Number of dust impacts onto the Lunar Ejecta and Meteorite (LEAM) experiment sensors per 3-hr period, integrated over 22 lunar days as function of the local time; from [RD 46]...... 39 Figure 6.2. The cumulative flux of meteoroids onto to a randomly spinning plate outside of the gravitational influence of the Earth and Moon at 1 AU as derived by RD 50...... 42 Figure 6.3. Frequency of the micro-impacts. Note the very large dispersion between the proposed models, depending on the technique used for monitoring these impacts. Actually, the direct observations of the meteoroids with mass ranging from 1 mg to 1 g has not been done and only extrapolations can be proposed...... 43 Figure 13.1. Time-dependent changes of a single ion-induced DNA damage streak, showing the typical motional behaviour of individual foci along the trajectory over the time course of 12 h after irradiation at the GSI accelerator facility. A human osteosarcoma cell line stably expressing GFP-tagged 53BP1 was used. 53BP1 is a repair protein readily recruited to the sites of DNA double-strand breaks that were here induced by a traversal of a single 6 MeV/n 28Ni- ion [RD 100]...... 90

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LIST OF TABLES

Table 5.1. Yearly integrated flux of solar energetic particles from RD 6...... 23 Table 5.2. The NOAA space weather scale for solar radiation storms [RD 6]. A single event may have a duration of more than one day. The flux values given are 5 minute averages...... 23 Table 5.3. The ranking of solar flares based on their peak X-ray output in the band 1 - 8Å [RD 6]. 24 Table 5.4. Typical values for the flux and energy range of GCRs at solar minimum and solar maximum as inferred from sunspot number. Values taken from [RD 6]...... 25 Table 5.5. Comparison of the effective dose rates from GCR and albedo neutrons calculated during the 1970 solar max and the 1977 solar min. Also shown is a comparison of the effective doses from the SEP in the October 1989 event and the albedo neutrons generated by the SEP during this event. The GCR and SEP effective doses were calculated behind 1 g/cm2 of aluminium shielding. Adapted from RD 15 and RD 16...... 27 Table 13.1. Requirements, which can be met through the inclusion of a stereo panoramic camera in the mission payload and the objectives for which those requirements apply...... 88 Table 13.2. Requirements, which can be met through the inclusion of a radiation monitor in the mission payload and the objectives for which those requirements apply...... 89 Table 13.3. Requirements, which can be met through the inclusion of a radiation biology experiment in the mission payload and the objectives for which those requirements apply...... 89 Table 13.4. Requirements, which can be met through the inclusion of a high resolution camera in the mission payload and the objectives for which those requirements apply...... 92 Table 13.5. Requirements, which may be met through the inclusion of a wet chemistry station in the mission payload and the objectives for which those requirements apply...... 92 Table 13.6. Requirements, which may be met through the inclusion of a dedicated experiment to observe the effects of lunar dust on microorganisms in the mission payload and the objectives for which those requirements apply...... 92 Table 13.7. Requirements, which may be met through the inclusion of a dust trajectory sensor in the mission payload and the objectives for which those requirements apply...... 93 Table 13.8. Requirements, which may be met through the inclusion of Langmuir probes in the mission payload and the objectives for which those requirements apply...... 94 Table 13.9. Requirements, which may be met through the inclusion of an optical microscope in the mission payload and the objectives for which those requirements apply...... 94 Table 13.10. Requirements, which may be met through the inclusion of an atomic force microscope in the mission payload and the objectives for which those requirements apply ...... 94 Table 13.11. Emission lines of major elements observable with an X-ray spectrometer with an Fe 55 excitation source...... 95 Table 13.12. Requirements, which may be met through the inclusion of an X-ray spectrometer in the mission payload and the objectives for which those requirements apply...... 95 Table 13.13. Requirements, which may be met through the inclusion of an X-ray diffractometer in the mission payload and the objectives for which those requirements apply...... 96

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Table 13.14. Requirements, which may be met through the inclusion of a LIBS spectrometer in the mission payload and the objectives for which those requirements apply...... 96 Table 13.15. Requirements, which may be met through the inclusion of a Mössbauer spectrometer in the mission payload and the objectives for which those requirements apply...... 97 Table 13.16. Requirements, which may be met through the inclusion of a Raman spectrometer in the mission payload and the objectives for which those requirements apply...... 97 Table 13.17. Some absorption features of interest for meeting defined requirements in the visible and near infrared...... 98 Table 13.18. Requirements, which may be met through the inclusion of an IR spectrometer in the mission payload and the objectives for which those requirements apply...... 99 Table 13.19. Requirements, which may be met through the inclusion of a Gamma ray spectrometer in the mission payload and the objectives for which those requirements apply...... 99 Table 13.20. Requirements, which may be met through the inclusion of a Neutral and mass spectrometer in the mission payload and the objectives for which those requirements apply. . 99 Table 13.21. Requirements, which may be met through the inclusion of a broad band seismometer in the mission payload and the objectives for which those requirements apply...... 100 Table 13.22. Requirements, which may be met through the inclusion of a short period seismometer in the mission payload and the objectives for which those requirements apply...... 100 Table 13.23. Requirements, which may be met through the inclusion of a mole and heat flow experiment in the mission payload and the objectives for which those requirements apply. .. 101 Table 13.24. Requirements, which may be met through the inclusion of a radio antenna in the mission payload and the objectives for which those requirements apply...... 101 Table 13.25. Requirements, which may be met through the inclusion of patch plates for imaging in the mission payload and the objectives for which those requirements apply...... 102 Table 13.26. Requirements, which may be met through the inclusion of a quartz crystal microbalance in the mission payload and the objectives for which those requirements apply...... 102 Table 13.27. Requirements, which may be met through the inclusion of a meteoroid impact detector in the mission payload and the objectives for which those requirements apply...... 102 Table 13.28. Requirements, which may be met through the inclusion of high definition video in the mission payload and the objectives for which those requirements apply...... 103 Table 13.29. Requirements, which may be met through the inclusion of a subsurface mass spectrometer in the mission payload and the objectives for which those requirements apply. 103 Table 13.30. Requirements, which may be met through the inclusion of a subsurface infrared spectrometer in the mission payload and the objectives for which those requirements apply. 103 Table 13.31. Requirements, which may be met through the inclusion of gas analysis package in the mission payload and the objectives for which those requirements apply...... 104 Table 13.32. Requirements, which may be met through the inclusion of rock abrasion tool or corer grinder in the mission payload and the objectives for which those requirements apply...... 104 Table 13.33. Requirements, which may be met through the inclusion of a particle and X-ray spectrometer in the mission payload and the objectives for which those requirements apply. 105

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Table 13.34. Requirements, which may be met through the inclusion of a sub surface dosimeter in the mission payload and the objectives for which those requirements apply...... 105 Table 14.1. High priority objectives and their implications for mission scenario in terms of landing site mission duration and mobility...... 107

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LIST OF ACRONYMS

AFM Atomic Force Microscope AKR Auroral Kilometric Radiation APSE Apollo Passive Seismic Experiment AU Astronomical Unit CME Coronal Mass Ejection CNSA China National Space Administration CoM Centre of Mass D&L Descent and Landing DDE Dust Detector Experiments DNA Deoxyribo-Nucleic Acid DSN Deep Space Network DSP Defence Support Programme DTE Direct-to-Earth DXB X-Ray Background ESA European Space Agency ESF European Science Foundation eV Electron Volts GCR Galactic Cosmic Rays GES Global Exploration Strategy GFP Green Fluorescent Protein GNC Guidance Navigation and Control GOES Geostationary Operational Environmental Satellite EVA Extra Vehicular Activity GRACE Gravity Recovery and Climate Experiment GRAIL Gravity Recovery and Interior Laboratory HA Hazard Avoidance HRC High Resolution Camera HZE High Z-number Energetic particles ILN International Lunar Network IMU Inertial Measurement Unit IR Infrared ISECG International Space Exploration Coordination Group ISRO Indian Space Research Organisation ISRU In-Situ Resource Utilisation JAXA Japanese Aerospace Exploration Agency LADEE Lunar Atmosphere and Dust Environment Explorer LAMS Laser Ablation Mass Spectrometer LCROSS Lunar Crater Observation and Sensing Satellites LEAG Lunar Exploration Analysis Group LEAM Lunar Ejecta and Meteorites LEDT Lunar Exploration Definition Team LEO Low Earth Orbit LET Linear Energetic Transfer LGRS Lunar Gravity Ranging System

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LIBS Laser Ionisation Breakdown Spectrometer LIDAR Light Detection and Ranging LLO Low Lunar Orbit TRN Terrain Relative Navigation LOFAR Low-Frequency Array LRO Lunar Reconnaissance Orbiter LRV Lunar Rover Vehicle LSWG Life Sciences Working Group LWA Long Wavelength Array MWA Murchison Widefield Array NASA National Aeronautical and Space Administration NIR Near Infra-Red NOAA National Oceanographic and Atmospheric Administration NRC National Research Council PSWG Physical Sciences Working Group RAE Radio Astronomy Explorers RBE Relative Biological Effectiveness RFI Request For Information RHU Radioisotope Heat Unit RTG Radioisotope Thermoelectric Generator SBE Surface Boundary Exosphere SDT Science Definition Team SEP Solar Energetic Particles SKA Square Kilometre Array SPA South Polar Aitken Basin SPE Solar Proton Events SPS Short Period Seismometer SWIP Solar Wind Implanted Particles SWP Solar Wind Particles TRL Technology Readiness Level UV Ultra-Violet VLBI Very Long Baseline Interferometry VSE Vision for Space Exploration XRD X-Ray Diffractometer XSM X-Ray Solar Monitor

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1 INTRODUCTION This document describes the definition of the objectives and mission requirements for the ESA Lunar Lander derived in the context of preparation for future human exploration. The objectives for this mission and their implications in terms of requirements at system level were derived to ensure that the definition and development of the first ESA Lunar Lander and its payload are driven to meet the optimal objectives for human exploration preparation. The definition was carried out by the Lunar Exploration Definition Team (LEDT) a team of invited specialists in various topics relevant to lunar exploration, from various ESA member states, with additional support from ESA. The group was derived from members of the Science Definition Team established in support of the MoonNEXT mission studies, supplemented by specialists nominated by national delegations in areas relevant to human exploration activities, following an invitation to nominate members made to all delegations (ESA/D/HSF/2009.2986/May 2009).

Members of the LEDT are listed below:

• Perry Johnson-Green (Canada) - Senior Program Scientist in Life and Physical Sciences at the Canadian Space Agency • Dag Linnarsson (Sweden) - Professor in Environmental Physiology at the Karolinska Institutet, Sweden • John Leif Jørgensen (Denmark) – Professor in the Div. of Measurement and Instrumentation, National Space Institute, Technical University of Denmark. • Norbert Henn (Germany) – Deutsches Zentrum für Luft und Raumfahrt • Marco Scharringhausen (Germany) - Deutsches Zentrum für Luft und Raumfahrt • Sasha Kempf (Germany) - MPI für Kernphysik, Heidelberg • Philippe Lognonne (France) – Professor of Geophysics, Institut de Physique du Globe de Paris • Heino Falke (The Netherlands) - Professor of Astroparticle Physics and Radio Astronomy, Radboud Universiteit Nijmegen • Ian Crawford (UK) - Reader in Planetary Science and Astrobiology, Department of Earth and Planetary Sciences, Birkbeck College.

Studies have been carried out previously into objectives for lunar exploration by various groups (e.g. European Science Foundation [RD 2], National Research Council [RD 3], Lunar Exploration Analysis Group [RD 4]). Such investigations were considered as important inputs to the mission definition process and the potential role of this lunar lander mission in addressing the objectives and priorities described by these documents

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was considered, within the context of a human exploration precursor of a scale compatible with a Soyuz (~60 kg total payload to surface) or shared Ariane V launch scenario (~150kg payload to surface). Mission scenarios with a larger potential payload capacity were not considered.

An additional major input to the definition process were the 195 submissions received from across European industry and academia following a Request For Information (RFI) on potential instruments and payloads which could be considered for a First Lunar Lander mission. Submissions were requested and received in line with the following high level goals:

1. To advance European technological capabilities for future human exploration of the Moon. 2. To characterise the lunar environment and potential in situ resources to identify their implications for future human exploration. 3. To progress in the definition of tools, interfaces and operational techniques for surface exploration. 4. To increase our understanding of the formation, history and evolution of the Moon.

Additional support and inputs were received from the independent topical team on new development in space radiation biology and dosimetry.

The definition proceeded with the guidance and support of the ESA’s Physical Sciences Working Group and Life Sciences Working Group.

The outcomes described in this document were derived between July 2009 and November 2009.

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2 THE CONTEXT FOR LUNAR EXPLORATION The last decade has seen a resurgence of interest in lunar exploration and the emergence of countries like China and India as space fairing nations. In 2004 the US announced a new Vision for Space Exploration, whose objectives were focused on human missions to the Moon and then on to Mars. Recent international missions have included the Japanese Kaguya orbiter in 2007, the Chinese Chang’e mission, India’s Chandrayaan (2008) and the US LRO/LCROSS mission (2009). All these orbital missions are advancing our understanding of the Moon and preparing for future surface and manned missions. Additional plans for future human exploration of the Moon have been declared by the agencies of several countries and the near future is likely to see the emergence of a worldwide drive to revisit the Moon as a first step in exploration of the Solar System.

This new interest in exploration is driven by the recognition that human development has been guided by a desire to explore and investigate the unknown and that historically exploration has yielded incalculable scientific, economic and cultural benefits for all humankind.

In an attempt to coordinate their exploration efforts 14 space agencies combined to formulate the Global Exploration Strategy (GES) in a document entitled “The Global Exploration Strategy: The Framework for Coordination” [RD 1]. This document provides an extended rationale for exploration and identifies a common themes and values for exploration of destinations in the Solar System where humans can live and work: primarily the Moon, Mars, and asteroids. The intent of those 14 space agencies was also to express their common interest in “creating a common language of exploration" to “enhance mutual understanding among partners and to identify areas for potential cooperation". This is not a proposal for a single global programme, like the International Space Station (ISS), but it recognizes that individual space exploration activities can achieve more through coordination and cooperation.

In July 2008 the members of the International Space Exploration Coordination Group (ISECG) agreed to collectively explore ideas and plans for human exploration of the Moon as a first step and develop the ISECG Human Lunar Reference Architecture. This architecture, which is to be defined by 2010, may be used to inform decision milestones of individual agencies.

Additional studies have been performed by ESA and JAXA on a bilateral basis. Comparative assessments of the architectures developed by ESA (primarily in the framework of the Aurora Core Programme), NASA and JAXA have also been performed.

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The initial findings of these assessments indicate that a lunar lander delivering cargo, payload and logistics delivery to the lunar surface would be a significant asset for exploration. Such a system would enhance the robustness of sortie missions, extend surface exploration opportunities by enabling enhanced human mobility, extend the possible duration of human missions on the lunar surface and provide new surface exploration opportunities. It would also allow the acceleration of the construction of a lunar outpost. For this reason a cargo lander was identified as a key element of a European contribution to international exploration undertakings.

Having identified a cargo lander as an important element ESA proposed to engage Europe in human lunar exploration at its 2008 ministerial council meeting. This proposal was made in the context of the considerable potential for international cooperation, under development in the framework of the ISECG. The ultimate goal of the proposal was to guarantee an opportunity for a European astronaut to walk on the Moon in the early stages of the return of humans to the Moon.

The development of a European lunar cargo and logistics capability requires a stepped approach to allow the development and demonstration of key technologies. An important element in this process has been identified as a precursor Lunar Lander mission by 2018. The primary objective of this mission is to demonstrate soft precision landing technology with hazard avoidance. The mission can then deploy and operate a payload on the surface of the Moon, which can address key objectives associated with the human exploration and prepare for future human activities.

Possible objectives for the mission, during its surface operations phase, have been defined by the LEDT. Objectives were selected considering the needs of a human exploration programme and the interests of European stakeholders, while ensuring complementarity with the achievements of recent, on-going and planned missions to the Moon.

To date the Apollo missions provide our only experience of human operations on the Moon or anywhere else beyond Low Earth Orbit (LEO) and much was learned from these missions which we can apply to future exploration activities. However the short durations of these sortie missions meant that many of the environmental effects that will be important for longer duration missions cannot be quantified at present. In addition long duration missions and the establishment of infrastructure on the Moon will require new technologies and capabilities, which must operate successfully and reliably in this lunar environment. The development of these technologies and their operation alongside humans in the lunar environment poses significant challenges for the exploration programme.

More recently, a renewed interest for the Moon, both as a planetary body and as a destination for human exploration has led to the development of several missions to the Moon and of lunar exploration plans. In the USA the “Vision for Space Exploration”,

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announced in January 2004, began plans for returning astronauts to the Moon. In addition China, India and Japan have also expressed their interest in exploring the Moon. All of these countries have adopted a stepwise approach to human exploration; beginning with robotic precursor missions. A fleet of orbiters have been orbiting the Moon in the past three years and they will be followed by landers and rovers in the coming decade. A summary of the main outcomes of these recent missions is provided in Appendix I to illustrate that the first ESA lunar lander is complementary to and synergistic with these international missions.

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3 ESA’S FIRST LUNAR LANDER

The primary goal for the First Lunar Lander is to demonstrate and mature the key technologies for a future lunar cargo landing capability; soft precision landing with hazard avoidance.

In addition a lunar lander in the 2018 time frame provides an opportunity to perform investigations on the Moon that are essential to the success and sustainability of lunar exploration and that must be carried out in advance of an extended human presence. Such investigations will address the health of humans in the lunar environment and ensure the sustainability of lunar exploration.

The theme for the First Lunar Lander mission is therefore,

“To ensure sustainable exploration”

The following sections describe areas considered of importance for the sustainability human activities on the Moon. Areas considered are radiation and its effects on human physiology and toxic effects of lunar dust for health, habitation, mobility, In Situ Resource Utilisation (ISRU) and preparations for the activities that human explorers will carry out on the Moon.

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4 LANDING The primary objective of the First European Lunar Lander mission is to demonstrate Europe’s ability to deliver payload safely and accurately to the Moon’s surface. More specifically the mission should demonstrate the technologies required to achieve a soft precise landing while avoiding the various hazards which are present on the lunar surface. Such a capability is critical if Europe is to participate to an international lunar exploration effort in an autonomous and significant way.

Regarding a potential future Cargo Lander function, lunar landing is the first critical link in the payload delivery chain that Europe needs to master. Reaching the lunar surface with a spacecraft launched by Ariane 5 and with the goal to deliver substantial payload to a specific surface site such as a future lunar base implies several specific features for the landing:

• Soft Landing, i.e. with relatively low velocities at touchdown, in order to land significant mass, including sensitive equipment, infrastructure etc; • Precision, in order to land in close proximity to already emplaced infrastructure while respecting a certain safety distance to minimise risk ; • Safety, i.e. with the capability of performing hazard (rocks, slope, and shadow) avoidance, in order to be able to land on various types of terrain and to improve mission success probability; • Autonomy, in order to perform real-time corrections and adjustments during landing without the need for ground support.

The landing may be the most critical phase of a surface exploration mission on any celestial body. It is highly dynamic and requires a timely and coordinated interaction between subsystems, such as propulsion, Navigation, Guidance and Control (GNC).

Landing was already identified as the primary mission objective and so was not the subject of the work performed by the LEDT; the following sections on landing therefore provide only a short summary of the main challenges involved.

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Figure 4.1. Descent and landing trajectory for soft precision landing at the lunar South Pole.

4.1 Navigation Navigation is the process of determining the current state of a system (position, velocity, attitude and angular rates, mass) in a given coordinate system, based on direct or indirect observations of the system state (measurements) and on a model of the system dynamics.

For a lunar lander, navigation is initially performed by ground tracking when in LLO. When autonomous navigation is triggered, several sensors and navigation filters are used for position and attitude estimation. This includes “classical” sensors such as Inertial Measurement Units (IMU), star-trackers, as well as Terrain Relative Navigation (TRN) systems, including cameras, LIDARs and altimeter/velocimeters. Measurements from all these sensors are fused into a proper on-board navigation filter.

The definition of the navigation chain should allow a navigation error that is within lander controllability at key-points, given the propulsion system capabilities for error correction, in order to achieve the required landing accuracy and avoid terrain hazards at touch-down. The sequence of events should allow enough time for the navigation filters to converge before update position and velocity estimates are needed.

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4.2 Guidance Guidance is the process of establishing a trajectory (for both position and attitude) that allows reaching a target state, given the initial or current state, along with the corresponding reference control action profile, needed to achieve such trajectory.

This is implemented as a set of algorithms loaded on the lander GNC computer. Such system (with the related hardware and software components) interacts with the ground segment, through telemetry and tele-commands, with on-board navigation sensors and with the actuators (mainly thrusters).

D&L Guidance design calls for a high level of:

• Optimization, in order to reduce fuel consumption, and to ensure compatibly with the available propulsion system • Precision, in order to correct for dispersions in position and velocities to achieve soft-precision landing • Autonomy, with no or little intervention from the ground, in order to cope with large uncertainties (navigation and control errors, CoM variation, gravitational anomalies etc) and hazardous landing conditions.

4.3 Control Control is the process of generating control commands that allows matching of the current or future estimated state with the desired state.

In a D&L scenario, typical control systems are involved in generating feed-back terms for trajectory control, commands for attitude control and fine control during terminal landing. Actuators are based on chemical propulsion.

In addition to performing a soft-precision landing with hazard avoidance, the First Lunar Lander mission should also perform a characterisation of the landing site with respect to future lander missions and the hazards which exist in the vicinity of the landing site. This is of particular relevance for a landing site in the South Polar region, where boulders, shadows and slopes may be more abundant and where illumination conditions make them more difficult to assess from orbit.

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5 HUMAN HEALTH Ensuring the long term health of human explorers on the surface of the Moon, or any other deep space environment, during and following long duration missions is a major challenge. The primary health risk is posed by radiation of both solar and galactic origins. In addition the properties of lunar dust may pose a significant health risk to humans. A sustainable human exploration programme requires that the effects of these threats to survival are understood and accounted for in mission design and planning. This section describes the radiation and dust environments of the moon as relevant to human health and their effects. A First Lunar Lander mission can be applied to improve the understanding of risks to human health and generate means to mitigate these risks. Potential objectives in line with this goal are presented along with their implications in terms of requirements for the mission.

5.1 Radiation Risks to Human Health

5.1.1 Lunar radiation environment The surface of the Moon is subject to various types of ionising radiation, which constitute a very significant hazard for human operations. Radiation is dominated by four distinct populations: low energy Solar Wind Particles (SWPs), high energy Galactic Cosmic Rays (GCRs), sporadic high energy particles released during Solar Energetic Proton (SEP) events and secondary radiation generated by the interactions of these primary sources with the lunar surface and subsurface to depths of approximately a meter. Secondary radiation will also be generated by particle interactions with materials in spacecraft and lunar surface infrastructure. In addition ionisation of the surface, to depths of several microns, results from solar UV and X-ray photons. Understanding and then mitigating this environment is essential for the future human exploration of the Moon.

5.1.1.1 Solar radiation In addition to the continuous flow of the solar wind the Sun is also the source of sporadic high fluxes of radiation associated with solar flares. Of primary concern for human exploration are SEP events in which ionised particles ejected from the Sun during Coronal Mass Ejections (CMEs). The SEPs are generated when plasma ejected during these vents carries with it the frozen in solar magnetic field. As the plasma propagates a transition region occurs between the between the frozen in magnetic fields and the interplanetary magnetic field. A shock is formed in this transition region and the interplanetary plasma is accelerated, generating the SEPs. The energies of the SEPs after acceleration are related to

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the plasma density and velocity of propagation of the original CME [RD 5]. The accelerated plasma moves outwards from the Sun at velocities, which can be relativistic, and which can be highly directional such that their arrival at 1 AU is anisotropic and the radial dependence of flux is poorly defined.

Particles associated with SEP events are predominantly protons and He2+ nuclei. The energies of these particles are typically between 20 and 80 MeV, although particle energies of GeV can be observed in very large events. Electrons of energies between ~ 0.5 and 1 MeV usually arrive at 1 AU along magnetic field lines with tens of minutes to hours of an event. These electrons precede the arrival of the protons and alpha particles, which usually arrive within several hours to tens of hours. Travel times to 1 AU can be as little as 20 minutes for flares in the Sun’s western hemisphere. During an SEP event proton flux can increase by several orders of magnitude over very short time scales, as illustrated in Figure 5.1. The distribution of flux between the various energy bands shown in Figure 5.1 is also typical, with the majority of particles having energies of < 30 MeV and the flux falling rapidly as a function of energy. The precise function describing the flux as a function of energy can be highly variable between events.

After the initial peak in particle flux, which can last for a period of several hours, flux tends to decrease gradually over a period of several days to weeks. Fluxes of the highest energy particles fall off rapidly while fluxes for lower energy particles fall off more gradually.

Figure 5.1. Proton Flux in four energy bands at 1AU measured during a typical SEP event by the proton monitor on the NOAA GOES-11 geostationary spacecraft in the period between 00:00 on 19 November 2005 to 23:00 on 23 November 2005. Data shown are hourly averages.

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The penetration of depth of SEPs is typically of the order of cm (0.3 cm CSDA range for 100 MeV protons in Al increasing to 6 cm for 500 MeV protons) and so the immediate risk from particles to human activities is low when Al shielding is sufficiently thick. Effects due to secondary radiation are considered in Section 5.1.1.3. Risks from SEPs are high however for EVA activities, where little shielding is available. The effects of space radiation exposure on human physiology are discussed in Section 5.1.2.

The frequency and magnitude of SEP events varies with the solar cycle, with the greatest number of large events occurring around solar maximum. The average integrated yearly flux of SEP particles at 1 AU is given in Table 5.1. The presented values of Table 5.1, while representative of long term integrated exposure do not allow for evaluation of the potential radiation exposure due to single large SEP events which may be encountered during short duration EVA activities. Table 5.2 shows the NOAA scale for solar radiation storms (SEP events) including an estimate of the frequency that might be expected for the occurrence such events.

Particle energy Integrated yearly flux at 1AU (protons cm-2) > 30 MeV ~ 8 × 109 (near solar maximum) ~ 5 × 105 (near solar minimum) > 100 MeV ~ 6 × 108 (near solar maximum) ~ 5 × 104 (near solar minimum)

Table 5.1. Yearly integrated flux of solar energetic particles from RD 6.

Scale Descriptor Flux of > MeV particles (Wm-2 s-1 sr-1) Events per cycle S5 Extreme 105 < 1 S4 Severe 104 3 S3 Strong 103 10 S2 Moderate 102 25 S1 Minor 10 50 Table 5.2. The NOAA space weather scale for solar radiation storms [RD 6]. A single event may have a duration of more than one day. The flux values given are 5 minute averages.

In addition to SEPs solar flares and CMEs are associated with increased fluxes of solar X- rays. During solar flares X-ray intensities can increase by several orders of magnitude and can be highly variable on time scales of minutes. Solar flare states are defined according to the total energy output of the sun measured in the wavelength range 1-8Å, as measured by the NOAA’s GOES spacecraft, in orbit around the Earth. Flare state is designated as solar quiet (A1 flare), B, C or M on a scale where an X1 flare is 10 times an M1 flare is 10 times a

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C1 flare etc. The classification scale for these events is shown in Table 5.3. The largest solar flare event measured to date was in November 2003 and is believed to have peaked at around X40. Figure 5.2 shows solar X-ray flux as a function of energy for various solar flare states measured at 1AU by the X-ray Solar Monitor (XSM) on SMART 1, along with polynomial approximations to flare states predicted by various models [RD 7]. The plot shows that for increasing flare state the total intensity and spectral hardness both increase. The frequency and mean magnitude of X-ray solar flares varies with the solar cycle, with a maximum for both occurring at solar maximum.

Class Peak flux in 1 – 8 Å band (W m-2) B < 10-6 C 10-6 – 10-5 M 10-5-10-4 X >10-4 Table 5.3. The ranking of solar flares based on their peak X-ray output in the band 1 - 8Å [RD 6].

Figure 5.2. Polynomial approximations to the solar X-ray spectrum in M1, C1and B1 flare states together with measured solar X-ray spectra from the X-ray Solar Monitor (XSM) instrument on SMART 1. Also shown is the predicted magnitude of the diffuse X-ray back ground (DXB) measured by XSM between 3 and 7keV (from RD 7).

5.1.1.2 Galactic cosmic rays Galactic Cosmic Rays (GCRs) are particles which originate outside of the solar system, but within our galaxy, and are incident in the inner solar system with an isotropic distribution. Their energies can be as high as 1020 eV [RD 8] but are typically in the range 109 – 1013 eV [RD 6]. The precise sources for these particles and the reasons for their high energies are

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not well understood. The GCR population is composed of 85% protons, 11.8% alpha particles, 1% atomic nuclei of Z>2, and 2% electrons and positrons. Of the high Z particles a significant proportion are found to be rare elements Li, Be, and B, or other minor elements with Z < Fe. This enhancement is a result of spallation reactions which occur during collisions with interstellar matter particles during the 107 year typical journey time from source to solar system [RD 8].

The entry of GCRs into the Solar System is moderated by the interplanetary magnetic field, which is carried by the solar wind. The inward diffusion of GCRs is balanced by the outward convection of the solar wind. The relationship between the density of GCR particles inside the solar system and outside has been modelled by several authors [e.g. RD 9, RD 10] and the results demonstrate a strong dependence on the properties of the solar wind, magnetic field and radius of the heliosphere and thus the level of solar activity is of prime importance. Indeed GCR flux is found to be inversely correlated with the solar cycle, which can be represented by sunspot number. The fluxes of GCR particles expected at solar maximum and solar minimum are given in Table 5.4 and are shown as a function of energy in Figure 5.3.

Property Value Energy range (MeV) 40 – 1013 (normally 103 -107) Sunspot Minimum Sunspot Maximum Flux (protons cm-2 s-1) 4 2 Integrated yearly rate (cm-2) 1.3 × 108 7 × 107

Table 5.4. Typical values for the flux and energy range of GCRs at solar minimum and solar maximum as inferred from sunspot number. Values taken from [RD 6].

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Figure 5.3. Galactic cosmic ray proton fluxes at 1 AU during solar minimum and solar maximum, modelled using the FLUX subroutine implemented in the CREME96 model [RD 11].

5.1.1.3 Secondary radiation SEP and GCR particles impacting on the lunar surface will interact with nuclei in the regolith and surface materials and secondary radiation can be produced via processes including neutron capture, elastic scattering and high energy spallation. The products of these reactions can include neutrons, gamma rays and various nuclear fragments. The precise composition and spectra of secondary emission is a function of the energy of the incident particles and the properties of the local regolith but the dominant products are neutrons.

Observations and of the secondary neutron environment made from orbit around the Moon by Lunar Prospector [RD 12] have been used to inform models of neutron production and the resultant doses received on the surface [RD 13]. These models indicate that secondary neutron fluxes contribute approximately 18 % to the total received doses received behind 1 g cm-2 received during periods of solar maximum and approximately 16 % during solar minimum. This is comparable to the uncertainties in predictions of GCR fluxes. During a single SEP event in October 1989 the secondary neutron dose was calculated to contribute approximately 2.4 % of the total dose associated with the event. Thus secondary neutron emission may make only a small contribution to the radiation hazard on the surface of the Moon.

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5.1.2 Effects on human physiology Lunar astronauts will be exposed to these various sources of radiation, described in the previous section. The protons and high-atomic-number energetic particles (HZE) may have significant biological effects, even at low fluences, and considerable uncertainties exist about the effects of secondary particles [RD 14]. The effective dose rates for the 1977 solar minimum and the 1970 solar maximum GCR environments in deep space [RD 15] are reported in Table 5.5 and compared with the estimated effective dose from albedo neutrons [RD 16], generated by interaction of GCR and SEP radiation with the lunar crust. In Table 1 we also report the effective dose from the October 1989 Solar particle event on the Moon behind a shield of 1 g cm-2 Al.

GCR SEP 1970 solar max 1977 solar min October 1989 (mSv/year) (mSv/year) (mSv) Charged particle dose 89 244 964 Albedo neutrons dose 26 28 14 Total 116 282 978

Table 5.5. Comparison of the effective dose rates from GCR and albedo neutrons calculated during the 1970 solar max and the 1977 solar min. Also shown is a comparison of the effective doses from the SEP in the October 1989 event and the albedo neutrons generated by the SEP during this event. The GCR and SEP effective doses were calculated behind 1 g/cm2 of aluminium shielding. Adapted from RD 15 and RD 16.

The risks to human physiology due to radiation exposure may be categorised as either acute risks, associated with solar particle events, or late stochastic risks, associated with chronic exposure to GCR, which may be 100 times greater on the Moon than on the Earth during solar minimum. Acute effects include radiation sickness, which can affect crew health and performance and thus represents the main operational concern related to radiation exposure in a moon mission scenario [RD 17]. In addition radiation damage to cells and the subsequent loss of cells may affect the functional integrity of the central nervous system; again a potentially mission compromising event [RD 18]. Of the chronic stochastic effects the primary concern is the induction of late-occurring cancers [RD 19, RD 20] and this is the primary parameter used to set the maximum allowable doses to astronauts in LEO. Other potential chronic radiation induced physiological problems include cataracts, which appears to progress linearly with exposure time to GCR. Studies have also indicated previously unknown mechanisms of radiation-induced cellular pathologies which follow communication between damaged and undamaged cells and the induction of unstable states leading to the late expression of genetic damage [RD 21].

Uncertainties about the effects of space radiation on human physiology arise primarily because of an inability to create analogous radiation environments on Earth in which to

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perform appropriate testing. Instead the approach to testing is to use experimental models to estimate the relative effectiveness of the radiation in question and γ-rays. The relative factor used most often is the Relative Biological Effectiveness (RBE). This is defined as the ratio of the dose of a reference radiation to the radiation under study that will produce an equal level of effect for a given experimental observation [RD 22]. Observations show however that RBE is a complex value that can vary by up to two orders of magnitude and is a function of the biological endpoint, cell or animal models, dose, dose rate and type of radiation [RD 23]. Additional multiple stressors in the unique environment of the moon (e.g. reduced gravity) can lead to synergistic or antagonistic effects which can only be investigated in the lunar environment.

Practical limitations on the determination of RBEs mean that values do not exist for many radiation types and environments. In addition for radiation with very high Linear Energy Transfer (LET) values it may be that effects are different from those observed from photons. As a result serious limitations exist in present methodologies for quantifying space radiation effects on biological systems.

The standard approach when using RBE values in the assessment of radiation risks to humans is to is to apply an LET dependent radiation quality factor, Q(L), also called a radiation weighting factor, wr,. This value is the factor by which an absorbed dose (measured in rad or gray) must be multiplied to obtain a quantity that expresses, on a common scale for all ionizing radiation, the biological damage (measured in rem or sievert) to the exposed tissue1.

RBE values are recommended by the International Commission on Radiological Protection. In proton therapy an RBE of 1.1 is assumed, based primarily on animal data but the RBE values associated with protons and heavier ions in the GCR and SEPs are poorly constrained, and may be modified at low dose rates.

5.1.3 Health effects of radiation - potential objectives Future human explorers will be exposed to the lunar radiation environment for long durations. To this end it is vital to improve our understanding of the radiation environment and its effects on human physiology. Investigations on the Moon by ESA’s First Lunar Lander can contribute significantly to this by achieving the following objectives.

• Improve current space weather forecast from the Moon to improve early warning systems for crews • Quantify the radiation risks to human lunar exploration due to GCRs

1 Definition provided by the Health Physics Society http://hps.org/publicinformation/radterms/radfact116.html

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• Improve current understanding of the response of biological systems to radiation damage in the integrated lunar environment such that risks assessment for humans can be improved • Determine the radiation shielding properties of lunar regolith

5.1.3.1 Improve current space weather forecast from the Moon to improve early warning systems for crews For acute radiation effects due to SEPs the primary emphasis for investigations should be to allow advance warning of the arrival of SEPs, thus allowing time for astronauts to move to an area of safety and reducing the risk of exposure to large solar particle events. Current capabilities for predicting SEP fluxes with reasonable accuracy are very limited [RD 24]. However, it has been shown that detection of relativistic solar electrons may enable up to one hour’s notice of impending proton events and allow prediction of the integral number of protons [RD 25]. These findings not only provide evidence of up to a one hour early detection capability, but may also allow prediction of the significance of an event. Based on these observations, it could be possible to eventually build a solar particle alert station on the Moon, with electron current detectors used to predict the arrival and intensity of SEP in about one hour and support human operations in real time. Observations of relativistic electrons and the subsequent SEP fluxes from the surface of the Moon can provide valuable insight into the underlying processes and prepare the way for future lunar space weather stations.

In order to achieve this measurements of solar protons (ideally with energies ideally in the range 1 – 500 MeV) are needed continuously during illumination including Linear Energy Transfer (LET) spectra . Measurements should accommodate the possible range of solar fluxes.

The fluxes of relativistic solar electrons are also required during illumination (ideally in the energy range 0.3 – 1.2 MeV)). Fluxes can vary in the range 1-10000 MeV cm-2 s-1 sr-1. It may also be beneficial to measure solar X-rays in the energy rage 0.5 – 7.7 keV. Solar X-ray fluxes can vary in the in the range 104 – 107 photons cm-2 s-1 keV-1 (at 2 keV).

The development of space weather forecasting capabilities for future deployment on the Moon may not require investigation on the Moon’s surface and may be achieved from orbits, outside of the magnetosphere. However the nature of weather forecasting is to build a model to accurately predict the weather at a specific location and at a specific time. Using a ground station to ground truth these models is important because, when used for real, this is what must be done. Space weather forecasting could also become a European contribution to a lunar infrastructure if the reliability of the technique can be demonstrated. For this reason this should be a medium priority objective, which can

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probably be achieved through augmentation of a radiation monitor already planned for other applications.

5.1.3.2 Quantify the radiation risks to human lunar exploration due to GCRs During precursor lunar missions extensive measurements of the lunar radiation environment may be performed. This is the first goal in radiation research that can be accomplished in non-manned missions, and arguably the simplest. Radiation monitoring [RD 26] was carried out by the Indian Chandrayaan-1 lunar orbiter, and will be one of the main tasks of the NASA Lunar Reconnaissance Orbiter mission. Surface dosimetry is an important addition to orbital measurements and can be addressed by ESA's First Lunar Lander.

In order to achieve this objective the flux of galactic cosmic rays must be monitored continuously throughout the mission and LET spectra of GCR particles are needed. The species of GCRs should also be determined. These data may be available from other missions at the time and are not necessarily required from the lunar surface. The contribution from secondary neutrons must however be accomplished at the surface of the Moon and in order to properly relate secondary neutron fluxes with incident radiation from other sources primary radiation from GCRs and other sources shod be measured in parallel at the lunar surface. Secondary neutron energies can vary in the range 0.01 - 1000 MeV.

Given the importance of the radiation environment and its effects for human exploration this is considered to be a high priority objective.

5.1.3.3 Improve current understanding of the response of biological systems to radiation damage in the integrated lunar environment such that risks assessment for humans can be improved Providing a meaningful contribution to improving estimates of the long term effects of the integrated lunar radiation environment is of high priority given the major uncertainties associated with current estimates of radiation risk and the potential implications for human explorers. In order to accomplish this experiment to test the effects of mixed radiation fields and the response of biological systems under stress conditions in the lunar environment are needed. Ground-based experiments are irreplaceable for providing accurate measurements of space radiation effects under well defined conditions [RD 27]. However, the lunar radiation environment is characterized by a mixed radiation field, including charged particles from H to Ni at energies from a few MeV/n to TeV/n, neutrons, X-rays, and an unfiltered UV spectrum. Moreover, exposure occurs in severe stress conditions caused by reduced gravity, hypoxia, etc. Only local biological experiments can incorporate all these factors for comparison with the predictions of ground-based experiments and experiments performed in Low Earth Orbit (LEO).

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Given the importance of improving radiation safety advice for future human explorers and the need to measure effects in situ to properly address the related issues this is considered a high priority objective. A discussion on a possible experimental solution is given in Section 13.3.

5.1.3.4 Determine the radiation shielding properties of lunar regolith Dosimetry at various depths in the Moon’s soil will provide information on regolith shielding that will be then used by human crews for in situ shielding construction. These measurements will help to benchmark and improve models of fluence, energy, dose and dose equivalence, which are needed for radiation risk modelling. Measurement of regolith properties are likely to be sufficient to allow effective modelling of regolith shielding properties, although measurements of radiation dose as a function of depth in the regolith would be beneficial for verification of radiation models.

Current understanding of the physical properties of the regolith is probably sufficient to estimate shielding properties. For this reason this objective is considered to be of low priority.

5.2 Health Risks of Lunar Dust During the era of Apollo, in the 1960s and 1970s, the field of dust toxicology was in its infancy and samples of lunar dust were not examined for toxicological effects. The focus was instead on the potential risks due to microbes. In the modern era the toxicity of dust particles has been recognised as an area of high importance for any return to the Moon as lunar explorers will be exposed to lunar dust. Section 6.2 contains a description of Apollo experiences of operating in the presence of lunar dust. Understanding the risks posed by these particles and mitigating exposure to them is of high importance. Understanding these risks requires a proper characterisation of the size, structure and chemistry of grains that pose a potential risk.

Lunar dust originates from the lunar regolith, a layer of rocks and fine grained particles at the lunar surface, whose thickness can vary between approximately 3 m and 20 m. The particles that make up the regolith have been generated by billions of years of meteoroid impacts, with subsequent space weathering by thermal cycling, solar wind erosion and impacts leading comminution and agglutination of original particles. Lunar soils can generally be described by log-normal size distributions with mean diameters typically between 45 µm and 100 µm; although particles can be at least as small as 10 nm [RD 28, RD 29]. Grain morphologies can vary from highly irregular and angular vesicular agglutinates to spherical glass beads, generated during impacts [RD 30, RD 31].

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Dust in the lunar regolith contains a number of minerals including plagioclases, olivine and pyroxene, ilmentite, cristobalite, aptite and metals such as Fe and Ni. The abundances and relative abundances of these, and other, minerals are variable depending on location. In general the basaltic terrains of lunar mare tend to be much richer in ilmenite and olivine whilst the more primitive lunar highlands are dominated by anorthite [RD 32]. The actual composition of lunar soils is however observed to be very localised, indicating a limited extent to lateral mixing [RD 31]. Composition can also vary as a function of grain size; with minerals which favour comminution (e.g. anorthites in feldspars) tending to parent smaller particle sizes than those from olivines and pyroxenes, whose properties are less favourable to comminution. The very smallest particles tend to accumulate into larger agglutinate particles.

Major Compositional Maria (% wt) Highlands (% wt) Elements

SiO2 40.09 44.77

TiO2 9.32 0.44

Al2O3 10.70 28.48

Cr2O3 0.49 - FeO 17.85 4.17 MnO 0.24 0.06 MgO 9.92 4.92 CaO 10.59 16.87

Na2O 0.36 0.52

K2O 0.08 0.07

Figure 5.4. Composition of typical lunar soils in lunar Maria (Apollo 17 soil 71060) and lunar highlands (Apollo 16 soils 67700). Data taken from RD 33.

It has been identified that lunar dust contains several types of reactive dust. Of these many are in the respirable range, defined previously as those particles with diameters <3.5 μm [RD 29] although < 10µm is considered by other authors. Particles < 10 µm make up approximately 10% of dust. In addition the surface areas available for chemical reaction are about 8 times that of a sphere of equivalent external size.

Small dust particles may be hazardous to human health if they were to enter the lungs, particularly if exposure were for a prolonged period of time, as might be the case for future lunar missions. Of these particles >80 wt% is composed of glass with high abundances of

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nanophase metallic iron particles, whose sizes can vary between ~3 nm and 30 nm. This impact glass may be easily dissolved in bodily fluids, releasing the np-Fe0 grains, which are very reactive, owing to their redox potential and relatively large surface area per unit mass. In addition the surfaces of these particles are unlike any terrestrial analogue and are likely to be highly reactive on account of radicals generated in the highly reducing lunar environment, in which there is no mode for passivation. The extent of this reactivity is key to the toxicity but is not known. Various attempts to reactivate lunar dust and analogues by fracturing and radiation exposure have been attempted but there is no means of verifying the results in the absence of in situ measurements or access to pristine, unpassivated lunar dust. The rate of passivation for particles upon contact with a humid atmosphere like that of a human habitat is not known but may be of the order of a day.

Understanding how these reactive components behave prior to inhalation and then upon contact with a moisture rich pulmonary environment is important in determining the toxicity of grains to humans and generating risk criteria for lunar dust exposure and lunar dust standards.

Measurements of the size distribution of lunar dust have shown a depletion of particles in the sub micron – nanometer size regime. This may be due to limitations in measurement techniques or may represent a real depletion in small particles in the samples either endemic in lunar soil or as an artefact of the sampling process (perhaps as a result of charging, levitation and transport of lunar dust as described in Section 6.2.1). Measurement of the size distribution in situ would provide important information on the prevalence of sub micron particles in the lunar environment.

Some work has been carried out to investigate the toxic effects of lunar dust. For example in RD 34, macrophages (a type of white blood cell that clears the lung alveoli from foreign material) were exposed to terrestrial volcanic ash. Volcanic ash was used as an analogue of lunar dust in respect to its particle size distribution and chemical composition. Aspects of lunar dust particles such as electrical charge and physical structure, which may affect the manner of adhesion to lung tissues, have not been considered. In other studies [e.g. RD 35] emulsions of dust have instilled in small rodents, however to date the inhalation of aerosols has not been considered.

RD 36 describes studies into the penetration of particles of relevant sizes into the human lung. It has been shown that in lunar gravity, particles are able to penetrate more deeply into the lungs than under terrestrial gravity. It has also been shown that reduced gas density also leads to a deeper penetration of particles, with implications for the conditions generated in a future lunar habitat.

5.2.1 Health effects of dust - potential objectives

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Astronauts working in the lunar environment are likely to be in an environment in which lunar dust is prevalent. Given the size distribution and likely chemical states of this dust it must be assumed that it poses a potential risk to human health. As a result the characteristics of lunar dust must be better understood in order that the potential effects can be studied. Existing samples of lunar dust from Apollo, have become passivated over time and no longer present the surface chemistry that would be experienced in situ. Analogues of lunar dust, derived from Apollo samples, may not representative of the chemistry or size distribution of lunar dust experienced in situ. It is important that in situ measurements of lunar dust are made to inform investigations into the health effects of exposure to lunar dust. For this reason the following is proposed as an objective for ESA’s First Lunar Lander mission.

• Quantify the health risks to human exploration posed by lunar dust unrepresented in sample collections

5.2.1.1 Quantify the health risks to human exploration posed by lunar dust unrepresented in sample collections In order to better understand the implications for humans of working in an environment in which lunar dust is prevalent, it is essential to allow the generation of improved analogues for lunar dust, which can be applied in animal models. These analogues should have properties which are better aligned to those aspects of dust that are important for its interaction with human lungs and physiology more generally. At present the best possible samples for use are regolith samples, which have been stored in a nitrogen atmosphere for up to 40 years. Activation of samples has been achieved buy crushing or exposure to protons. However there is no way of validating whether these materials, once activated, have the same surface properties as fresh lunar samples and there has been no recreation of the burnt gunpowder smell reported by Apollo astronauts, which indicates that properties are not the case. Under such circumstances the reliability of investigations into toxicology of lunar dust are uncertain. In addition it is important to establish the rate of passivation of particles once in a humid atmosphere, analogous to a habitat.

Important investigations then are the following, which can be ordered in terms their relative importance into High and Medium priority.

High priority: • Investigate the size distribution of dust particles of the order for 10 nm and larger. • Detect and quantify the extent of nanophase Fe • Determine themineralogical composition of dust grains • Determine the surface chemical reactivity of lunar dust grains. This could potentially be performed through observations of water uptake, oxygen

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uptake, free radical yield, charge or metallic ion release when in contact with chelators/simulated body fluids. • Determine the rate of passivation of particles after coming into contact with a humid atmosphere.

Medium Priority • Quantify the stickiness of Lunar dust grains • Determine the structures of Lunar dust grains < 10µm with a goal of extending this to grains > 10nm • Determine the elemental composition of dust grains

Health effects of lunar dust are critical to the health and survival of future lunar astronauts. For this reason this objective is considered to be of high priority.

In addition parallel in situ measurements of the effects of lunar dust on biological/microbial systems may provide a mechanism for evaluating the potential health effects of pristine dust.

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6 HABITATION Habitation as a capability encompasses the systems and technologies employed to guarantee the required living and working conditions for human explorers, in this case on the lunar surface. In many cases these systems are designed to mitigate risks to human health already described in Section 5 such as dust and radiation; however they must also ensure adequate air and water supplies, power, waste management, sustainability of a suitable atmospheric pressure, and interfaces between habitable volumes, and with the outside world, in this case the lunar surface. The systems and technologies which make up a habitat must also fulfil their functions while themselves being robust to the properties of the environment.

A number of scenarios can be considered in which different types of habitats, or more specifically systems and technologies, might be applied: from short-medium term ‘temporary’ habitats akin to those employed during the Apollo era, through habitats intended to form part of a mobile system such as a pressurised rover or on a smaller scale a surface EVA suit, to longer term sustainable habitats which may be required for long durations and to serve multiple missions. This section describes some of the factors and effects which are important for habitation, with respect to the lunar environment, and introduces some already identified objectives which can be addressed by a First European Lunar Lander to inform future technology, development and planning activities on habitation. It is important to note that habitation can encompass a range of technologies and concepts which might be applied at various stages of exploration and those objectives described here focus on what a first lander can usefully contribute as opposed to the investigations and experiments on habitation which may be performed by later missions.

6.1 The Suitability of a Potential Future Landing Site for Human Exploration Future exploration activities may take human explorers away from the well characterised and fairly benign landscapes of the Apollo missions. Landing sites at locations such as the lunar South Pole and Aitken basin or the lunar highlands are of the greatest interest scientifically but present very significant challenges for landing and for human surface operation. Characterisation of the topography, rock and crater distributions and other characteristics of these landing sites, beyond what can be accomplished from orbit are of great importance for the design and planning of future missions and the associated infrastructure. To this end a potential objective for the mission is:

• Characterise the suitability of a potential future landing site for future exploration.

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6.1.1.1 Characterise the suitability of a potential future landing site for future exploration

Characterisation of a landing site from the surface will require measurement of several important parameters, as well as returning data to allow the revision and validation of models of key surface characteristics. Such parameters and characteristics which should be measured or addressed include:

• Illumination environment at the surface (duration/pattern) • Thermal environment at the surface (effects of shadowing, influence of the regolith and surrounding terrain) • Local surface features such as boulder/rock distribution, crater distribution, slopes etc. • Mechanical properties of the surface w.r.t load bearing/vehicle carrying capacity

Given that the First Lunar Lander may be the first surface mission to the South Pole region, and taking into account the attractiveness of this location for future human missions, this objective is regarded as being of a high priority.

6.2 Lunar Dust and Effects on Habitation During the brief periods of time spent on the Moon during Apollo it became apparent that lunar dust could pose significant problems for the operations of both people and equipment. Dust was found to adhere to clothing and equipment, it reduced visibility during landings, mechanical devices were severely compromised by lunar dust contamination, optical components were covered with visible dust layers and Apollo astronaut spacesuits became coated with fine-grained dust. Once inside the spacecraft dust caused breathing difficulties and inhibited vision [RD 37]. In addition dust was also found to prevent effective sealing of pressurised and depressurised containers. None of the containers containing rock samples from any of the Apollo missions was found to be able to hold vacuum after return to Earth due to dust grains inhibiting the knife edge indium seals. Pressurisation of lunar modules after the initial opening required more oxygen in order to counter the effects of dust on the seals.

The adhesion of dust to both spacesuits and machinery during operations was found to occur by both mechanical and electrostatic means. Mechanical adhesion occurred as a result of the irregular and angular structures of much of the lunar dust and electrostatic adhesion occurred as a result of electrostatic charging. Although adhesion forces between

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dust particles are primarily the result of van der Waals forces [RD 38], the charging of lunar dust drives the transport and mobility of dust particles and is important for adhesion. Lunar dust was observed to adhere to painted surfaces with a strength of ~ 104 dynes / cm2 and to metallic surfaces with a strength of ~ 2x103 – 3x103 dynes / cm2 [RD 30].

These dust particles were found to have an abrasive effect on materials of both spacesuits and mechanical surfaces found in equipment such as rovers. Abrasive effects were also observed on both aluminium and painted surfaces retrieved from the Surveyor 3 lander during the Apollo 12 mission. These abrasion and dust adhesion were related, for the most part, to particles propelled during the landing of the lunar module 183m away [RD 39].

The processes by which lunar dust is charged and transported around the lunar surface are complex and require an understanding of the properties of dust particles and how they interact with ionising radiation and the plasma and electric fields on the Moon.

Dust on the day side of the Moon is exposed to solar Ultra-Violet and X-ray photons and solar wind plasma. Ionisation occurs, dominated by photoionisation. The electrical conductivity of the regolith is typically 10-12 – 10-13 Ω-1m-1 [RD 30], sufficient that dust particle can retain charge following ionisation. During photoionisation the electrical conductivity of particles is observed to vary by up to 6 orders of magnitude but tends to return to its original value once the ionisation source s removed [RD 40]. The magnitude of this conductivity change is observed to be highly dependent on the temperature at which photoionisation occurs and the energy of the incident ionising photons. The net charge of lunar dust on the day side as a result of photoionisation is therefore positive and the day side surface is likely to achieve a potential of a few V [RD 41]. On the night side of the Moon charging of lunar dust particles occurs as a result of thermal currents of subsonic electrons and supersonic flows of ions. The balancing potential for the surface dust in this case may be ~ 1 kV [RD 42, RD 43,]. Local differences in topography and composition may have a significant effect on the actual charging and potential of dust.

A global scale potential difference may therefore exist between the day and night sides of the Moon across the, terminator [RD 44]. Electric fields across the terminator become very large when solar wind fluxes are high and a plasma wake is formed at the night side [RD 37]. While traversing through the Earth’s magnetosphere the Moon’s surface is subject to a plasma environment which is significantly different from that of the solar wind, being much more tenuous but of much higher energy. Under these circumstances the conditions for surface charging will be changed considerably from those under standard conditions.

The electric fields generated at the surface may be sufficient to result in the levitation of small dust particles, a possibility supported by a number of observations from spacecraft, surface observers and experiments. The Surveyor 5, 6 and 7 spacecraft observed a “horizon glow” along the western horizon of the moon following sunset. This glow was attributed to the forward scattering of sunlight by electrostatically levitated dust grains with diameters

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of <10 µm, at altitudes of 10 – 30 cm. Apollo 17 astronauts reported observing seeing bright “streamers”, whose brightness changed on timescales of the order of seconds to minutes, and which extended to altitudes in excess of 100 km. These streamers have been attributed to the sporadic elevation of 100 nm scale particles by an effect referred to as the “dynamic dust fountain” [RD 45].

The only direct measurement of dust levitation was performed by the Lunar Ejecta And Meteorites (LEAM) experiment deployed during the Apollo 17 mission [RD 46]. This experiment was intended to investigate hypervelocity impacts by meteoroids but serendipitously detected impacts by slower (< 1km / s) charged dust particles. The experiment included three sensor systems, facing east, west, and vertical. Data showed an increase by a factor of 100 in the impact rate for these slow particles on the east and vertical pointing sensors at dawn. The increase began between 3 and 40 hours before the terminator and fell to ~ 0 within 30 hours of the passage of the terminator. The LEAM data is shown in Figure 6.1. The available data suggest a general dust migration from the day side to the night side of the Moon.

Figure 6.1. Number of dust impacts onto the Lunar Ejecta and Meteorite (LEAM) experiment sensors per 3-hr period, integrated over 22 lunar days as function of the local time; from [RD 46].

Additional measurements of the effects of lunar dust have been provided by recent re- analysis of data from the Dust Detector Experiments (DDEs) deployed during the Apollo 11 and 12 missions [RD 47]. These data have shown that the Apollo 11 seismometer failed following contamination by dust during the ascent of the Apollo 11 module. In addition it was shown that the strength of electrostatic adhesive forces, binding dust to both horizontal and vertical and smooth (Si) surfaces, increases as a function of the incident angle of solar radiation. The transition point, at which electrostatic forces are just sufficient to counter the downward force due to lunar gravity occurs when Solar brightness is

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~100mW cm-2. This corresponds to 70% of full solar intensity at an incident angle of 45° at mid Morning or afternoon; twice that on the lunar surface during Apollo. Thus clinging dust experience by Apollo astronauts, at solar elevations much less that 45°, is most likely to have been driven by forces other than electrostatic ones, such as mechanical.

6.2.1 Dust and soil effects on habitation - potential objectives Experience on the surface of the Moon shows that lunar dust can migrate into habitats, with potential issues for human health and operations. In addition the charging , levitation, transport and adhesion of lunar dust may be an important aspect in the design of habitation and other systems for human operations on the lunar surface. Habitats will be constructed on lunar soil and thus the bulk properties of the lunar soil are important for the design of such habitats. For these reasons the following are proposed as objectives for ESA’s First Lunar Lander, which relate to lunar soil and dust:

• Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities. • Determine thermal and heat flow properties of the regolith

6.2.1.1 Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities The charging, levitation and transport of lunar dust are the result of the complex relationship between dust, ionising radiation local electric fields and the plasma environment. Thus a complete understanding of dust properties and behaviour requires parallel investigations of all of the above. Adhesion and abrasion are functions of surface charging, composition and structure. As a result dust investigations require that all these properties of dust be investigated in parallel. As a result the following properties of lunar dust, the surface and local plasma environment should be determined:

• Charges on levitating dust grains (nominally > 0.1 fC) • Velocities of levitating dust grains (expected in the range 1 - 5000 m/s) • The trajectories of levitating dust particles (nominally within 1°) • Surface potentials during illumination and darkness (nominally in the range 10 V and -10 kV). • The density and temperature of the local plasma. • Mineralogical and elemental composition of dust grains. • The size distribution of dust grains, particularly in the nm size regime. • The adhesion of dust grains as a function of solar incidence angle.

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Due to the highlighted criticality of dust effects for the design and operation of habitats, and particularly taking into account the need to inject lessons learned on the properties and behaviour of lunar dust early into the technology development and system design process, this objective is regarded considered a high priority.

6.2.1.2 Determine thermal and heat flow properties of the regolith Future habitats are going to be constructed upon a bed of lunar regolith and lunar dust. Lunar regolith may also eventually provide the raw materials for construction. For this reason it will be important that the physical properties of the regolith are known, including thermal properties and heat flow. However while these effects are understood to have an impact on habitat design etc. the dependence is not considered strong enough to rank this objective higher than low priority.

6.3 Impact Risks for Habitation The surface of the moon is continually subject to bombardment by meteoroids from interplanetary space. These objects have a variety of origins but are predominantly of asteroidal and cometary descent. The masses of particles can vary over many orders of magnitude from < 10-18g for the smallest nanometer scale dust particles to objects with masses of several kg and more. These particle impact at hypervelocity, such that the strength of the material is small compared with the inertial stresses during the impact. Velocities for meteoroids at the Moon are calculated to range from 13 – 18 km s-1 [RD 48], although some populations can have much higher velocities. Impacts at these velocities generate craters and can completely penetrate surfaces several times thicker than the diameter of the impactor. The precise extent of damage is a complex function of the mass, velocity, incident angle and the material properties of both impactor and target. Equations describing the extent of damage resulting from impacts are generated by fitting to empirical data generated in laboratory experiments. A comprehensive list of such equations, generated by multiple authors, is presented in RD 49. In general these equations describe damage in ductile materials such as Al. In brittle materials such as ceramics and glasses cracking which follows the cratering process can lead to the physical extent of damage being significantly larger than that predicted.

The natural, sporadic, flux of meteoroids at 1 AU has been derived by Grün et al. (1985) [RD 50], accounting for in situ measurements made by space instruments and measurements of microparticle impacts on retrieved lunar samples. More recent models exist but do not differ significantly from the Grün model (see [RD 51] for a summary). The resultant curve describing the cumulative mean flux, at 1AU, on a randomly spinning plate and outside of the gravitational influence of either the Earth or the Moon is shown in Figure 6.2. In low Earth orbit there is a general enhancement in the flux of impactors resulting from gravitational focussing of the dust population by a factor of 1.99 [RD 49].

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Observations of impact fluxes at the Moon are very limited and so no reliable models of impact flux currently exist. The limited observations that have been made from orbit around the Moon indicate a factor of two reduction in flux compared with measurements made in LEO [RD 52]. This is probably a combination of a reduced gravitational enhancement of both flux and impact velocity, leading to a reduced detection threshold for the particles. While the fluxes of micrometeoroids are likely to be less than that experienced in Low Earth Orbit the actual flux of impacts at the lunar surface may be much greater as a result of impacts by secondary ejecta following primary meteoroid impacts. The impact risks and long term effects of impacts by these secondary particles is not currently constrained.

Figure 6.2. The cumulative flux of meteoroids onto to a randomly spinning plate outside of the gravitational influence of the Earth and Moon at 1 AU as derived by RD 50.

The relationship between meteoroid size and flux at the Moon and the resultant risks to a future habitat on the Moon are not known precisely. Figure 6.3 shows estimates for impacts as a function of mass at 1 AU for various models. Impacts of 10 mg are expected to occur with a flux of 10 to 300 impacts in 1 year per km2. At a typical meteoroid velocity of 20 km/s a 10 mg particle deposits equivalent energy to a 5.56mm bullet at 1 km/s. Other comparative studies of meteoroid fluxes predicted at 1AU by various models demonstrate differences on similar scales in this size regime [RD 53]

Very large uncertainties remain therefore in the estimation and quantification of impact hazards. This occurs primarily because most small impacts are not observed on the Earth, due the shielding by the atmosphere and the resultant lack of observable events. Fluxes can only therefore be derived by extrapolation from other size regimes, either from the

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observation of larger impacts, by the US DSP satellites [RD 54], recording of luminous flashes [RD 55] on the Moon or from observations of the small impacts in space exposure experiments [RD 56]. Direct measurement of the real flux of impactors in the range of g to milligrams, which are expected to generate most of the hazards of the future Lunar Installation, is therefore mandatory to fully quantify this hazard.

In addition to the primary flux any habitation element or infrastructure will encounter a flux of secondary ejecta particles, which follow the primary impacts. The flux, velocity and size distributions of these secondary particles in unknown at present but this population is likely to provide a significant contribution to the degradation of surfaces and the overall impact risk.

Figure 6.3. Frequency of the micro-impacts. Note the very large dispersion between the proposed models, depending on the technique used for monitoring these impacts. Actually, the direct observations of the meteoroids with mass ranging from 1 mg to 1 g has not been done and only extrapolations can be proposed.

6.3.1 Impact risk for habitation - potential objectives Impacts pose a risk to future lunar exploration, both through continuous degradation of materials by small impacts and by single, potentially catastrophic, impacts by larger impactors. In both cases serious uncertainties exist in the understanding of impactors, their effects and their fluxes. Investigations on the Moon can contribute significantly to our ability to predict and mitigate the associated risks for lunar exploration. A lunar lander offers an opportunity to quantify the risk posed by impacts to human exploration, through investigations which are uniquely enabled by location on the lunar surface. To this end the following is proposed as an objective for ESA’s First Lunar Lander.

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• Quantify the risk to human exploration posed by impacts

6.3.1.1 Quantify the risk to human exploration posed by impacts In order to quantify the impact risks due to single impact events the flux of impactors in the size regime 1 mg – 1 g must be determined. In order to gather meaningful statistics on impact numbers any monitoring of impacts in this size regime requires a minimum detection time area product of approximately 1 km year and sensitivity to impacts > 1 mg.

In addition the risks and cumulative degradation due to impacts by primary micrometeoroids and secondary ejecta particles should be established through the monitoring of the number of impacts in the size regime > 10 µm including where possible the separation of populations.

The design of surface elements for future exploration must consider the effects of impacts and the degradation to surfaces will drive the expected lifetime of system elements. For this reason the is considered to be a high priority.

6.4 Seismic Risks for Human Habitation The Apollo Passive Seismic Experiment (APSE) operated on the surface of the Moon between April 1972 and September 1977. During this period APSE demonstrated that the Moon’s seismic activity is similar to that of an intraplate terrestrial setting. In total four types of event were observed: thermal moonquakes, deep moonquakes, meteoroid impacts and shallow moonquakes.

Thermal moonquakes had the smallest magnitude and were attributed to stresses induced by diurnal temperature changes at the lunar surface [RD 57]. Deep moonquakes had a magnitudes of < 2 and were associated with the tidal effects of the Earths gravitational pull. These quakes occurred at depths of between 700 and 1200 km and > 7000 were detected in total [e.g., RD 58, RD 59, RD 60, RD 61, RD 62]. Impacts by meteoroids with masses between 0.1 and 1000 kg represented > 1700 events [RD 63, RD 64, RD 65, RD 66, RD 67, RD 68, RD 3. Shallow moonquakes were the strongest events, with 7 of the 28 recorded events having magnitude > 5, sufficient to damage terrestrial structures [RD 69, RD 70, RD 71, RD 72]. The causes, locations and depths of these events could not be determined.

Future human habitats will have to survive and operate in the Moon’s seismic environment. In addition to the threat posed from impacts directly, shallow moonquakes pose the greatest potential seismic risk. However the extent of ground motion associated with shallow quakes is uncertain. The ground acceleration at the epicenter of a magnitude 5.7 shallow moonquake are estimated to be ~0.75 m s-2 for a focal depth of 25 km and

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~0.22 m s-2 for a focal depth of 100 km but this may be unreliable as the calculations were made using formulations developed for earthquakes and there are distinct differences in seismic wave transmission on the Moon and Earth. For example, the peak intensity of a shallow moonquake can last for approximately 10 minutes before falling off slowly over several hours. It may be concluded then that seismic energy is propagated through the Moon with greater efficiency than on the Earth, particularly at high frequencies, where the energy dissipated by shallow moonquakes is concentrated.

6.4.1 Seismic risks for habitation - potential objectives Moonquakes may be a risk to long term lunar habitats. A First Lunar Lander can contribute to a better understanding of this risk by achieving the following objective:

• Determine the seismic risk to future human exploration activities

6.4.1.1 Determine the seismic risk to future human exploration activities To determine the seismic risk to future human habitats the frequency of seismic events which pose a potential threat to human activities and structures must be determined. In order to do this the mission must determine the frequency of seismic events which pose a risk to human activities and structures, determine the spatial distribution of seismic events which pose a risk to human activities and structures and determine the crustal amplification of seismic waves in a location of a potential human base. These investigations require that all quakes potentially generating ground accelerations larger than 10 cm s-2 at the hypocenter location must be detected. The spatial distribution of these quakes is also important. To determine the spatial distribution of the quakes the epicentre distance of the quakes must be determined. Finally the crustal amplification of seismic waves at a potential location of a future outpost must be determined. To achieve this is a relative vertical layered seismic model of the crust must be generated to a relative accuracy of better than 10 %.

Seismic risks to lunar habitats, while real, are considered low enough given the known frequency of lunar events and the robust design requirements for space hardware, that they are considered a low priority here.

6.5 Enabling Research for Habitation Technologies A large range of different technologies and systems are required to make up a habitat, whether it be an EVA suit, a pressurised rover module, a short-stay static habitat or a longer term base element. Past and ongoing studies and development work are exploring

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the requirements associated with the types of habitat which may be needed in future exploration missions, with a significant body of experience being built in Europe on this topic.

Required technologies include, life support systems, power generation and storage, communications etc. While the development of necessary technologies and their incorporation into a habitation system presents significant challenges which must be overcome, some of the major unknowns come on the effects of the lunar environment on several key technology elements.

6.5.1 Enabling research for habitation technologies – potential objectives Considering the timeframe of the First Lunar Lander mission, and those open issues which may have a key impact on the development of future habitation technologies, the following objectives are defined.

• Understand the effects of reduced gravity on multiphasic properties critical in habitation technologies • Understand the impact of the lunar environment on biological processes important for life support technologies

6.5.1.1 Understand the effects of reduced gravity on multiphasic properties critical in habitation technologies The lunar surface presents a gravity environment which lies between the 1-g found on Earth and the micro-gravity found for example on the ISS in low Earth orbit. This intermediate gravity can have a significant effect on processes in which buoyancy and multi-phasic flows play an important part, such as life-support systems, heat transfer and components of, for example, fuel cell based power storage and in-situ resource utilisation. Understanding these effects early in the design phase of future lunar surface systems, and indeed exploration architectures, is key in ensuring the appropriate selection and development of critical technologies. Given that the specific technologies are currently under assessment and preliminary development, and given that the precise sensitivity of those technologies to the gravity environment is still to be clarified, this objective is currently considered to be of a medium priority.

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6.5.1.2 Understand the impact of the lunar environment on biological processes important for life support technologies The radiation environment found at the lunar surface poses a risk not only to humans living and working there, but also to the materials, components and systems which are employed. This can have a significant effect particularly on life support systems which employ micro-organisms as part of air or water recycling processes. Combined with the effects of the reduced lunar gravity on such biological components, the overall lunar environment can have a significant effect on the way such elements operate as part of an overall life support system. Given that the overall sensitivity of such systems to the performance of micro-organisms still requires further assessment, this objective is currently considered to be of a medium priority.

6.5.1.3 Demonstrate advanced power storage technologies While critical effects of key environmental conditions such as the reduced lunar gravity on particularly sensitive processes (e.g. multiphasic properties of certain processes and technologies) is considered important and is addressed by a separate objective, the system level demonstration of advanced power storage technology, taking regenerative fuel cells as an example, can also have a high importance. This would provide design maturity and confidence at technology level and work towards promoting the use of such technology, where it can provide benefit, in follow-on missions. Both autonomous and human missions can benefit from the use of such technology. While the stand-alone technology demonstration of such a power storage element is not considered in itself to be of sufficient value for an early lunar mission, if it can be coupled with enabling extended/opportunistic operations of certain other payloads e.g. during periods of darkness, then this objective would be considered to be of a high-priority.

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7 RESOURCES

7.1 In Situ Resources and their Utilisation In Situ Resource Utilisation (ISRU) is the term used to refer to the generation of consumables for autonomous or human activities from raw materials found in-situ on the moon. The use of ISRU may provide a means of reducing the ultimate cost and risk of operation on the moon and provide a means for commercial contributions to lunar exploration. Potential products include O2 and H2O for life support or H2 and O2 for fuel and propellant (also potentially by hydrazine production from N2, NH3 and H2O2).

If ISRU is to be applied n the future then it is important that landing sites, operations and ISRU technologies are identified with knowledge of the availability and distribution of potential resources on the Moon and understanding of the workings of the various processes available. In the following sections the potential application of the First Lunar Lander in addressing objectives related to ISRU and the availability of potential resources is discussed.

7.1.1 In situ resources - potential objectives The sustainable future of lunar exploration is likely to depend upon the effective use of in situ resources to generate products such as oxygen, water and other used consumables. The choice of which ISRU processes might be applied in the future is dependent on both technical maturity and the availability and distribution of resources that might be used. At present the status of both of these elements is considered to be insufficient to allow the selection of a single ISRU process for demonstration at the lunar surface.

It is anticipated that the First Lunar Lander can best contribute to future ISRU activities by aiding the determination of availability, distribution and abundance of potential in-situ resources, in order to inform the future development of ISRU capabilities and mission planning.

The following have been identified as potential objectives for the mission with regard to determining the availability, distribution and abundance of potential resources:

• Identify the presence or otherwise of water ice in permanently shadowed craters • Identify the abundance and distribution of ilmenite

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• Improve our understanding of the potential use of highlands regolith as a resource • Improve our understanding of the potential use of mare regolith as a resource • Provide ground truth to support orbital observations, by other missions, of potential in situ resources • Determine the abundance as a function of depth and distribution of H2O and OH in the regolith. • Determine the abundance and distribution of hydrated minerals in the regolith. • Determine the abundance and distribution of solar wind implanted volatiles in a non Apollo locality • Perform "proof of concept" in-situ resource extraction based on SWIP volatiles • Perform "proof of concept" in-situ resource extraction based on water/OH in the regolith • Perform "proof of concept" in-situ resource extraction based on: . ilmenite reduction . carbothermal reduction . molten silicate electrolysis

At most, only one of the three ISRU "proof of concept" studies indicated could be addressed with this mission.

7.1.1.1 Identify the presence or otherwise of water ice in permanently shadowed craters It has long been suggested that water ice might be present in permanently dark and near polar craters on the Moon [RD 73]. The interior of these craters has recently been shown to be as cold as 35 K by the Diviner instrument on Chandrayaan. Increased levels of hydrogen at both the North and South lunar poles were confirmed by Lunar Prospector (up to ~1700 ppm) [RD 74, RD 75]. After much speculation on the nature of observed hydrogen and whether or not it was contained in water [RD 76, RD 77, RD 78, RD 79]. Recent measurements by the L-CROSS mission (announced but not yet published) have seemingly confirmed that the water is indeed present.

The presence of large quantities of water on the surface of the Moon has major implications for ISRU as a potential source of water and oxygen for life support and hydrogen for fuel. In this case the major challenge for ISRU technologies will be the extraction of ice from such cold and dark environments. As a first step however the extent, quantity, distribution and nature of this ice must be identified. It has been speculated that ice in craters will be buried under a layer of dust and the extent and distribution of ice is by no means certain.

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Understanding these aspects is essential to any proposal for extraction and utilisation of this potential resource.

It is recognised that accessing permanently dark craters and identifying the presence or otherwise of in situ ice as a potential resource poses a major technical challenge and is probably beyond the scope of a near term mission of restricted scale, however this should be considered a high priority for future exploration missions. To achieve the objective would require access to and operations in a permanently shadowed area and the ability to access and positively identify water ice. It has already been determined prior to the beginning of this process that such capabilities will not be available on the First Lunar Lander and so this is not considered further here.

7.1.1.2 Identify the abundance and distribution of ilmenite Ti rich lunar regolith has been found to contain relatively high abundances of ilmenite, a potential resource for the extraction of oxygen through the reduction reaction [e.g. RD 80, RD 81, RD 82]

heating FeTiO3 → Fe + TiO2 + 0.5O2 . (1)

In the presence of hydrogen, either introduced as a separate feedstock or present in the surface through solar wind implantation, the above process can be modified to,

heating FeTiO3 + 2H → Fe + TiO2 + H 2O . (2)

In the later case (equation 2) the resulting water can be used either as an end product in its self or as a feedstock for electrolysis for the reclamation of hydrogen.

Ilmentite reduction is currently a favoured process for ISRU owing to its relative simplicity compared with alternative processes and the relative maturity of the required technologies. However the application of ilmenite reduction as a technique is almost certainly limited to areas with high ilmenite abundance (i.e. high Ti mare basalts terrains) in near equatorial sites. The distribution of these terrains is fairly well characterised on a global scale on the basis of maps of Ti generated by Lunar prospector and Clemantine.

Given the relatively well understood distribution of Ti and thus ilmenite on the lunar surface it has been deemed that investigations into the extent and abundance of ilmentite as a potential resource should not be a driver for the mission design. However the capability to identify the abundance of ilmenite at any new landing site has merit as ground truth to orbital measurements and thus should be considered as an objective, albeit of low priority.

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In order to achieve the objective the detection and quantification of the abundance of Ti is required.

7.1.1.3 Improve our understanding of the potential use of highlands regolith as a resource All previous in-situ measurements of lunar regolith and rocks, as well as sample return missions have provided analysis of material from sites which are known to be unrepresentative of the lunar surface as a whole. Knowledge of lunar highlands material comes from analyses of remote sensing data and lunar meteorites, and a limited number of Apollo samples.

Future missions to lunar highlands and non-mare locations (e.g. the lunar South Pole) at which ISRU is to be applied will require a process which is appropriate to the available feedstock, in this case lunar highlands regolith. To this end it is beneficial to determine the properties of this feedstock in terms of its composition and physical properties.

It was considered that this objective should be considered a low priority and should not be a mission driver as it is unlikely that a significant increase in knowledge would be gained by seeking to achieve it. However in-situ measurements of highlands regolith would be beneficial, particularly as ground truth for remote sensing data. Investigations into geochemistry to address other objectives will necessarily address this objective as well. For this reason the capability to investigate highlands regolith should be considered if a highlands landing site is selected for other reasons.

7.1.1.4 Improve our understanding of the potential use of mare regolith as a resource Knowledge of the composition and properties of regolith in lunar mare can be considered fairly mature and the potential impact of measurements made by a lunar lander in the lunar mare is low. As such this objective should not be considered a mission driver. However should a mare landing site be considered the capability to determine the properties of the regolith as relevant to ISRU would add to current knowledge and provide ground truth for orbital measurements and would thus be of benefit.

7.1.1.5 Provide ground truth to support orbital observations, by other missions, of potential in situ resources Providing ground truth for remote sensing measurements adds value to all previous data sets and can be achieved at any landing site. As such this is considered to be a medium priority and requires that the mission.

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In addition understanding of the particle size distribution for the local regolith is also of benefit.

7.1.1.6 Determine the abundance as a function of depth and distribution of H2O, OH and hydrated minerals in the regolith. Recently published results from the missions Chandrayaan, Deep Impact and Cassini [RD 83, RD 84, RD 85] have revealed the presence of either hydroxyl (OH) or water (H2O) or both in the lunar regolith through identification of absorption features near to 3µm wavelength. This feature corresponds to the fundamental vibration of absorption for the OH chemical group and thus is an indicator of OH and H2O. Initial indications are that up to a few tenths of a percent by weight of water might be present to optical depths of a ~ 1 mm at the surface. The abundance of water observed appears to increase as a function of latitude so that the highest concentrations are observed close to the poles.

Variations in absorption were also observed for different geological features, in particular associated with plagioclase feldspar [RD 83] which may indicate a relationship with deep water [RD 86]. Time variations in the strength of the absorption feature indicate that the water is dynamic and migrating across the lunar surface, possibly providing a source for ice trapped at the lunar poles.

It may be that unsampled areas exist on the Moon, in which much greater concentrations of water exist and that water bearing minerals observed in lunar samples [RD 87] may be lunar in origin and not due to terrestrial contamination as had been believed [RD 88].

The presence of water at the lunar surface has potential implications for ISRU in future lunar exploration both as a resource in its self and also as a source for oxygen and hydrogen for fuel, through electrolysis. If water is present in significant quantities in the lunar soil then its extraction as a resource might be feasible. In order to determine if this is the case the distribution of water as a function of depth into the surface should be determined, as must its origins.

In order to achieve this, the mission must include key elements. Firstly a landing site at high latitude is preferable, ideally in a site which has been indicated by orbital measurements to have surface water / hydroxide. In addition mobility, of the order of 100 m, is required in order to leave the area of the surface most affected by contamination by the impingement of plumes from the landing engines. The mobile element must then carry a capability to determine the presence or not of water and hydroxide as a function of depth and the ability to differentiate between the two and hydrated minerals. Sensitivity of measurements to abundances > 10 ppm is required. The depth of measurements should be

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at least 20 cm (although a meter is preferable if feasible) and a depth resolution of 5mm may be appropriate, although increased resolution may be required close to the surface.

Given the potential impact of these investigations this objective is considered to be a high priority.

7.1.1.7 Determine the abundance and distribution of solar wind implanted volatiles in a non Apollo locality Solar wind implanted volatiles are another potential resource, with the advantage over others that their extraction from the regolith can be achieved by heating alone. These volatiles have a number of potential applications, including their use as a feed product for the reduction element oxides (e.g. FeO) for the production of O and H2O. Solar wind implanted volatiles include the elements H, N, C and He. These elements are important for various aspects of the maintenance of a lunar outpost and so volatile extraction may reduce the requirements for replenishment of these elements from a terrestrial source. The abundance of these elements is in general fairly low and so their practical application to a future exploration scenario remains to be seen.

In order to achieve this objective a landing site which is significantly different from the Apollo sites is required, preferably at high latitude as it is here that volatiles are most likely to have been implanted in the greatest quantities. Mobility which is sufficient to escape contamination of the surface by landing engines is ideal. Access to measure the subsurface and the ability to determine the abundance and composition (elemental and isotopic) of implanted volatiles is required. In the frame of human exploration this was deemed to be of medium priority as it informs the possible utilisation of volatiles in the future.

7.1.1.8 Perform "proof of concept" in-situ resource extraction based on SWIP volatiles It may be possible to demonstrate that volatiles can be extracted from the lunar regolith by heating. Volatile extraction is probably the simplest example of ISRU and so was considered a high priority by the LEDT, provided abundance could be demonstrated to be sufficiently high that such investigations had merit.

7.1.1.9 Perform "proof of concept" in-situ resource extraction based on water/OH in the regolith Extraction of water from the regolith should be possible by the same means as the extraction of other volatiles by simple heating. However this was considered to be of low

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priority as a mission objective for the reason that if water is there then it’s extraction should be fairly straight forwards and demonstration has limited merit.

7.1.1.10 Perform "proof of concept" in-situ resource extraction based on ilmenite reduction, carbothermal reduction or molten silicate electrolysis. No ISRU process has been demonstrated on the Moon and for this reason is not considered on the critical path of any lunar exploration architecture. To demonstrate ISRU on the lunar surface would lend confidence to the potential application of the technique and mature the use of the various technologies required. However, given the current immaturity of ISRU technologies it is not possible to make definitive decisions on an optimal ISRU technique for the future. In addition it is likely to be the case that ISRU demonstration is unfeasible on a mission of this scale. For this reason demonstration of ISRU is considered a medium priority for this mission.

We assume here that O2 is the most likely product needed from ISRU and so an ISRU demonstration should generate O2 from lunar regolith. H2O is, for many potential processes, an intermediate product between the initial input regolith and the final O2 product.

Success for an ISRU demonstration would be achieved upon the generation of oxygen form regolith, probably by one of the three candidate ISRU processes ilmenite reduction, carbothermal reduction and molten silicate electrolysis, which currently appear to offer the most feasible and efficient option.

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8 ROBOTICS AND MOBILITY Key enabling capabilities for the exploration of the Moon are to be able to traverse over the surface between points of interest, gain access to sites of scientific importance, manipulate payloads and other hardware elements and to have the operational flexibility to perform these safely and efficiently. In this regard robotics and mobility are important elements operating on the surface either in support to autonomous missions or to human activities, as well as for mobile systems intended to transport humans over the surface. Mobile systems also represent only a subset of robotics which also includes dedicated manipulation systems such as deployment and manipulation arms.

Each of the applications mentioned, from small scale rovers and robotics, up to human and cargo transportation systems imply specific technologies and concepts from locomotion systems, surface navigation systems, intelligent manipulation robotics, varying degrees of autonomy etc. Such systems are by nature complex in the interaction of many components and elements, as well as their direct interaction with the planetary environment, and in particular the surface terrain.

8.1 Challenges for Robotics and Mobility For the various applications described above, the complex interaction of the many subsystems with each other and with the environment represents a significant challenge. In terms of technology, feasibility and confidence in design can be built through dedicated programmes of development and testing, utilising planetary test beds and other simulation environments. However having an accurate knowledge of the environment, specifically for what regards those properties which have a strong impact on robotic systems, is critical to ensure the value and represantativity of such tests and ultimately to have confidence in the operation of those robotic systems in-situ.

8.1.1 Robotics and mobility - potential objectives It is important to note that while pure technology demonstration for robotics and mobility is not judged to be sufficiently justifiable in the frame of the First Lunar Lander mission, there are a number of other objectives (e.g. deployment of instruments, sampling of surface material etc.) which may require robotic or mobile elements in order to carry out the necessary investigations – in this case it is clear that the lessons learned from operating such systems in-situ will be of great value in the development and operation of future systems.

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The First Lunar Lander mission can serve to address two main objectives regarding robotics and mobility: • Characterise the key environmental parameters having a major impact on robotics and mobility elements • Investigate environmental effects on communications (surface - surface)

8.1.1.1 Characterise the key environmental parameters having a major impact on robotics and mobility elements Robotics, and in particular mobile vehicles, are highly sensitive to the properties of the dust and regolith at the lunar surface, both in terms of the abrasive and adhesive effects of dust and on the terramechanical properties of the regolith. The characterisation of these environmental properties, particularly for what regards the design optimisation of future vehicles for autonomous and human operations on the surface, is an objective which could be addressed by the First Lunar Lander mission, particularly effectively at sites not already visited by landers from the Apollo era. Since the particular sensitivity of robotics and mobile systems, in terms of technology development and testing, to key lunar environmental parameters requires further investigation and clarification, this objective is regarded as a medium priority objective.

8.1.1.2 Investigate environmental effects on communications (surface - surface) To date, communications with landers and vehicles on the lunar surface has been ensured via a Direct-to-Earth (DTE) link. This was possible since missions so far have targeted landing sites on the near-side (i.e. permanently Earth facing), and in the case of Apollo ensured communications with the astronauts on excursion in the Lunar Rover Vehicle (LRV) regardless of their ability to communicate with the lander. However DTE communications is certainly not an option on the far-side, and is strongly dependent on the local topography at sites on the Moon where the Earth appears at very low elevation. Critically, at the polar regions, due to the inclination of the Moon’s orbit around the Earth, DTE communications can be restricted to around 2 weeks per month.

Given that the polar regions, and in particular the South pole, represent attractive destinations for both autonomous and human missions, the ability to relay communications between surface elements and ultimately to Earth has a high importance. The Moon environment does not have an ionosphere off which to bounce surface-surface communications, therefore any communication is likely to be strongly dependent on the effects on signal propagation of the lunar surface (rock and soil composition, as well as the electrical properties of dust levitated near the surface).

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Given the importance of surface-surface communications for the development of autonomous measurement packages (including rovers) in the near-term, and in the longer term for the design of human systems and the planning of their operations, the investigation of environmental effects on surface-surface communications has been given a high priority.

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9 HUMAN ACTIVITIES

9.1 The Research Activities of Future Human Explorers A significant part of the exploration efforts of humans living and working on the Moon will be directed at performing fundamental research. Investigations will be in diverse areas, from the origin and history of the Moon, to using the Moon as an enabling platform for astronomy, physical sciences and life sciences research. As a contribution to ensuring the sustainability of lunar exploration ESA’s First Lunar Lander can help optimise output for the early missions by preparing the way. Significant ground work can be done in advance of human explorers to ensure effective planning and preparation for human missions and research activities.

At present our understanding of the Moon is derived almost entirely from results gained during the Apollo missions and by analysis of samples which were returned from the Moon and data obtained from experiments flown on these missions. In the Post Apollo era we are left with three major hypotheses upon which we base our understanding of the Moon:

• The Moon was created following a giant impact of a Mars sized body with the Early Earth. • The formation of the Moon’s surface occurred via a Magma Ocean, which crystallised to form the present lunar highlands. • The early Moon, and thus the entire inner Solar System, experienced a Terminal Cataclysm, also referred to as the period of late heavy bombardment, when the majority of craters now visible on the lunar surface were created. This hypothesis, along with the dates determined for returned lunar rocks, provide the basis for our dating of all other surfaces in the inner Solar System.

Since 1994 the data from Apollo, which were sourced from a limited set of regions on the lunar near side, have been complimented by data from several orbital missions, providing a global context for the first time (see Section 2). Some of the results from these more recent missions have called into question our hypotheses of the Moon and revealed the importance of further investigation.

The major contributions of the various missions to our understanding of the origins, history and evolution of the Moon are extensive and have been well documented and described by many previous authors as have the major scientific questions for future investigations (e.g. RD 1, RD 3, RD 2, RD 89, and RD 90). A review of the current state of

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knowledge including summaries and highlights of major reports on what remains to be discovered and the relative priorities of these is provided by RD 91.

In many science areas, and particularly in astronomy, the Moon presents possibly the only feasible platform from which many important observations can be made. Future human missions to explore the Moon are likely to engage in science investigations from the Moon, which address otherwise inaccessible science goals.

In the case of astronomy the Moon’s stable surface, large solid volume and exposure to almost free-space may play an important role, following some of the most remote and deserted areas on Earth. On Earth some of the regions most hostile to life that have become a focus of major research activities in geophysics, climate research, astronomy and astrophysics. For example, one hundred years after the exploration of Antarctica, its ice is now being used as a cubic kilometre detector of ultra-high energy neutrinos in the IceCube project, and the extremely high-altitude deserts and mountains of the Andes host some of the biggest optical and radio telescopes in the world, with a host of smaller experiments following suite.

It is conceivable that within a couple of decades the Moon will offer a similarly popular focus for a wide range of science investigations and a goal of recent exploration studies has been to identify the most promising applications for science on and from the Moon. An important area, for which the Moon may be enabling, is low-frequency radio astronomy and astrophysics (e.g. RD 3). This is because the far side of the Moon is expected to offer a uniquely radio-quiet environment, outside the Earth’s ionosphere, that allows the study the earliest phase of the observable universe and planetary plasma environments.

The Scientific Context for Exploration of the Moon [RD 3] was generated in 2007 by the National Research Council in the US. It presents a community consensus of the various topics and objectives for scientific investigation on the Moon and presents these objectives in order of priority. These objectives and their order of priority are accepted here as correct. It is assumed that research performed by astronauts on the surface of the Moon will in large part be driven by these objectives and their priorities, which are as follows:

• Test the cataclysm hypothesis by determining the spacing in time of the creation of the lunar basins. • Anchor the early Earth-Moon impact flux curve by determining the age of the oldest lunar basin (SPA). • Establish a precise absolute chronology. • Determine the composition and distribution of the volatile component in lunar polar regions. • Determine the extent and composition of the primary feldspathic crust, KREEP layer, and other products of planetary differentiation.

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• Determine the thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and global scales. • Characterize the chemical/physical stratification in the mantle, particularly the nature of the putative 500-km discontinuity and the composition of the lower mantle. • Determine the global density, composition, and time variability of the fragile lunar atmosphere before it is perturbed by further human activity. • Determine the size, composition, and state (solid/liquid) of the core of the Moon. • Inventory the variety, age, distribution, and origin of lunar rock types. • Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar exploration and lunar-based astronomy. • Demonstrate the suitability of the lunar surface as a platform for astronomy.

The background to these objectives and their justifications are given in RD 3.

9.1.1 Potential objectives Human researchers working in situ on the surface of the Moon will work to address the science goals described above. Since any earlier mission will be preparatory to human exploration we assume that a human presence on the surface of the Moon is assured and that human explorers will be able to address science questions to a greater extent than can be achieved with unmanned missions. For this reason here we address how ESA’s First Lunar Lander might prepare for and optimise the work of human explorers. Potential objectives for the mission are:

• Inventory the variety, distribution, and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return • Determine the density, composition, and time variability of the fragile lunar exosphere at the landing site before it is perturbed by further human activity. • Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar exploration. • Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar-based astronomy. • Determine the regional thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and global scales • Demonstrate the suitability of the lunar surface as a platform for low frequency radio astronomy

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9.1.1.1 Inventory the variety, distribution, and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return The formation of the Moon, its differentiation and evolution are recorded in the rocks that exist there. These are fundamental to understanding planetary differentiation and evolution more generally. As a result one of the major themes of RD 3 is “Key planetary processes are manifested in the diversity of lunar crustal rocks”. Providing an inventory of lunar rock types is key element improving understanding of these processes and will also provide a background to inform the scientific planning of future missions.

9.1.1.2 Determine the density, composition, and time variability of the fragile lunar exosphere at the landing site before it is perturbed by further human activity. The Moon’s Surface Boundary Exosphere (SBE) is a tenuous atmosphere produced by vaporisation of surface material, by ion sputtering and meteoritic impacts, under conditions where collisions between individual atoms and molecules are extremely rare and liberated gases may therefore have long parabolic trajectories back to the surface or may escape from the surface all together [RD 92]. Other bodies in the solar system which have SBEs include Mercury, Europa, Ganymede, Calisto and Enceladus and SBEs may be present on other satellites and Kuiper belt objects. SBEs are poorly understood and the Moon offers the best, and perhaps only, opportunity to perform detailed studies of their sources and dynamics. Currently the composition and properties of the Moon’s SBE are poorly known and significant investigation is required to improve knowledge and extend the understanding gained to other bodies in the Solar System.

The total mass of the lunar exosphere is of the order of 100 Tonnes. This compares with a mass of exhaust gasses ejected during landing of 10 – 20 Tonnes [RD 3]. As a result once human exploration begins in earnest the environment will quickly become dominated by the gaseous products of these activities and measurements of the exosphere will no longer be possible. Thus early exploration missions will provide the only opportunity to study the natural lunar exosphere and plasma environment. For this reason measurements of the lunar exosphere are considered a high priority.

9.1.1.3 Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar exploration.

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For the reasons described in previous sections the lunar dust environment is of key importance for any long term operations on the surface of the moon. As such understanding the dust environment is key to all future human activities on the surface of the Moon.

9.1.1.4 Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar-based astronomy. Future astronomical observatories will also have to function in the lunar dust environment and this may affect the feasibility of some observations and the design of observatories. Significant overlap exists between this and the previous objective. However it was determined that the priority associated with the two was different and so it was necessary to separate them.

9.1.1.5 Determine the regional thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and global scales Geological investigations on the lunar surface by future human explorers will be planned and executed in order to optimise the return from selected samples. Key to selecting samples for analysis and interpretation of results is the geological context of the site in which the samples were found. Determining geological context requires observations of the surface topography and rock lithology together with an understanding of the sub surface structure and in the lunar case crustal thickness.

Note that achieving this and other geophysics related objectives would be enhanced if this lander, and its geophysics instrumentation, was part of the International Lunar Network (ILN). The timescales of the ESA lander and the ILN may overlap. The US will only decide to go ahead with its ILN 'Anchor Nodes' if these are rated highly by the Decadal Survey, which will report in early 2011. If the ILN goes ahead and the timing matches that envisaged for this mission, then this crossover will significantly add to our ability to meet the geophysics objectives specified here.

In order to inform in situ investigations crustal thickness must be determined in advance of human exploration of a site. For this reason this is considered to be a high priority objective.

9.1.1.6 Demonstrate the suitability of the lunar surface as a platform for low frequency radio astronomy Long wavelength radio interferometry is singular in nature in that it is the only astronomical observation for which the Moon is potentially the only available platform. As

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such it is likely that the Moon will eventually provide a platform for radio observatories. If such activities are to be prepared then the radio environment on the Moon must be shown to be compatible with long wavelength radio astronomy.

It is conceivable that within a couple of decades the Moon will offer a similarly popular focus for a wide range of science investigations and a goal of recent exploration studies has been to identify the most promising applications for science on and from the Moon. A clearly identified top-priority has been low-frequency radio astronomy and astrophysics (e.g. RD 3). This is because the far side of the Moon is expected to offer a uniquely radio- quiet environment, outside the Earth’s ionosphere, that allows the study the earliest phase of the observable universe and planetary plasma environments.

The problem for low-frequency radio astronomy is the Earth's turbulent ionosphere, which causes ground-based radio observations of the sky to become difficult below about 100 MHz due to ionospheric “seeing”. Below about 10-30 MHz the properties of the ionosphere cause radio waves to be reflected. This property allows long-distance short wave transmission around the Earth, but prevents observations of the sky. Observations at frequencies just above the cut off (i.e., between ~10-50 MHz) require especially favourable geomagnetic and ionospheric conditions. Frequencies below this cut off are only observable from space. Hence, the dominant “low-frequency/long-wavelength” regime for ground- based telescopes is at >30 MHz and wavelengths <10 m.

The highest angular resolution image achieved in the ultra-low-frequency range to date has a resolution of ~5°, but images with resolutions of 10s° are more typical. These resolutions compare rather unfavourably with the milli-arcsecond resolution routinely achieved using Very Long Baseline Interferometry (VLBI) at higher radio frequencies. The low-frequency Universe is therefore the worst-charted region of the radio spectrum, and perhaps even of the entire electromagnetic spectrum. To date only two kinds of maps of the sky have been made at frequencies below 30 MHz. The first are maps of a part of the southern sky near the Galactic centre [RD 93, RD 94, and RD 95] from Tasmania. These have angular resolutions ranging from 5° to 30°. The second are maps obtained by the RAE-2 satellite [RD 96] which have an angular resolution of 30° or worse.

To improve this situation and to overcome the limitations imposed by the terrestrial environment, space-based low-frequency telescopes are required for all observations below the ionospheric cut off [RD 97]. This is also true for a significant part of the seeing-affected frequency range above the cut-off frequency where high-resolution and high-dynamic range observations are required, such as imaging of 21-cm (1.4 GHz) emission of neutral hydrogen in the very early Universe [RD 98] redshifted to below 100 MHz.

Low-frequency radio imaging is realized as digitally phased arrays of simple dipole antennas that are spread over a large area. This wide distribution puts a serious constraint on any realization consisting of free-flying antennas in space but is ideal for lunar surface-

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based concepts that have been studied extensively in the past (e.g. RD 97 and references within).

A major issue, however, is that the lunar surface radio environment has never been studied in any detail. There are indications that a lunar ionosphere might exist during day periods and affect radio wave propagation below 1 MHz. In addition a number of natural impulsive radio noise sources are expected. Space radio experiments have discovered that the hypervelocity impacts of dust particles lead to electric discharges and related radio sparks. Similar effects might be expected from larger dust grains hitting the lunar surface or even larger meteorite impacts. It has also been shown in accelerator experiments that ultra-high energy cosmic ray particles, which are known to exist, produce particle showers in solid media that also lead to strong Cherenkov-like radio pulses. These effects have never been measured in-situ and provide a potential noise background on the one hand and an interesting diagnostic on the other hand.

Before the construction of any large-scale Lunar radio interferometer, a thorough investigation of the Lunar radio environment in crucial and a technical demonstration of the principle of Lunar radio interferometry would be of benefit. This mission is a potential platform from which to perform these investigations and lay the ground work for all future lunar astronomy activities on the Moon. The inclusion of a Rover in the mission scenario will enable the production of the very first ever high-resolution radio images at frequencies below 20 MHz by the first radio telescope on the Moon.

9.1.1.7 Piggy back science While not a priority for the mission it should be recognised that investigations aimed at targeting the objectives described elsewhere in this document are closely aligned with measurements that can help address fundamental scientific questions. Identical investigations or investigations with limited additional capabilities may be able to address some of these questions at little additional cost to the mission. These areas are referred to here as piggy back science. The main examples of objectives that maybe achieved through fundamental science investigations piggy backing on an exploration preparation mission are given below:

• Contribute to characterising the chemical/physical stratification in the mantle, particularly the nature of the putative 500-km discontinuity and the composition of the lower mantle. • Contribute to determining the size, composition, and state (solid/liquid) of the core of the Moon. • Determine the effects of the combined lunar environment, including the mixed radiation field, reduced gravity and stressors (related to hypoxia and other environmental factors) on cellular survival and physiologically relevant

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measures (this becomes piggy back science when it goes beyond what is required for radiation risk assessment for human health and risk assessment). • Contribute to understanding panspermia with exposure of dormant cells • Contribute to the understanding of the origins of life in the solar system (perhaps through analysis of organics in impact ejecta from craters or analysis of effects of long term exposure of biology to the environment) • Investigate the regolith as a recorder of extra-lunar processes • Test of the Strong Equivalence Principle in Gravitational Field Theory • Detect the presence of Strange Quark Matter

In all cases it is expected that results with significant scientific merit can be achieved as an adjunct to the objectives described in the context of human space flight preparation by the same techniques and instrumentation, with little or no delta on requirements or capabilities.

Note that here, as in Section 9.1.1.5, achieving this and other geophysics related objectives would be enhanced if this lander, and its geophysics instrumentation, was part of the International Lunar Network (ILN). The timescales of the ESA lander and the ILN may overlap. The US will only decide to go ahead with its ILN 'Anchor Nodes' if these are rated highly by the Decadal Survey, which will report in early 2011. If the ILN goes ahead and the timing matches that envisaged for this mission, then this crossover will significantly add to our ability to meet the geophysics objectives specified here.

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10 PUBLIC ENGAGEMENT

The engagement of the public is vital for an exploration mission. Exploration incorporates scientific discovery but ultimately extends further, and should capture the imagination the wider community. Human space flight and exploration is an anchor for inspiring the next generation of scientists and engineers. These are the people who will ultimately perform the activities that this mission prepares for. As the mission is developed so it is important to ensure that provision is made to inform and communicate with the public and optimise the impact there.

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11 PRIORITISATION OF OBJECTIVES The objectives derived in the previous sections have been allocated a priority of either high medium or low, as described in the text, given a context of preparation for human exploration. Here we list these objectives according to priority and provide reference to the objectives for use in later sections.

11.1 High Priority Objectives The objectives allocated a high priority are as follows.

Landing OB-LG- 1 Demonstrate soft precision landing with hazard avoidance

Health OB-HT- 1 Improve current understanding of the response of biological systems to radiation damage in the integrated lunar environment such that risks assessment for humans can be improved

OB-HT- 2 Quantify the radiation risk to humans due to galactic cosmic rays

OB-HT- 3 Quantify the health risks to human exploration posed by lunar dust unrepresented in sample collections

Habitation OB-HN- 1 Characterise the suitability of a potential future landing site for future exploration

OB-HN- 2 Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities

OB-HN- 3 Quantify the risk to human exploration posed by impacts

OB-HN- 4 Demonstrate advanced power storage technologies (regenerative fuel cells) if enabling for other objectives

Resources OB-RS- 1 Determine the abundance as a function of depth and distribution of H2O / OH / hydrated minerals in the regolith

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OB-RS- 2 Perform "proof of concept" in-situ resource extraction based on SWIP volatiles

Preparations for human activity OB-PH- 1 Determine the density, composition, and time variability of the fragile lunar exosphere at the landing site before it is perturbed by further human activity

OB-PH- 2 Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar exploration

OB-PH- 3 Determine the regional thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and global scales

OB-PH- 4 Demonstrate the suitability of the lunar surface as a platform for low frequency radio astronomy

Mobility OB-MB- 1 Investigate environmental effects on surface – surface communications

Public Outreach OB-PO- 1 Engage the Public

11.2 Medium Priority Objectives Objectives considered to be of medium priority are:

Health OB-HT- 4 Improve current space weather forecast from the Moon to improve early warning systems for crews

Habitation OB-HN- 5 Understand the effects of reduced gravity on multiphasic properties critical in habitation technologies

OB-HN- 6 Understand the impact of the lunar environment on biological processes important for life support technologies

Resources OB-RS- 3 Provide ground truth to support orbital observations, by other missions, of potential in-situ resources

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OB-RS- 4 Determine abundance and distribution of solar wind implanted volatiles in a non-Apollo locality

OB-RS- 5 Perform ‘proof-of-concept’ in-situ resource extraction based on one possible ISRU process: ilmenite reduction, carbothermal reduction or molten silicate electrolysis

Preparations for human activity OB-PH- 5 Inventory the variety, distribution and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return

Piggy back science OB-SC- 1 Identify the presence of precursor chemistry for life in primitive ices

Mobility OB-MB- 2 Characterise the key environmental parameters having a major impact on robotics and mobility elements

11.3 Low Priority Objectives Objectives considered to be of low priority are:

Health

OB-HT- 5 Determine the radiation shielding properties of lunar regolith

Habitation OB-HN- 7 Determine thermal and heat flow properties of the regolith

OB-HN- 8 Determine the seismic risk to future human exploration activities

Resources OB-RS- 6 Identify the abundance and distribution of ilmenite

OB-RS- 7 Improve our understanding of the potential use of highlands regolith as a resource

OB-RS- 8 Improve our understanding of the potential use of mare regolith as a resource

OB-RS- 9 Perform "proof of concept" in-situ resource extraction based on water/OH in the regolith

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Preparations for human activity OB-PH- 6 Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar-based astronomy

11.4 Piggy Back Science Objectives Areas referred to as piggy back science in the text are not considered as priorities for the mission. Rather they are elements which may be achieved if they are synergistic with techniques applied to achieve other objectives, defined in the human space flight context. Areas considered for piggy back science are:

OB-SC- 2 Contribute to characterising the chemical/physical stratification in the mantle, particularly the nature of the putative 500-km discontinuity and the composition of the lower mantle

OB-SC- 3 Contribute to determining the size, composition, and state (solid/liquid) of the core of the Moon

OB-SC- 4 Investigate the regolith as a recorder of extra-lunar processes

OB-SC- 5 Test of the Strong Equivalence Principle in Gravitational Field Theory

OB-SC- 6 Detect the presence of SQMs (note this is not an objective which should be targeted but could be achieved through serendipity by seismic measurements applied to achieve other objectives)

OB-SC- 7 Determine the effects of the combined lunar environment, including the mixed radiation field, reduced gravity and stressors (related to hypoxia and other environmental factors) on cellular survival and physiologically relevant measures

OB-SC- 8 Contribute to understanding panspermia with exposure of dormant cells

OB-SC- 9 Contribute to the understanding of the origins of life in the solar system (perhaps through analysis of organics in impact ejecta from craters or analysis of effects of long term exposure of biology to the environment)

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12 REQUIREMENTS Following the discussions of previous sections requirements are defined here for a system which is to achieve the objectives described in Section 11. Requirements can apply to apply to: • The mission scenario, in terms of landing site, duration, mobility etc. • Instrumentation, in terms of values to be measured, sensitivity etc.

In the first instance these requirements can then be used to inform the definition of a mission scenario and to determine the feasibility of achieving any given objective given any practical constraints on a feasible mission scenario.

In the later case requirements can be used to inform the selection of instrumentation and the manner in which it is applied to achieve a given mission objectives.

Potential instruments and techniques, which may be applied to meet the given requirements, are also summarized very briefly in this section. Instruments and techniques are described further in Section 13 but a detailed explanation and description is considered beyond the scope of this document.

12.1 Requirements to Meet High Priority Objectives

This section presents the requirements which must be met in order to achieve the high priority objectives derived in the previous sections and listed in Section 11.1.

Objective OB-LG- 1 Demonstrate soft precision landing with hazard avoidance c an only be achieved through the system level integration of a descent and landing system implementing key technologies and capabilities such autonomous terrain relative navigation and hazard detection and avoidance with, for example, camera/LIDAR based sensors and the necessary HA algorithms. The following requirement is therefore generated:

RQ-LG- 1 The mission shall demonstrate soft precision landing with hazard avoidance

In order to achieve objective OB-HT- 1 Improve current understanding of the response of biological systems to radiation damage in the integrated lunar environment such that risks assessment for humans can be improved, introduced in Section 5.1.3.3 the following requirements have been defined:

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RQ-HT- 1 Cell systems shall be used to characterize the radiation response of cells on the Moon

RQ-HT- 2 Cell response shall be monitored in real time

RQ-HT- 3 Maintain living cells to point of exposure to the radiation environment.

RQ-HT- 4 Cell cultures shall be kept alive for several weeks during exposure

RQ-HT- 5 Cell death shall be detected when it occurs

The above requirements require the development of a dedicated experimental facility for human radiation biology.

RQ-HT- 6 GCR fluxes shall be monitored continuously during cell exposure

RQ-HT- 7 LET spectra shall be determined for GCRs

RQ-HT- 8 The species of GCRs particles shall be determined

The above requirements may be achieved through the use of a radiation monitor.

RQ-HT- 9 A mission duration shall be greater than 1 month (TBC) with a goal of >1 year.

No requirements are placed on landing site.

In order to achieve objective OB-HT- 2 Quantify the radiation risk to humans due to galactic cosmic rays, introduced in Section 5.1.3.2, requirements RQ-HT- 6, RQ-HT- 7 and RQ-HT- 8 must be met although these measurements need not be recorded on the Moon and may be provided by another mission. In addition following must be achieved:

RQ-HT- 10 The flux of secondary neutrons shall be monitored throughout the mission.

A radiation monitor with sensitivity to neutrons can meet this requirement.

In order to achieve OB-HT- 3 Quantify the health risks to human exploration posed by lunar dust unrepresented in sample collections introduced in Section 5.2.1.1, the following must be achieved:

RQ-HT- 11 The size distribution of lunar dust shall be determined for particles of the order of 10 nm and larger.

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Determination of the charge of levitating dust grains using a dust charge and trajectory sensor together with local electric potential measured with Langmuir probes can be used to determine the sizes of levitating dust grains. The size distribution of any nanometer scale dust grains in the surface requires more complex techniques. An Atomic Force Microscope (AFM) may provide a solution but the time required to scan samples to find nanometer scale particles may prove prohibitive. Microscopic particles may be observable using an optical microscope. Such particles may not be significantly different from those identified in Apollo samples however. In both cases dust samples might have to be collected and delivered to a dedicated microscopy station containing the instruments. In larger size regimes a high resolution camera on an arm would be appropriate.

RQ-HT- 12 The presence and abundance of nanophase Fe shall be determined

The presence and extent of nanophase Fe particle may be derterminned through it’s spectral properties through hyperspectral microscopy.

RQ-HT- 13 The mineralogical/chemical composition of lunar dust grains shall be determined

The bulk mineralogy of Fe based minerals may be achieved through an X-ray diffractometer. Raman spectroscopy may offer a preferred solution as the small spot size of a single measurement may allow single or small groups of grains to be isolated. In this case a small number of grains (but probably > 1) maybe measured in single measurements. Another possibility is hyperspectral imaging microscopy.

RQ-HT- 14 The surface chemical reactivity of lunar dust grains shall be determined

RQ-HT- 15 The passivation rate in habitat like conditions shall be determined for lunar dust grains.

It is not clear exactly how such investigations might be achieved. One possibility s the use of a wet chemistry station to determine bulk properties of surface dust such as pH, redox potential, oxidant and reductants content and other properties. Such a system would require the delivery of samples from the surface to the instrument and was implemented in the Phoenix Mars mission. An alternative instrument has been studied in the US for this purpose using induced UV fluorescence of free radicals or electron spin resonance as a marker for surface reactivity.

RQ-HT- 16 the stickiness of lunar dust grains shall be quantified

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RQ-HT- 17 The structures of lunar dust grains < 10µm shall be determined, with a goal of extending this distribution to grains > 10nm.

Structures of dust grains on 10s microns scale may be achieved by an optical microscope. On larger scales a high resolution camera on a movable arm might be used. On smaller scales an atomic force microscope might be applied.

RQ-HT- 18 The elemental composition of lunar dust grains shall be determined

It is unclear how this can be achieved on a grain by grain basis. Bulk elemental composition may be achieved thorough the use of a contact X-ray spectrometer could provide bulk composition for dust for major elements. Laser Ionisation Breakdown spectrometer may provide elemental composition with ~50 µm resolution which may be applied in parallel with visible microscopy. In the later case sufficient sensitivity in high vacuum environments must be demonstrated.

RQ-HT- 19 A landing site representative of those likely to be selected for future human missions shall be selected.

RQ-HT- 20 The effects of lunar dust on biological analogues to human physiology shall be monitored in situ

A dedicated experiment observing dust effects in microorganisms following interactions with lunar dust delivered by a sampling and delivery system would be needed to meet this requirement.

In order to achieve objective OB-HN- 1 Characterise the suitability of a potential future landing site for future exploration, the following requirement must be met.

RQ-HN- 1 Panoramic stereo images of the landing site shall be produced.

In order to achieve objective OB-HN- 2 Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities, introduced in Section 6.2.1.1, the following requirements must be achieved:

RQ-HN- 2 The charges on levitating lunar dust particles (> 0.1 fC) shall be measured as a function of time (and height as far as is practical).

RQ-HN- 3 The velocities for levitating lunar dust particles shall be measured in the velocity range 1 – 5000 km / s

RQ-HN- 4 The trajectory of levitated dust particles shall be determined to < 1°

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A dust charge and trajectory sensor can be applied to meet these requirements.

RQ-HN- 5 The temperature of the local plasma shall be measured

RQ-HN- 6 The density of the local plasma shall be measured

RQ-HN- 7 Electric surface potential shall be measured in the range ±1V – 10 kV

Langmuir probes (ideally 2 but minimum 1) on booms ~3m in length (TBC) can be used to meet these requirements.

RQ-HN- 8 Requirement RQ-HT- 11 applies

RQ-HN- 9 Requirement RQ-HT- 17 applies

An atomic force microscope and optical microscope may be applied to meet these requirements.

RQ-HN- 10 Measurements relating to requirements RQ-HN- 2 to RQ-HN- 4 shall be performed during the transition from illumination by the sun into shadow / night.

RQ-HN- 11 Measurements relating to requirements RQ-HN- 2 to RQ-HN- 4 shall be performed throughout periods of illumination.

RQ-HN- 12 The rate of adhesion of lunar dust on surfaces shall be measured throughout the mission.

This requirement may be achieved by the use of a high resolution camera and patch plates and / or using a quartz crystal microbalance based instrument.

RQ-HN- 13 The mission duration shall be maximised.

In addition the requirements RQ-HT- 11 to should be met.

No requirements are imposed on landing site.

RQ-HN- 14 Forward scattering of levitated dust shall be observed at sunset

In order to achieve objective OB-HN- 3 Quantify the risk to human exploration posed by impacts, introduced in Section 6.3.1.1, the following requirements must be met.

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RQ-HN- 15 The flux of meteoroids in the mass range 1 mg – 1 g impacting the lunar surface shall be measured

A potential solution to meet this requirement is the deployment of short period seismometers on the lunar surface. A minimum time area product for impact detection of approximately 1 km year is required. To achieve this almost certainly requires mobility on the scale of several km and a mission duration greater than 1 year. An alternative solution uses the detection of radio / microwave pulses from impacts using a radio antenna. In the absence of mobility a combination of measurements by a single geophone at the lander and a radio antenna may be used to achieve some coincidence of measurements and infer distance of impact thus impactor properties.

RQ-HN- 16 Mission duration shall be > 1 year

RQ-HN- 17 The flux of meteoroid and ejecta impactors in the size regime > 10 µm shall be determined.

A number of instrument types exist which can address this requirement. The favoured micrometeoroid impact detector solution is one based on impact ionisation.

No requirements on landing site are imposed.

In order to achieve objective OB-HN- 4 Demonstrate advanced power storage technologies (regenerative fuel cells) if enabling for other objectives the following requirement must be achieved:

RQ-HN- 18 Advanced power storage technology shall be applied in such a way that the duration of payload operations is increased

In order to achieve the objective OB-MB- 1 Investigate environmental effects on surface – surface communications the following requirements must be achieved:

RQ-MB- 1 The density of the local plasma shall be determined (TBC)

RQ-MB- 2 The composition of the local plasma shall be determined (TBC)

RQ-MB- 3 The time variability of the properties of local plasma shall be determined (TBC)

The above may be determined with a combination of Langmuir probes (TBC).

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In order to directly achieve objective OB-RS- 1 Determine the abundance as a function of depth and distribution of H2O / OH / hydrated minerals in the regolith introduced in Section 7.1.1.1, the following requirements must be met:

RQ-RS- 1 It shall be possible to differentiate between hydrated minerals and surface H2O, OH

RQ-RS- 2 Concentrations of H2O and OH on the surface shall be measured for concentrations greater than 10 ppm.

RQ-RS- 3 The concentration of H2O / OH in the regolith shall be measured to a depth of 20 cm (TBC) and with <5 mm resolution (higher resolution may be preferable close to the surface).

In order to meet the above requirements access to the subsurface from a rover is required. The instrumentation utilised to achieve the required measurements may be an infrared imaging spectrometer or a miniaturised mass spectrometer.

RQ-RS- 4 The mission shall provide mobile access to areas > 100 m from the lander to minimize contamination of the surface under contamination following the landing.

RQ-RS- 5 Landing site shall be at a location where orbital observations have suggested the presence of H2O, OH or hydrated minerals

In order to achieve objective OB-RS- 2 Perform "proof of concept" in-situ resource extraction based on SWIP volatiles, introduced in Section 7.1.1.8, the following requirements should be achieved:

RQ-RS- 6 Volatiles shall be liberated from lunar regolith.

RQ-RS- 7 The species of volatiles liberated shall be identified.

RQ-RS- 8 The quantities of volatiles extracted shall be determined.

RQ-RS- 9 The abundances and concentrations of those species in the lunar regolith shall be determined.

RQ-RS- 10 The mission shall provide mobile access to areas > 100 m from the lander to minimize contamination of the surface under contamination following the landing.

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The above requirements may be achieved through the application of a gas analysis package.

RQ-RS- 11 Contamination from the landing shall be no more than (TBD) (this may require mobility > 100m).

RQ-RS- 12 landing site shall be at a high latitude.

In order to achieve objective OB-PH- 1 Determine the density, composition, and time variability of the fragile lunar exosphere at the landing site before it is perturbed by further human activity, introduced in Section 9.1.1.2, the following requirements should be achieved:

RQ-PH- 1 Measure the number density and composition of neutrals in the lunar exosphere (nominally to include the following species: Ne, Ar, H, He, Na, K, CH4, H2O, OH, CO2, NH3).

RQ-PH- 2 Measure the number density and composition of ions in the lunar exosphere (nominally to include the following species: Ne, Ar, H, He, Na, K, CH4, H2O, OH, CO2, NH3).

The above requirements may be met by a neutral and ion mass spectrometer. Parallel measurements by Langmuir probes would also be beneficial.

Requirements for objective OB-PH- 2 Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar exploration are included in those derived to meet objective OB-HN- 2 Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities

In order to meet objective OB-PH- 3 Determine the regional thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and global scales introduced in Section 9.1.1.5 the following requirements must be met:

RQ-PH- 3 Ground based monitoring of impact flashes on the lunar surface must be made throughout the mission, with a sensitivity sufficient to detect light flashes attributed to impacts by meteoroids of mass > 1kg.

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This requirement is met ground based optic monitoring and cannot be provided by the lander payload.

RQ-PH- 4 Seismic events shall be measured in the frequency range 10-1 Hz-20 Hz with resolution 10 times better than Apollo LP and SP instruments (< 0.5 x 10-10 ms-1/Hz1/2 between 0.1 and 1Hz, 1/√f and f dependence for f<0.1 Hz and f>1 Hz respectively) and with > 22 bits resolution (e.g. 24 bits A/D).

RQ-PH- 5 Seismic waves shall be recorded with a time resolution of 10 ms on seismic samples.

The above requirements can be achieved through the application of both broad band and short period seismometers.

RQ-PH- 6 Heat flow measurements shall be made in the lunar soil to a depth of 3-5 m.

This requirement can be met by heat flow probes on a mole.

RQ-PH- 7 Landing site shall have a large separation from Apollo sites.

RQ-PH- 8 Mission duration shall be > 2 years (possibly 5 years) for seismic observations.

RQ-PH- 9 Measurements shall be continuous during illumination and darkness (for seismic observations).

RQ-PH- 10 Heat flow shall be recorded in a location other than that revealed in Lunar prospector data as having high U, Th content.

RQ-PH- 11 Heat flow measurements shall be performed for a period > 2 years (possibly 5 years).

RQ-PH- 12 Heat flow shall be measured with an accuracy of < 0.05 °C (0.001 °C for Apollo).

In order to fully achieve OB-PH- 4 Demonstrate the suitability of the lunar surface as a platform for low frequency radio astronomy, introduced in Section 9.1.1.6, the following requirements must be met (note that meeting some of the below requirements may still hold merit for future investigations).

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RQ-PH- 13 The radio background on the moon in the spectral and temporal domain shall be monitored.

RQ-PH- 14 Sources of temporal radio noise (e.g., meteoritic impacts, cosmic ray hits, geophysical) shall be determined.

RQ-PH- 15 The relative phase stability of radio waves (i.e., ionospheric turbulence) as a function of baseline length (i.e., separation of two radio antennas) shall be determined (if feasible).

RQ-PH- 16 Radio reflection and transmission of moon surface (crater rims, mountains) and regolith below 100 MHz (i.e., get dielectric constant) shall be measured.

A radio antenna and appropriate electronics can be used to meet the above requirements.

RQ-PH- 17 The column density of free electrons in the moon’s exosphere as a function of time and location shall be measured.

RQ-PH- 18 The ionospheric cut-off frequency shall be determined.

A radio antenna in conjunction with Langmuir probes may be applied to meet these requirements.

RQ-PH- 19 Solar irradiation shall be measured to calculate heating and cooling as well as energy supply at various locations (TBC).

RQ-PH- 20 Temperature variations at likely antenna locations shall be measured (TBC).

Temperature sensors on the lunar surface can contribute to this.

Objective OB-PO- 1 Engage the Public requires that the mission allow for public interest to be engaged.

RQ-PO- 1 The payload shall include elements to ensure public engagement and interest in the lunar lander.

There are many ways to meet this requirement. One possibility is high definition TV of the descent and landing and any surface operations. A small payload allocation for education or an open competition may also be an option. As a minimum high resolution imaging of the landing site is required.

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12.2 Requirements to Meet Medium Priority Objectives In order to achieve the objective OB-HT- 4 Improve current space weather forecast from the Moon to improve early warning systems for crews the following requirements should be met:

RQ-HT- 21 Solar protons with energies in the range 1 – 500 MeV shall be monitored continuously during illumination.

RQ-HT- 22 A dynamic range of proton fluxes between 10 and 106 W m-2 s-1 sr-1 shall be measurable.

RQ-HT- 23 Linear energy transfer spectra for SEPs shall be measured.

RQ-HT- 24 The flux of relativistic solar electrons in the energy range 0.3 – 1.2 MeV shall be measured during illumination.

RQ-HT- 25 A goal shall be the measurement of relativistic electron fluxes in the range 1- 10000 MeV cm-2 s-1 sr-1 along

RQ-HT- 26 Energy spectra energy for relativistic electrons shall be measured.

RQ-HT- 27 As a goal solar X-rays in the energy rage 0.5 – 7.7 keV shall be measured.

An X-ray and particle measuring solar monitor may be used to achieve the above requirement

In order to achieve the objective OB-RS- 3 Provide ground truth to support orbital observations, by other missions, of potential in-situ resources the following requirements should be met:

RQ-RS- 13 The mission shall measure the presence and % abundance of the following minerals in surface regolith in abundances greater than 0.05 % vol. (TBC): plagioclase, pyroxene (distinguishing between OPX, Augite etc.), olivine, silica, ilmenite, spinel, glasses.

An X-ray diffractometer may be applied to meet the above requirement or a Raman spectrometer or infrared spectrometer in conjunction with the one of the instruments listed with respect to the below requirement.

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RQ-RS- 14 The mission shall measure the % concentration (as a minimum) of the following elements, O, Al, Si, Mg, Ca, Ti, Fe, Mn, and ideally K, Cr and Na, to a precision of 0.1 wt% (TBC)

LIBS or a contact X-ray spectrometer may be applied to meet this requirement. The ultimate sensitivity may be achieved with a Laser Ablation Mass Spectrometer (LAMS)

RQ-RS- 15 The mission shall measure the concentration in ppm of the following elements: U, Th and other trace elements (e.g. Ni, Co, Sc, Sm, Sr, Ba, Zr) to a precision of a few ppm (TBC)

A gamma ray spectrometer may be applied to meet this requirement

RQ-RS- 16 The mission shall the concentration in ppm of H2O and OH on the surface to a precision of ~10 ppm (TBC)

In order to meet the above requirement access to the subsurface from a rover is required. The instrumentation utilized to achieve the required measurements may be an infrared imaging spectrometer or a mass spectrometer.

In order to achieve the objective OB-RS- 4 Determine abundance and distribution of solar wind implanted volatiles in a non-Apollo locality the following requirements should be met:

RQ-RS- 17 Solar wind implanted species shall be identified in lunar regolith to a depth of > 10 cm with a goal of 1m.

RQ-RS- 18 The isotopes of solar wind implanted species shall be identified.

RQ-RS- 19 The abundance of solar wind implanted species shall be determined

The above requirements may be achieved through the application of a gas analysing mass spectrometer.

RQ-RS- 20 Contamination of regolith by landing shall be minimized (may require mobility of ~100m and / or subsurface access).

In order to achieve the objective Preparations for human activity

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OB-PH- 5 Inventory the variety, distribution and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return the following requirements should be met:

RQ-PH- 21 As a minimum the mobile payload shall measure the abundance of the following elements, O, Al, Si, Mg, Ca, Ti, Fe, Mn, and ideally K, Cr and Na, to a precision of 0.1 wt% (TBC). It is also beneficial to measure the abundance of the following elements: U, Th and other trace elements (e.g. Ni, Co, Sc, Sm, Sr, Ba, Zr) to a precision of a few ppm (TBC).

LIBS or a contact X-ray spectrometer may be applied to meet this requirement in combination with a gamma ray spectrometer may be applied to meet this requirement. The ultimate geochemical sensitivity would be achieved by a LAMS.

RQ-PH- 22 The payload shall be capable to distinguish, as a minimum, the following minerals: Plagioclase, pyroxene (distinguishing between OPX, Augite etc.), olivine, silica, ilmenite, spinel, glasses, to a precision of ~0.1 vol % (TBC)

An X-ray diffractometer may be applied to meet the above requirement or a Raman spectrometer or infrared spectrometer in conjunction with the one of the instruments listed with respect to the below requirement.

RQ-PH- 23 It shall be possible to identify lithologies at distance

A Stereo panoramic imager can be used to achieve this objective in conjunction with a high resolution camera.

RQ-PH- 24 Dust and weathered rock shall be removed from rock surfaces prior to analysis so that rock subsurface beneath weathered layers can be accessed.

This requirement can be met by a rock abrasion tool, corer grinder or laser ablation.

RQ-PH- 25 The landing site shall be in a previously unexplored area. For sample return preparation landing site must be in a region of interest for future sample return (e.g. SPA). For studies of lunar crust a feldspathic highlands location would be of interest.

RQ-PH- 26 The system shall provide mobility with a range > 10 km

RQ-PH- 27 The system shall provide mobile access to regions of blocky ejecta of small impact craters (< ~100m)

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RQ-PH- 28 The system shall provide mobility in mountainous highlands terrain for crustal investigations.

In order to achieve the objective OB-SC- 1 Identify the presence of precursor chemistry for life in primitive ices the following requirements should be met:

RQ-SC- 1 The landing site shall be close to areas containing ice

RQ-SC- 2 Ice in permanently shadowed areas shall be accessed

RQ-SC- 3 Amino acids shall be detected and identified in concentrations > 1 ppm

RQ-SC- 4 Abundance ratios of amino acids shall be determined

RQ-SC- 5 Chirality of detected amino acids shall be determined

RQ-SC- 6 Stable isotope ratios of H, C, N, and S shall be determined

The above requirements need access to permanently shadowed areas. This is already established as being unfeasible for this mission and so requirements are not pursued further. Analysis of mass spectra of ejecta produced by impacts in permanently shadowed areas by a micrometeoroid impact detector with mass spectrometer applied to achieve other objectives may allow the above to be realised but these requirements will not be targeted specifically.

In order to achieve objective technologies the following requirement must be achieved:

RQ-HN- 19 TBC

In order to achieve objective technologies the following requirement must be achieved:

RQ-HN- 20 TBC

In order to achieve the objective OB-RS- 5 Perform ‘proof-of-concept’ in-situ resource extraction based on one possible ISRU process: ilmenite reduction, carbothermal reduction or molten silicate electrolysis one of the following requirements should be met:

RQ-RS- 21 Generate oxygen from regolith through ilmenite reduction

An ilmentite reduction system is required to meet the above. This is not considered feasible within the likely mass available for the mission.

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RQ-RS- 22 Generate oxygen from regolith through carbothermal reduction

A carbothermal reduction system is required to meet the above. This is not considered feasible within the likely mass available for the mission.

RQ-RS- 23 Generate oxygen from regolith through molten silicate electrolysis

A molten silicate electrolysis system is required to meet the above. This is not considered feasible within the likely mass available for the mission.

In order to achieve the objective OB-MB- 2 Characterise the key environmental parameters having a major impact on robotics and mobility elements the following requirements should be met:

RQ-MB- 4 The adhesive properties of the regolith shall be determined

RQ-MB- 5 The angle of internal friction of the regolith shall be determined

RQ-MB- 6 the bearing strength and cohesion of the lunar regolith shall be determined

RQ-MB- 7 The bulk density of the regolith shall be determined

RQ-MB- 8 The grain size distribution of the regolith shall be determined

RQ-MB- 9 The heterogeneity of the lunar regolith shall be determined

RQ-MB- 10 The penetration resistance of the lunar regolith shall be determined

The above requirements may be met by an instrumented robotic arm with high resolution cameras.

12.3 Requirements to Meet Low Priority Objectives

In order to achieve the objective OB-HT- 5 Determine the radiation shielding properties of lunar regolith the following requirements should be met:

RQ-HT- 28 Tissue dose equivalent shall be measured at various depths beneath the lunar surface as a function of time

A radiation monitor or dosimeter beneath the surface may be applied meet this requirement although understanding regolith properties is probably sufficient to calculate

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this (but in situ verification of models is important). The may be achieved by establishing soil properties and composition.

In order to achieve the objective OB-HN- 7 Determine thermal and heat flow properties of the regolith the following requirements should be met:

RQ-HN- 21 Heat flow to a depth of 3 – 5 m shall be measured

The above requirement can be met buy a mole with heat flow instrumentation.

RQ-HN- 22 The landing site shall be distinct from Apollo landing sites

RQ-HN- 23 The landing site shall be away from areas revealed in Lunar prospector data as having high U, Th content.

RQ-HN- 24 Mission duration shall be > 1 year

In order to achieve the objective OB-HN- 8 Determine the seismic risk to future human exploration activities, introduced in Section 6.4.1.1 the following requirements should be met:

RQ-HN- 25 All quakes potentially generating ground acceleration larger than 10 cm/s/s at the hypocenter location shall be detected

RQ-HN- 26 The distance to the epicentre of all quakes potentially generating ground acceleration larger than 10 cm/s/s at the hypocenter location shall be determined.

RQ-HN- 27 A vertical layered seismic model of the crust in a location of a potential human base shall be determined to better than 10% of relative

The above requirements can be met by a combination of short and long period seismometers.

In order to achieve the objective OB-RS- 6 Identify the abundance and distribution of ilmenite the following requirements should be met:

RQ-RS- 24 It shall be possible to determine presence and concentration of ilmentite in lunar regolith

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An X-ray diffractometer may be applied to meet the above requirement or a Raman spectrometer or infrared spectrometer in conjunction with an X-ray spectrometer or LIBS instrument. This requirement would be met in any case if RQ-RS- 14 and RQ-RS- 15 are met.

RQ-RS- 25 It shall be possible to access and analyse regolith > 1 cm beneath the surface

Note that while ilmentite should not be a driver of landing site determination the ability to detect and quantify the abundance of ilmanite in regolith is beneficial at any landing site. This objective will be addressed anyway if the medium priority objective OB-PH- 5 is addressed.

In order to achieve the objective OB-RS- 7 Improve our understanding of the potential use of highlands regolith as a resource the following requirements should be met:

Requirements to achieve this are included in RQ-RS- 13, RQ-RS- 14, RQ-RS- 15 and RQ- RS- 16 .

This objective will be addressed anyway if the medium priority objective OB-PH- 5 is addressed.

In order to achieve the objective OB-RS- 8 Improve our understanding of the potential use of mare regolith as a resource the following requirements should be met:

Requirements to achieve this are included in RQ-RS- 13, RQ-RS- 14, RQ-RS- 15 and RQ- RS- 16

This objective will be addressed anyway if the medium priority objective OB-PH- 5 is addressed.

In order to achieve the objective OB-RS- 9 Perform "proof of concept" in-situ resource extraction based on water/OH in the regolith the following requirements should be met:

RQ-RS- 26 If seen to be present then water shall be extracted from the lunar regolith.

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13 POTENTIAL INSTRUMENTATION AND TECHNIQUES

In order to meet the requirements derived in Section 12 a suite of instruments must be applied. In this section a number of measurement and experimental techniques are outlined along with their development status and heritage relevant to application on the lunar lander mission. The requirements which they may be applied to address are referenced. Specifications on the instrument performance and characteristics are not given here.

13.1 Stereo Panoramic Cameras Stereo cameras providing panoramic imaging can be used to characterise the topography and geological context around the landing sites and allow the production of 3D models of the surrounding terrain.

Appropriate cameras have been developed in Europe and have a high TRL of 4-5.

Requirements Related objectives Comments met High RQ-HN- 1 OB-HN- 1 Characterise the suitability of a potential future landing site for future exploration RQ-HN- 14 OB-HN- 2 Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities RQ-PO- 1 OB-PO- 1 Engage the Public Medium RQ-PH- 23 OB-PH- 5 Inventory the variety, distribution and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return

Table 13.1. Requirements, which can be met through the inclusion of a stereo panoramic camera in the mission payload and the objectives for which those requirements apply.

13.2 Radiation Monitor Radiation monitors are available in Europe and have flown on a number of missions. While radiation monitors of varying capabilities are available with varying TRLs radiation monitors generally may be considered as instruments with a high TRL of 5 or less depending on the capabilities required.

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A radiation monitor can be applied to meet requirements given on Table 13.2.

Requirements Related objectives Comments met High RQ-HT- 6 RQ- OB-HT- 1 Improve current understanding of the response of Can contribute in HT- 7 RQ-HT- 8 biological systems to radiation damage in the integrated lunar conjunction with environment such that risks assessment for humans can be improved other experiments RQ-HT- 10 OB-HT- 2 Quantify the radiation risk to humans due to galactic cosmic rays

Table 13.2. Requirements, which can be met through the inclusion of a radiation monitor in the mission payload and the objectives for which those requirements apply.

13.3 Radiation Biology Experiment A dedicated radiation biology experiment addressing radiation effects in human physiology in the integrated lunar environment requires a dedicated development and feasibility assessment within the constraints of the mission. Below we describe a favoured approach to an experiment which could be applied to address requirements given in Table 13.3.

Requirements Related objectives Comments met High RQ-HT- 1 OB-HT- 1 Improve current understanding of the response of In combination with biological systems to radiation damage in the integrated lunar environment radiation monitor such that risks assessment for humans can be improved RQ-HT- 2 RQ-HT- 3 RQ-HT- 4 RQ-HT- 5

Table 13.3. Requirements, which can be met through the inclusion of a radiation biology experiment in the mission payload and the objectives for which those requirements apply.

As a first step, cell cultures can be used to characterize radiation response. Cell lines can be genetically engineered to constitutionally express fluorescent markers such as Green Fluorescent-Protein (GFP) or luciferase. These markers can monitor transcriptional activity of specific promoters, thus providing real-time information on the viability and metabolic activity of the cells, or allowing live visualization of recruitment of DNA repair proteins to sites of heavy ion hits [RD 100] (Figure 13.1). The method could be used to provide real-time biodosimetry from patterns of foci, thus addressing specifically the issue

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of the mixed-radiation field exposure. Moreover they can be used to trace cell division and the resulting progeny. Bioluminescence assays can be applied to monitor a number of transcriptional and metabolic pathways that can be activated in response to radiation and stress, such as the NF-κB pathway [RD 101], as well as other endpoints expected to be altered in reduced microgravity, such as the cytoskeleton functional status [RD 102]. Samples in containers with different shielding can be used to single out the radiation effects from the other stress-related response. Obviously telemonitoring and teleoperation will require a very sophisticated technology, particularly considering the mass/volume constraints. Nevertheless, normal human cell lines expressing fluorescent markers are the most promising biological systems for preliminary radiobiology experiments on the Moon, and could provide first information on the cellular response to the complex radiation field under stress conditions.

Figure 13.1. Time-dependent changes of a single ion-induced DNA damage streak, showing the typical motional behaviour of individual foci along the trajectory over the time course of 12 h after irradiation at the GSI accelerator facility. A human osteosarcoma cell line stably expressing GFP-tagged 53BP1 was used. 53BP1 is a repair protein readily recruited to the sites of DNA double-strand breaks that were here induced by a traversal of a single 6 MeV/n 28Ni-ion [RD 100].

In order to achieve the above cell systems must be used to characterize the radiation response of cells on the Moon. These cells need to be maintained to point of exposure to the radiation environment and then kept alive for several weeks during exposure. Cell death must be detected if it occurs. Monitoring transcriptional activity of specific

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promoters can provide real-time information on the viability and metabolic activity of the cells, or allow live visualization of recruitment of DNA repair proteins to sites of heavy ion hits. This probably needs to be done through cells engineered to constitutionally express fluorescent markers such as green-fluorescent-protein (GFP) or luciferase. Considering the size of the cell nucleus and the flux of ions on the moon, it is expected that approximately 2 protons and 0.4 heavier ions per nucleus could be observed per week. Telemonitoring could be able to monitor several hundred cells for extended periods. A minimum duration for exposure for any investigation of this nature is expected to be > 1 month with a goal of > 1 year. Within the practical constraints

In parallel the radiation environment must be monitored as described in Sections 5.1.3.1 and 5.1.3.2.

Heritage in the techniques applied exists in ground based observations in accelerator faculties. Adaptation for a lunar mission on this scale is probably feasible in the given time frame but may represent considerable effort.

13.4 High Resolution Camera A high resolution camera can be accommodated together with panoramic cameras or on a robotic arm. Suitable cameras have been developed in Europe and have a TRL of around 5.

Requirements Related objectives Comments met High RQ-HT- 11 OB-HT- 3 Quantify the health risks to human exploration posed by In largest size lunar dust unrepresented in sample collections regime RQ-HN- 12 OB-HN- 2 Improve current models of charging, transport, adhesion By imaging dust and abrasion of lunar dust as relevant to future lunar exploration activities accumulation on OB-PH- 2 Determine the size, charge, and spatial distribution of lander surfaces and electrostatically transported dust grains and assess their likely effects on patch plates lunar exploration Medium RQ-PH- 21 OB-PH- 5 Inventory the variety, distribution and origin of lunar Requires rock types in order to advance our understanding of the lunar crust and accommodation a prepare for future human missions and sample return mobile platform. RQ-PH- 23 RQ-MB- 4 OB-MB- 2 Characterise the key environmental parameters having a Together with an RQ-MB- 5 major impact on robotics and mobility elements with an arm and / or RQ-MB- 6 mobility element RQ-MB- 7 RQ-MB- 8 RQ-MB- 9 RQ-MB- 10

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Table 13.4. Requirements, which can be met through the inclusion of a high resolution camera in the mission payload and the objectives for which those requirements apply.

13.5 Wet Chemistry Station A wet chemistry station of similar design to that accommodated on the Phoenix lander, which was originally developed to investigate the effects of Martian dust for human spaceflight, may provide a means to determine chemical properties of lunar regolith and dust in situ. Properties measured include, pH, redox potential, oxidants and reductants and ion species [RD 99]. There is no European heritage in such an instrument and the feasibility and applicability would need to be assessed.

Requirements Related objectives Comments met High RQ-HT- 14 OB-HT- 3 Quantify the health risks to human exploration posed by Requires samples to lunar dust unrepresented in sample collections be delivered.

Table 13.5. Requirements, which may be met through the inclusion of a wet chemistry station in the mission payload and the objectives for which those requirements apply.

13.6 Dust Effects on Microorganisms Experiment A dedicated experiment requiring the delivery of dust and the monitoring of its effects on microbes could be achieved. Current TRL is ~2 so significant development effort would be required. The experiment mass may be critical.

Requirements Related objectives Comments met High RQ-HT- 20 OB-HT- 3 Quantify the health risks to human exploration posed by lunar dust unrepresented in sample collections Table 13.6. Requirements, which may be met through the inclusion of a dedicated experiment to observe the effects of lunar dust on microorganisms in the mission payload and the objectives for which those requirements apply.

13.7 Dust Trajectory Sensor Dust trajectory sensors have been developed at breadboard level for use in micometeoroid impact sensors.

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Requirements Related objectives Comments met High RQ-HT- 20 OB-HT- 3 Quantify the health risks to human exploration posed by in conjunction with lunar dust unrepresented in sample collections Langmuir probe and only levitated grains OB-HN- 3 Quantify the risk to human exploration posed by impacts While not achieving requirements linked to this objective the instrument may contribute RQ-HN- 2 OB-HN- 2 Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar RQ-HN- 3 exploration activities OB-PH- 2 Determine the size, charge, and spatial distribution of RQ-HN- 4 electrostatically transported dust grains and assess their likely effects on lunar exploration Table 13.7. Requirements, which may be met through the inclusion of a dust trajectory sensor in the mission payload and the objectives for which those requirements apply.

13.8 Langmuir Probes Langmuir probes have extensive heritage in space applications.

Requirements Related objectives Comments met High RQ-HT- 11 OB-HT- 3 Quantify the health risks to human exploration posed by in conjunction with lunar dust unrepresented in sample collections dust sensor, only for levitated grains RQ-HN- 5 OB-HN- 2 Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities RQ-HN- 6 OB-PH- 2 Determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on RQ-HN- 7 lunar exploration RQ-MB- 1 OB-MB- 1 Investigate environmental effects on surface – surface Contributes but communications limited benefit as stand alone. RQ-MB- 2 RQ-MB- 3 RQ-PH- 17 OB-PH- 4 Demonstrate the suitability of the lunar surface as a RQ-PH- 18 platform for low frequency radio astronomy

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Table 13.8. Requirements, which may be met through the inclusion of Langmuir probes in the mission payload and the objectives for which those requirements apply.

13.9 Optical Microscope

Requirements Related objectives Comments met High RQ-HT- 11 OB-HT- 3 Quantify the health risks to human exploration posed by Medium to large lunar dust unrepresented in sample collections size regime RQ-HT- 12 If hyperspectral capability included RQ-HN- 8 OB-HN- 2 Improve current models of charging, transport, adhesion RQ-HN- 9 and abrasion of lunar dust as relevant to future lunar exploration activities Table 13.9. Requirements, which may be met through the inclusion of an optical microscope in the mission payload and the objectives for which those requirements apply.

13.10 Atomic Force Microscope Atomic force microscopes for space applications have been developed for Phoenix and Rosetta and thus have a high TRL. In this case a Phoenix like instrument requiring samples to be delivered is probably the preferred choice. Such an instrument provides the only access to the nanometer size regime in surface dust but practicalities of using the instrument for scanning of dust samples for small particles are likely to make its application to investigating nanoscale dust unfeasible. Nanometer scale features on larger dust particles would be feasible.

Requirements Related objectives Comments met High RQ-HT- 11 OB-HT- 3 Quantify the health risks to human exploration posed by RQ-HT- 17 lunar dust unrepresented in sample collections RQ-HN- 8 OB-HN- 2 Improve current models of charging, transport, adhesion RQ-HN- 9 and abrasion of lunar dust as relevant to future lunar exploration activities Table 13.10. Requirements, which may be met through the inclusion of an atomic force microscope in the mission payload and the objectives for which those requirements apply

13.11 X-ray Spectrometer An X-ray spectrometer provides the surface (to a depth of a few microns) composition of major elements in a bulk sample of lunar regolith, dust or a rock under examination. X-ray

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spectrometers of varying types have been applied on several planetary missions and the TRL can be considered high. An instrument with for example and Fe 55 excitation source (5.9 keV emission) could provide access to elements given in Table 13.11, assuming sensitivity to ~0.5 keV.

Requirements which may be addressed by an X-ray spectrometer and the objectives to which they contribute are given in Table 13.12.

Element Line Energy (keV) Fe L 0.71 Na K 1.04 Mg K 1.25 Al K 1.49 Si K 1.74 P K 2.02 S K 2.31 K K 3.35 Ca Kα 3.70 Ca Kβ 4.02 Ti K 4.51 V K 4.96 Cr K 5.43 Table 13.11. Emission lines of major elements observable with an X-ray spectrometer with an Fe 55 excitation source.

Requirements Related objectives Comments met High OB-HT- 3 Quantify the health risks to human exploration posed by bulk composition lunar dust unrepresented in sample collections only Medium RQ-RS- 14 OB-RS- 3 Provide ground truth to support orbital observations, by other missions, of potential in-situ resources RQ-PH- 21 OB-PH- 5 Inventory the variety, distribution and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return

Table 13.12. Requirements, which may be met through the inclusion of an X-ray spectrometer in the mission payload and the objectives for which those requirements apply.

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13.12 X-ray Diffractometer An X-ray diffractometer is currently under development for Exomars and extensive relevant expertise exists in Europe. The instrument provides the mineralogical and elemental composition of powdered samples. The technique is the standard technique for establishing mineralogy in terrestrial laboratories. In the case of regolith the bulk composition is determined. For rocks complex sampling and preparation are required.

Requirements Related objectives Comments met High OB-HT- 3 Quantify the health risks to human exploration posed by Requires sampling lunar dust unrepresented in sample collections – bulk composition only Medium RQ-RS- 13 OB-RS- 3 Provide ground truth to support orbital observations, by other missions, of potential in-situ resources RQ-PH- 22 OB-PH- 5 Inventory the variety, distribution and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return Low RQ-RS- 24 OB-RS- 6 Identify the abundance and distribution of ilmenite OB-RS- 7 Improve our understanding of the potential use of same as OB-RS-4 highlands regolith as a resource OB-RS- 8 Improve our understanding of the potential use of mare same as OB-RS-4 regolith as a resource Table 13.13. Requirements, which may be met through the inclusion of an X-ray diffractometer in the mission payload and the objectives for which those requirements apply.

13.13 Laser Ionisation Breakdown Spectrometer

Requirements Related objectives Comments met High RQ-HT- 18 OB-HT- 3 Quantify the health risks to human exploration posed by lunar dust unrepresented in sample collections Medium RQ-RS- 14 OB-RS- 3 Provide ground truth to support orbital observations, by other missions, of potential in-situ resources RQ-PH- 21 OB-PH- 5 Inventory the variety, distribution and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return Table 13.14. Requirements, which may be met through the inclusion of a LIBS spectrometer in the mission payload and the objectives for which those requirements apply.

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A LIBS spectrometer can provide elemental composition of rocks and soils under analysis. The application of the technique in high vacuum environments results in a loss of sensitivity compared with the Martian atmosphere and so the implication so of this for application in the mission must be determined.

13.14 Mössbauer Spectrometer An instrument of choice in previous rover missions to Mars Mössbauer provides information on Fe bearing minerals.

Requirements Related objectives Comments met High OB-HT- 3 Quantify the health risks to human exploration posed by Merits of Fe lunar dust unrepresented in sample collections minerals needs clarification Medium RQ-RS- 13 OB-RS- 3 Provide ground truth to support orbital observations, by Contributes other missions, of potential in-situ resources RQ-RS- 16 OB-PH- 5 Inventory the variety, distribution and origin of lunar Contributes rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return Table 13.15. Requirements, which may be met through the inclusion of a Mössbauer spectrometer in the mission payload and the objectives for which those requirements apply.

13.15 Raman Spectrometer

Requirements Related objectives Comments met High RQ-HT- 13 OB-HT- 3 Quantify the health risks to human exploration posed by lunar dust unrepresented in sample collections Medium RQ-RS- 13 OB-RS- 3 Provide ground truth to support orbital observations, by other missions, of potential in-situ resources RQ-PH- 22 OB-PH- 5 Inventory the variety, distribution and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return Table 13.16. Requirements, which may be met through the inclusion of a Raman spectrometer in the mission payload and the objectives for which those requirements apply.

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13.16 IR spectrometer IR spectrometers in different wavebands will have sensitivity to different minerals and chemicals of interest. Examples of relevant IR absorption features in the visible and near infrared are given in are given in Table 13.17. NIR spectroscopy can be applied in instruments for macroscopic viewing of the lunar surface or microscopic imaging of samples.

Requirements which can be met by an IR spectrometer are given along with their associated objectives in Table 13.18.

Species Wavelength (nm) Absorption Feature Hydrated minerals 2750 HO vibration, narrow Hydrated minerals 2800-3200 H2O collective mode, very large Water ice (subdued) 2940 Subdued Water ice 3100 Wide Hydroxides 650 Fe3+ transition in iron oxides & hydroxides Hydroxides ~750 Local max in iron oxides & hydroxides Pyroxenes 1900-2200 Second Fe transition in pyroxenes. Orthopyroxenes 900 Centre of Fe2+ band in orthopyroxenes (e.g., enstatite, hypersthene). Band would be absent in Fe-free enstatite Pyroxenes 930 Centre of Fe2+ band in low-Ca clinopyroxenes (e.g., pigeonite) Pyroxenes 950 Centre of Fe2+ band in mid-Ca clinopyroxenes (e.g., augite) Pyroxenes 1000 Centre of Fe2+ band in high-Ca clinopyroxenes (e.g., diopside). Band would be absent in Fe-free diopside olivine 900-1050 Olivine triplet. Very marked band, more easily detected if low Fe contents Feldspar ~1100-1300 Large but very shallow feldspar band (Major diagnostic of anorthositic crust)

Ilmenite 400-500 Near-center of a very large and wide transition in titanium oxides Iron oxides 800-900 Center of Fe3+ transition in iron oxides Table 13.17. Some absorption features of interest for meeting defined requirements in the visible and near infrared.

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Requirements Related objectives Comments met High RQ-RS- 2 OB-RS- 1 Determine the abundance as a function of depth and Remote distribution of H2O / OH / hydrated minerals in the regolith observations may contribute without mobility. Medium RQ-RS- 13 OB-RS- 3 Provide ground truth to support orbital observations, by RQ-RS- 16 other missions, of potential in-situ resources RQ-PH- 22 OB-PH- 5 Inventory the variety, distribution and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return Table 13.18. Requirements, which may be met through the inclusion of an IR spectrometer in the mission payload and the objectives for which those requirements apply.

13.17 Gamma Ray Spectrometer

Requirements Related objectives Comments met Medium RQ-RS- 15 OB-RS- 3 Provide ground truth to support orbital observations, by other missions, of potential in-situ resources

Table 13.19. Requirements, which may be met through the inclusion of a Gamma ray spectrometer in the mission payload and the objectives for which those requirements apply.

13.18 Neutral and Ion Spectrometer

Requirements Related objectives Comments met High RQ-PH- 1 OB-PH- 1 Determine the density, composition, and time variability of the fragile lunar exosphere at the landing site before it is perturbed by RQ-PH- 2 further human activity Table 13.20. Requirements, which may be met through the inclusion of a Neutral and mass spectrometer in the mission payload and the objectives for which those requirements apply.

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13.19 Broad Band Seismometer

Requirements Related objectives Comments met High RQ-PH- 4 OB-PH- 3 Determine the regional thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and RQ-PH- 5 global scales Low RQ-HN- 25 OB-HN- 8 Determine the seismic risk to future human exploration RQ-HN- 26 activities RQ-HN- 27 Table 13.21. Requirements, which may be met through the inclusion of a broad band seismometer in the mission payload and the objectives for which those requirements apply.

13.20 Short Period Seismometer

Requirements Related objectives Comments met High RQ-HN- 15 OB-HN- 3 Quantify the risk to human exploration posed by impacts

RQ-PH- 4 OB-PH- 3 Determine the regional thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and RQ-PH- 5 global scales Low RQ-HN- 25 OB-HN- 8 Determine the seismic risk to future human exploration RQ-HN- 26 activities RQ-HN- 27 Table 13.22. Requirements, which may be met through the inclusion of a short period seismometer in the mission payload and the objectives for which those requirements apply.

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13.21 Mole and Heat Flow Experiment

Requirements Related objectives Comments met High RQ-PH- 6 OB-PH- 3 Determine the regional thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and global scales RQ-PH- 20 OB-PH- 4 Demonstrate the suitability of the lunar surface as a platform for low frequency radio astronomy Low RQ-HN- 21 OB-HN- 7 Determine thermal and heat flow properties of the regolith Table 13.23. Requirements, which may be met through the inclusion of a mole and heat flow experiment in the mission payload and the objectives for which those requirements apply.

13.22 Radio Antenna

Requirements Related objectives Comments met High RQ-HN- 15 OB-HN- 3 Quantify the risk to human exploration posed by impacts

RQ-PH- 13 OB-PH- 4 Demonstrate the suitability of the lunar surface as a RQ-PH- 14 platform for low frequency radio astronomy RQ-PH- 15 RQ-PH- 16 RQ-PH- 17 RQ-PH- 18

Table 13.24. Requirements, which may be met through the inclusion of a radio antenna in the mission payload and the objectives for which those requirements apply.

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13.23 Patch Plates

Requirements Related objectives Comments met High RQ-HN- 12 OB-HN- 2 Improve current models of charging, transport, together with high adhesion and abrasion of lunar dust as relevant to future lunar resolution imager exploration activities Table 13.25. Requirements, which may be met through the inclusion of patch plates for imaging in the mission payload and the objectives for which those requirements apply.

13.24 Quartz Crystal Microbalance

Requirements Related objectives Comments met High RQ-HN- 12 OB-HN- 2 Improve current models of charging, transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities Table 13.26. Requirements, which may be met through the inclusion of a quartz crystal microbalance in the mission payload and the objectives for which those requirements apply.

13.25 Micrometeoroid Impact Detector A meteoroid impact detector with a mass spectroscopy capability may also detect water ice particles in ejecta from within craters. Requirements in line with this objective are not defined because success cannot be assured within the scope of this mission but however to contribute to this would have a high impact (see Section 7.1.1.1).

Requirements Related objectives Comments met High RQ-HN- 17 OB-HN- 3 Quantify the risk to human exploration posed by impacts

N/A OB-SC- 1 Identify the presence of precursor chemistry for life in May contribute if a primitive ices mass spectrometer is included Table 13.27. Requirements, which may be met through the inclusion of a meteoroid impact detector in the mission payload and the objectives for which those requirements apply.

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13.26 High Definition Video

Requirements Related objectives Comments met High RQ-HN- 17 OB-PO- 1 Engage the Public Table 13.28. Requirements, which may be met through the inclusion of high definition video in the mission payload and the objectives for which those requirements apply.

13.27 Subsurface Mass Spectrometer

Requirements Related objectives Comments met High RQ-RS- 1 OB-RS- 1 Determine the abundance as a function of depth and RQ-RS- 2 distribution of H2O / OH / hydrated minerals in the regolith RQ-RS- 3 Table 13.29. Requirements, which may be met through the inclusion of a subsurface mass spectrometer in the mission payload and the objectives for which those requirements apply.

13.28 Subsurface Imaging Infrared Spectrometer

Requirements Related objectives Comments met High RQ-RS- 1 OB-RS- 1 Determine the abundance as a function of depth and RQ-RS- 2 distribution of H2O / OH / hydrated minerals in the regolith RQ-RS- 3

Table 13.30. Requirements, which may be met through the inclusion of a subsurface infrared spectrometer in the mission payload and the objectives for which those requirements apply.

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13.29 Gas Analysis Package

Requirements Related objectives Comments met High RQ-RS- 6 OB-RS- 2 Perform "proof of concept" in-situ resource extraction RQ-RS- 7 based on SWIP volatiles RQ-RS- 8 RQ-PH- 1 OB-PH- 1 Determine the density, composition, and time variability of the fragile lunar exosphere at the landing site before it is perturbed by RQ-PH- 2 further human activity Medium

RQ-RS- 16 OB-RS- 3 Provide ground truth to support orbital observations, by other missions, of potential in-situ resources RQ-RS- 17 OB-RS- 4 Determine abundance and distribution of solar wind RQ-RS- 18 implanted volatiles in a non-Apollo locality RQ-RS- 19 Low

RQ-RS- 26 OB-RS- 9 Perform "proof of concept" in-situ resource extraction based on water/OH in the regolith

Table 13.31. Requirements, which may be met through the inclusion of gas analysis package in the mission payload and the objectives for which those requirements apply.

13.30 Rock abrasion tool / corer grinder Access to surfaces beneath weathered layers on rocks requires a corer grinder or rock abrasion tool.

Requirements Related objectives Comments met Medium RQ-PH- 24 OB-PH- 5 Inventory the variety, distribution and origin of lunar rock types in order to advance our understanding of the lunar crust and prepare for future human missions and sample return Table 13.32. Requirements, which may be met through the inclusion of rock abrasion tool or corer grinder in the mission payload and the objectives for which those requirements apply.

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13.31 X-ray and Particle measuring Solar Monitor

Requirements Related objectives Comments met Low RQ-HT- 21 OB-HT- 4 Improve current space weather forecast from the Moon to RQ-HT- 22 improve early warning systems for crews RQ-HT- 23 RQ-HT- 24 RQ-HT- 25 RQ-HT- 26 RQ-HT- 27 Table 13.33. Requirements, which may be met through the inclusion of a particle and X-ray spectrometer in the mission payload and the objectives for which those requirements apply.

13.32 Subsurface dosimeter

Requirements Related objectives Comments met Low RQ-HT- 28 OB-HT- 5 Determine the radiation shielding properties of lunar regolith

Table 13.34. Requirements, which may be met through the inclusion of a sub surface dosimeter in the mission payload and the objectives for which those requirements apply.

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14 MISSION SCENARIO AND IMPLICATIONS FOR ACHIEVABLE OBJECTIVES While the ideal mission scenario is one in which all objectives defined in this document can be achieved the practical constraints on the mission may be such that optimising the return from what is available is important. In order to identify the key elements of a mission to meet the objectives defined here high priority objectives listed in Section 11.1 and the requirements they generate with regard to requirements for landing site, mission duration and mobility are summarised in Table 14.1.

Analysis of these requirements shows that an optimal mission has duration of several years, can survive long periods without illumination, provides mobility on a scale of 10s km as well as a lander with a fixed payload, and allows some instruments to operate during periods of darkness. Restrictions on the costs of the mission or the available technologies (RHUs and RTGs) are likely to lead to scenarios in which mobility is restricted in operations or not available or in which long duration survival is not possible. The total mass available for payload is also an important consideration.

In the following sections we consider the importance of mission duration, night operations, landing site and mobility on the objectives that can be achieved.

Objective Landing site Duration Mobility OB-LG- 1 Demonstrate soft precision landing with No No No hazard avoidance OB-HT- 1 Improve current understanding of the No >1 month No response of biological systems to radiation damage in the goal > 1year integrated lunar environment such that risks assessment RQ-HT- 9 for humans can be improved OB-HT- 2 Quantify the radiation risk to humans due No No to galactic cosmic rays OB-HT- 3 Quantify the health risks to human Representative No No (could exploration posed by lunar dust unrepresented in sample of a possible benefit from collections future site mobility > RQ-HT- 19 100 m) OB-HN- 1 Characterise the suitability of a potential Representative No No future landing site for future exploration of a possible future site RQ-HT- 19 OB-HN- 2 Improve current models of charging, No Maximised No transport, adhesion and abrasion of lunar dust as relevant to future lunar exploration activities OB-HN- 3 Quantify the risk to human exploration No > 1 year Ideal case posed by impacts (possibly several km

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more depending on time for deployment) RQ-HN- 16 OB-HN- 4 Demonstrate advanced power storage No No No technologies (regenerative fuel cells) if enabling for other objectives OB-MB- 1 Investigate environmental effects on No No No but would surface – surface communications benefit from mobility OB-RS- 1 Determine the abundance as a function of High latitude No > 100m depth and distribution of H2O / OH / hydrated minerals in previously RQ-RS- 4 the regolith identified site RQ-RS- 5 OB-RS- 2 Perform "proof of concept" in-situ High latitudes No No (but may resource extraction based on SWIP volatiles RQ-RS- 12 benefit from mobility > 100m) OB-PH- 1 Determine the density, composition, and No No No time variability of the fragile lunar exosphere at the landing site before it is perturbed by further human activity OB-PH- 2 Determine the size, charge, and spatial No No No distribution of electrostatically transported dust grains and assess their likely effects on lunar exploration OB-PH- 3 Determine the regional thickness of the Far from > 2 years No lunar crust (upper and lower) and characterize its lateral Apollo RQ- (possibly 5) variability on regional and global scales PH- 7 RQ-PH- 8 RQ-PH- 11 OB-PH- 4 Demonstrate the suitability of the lunar Polar or far No No surface as a platform for low frequency radio astronomy side preferred OB-PO- 1 Engage the Public No No No Table 14.1. High priority objectives and their implications for mission scenario in terms of landing site mission duration and mobility.

14.1 Mission duration An ideal scenario would see a mission duration of > 2 years and ideally 5 – 6. This would ensure that all high priority mission objectives were achieved. Long duration operations are not mandatory for all objectives but output for all will be optimised if the duration of surface operations can be extended as far as possible. To achieve such a scenario will require that the mission survive sustained periods of darkness. Analyses of the topography of the lunar South Pole indicate that a minimum night duration which must be survived in order to ensure a mission > 1 year, can be strongly site dependent and can vary between a few days up to several 10’s of days. For equatorial sites a two week survival period per

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month is required. The survival of darkness periods should therefore be a goal, to ensure that the mission duration can be long a period as possible. Once the maximum duration of survival that can be assured has been ascertained the objectives which are achievable can be identified and this will drive the selection of a model payload.

The availability and application of Radioisotope Heating Units (RHUs) is likely to be key to long duration survival in darkness (>200 hours). In the event of a mission without RHUs a mission duration of < 1 year must be assumed as the nominal case (likely to be ~7 months maximum for a near South Pole locality selected for maximum illumination duration). In this eventuality it is recommended that efforts be made to increase this duration as far as is possible.

14.2 Night operations Some investigations benefit from operations during periods of darkness (e.g. seismology), or through part of the periods of darkness (e.g. dust dynamics). Enabling this capability is a high priority but is secondary to maximising the mission duration.

14.3 Landing site Most objectives do not impose restrictions on landing sites. For those that do a high latitude landing site would be appropriate, in the highlands or near to the South Pole Aitken basin. A driver for landing site is likely to be mission duration which would also favour a landing site near to the South Pole.

14.4 Mobility A strong return can be achieved without mobility as most of the investigations relating to high priority objectives do not require mobility. Mobility as a stand alone technology preparation has limited merit beyond laboratory testing, although mobility in support of other objectives would be useful for future preparation. Mobility > 100m would enable one high priority objective of measuring the depth distribution of H2O and OH in the regolith as a potential future resource. Mobility of several km is enabling for meteoroid impact related investigations although a mission duration > 1 year is also required to achieve this.

Radio astronomy preparation also benefits from mobility of more than a few hundred meters, as will the ability to access small patches of permanent shadow which may exist under rocks close to the landing site.

For a near polar location the operations of a mobile element beyond several hundred meters of a landing site, selected for favourable illumination conditions, are likely to be driven by the illumination; its variability and extent.

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RD 70 Nakamura Y., Shallow Moonquakes: How they compare with Earthquakes. Proc. Lunar Planet. Sci. Conf. 11th, 1847-1853, 1980. RD 71 Oberst J., Unusually high stress drops associated with shallow Moonquakes. J. Geophys. Res. 92, 1397-1405, 1987. RD 72 Oberst J. and Nakamura Y., A seismic risk for the lunar base. Lunar Bases & Space Activities 2, 231-233. Lunar & Planetary Institute, Houston, 1992. RD 73 Arnold, J.R.,Ice at the lunar poles, J.Geophys.Res., 84, 5659–5668, 1979. RD 74 Feldman, W.C., Maurice, S., Binder, A.B., Barraclough, B.L., Elphic, R.C., Lawrence, D.J., 1998. Fluxes of fast and epithermal neutrons from Lunar Prospector: evidence for water ice at the lunar poles, Science, 281, 1496–1500, 1998. RD 75 Feldman, W.C., Lawrence, D.J., Elphic, R.C., Vaniman, D.T., Thomsen, D.R., Barraclough, B.L., Binder,A.B., Chemical information content of lunar thermal and epithermal neutrons, J. Geophys. Res. 105, 20347–20363, 2000. RD 76 Nozette, S., Spudis, P.D., Robinson, M.S., Bussey, D.B.J., Lichtenberg, C., Bonner, R., Integration of lunar, polar remote sensing datasets: evidence for ice at the lunar south pole. J. Geophys. Res., 106 ,23253–23266, 2001. RD 77 Hodges, R., Ice in the lunar polar regions revisited, J. Geophys. Res.,107, 5011, 2002. RD 78 Campbell, B.A., Campbell, D.B., Carter, L.M., Margot, J.-L., Stacy, N.J.S., No evidence for thick deposits of ice at the lunar south pole. Nature, 443, 835–837, 2006. RD 79 Crider, D.H.,Vondrak, R.R., Hydrogen migration to the lunar poles by solar wind bombardment of the Moon. Adv. Space Res., 30, 1869–1874, 2002. RD 80 Gibson, M.A., Knudsen, C.W., Lunar oxygen production from ilmenite, In “Lunar Bases and Space Activities of the 21st Century”, Ed. Mendell, W.W., Lunar and Planetary Institute, Houston, 543–550, 1985. RD 81 Williams, R.J., 1985. Oxygen extraction from lunar materials: an experimental test of an ilmenite reduction process, In “Lunar Bases and Space Activities of the 21st Century”, Ed. Mendell, W.W., Lunar and Planetary Institute, Houston, 551–558, 1985. RD 82 Cutler, A.H. and Krag, P., A carbothermal scheme for lunar oxygen production, In “Lunar Bases and Space Activities of the 21st Century”, Ed. Mendell, W.W., Lunar and Planetary Institute, Houston, 559–569, 1985. RD 83 Pieters, C. M., Goswami, J. N., Clark, R. N. et al., Character and Spatial Distribution of OH/H2O on the Surface of the Moon Seen by M3 on Chandrayaan-1, Science, 326, 5952, 568, 2009. RD 84 Sunshine, J.M., Farnham, T.L., Feaga, L.M., Groussin, O., Merlin, F., Milliken, R. E., A'Hearn, M.F., Temporal and spatial variability of lunar hydration as observed by the Deep Impact spacecraft, Science, 326, 5952, 565, 2009. RD 85 Clark, R.N., Detection of adsorbed water and hydroxyl on the Moon, Science, 326, 5952, 562, 2009.

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RD 86 Saal, A.E., Hauri, E.H., Cascio, M.L., van Orman, J.A., Rutherford, M.C., Cooper, R.F., Volatile content of lunar volcanic glasses and the presence of water in the Moon's interior, Nature, 454, 7201, 192-195, 2008. RD 87 El Goresy, A., Ramdohr, P., Pavićević, M., Medenbach, O., Müller, O., Gentner, W., Zinc, lead, chlorine and FeOOH-bearing assemblages in the Apollo 16 sample 66095: origin by impact of a comet or a carbonaceous chondrite?, Earth and Planetary Science Letters, 18, 411, 1973. RD 88 Taylor, L. A., Mao, H. K., Bell, P. M., Identification of the hydrated iron oxide mineral akaganéite in Apollo 16 lunar rocks, Geology, 2, 429 – 432, 1974.

RD 89 Stooke, P.J., The international atlas of lunar exploration, Cambridge University Press, 2007. RD 90 Carpenter, J.D. and the MoonNEXT Science Definition Team, MoonNEXT Science and Payload Definition Document, ESA document NEXT-LL-SPDD- ESA(HME)-0001, 2008. RD 91 Neal, C.R., The Moon 35 years after Apollo: What’s left to learn?, Chemie Erde- Geochemistry, doi:10.1016/j.chemer.2008.07.002, 2008. RD 92 Mendillo, M., The atmosphere of the Moon, Proc. Earth-Moon Relationships, Padova, 2001. RD 93 Cane, H.V. and Whitham, P.S., Observations of the southern sky at five frequencies in the range 2-20 MHz, MNRAS, 179, 21, 1977. RD 94 Elis, G.R.A. and Mendillo, M, A 1.6 MHz survey of the galactic background radio emission, Australian Journal of Physics, 40, 705, 1987. RD 95 Cane, H.V. and Erickson, W.C., A 10 MHz map of the galaxy, Radio Science, 36, 1765, 2001. RD 96 Novaco, J.C. and Brown, L.W., Nonthermal galactic emission below 10 megahertz, ApJ, 221, 114, 1978. RD 97 Jester, S. and Falcke, H., Science with a lunar low-frequency array: from the dark ages of the Universe to nearby exoplanets, A&A, under review, 2007. RD 98 Carilli, C.L., Hewit, J.N. and Loeb, A., in Proc. "Astronomy enabled by a return to the Moon”, ed. M. Livio, Cambridge University Press, in press [astro-ph/072070], 2007. RD 99 Kounaves, S.P., Lukow, S.R., Comeau, B.P., Hecht, M.H., Grannan-Feldman, S.M., Manatt, K., West, S.J.; Wen, X., Frant, M., Gillette, T., Mars Surveyor Program '01 Mars Environmental Compatibility Assessment wet chemistry lab: A sensor array for chemical analysis of the Martian soil RD 100 Jakob, B., Splinter, J., Durante, M. and Taucher-Scholz, G., Live cell microscopy analysis of radiation induced DNA double-strand break motion. Proc. Natl. Acad. Sci. USA, 106, 3172-3177, 2009. RD 101 Baumstark-Khan, C., Hellweg, C.E., Arenz, A. and Meier, M.M., Cellular monitoring of the nuclear factor kappaB pathway for assessment of space environmental radiation. Radiat Res., 164 527-530, 2005.

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RD 102 Kordyum, E.L., Shevchenko, G.V., Yemets, A.I. Nyporko, A.I. and Blume, Y.B., Application of GFP technique for cytoskeleton visualization onboard the International Space Station. Acta Astronaut., 56, 613-621. 2005.

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APPENDIX I

SELENE (Selenological and Engineering Explorer) – Kaguya (JAXA) The SELENE spacecraft was launched in September 2007 together with two sub-satellites Rstar and Vstar; one of which provided data relay and the other allowed measurement of the gravity field. After successfully orbiting the Moon for 1 year and 8 months, the main orbiter was intentionally crashed onto the lunar surface in June 2009.

SELENE was developed mission were to increase understanding of the Moon’s origin and evolution, and to observe the Moon in various ways in order to utilize it in the future. The mission addressed a strong interest in technology development for future lunar exploration (lunar orbit insertion, telecommunication, remote sensing from lunar orbit) and scientific objectives; primarily to observe the Moon’s:

• Elemental and mineralogical composition • Geography • Surface and sub-surface structure • Remnant of its magnetic field • Gravity field

Observations were also made of plasma and high-energy particles.

Important outcomes of the mission include:

• Improved lunar global topography maps • Detailed gravity map of the whole surface of the Moon including the far side for the first time • First optical observation of the permanently shadowed interior of Shackleton crater at the lunar South pole • K, Th, U maps, mineral distribution and composition, geological features, subsurface structures, crater counting down to 100m in diameter, a detailed magnetic field map including the far side and data related to the plasma environment, to the cosmic radiation (e-, protons and α particles, no heavy ions measurements because the Cosmic ray telescope failed). Last, due to low solar activity, the X-ray spectrometer did not work as expected. • A High Definition TV system also collected astonishing images and movies of the Moon surface and of the Earth.

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Chang’e 1 (CNSA) Chang’e 1 was China’s first interplanetary mission. It was launched in October 2007 and it ended after impacting the lunar surface in March 2009.

The Chang’e mission was the first mission in a long-term programme leading to human exploration of the Moon and to look at its resources. The objectives of this first mission were:

• To “draw” pictures of the moon, or to obtain 3-dimensional imagery of the lunar surface • To detect the contents and distribution of a number of chemical elements on the lunar surface • To probe preliminarily the depth of lunar soil, or regolith • To explore the lunar space environment

Upon conclusion the mission had collected the expected data including, full coverage topography map of the moon, measurements with micro-wave techniques of the regolith thickness (3 and 37 GHz) and elemental distribution maps.

Chandrayaan 1 (ISRO) The Indian spacecraft Chandrayaan 1 was launched in October 2008, with planned mission duration of two years. Control of the satellite was lost and the mission ended prematurely in August 2009 but the primary objectives of the mission were achieved. An impactor was released in November at the lunar South Pole as a fore-runner to future soft-landing missions.

The mission objectives were:

• To realise the mission goal of harnessing the science payloads, lunar craft and the launch vehicle with suitable ground support systems including Deep Space Network (DSN) station • To realise integration and testing, launch and lunar polar orbit of about 100 km, in-orbit operation of experiments, communication / telecommand, telemetry data reception, quick look data and archival for scientific utilisation by scientists.

The Chandrayaan-1 mission was aimed at high-resolution remote sensing of the Moon in visible, near infrared (NIR), low energy X-rays and high-energy X-ray regions. Specifically the objectives were:

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• To prepare a three-dimensional atlas (with high spatial and altitude resolution of 5-10 m) of both near and far side of the Moon. • To conduct chemical and mineralogical mapping of the entire lunar surface for distribution of mineral and chemical elements such as magnesium, aluminium, silicon, calcium, iron and titanium as well as high atomic number elements such as radon, uranium & thorium with high spatial resolution.

Beyond a topography map of 5m resolution, the most outstanding discovery of the mission to date has been the observation of OH/H2O/hydrated minerals on the surface of the Moon. Data analysis is still on-going and other results to come.

Lunar Reconnaissance Orbiter - LRO (NASA) LRO is the first mission in the NASA Exploration Programme to prepare the return of humans to the Moon. It was launched in June 2009 and will operate for one year on a polar circular orbit at 50km altitude. Investigations planned are targeted at preparations for future human exploration of the Moon. The main mission objectives are thus:

• Locate potential resources (hydrogen/water at the lunar poles, continuous Solar energy, mineralogy) • Identify safe landing sites (high resolution imagery, global geodetic grid, topography, rock abundances) • Characterize the radiation environment (energetic particles, neutrons)

Preliminary results have shown lower then expected temperatures in permanently shadowed craters and high resolution images of the Apollo landing sites.

Lunar CRater Observation and Sensing Satellite - LCROSS (NASA) Launched together with LRO, LCROSS impacted the permanently shadowed Cabeus crater on October 9th, 2009 and revealed the presence of water and other volatiles in the crater. The mission included a shepherding spacecraft to make observations and an impactor (Centaur upper stage rocket).

Gravity Recovery and Interior Laboratory – GRAIL (NASA) GRAIL is a NASA Discovery Mission based on twin spacecraft flying in tandem around the Moon. The mission will:

• Measure and map variations in the Moon's gravitational field • Reveal differences in density of the Moon's crust and mantle

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• Answer fundamental questions about the Moon's internal structure and its thermal evolution

In addition, it will:

• Extend knowledge gained on the internal structure and thermal evolution of the Moon to other terrestrial planets • Reduce risk to future lunar robotic or human science and exploration missions by providing a high resolution, global gravity field that will eliminate gravity uncertainties for precision lunar navigation and landings

The main product of the mission will be a global, high-accuracy (<10mGal), high- resolution (30km) lunar gravity map.

The mission is scheduled for launch in 2011 and after a trans-lunar cruise of about 3 - 5 months (low energy transfer via L1) it will operate for a 90 days science phase in a polar circular 50km orbit. To measure the inter-spacecraft range-rate, each spacecraft has a Ka- band Lunar Gravity Ranging System (LGRS) derived from the GRACE instrument.

Lunar Dust - LADEE (NASA) LADEE implements an early priority of the National Research Council’s report, The Scientific Context for the Exploration of the Moon (NRC, 2007), namely to “determine the global density, composition, and time variability of the fragile lunar atmosphere before it is perturbed by further human activity“.

LADEE is designed to characterize the tenuous lunar atmosphere and dust environment from orbit. It will gather detailed information about conditions near the surface and environmental influences on lunar dust. A thorough understanding of these influences will help researchers understand how future exploration may shape the lunar environment and how the environment may affect future explorers.

Its main scientific objectives are reported in the following:

• Determine the composition and the global density of the lunar atmosphere and investigate the processes that control its distribution and variability, including sources, sinks, and surface interactions • Characterize the lunar exospheric dust environment and measure any spatial and temporal variability and impacts on the lunar atmosphere (size, shape, charge, frequency) • Determine if the Apollo astronaut sightings of diffuse emission at 10s of km above the surface were Na glow or dust

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Launch will take place in May 2012 out of Wallops with a Minotaur-5 launch vehicle. After 5 months I will reach its nominal orbit. 100 days of science operations in a near-circular (~ 50km) retrograde equatorial orbit will take place followed by 9 months of operations on a higher elliptical orbit for technology demonstration of optical communications.

Planned missions A number of missions and mission concepts are being studied by several agencies. These include orbiters, landers and rovers and address objectives related to lunar science and preparations for human exploration. Of particular note here, in the time frame of the ESA lunar lander are:

• MoonRise (NASA), Selected in July 2009 as one of three contenders to be the third New Frontiers mission, would have a launch not later than December 2018. The proposed mission proposes to return samples from Lunar South Pole-Aitken Basin. The samples would provide new insight into the early history of the Earth-moon system. • The International Lunar Network (NASA led). This would be a network of landers with geophysicial instrumentation to determine the internal structure of the Moon. ILN landers may be contributed by other agencies. ILN is currently under consideration as part of decadal survey. • SELENE 2 is a lander mission with a rover in Phase A study by JAXA. The mission may target either the South Pole or the peak of a crater. The mission is in part a preparation for a lunar cargo and logistics capability, demonstrating soft precision landing and hazard avoidance. • Chang’e 3 is a lander plus rover mission under consideration by China

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