HUMAN-AIDED CONSTRUCTION OF A LARGE LUNAR TELESCOPE

by

Paul van Susante A thesis submitted to the Faculty and the Board of Trustees of the Colorado

School of Mines in partial fulfillment of the requirements for the degree of Master of Science (Engineering Systems)

Golden, Colorado

Date ______

Signed: ______Paul van Susante

Approved: ______Dr. R.H. King Thesis Advisor

Golden, Colorado

Date ______

______Dr. D. Munoz Department Head Division of Engineering

ii ABSTRACT

The Moon is an excellent platform for operations for astronomical purposes while at the same time it is possible to combine such scientific activities with exploration and resource utilization. The purpose of this NASA-sponsored study was to find out how a large infrared telescope can be built inside a permanently shadowed crater on the Moon using humans and robots, to define the required infrastructure. The results will give NASA a lunar reference to compare to a telescope mission to free-space. The alt-azimuth telescope design will consist of a 25 m diameter segmented primary mirror. The secondary mirror will be 50 meter above the primary and will be supported by three truss structures. It will use super-conducting magnetic bearings and a counterweight / instrument housing.

The required infrastructure for constructing this telescope includes space- and surface transportation. A (temporary) lunar base will need to be established and a smaller construction outpost will be required. The surface transportation will consists of robots and a ski-lift-type cable system. Communication links will be needed at Malapert Mountain and at the rim of Shackleton crater to guarantee continuous communications. Power for the telescope and the lunar base will be

iii generated at the so-called Peak of Eternal Light and transported using the lift

cables.

To construct this telescope five different types of robots will be needed

and two humans will be supervising the robots during certain phases while the

robots will be remotely controlled from the lunar base or from Earth. During this report it is shown that for such large telescopes, it is possible to think of ways to deal with the perceived negative aspects of the Moon such as dust, gravity, temperatures, etc. The choice between free space (Sun-Earth L2) and the lunar surface for a large infrared telescope is not immediately clear. Both locations have advantages and disadvantages. The major advantage of S-E L2 is the possibility to observe the whole universe, while the major advantage of the lunar

South Pole is the possibility to operate for many years longer and at the same time allowing easier maintenance and expansion than possible in S-E L2. For a choice it is not only important to look at the possible astronomy, but also to the construction, operations and other factors such as maintenance options, efficiency, expansion possibilities and the support of a larger infrastructure.

Many improvements will be required in many technological areas dealing mostly with the capabilities of robots, the extension of operational environment into the extremely cold regions of 40 K, remotely operated performing delicate construction tasks, the creation of infrastructure, the super-conducting magnetic

iv bearings in a much larger type and their required three orders of magnitudes increase in precision, but none seem unacceptably far in the future.

Next to technology improvements, there is also the need to know more about the lunar local environment such as the dust behavior, the topography with a vertical and horizontal spatial resolution better than one meter, absolute temperature measurements and the temperature fluctuations. Some of these measurements will be done by lunar missions that will reach the Moon in the coming years such as SMART-1, LUNAR-A and SELENE. As far as humans are concerned it will require augmentations in the space-suits of the astronauts, such as enhanced sensors, artificial muscles in the suit and display capabilities in the helmet, to make sure the humans are optimally equipped to handle all situations during the construction process.

A change in philosophy will be required in scientists and other involved partners to build and invest in infrastructure instead of going the path of "throw- away" missions every few years. This change in philosophy might prove to be the most difficult of all steps forward.

v TABLE OF CONTENTS

ABSTRACT ...... iii

LIST OF FIGURES ...... xi

LIST OF TABLES ...... xiv

LIST OF ABREVIATIONS ...... xvi

ACKNOWLEDGEMENTS...... xviii

Chapter 1 INTRODUCTION...... 1

Chapter 2 SUPPORT INFRASTRUCTURE ...... 6

2.1 Transportation to the lunar surface ...... 6 2.2 Power generation ...... 8 2.3 Power storage ...... 13 2.4 Power transmission...... 13 2.5 Communication ...... 15 2.6 Lunar base ...... 16 2.7 Lift system...... 17 2.8 Transportation on the lunar surface ...... 20 2.9 Construction site ...... 22

Chapter 3. STATE OF THE ART OF ROBOTICS IN SPACE & CONSTRUCTION ...... 23 3.1 Earth construction robotics...... 23 3.2 Earth mining automation ...... 24 3.3 Space robotics ...... 25 3.4 Space construction...... 26 3.5 General research ...... 27 3.6 Supervised autonomy and teamwork ...... 29

vi Chapter 4. THE LUNAR ENVIRONMENT AND ITS RELEVANCE TO TELESCOPE-DESIGN AND OPERATIONS ...... 31

4.1 Location topography...... 31 4.2 Gravity...... 33

4.2.1 Effect of zero- or micro-gravity on a large telescope ...... 33 4.2.2 Deformation of the mirror due to gravity ...... 34 4.2.3 Vibration generation and damping in the structure ...... 40 4.2.4 Pointing and tracking of the telescope...... 42 4.2.5 Construction ...... 43 4.2.6 General influences on engineering ...... 44

4.3 Vacuum...... 45

4.3.1 No atmospheric absorption...... 45 4.3.2 Contamination of the vacuum...... 45 4.3.3 Thermal heat rejection...... 46

4.4 Dust...... 46

4.4.1 Contamination of surfaces and sensitive elements...... 47 4.4.2 Wear and tear of moving parts ...... 48 4.4.3 Foundation design ...... 48

4.5 Temperature...... 49

4.5.1 Absolute temperature must be very low ...... 50 4.5.2 Thermal gradients...... 52 4.5.3 Thermal control...... 52

4.6 Lighting conditions ...... 53 4.7 Seismicity...... 53 4.8 Meteoroid impacts...... 54

Chapter 5. TELESCOPE DESIGN & DESIGN DECISIONS ...... 57

5.1 Relevant general parameters for a telescope & its construction .. 57 5.2 Requirements for a large lunar telescope ...... 65 5.3 Space transportation influences on elements...... 67 5.4 Optimization of construction elements, transportation and robots 69

vii 5.5 Phases in the construction process...... 69

5.5.1 Main Phases...... 70 5.5.2 Subphases ...... 70

5.6 Timeline ...... 72

Chapter 6. TELESCOPE DESIGN AND CONSTRUCTION SEQUENCE...... 74

6.1 Communication ...... 74 6.2 Energy / transportation system installation...... 75 6.3 Lunar base ...... 75 6.4 Transportation etc. into crater ...... 76 6.5 Landing of construction outpost ...... 77 6.6 Site preparation...... 77 6.7 Foundation construction...... 78 6.8 First ring construction...... 80 6.9 Power-, data-, communication-line to first ring ...... 81 6.10 Second ring construction...... 81 6.11 The on-telescope robots ...... 82 6.12 Main support struts installation...... 82 6.13 Main axis installation ...... 82 6.14 Instrument and counter weight housing ...... 84 6.15 Main mirror support structure ...... 84 6.16 Secondary mirror support struts installation ...... 84 6.17 Secondary mirror installation...... 85 6.18 Instrument installation ...... 86 6.19 Main mirror panels installation...... 86 6.20 Commissioning phase...... 88 6.21 Operational phase...... 88

Chapter 7. ROLES OF HUMANS AND ROBOTS...... 91

7.1 Unique qualities / capabilities...... 91

7.1.1 Unique for humans ...... 91 7.1.2 Unique for robots...... 92 7.1.3 Advantages one over the other...... 92

7.2 Robots required...... 93 7.3 Humans required...... 95

viii 7.4 Task list and workforce role...... 98

7.4.1 Main Phase I: Infrastructure outside Shackleton Crater ...... 98 7.4.2 Main Phase II: Infrastructure inside Shackleton Crater ..... 102 7.4.3 Main Phase III: Telescope construction and assembly...... 104 7.4.4 Main Phase IV: Commissioning and operations...... 108

Chapter 8. CAPABILITIES / CAPACITIES TO DEVELOP...... 111

8.1 Technology...... 111

8.1.1 Precision...... 111 8.1.2 Power ...... 112 8.1.3 Communications...... 113 8.1.4 Flexibility in command ...... 114 8.1.5 Versatility...... 115 8.1.6 Environmental operations...... 116 8.1.7 Team work...... 117 8.1.8 Human tool improvements...... 118

8.2 Telescope parts...... 119 8.3 Integration and commitment...... 120

Chapter 9. POSSIBLE PRECURSORS AND RESEARCH REQUIRED...... 122

9.1 Experiments on Earth ...... 122

9.1.1 Knowledge about the location ...... 122 9.1.2 Equipment and material testing...... 123 9.1.3 Operational testing ...... 123

9.2 Activities at a lunar outpost or base ...... 124

9.2.1 Knowledge about the location ...... 125 9.2.2 Environment measurements...... 125 9.2.3 Equipment tests ...... 128 9.2.4 Operations tests ...... 130

9.3 Design and engineering optimization...... 130

ix Chapter 10. CONCLUSIONS...... 132

REFERENCES CITED ...... 135

SELECTED BIBLIOGRAPHY...... 151

APPENDIX A...... 158

APPENDIX B...... 162

x LIST OF FIGURES

Figure 1.1: The Very Large Telescope (VLT) in Chile, all four 8.2 meter mirrors have been operational since 2000. Image courtesy: ESO...... 2

Figure 1.2: Spectrum of our galaxy. Image courtesy: NASA ...... 2

Figure 1.3: Atmospheric transmissivity of the Earth's atmosphere. Image courtesy: NOAA...... 3

Figure 1.4: Artist impression of the James Webb Space Telescope. Image courtesy : NASA ...... 4

Figure 2.1 : The Earth-Moon system to scale with the Lagrange points indicated. These locations are fixed with respect to the Earth and Moon positions ...... 7

Figure 2.2: On the right a schematic indication of landing site locations on the lunar surface on the same scale as the image on the left. The intersection of the dotted lines is the approximate location of the lunar South Pole. The white box indicates the area displayed in Figure 2.3 ...... 9

Figure 2.3: Shackleton crater and the lunar base site ...... 10

Figure 2.4: Lunar base location and the lift system ...... 10

Figure 2.5: Black and white version of the illumination chart of the lunar South Pole with the central crater being Shackleton. The squares indicate the areas with more than 80% illumination per month (Bussey 1998) ...... 12

Figure 2.6: Layout and deployment of the first leg of the cable transport system ...... 19

Figure 2.7: Installation of the second leg of the lift system into the crater ...... 19

Figure 2.8: The lift system completed...... 20

Figure 2.9: Cross-section of surface infrastructure (not to scale) ...... 21

xi Figure 4.1: A picture of full Moon...... 32

Figure 4.2: A simple supported beam with a distributed load q generated by its own weight, deflection wmiddle and rotations θ and θ2 The beam has a cross- section of A, a specific mass of ρ , length L and a bending stiffness of EI...... 36

Figure 4.3: Transportation of one of the four, 8.2 m diameter, mirrors of the VLT. Image courtesy: ESO ...... 38

Figure 4.4: The 10 meter diameter segmented main mirror of the Keck telescope in Hawaii...... 38

Figure 4.5: Comparison between the 10 meter diameter segmented main mirror of the Keck telescope and the planned 30 meter diameter California Extremely Large Telescope main mirror...... 39

Figure 4.6: Structural model of the Over-Whelmingly Large telescope with a 100 meter diameter segmented main mirror. Image courtesy: ESO...... 39

Figure 4.7: Noise Equivalent Flux Density (NEFD) (sensitivity) for different telescope temperatures and sizes...... 51

Figure 4.8: Impact of a micrometeoroid on the Hubble Space Telescope's old photovoltaic arrays. image courtesy: ESA ...... 56

Figure 5.1: Ariane 5 payload fairing dimensions. Image Courtesy: Arianespace ...... 68

Figure 5.2: Overview of main- and subphases of the telescope construction process...... 73

Figure 6.1: The first rolling cable distributor as it has arrived at the possible lunar base site. Original image courtesy: NASA...... 76

Figure 6.2: A depiction of how laser range finders could assist in the correct placement of elements during the telescope construction. For simplicity it only contains six foundation poles rather than 15 ...... 78

xii Figure 6.3: Placement sequence of a foundation pole. First the placement, then the compaction and application of the pre-loading and finally the deployment of the support-arms ...... 79

Figure 6.4: Placement of the first element of the lower super-conducting azimuth ring. In this figure the layer of regolith covering the foot of the foundation poles is not shown...... 80

Figure 6.5: The lower azimuth ring is complete, positioned and fixed. The power and data line can now be connected ...... 81

Figure 6.6: An impression of the telescope structure after completion of the second part of the azimuth ring, the main support struts, the main axis and the housing for the counter-weight and instruments...... 83

Figure 6.7: The main mirror support structure is in place. This is a truss structure covered in a layer of MLI ...... 85

Figure 6.8: The entire telescope structure is complete except for the most delicate elements...... 87

Figure 6.9: The telescope is completely assembled and the commisioning phase can begin ...... 89

Figure 6.10: The telescope in operational position after the main axis is unlocked ...... 90

Figure 7.1: A rolling cable distributor as it could look, to deploy the cable from the top of the crater rim to the bottom of the crater...... 96

Figure 7.2: A sketch of the "dirty" work-robot...... 96

Figure 7.3: A first sketch of one of the two, on-telescope robots. It has multiple end-effectors and can thus perform multiple operations with different tools. It also has three legs to move around with and to hold onto three points when lifting heavy loads ...... 97

Figure 7.4: A sketch of how the rails might be incorporated into the structure such that the robot need not worry about umbilical cords or grapple-points ...... 97

xiii LIST OF TABLES

Table 2.1: Power generation options. * indicates chosen system...... 12

Table 2.2: options of power transportation. * indicates chosen option...... 14

Table 4.1: Natural frequencies of the first eight symmetric in-plane modes as a function of λ2 ...... 41

Table 5.1: Description of factors of influence on telescope ...... 58

Table 5.2: Qualitative comparison between possible telescope locations ...... 64

Table 5.3: Minimum requirements ...... 65

Table 5.4: Design parameters for a 25 m lunar infrared telescope...... 66

Table 7.1: Overview of robots needed for telescope construction process...... 95

Table 7.2: Activities in subphase 1 ...... 99

Table 7.3: Activities in subphase 2 ...... 100

Table 7.4: Activities in subphase 3 ...... 101

Table 7.5: Activities in subphase 4 ...... 102

Table 7.6: Activities in subphase 5 ...... 103

Table 7.7: Activities in subphase 6 ...... 104

Table 7.8: Activities in subphase 7 ...... 106

Table 7.9: Activities in subphase 8 ...... 107

Table 7.10: Activities in subphase 9 ...... 108

xiv Table 7.11: Activities in subphase 10 ...... 109

Table 7.12: Activities in subphase 11 ...... 110

Table A-1: Planned leading telescopes available in 2020 ...... 159

Table B-1: Overview version of the construction timeline ...... 163

Table B-2a : Expanded version of the construction timeline I...... 164

Table B-2b : Expanded version of the construction timeline II...... 165

xv LIST OF ABBREVIATIONS

CELT California Extremely Large Telescope CSM Colorado School of Mines ERA European Robotic Arm ESA European Space Agency ESO European Southern Observatory EVA Extra Vehicular Activity G Earth's Gravity (9.81 m/s2) GPS Global Positioning System ICASE Institute for research in Applied and Numerical Mathematics, Computer Science and Fluid Mechanics. ISRU In Situ Resource Utilization ISS International Space Station JWST James Webb Space Telescope L1 Lagrange point 1 L2 Lagrange point 2 LEO Lower Earth Orbit LH2 Liquid Hydrogen LHD's Load Haul Dump vehicles LOX Liquid Oxygen MLI Multi Layer Insulation MSS Mobile Servicing System NASA National Aeronautics and Space Administration NEFD Noise Equivalent Flux Density NeXT NASA exploration Team

xvi NIST National Institute of Standards and Technology NOAA National Oceanic and Atmospheric Administration OWL Over-Whelmingly Large Telescope PEL Peak of Eternal Light POMA Pomagalski S.A. France PV-cells Photo-Voltaic-Cells RASC Revolutionary Aerospace System Concepts RoCaDi Rolling Cable Distributor RSI Repetitive Strain Injury RTG Radio-Isotope Thermonuclear Generator SIRTF Space InfraRed Telescope Facility SPDM Special Purpose Dexterous Manipulator TU-Delft Delft University of Technology VLT Very Large Telescope VLTI Very Large Telescope Interferometer VR Virtual Reality Zero-G Zero Gravity

xvii ACKNOWLEDGEMENTS

This thesis work advances my previous work for the European Space

Agency and the Delft University of Technology. I would like to thank one of my thesis advisors from then; Dr. Peter Eckart, for bringing me in contact with one of my current advisors; Dr. Mike Duke. Without them I would not have been here and this work would not have been completed. Of course I want to thank Dr.

Duke for giving me this opportunity and providing a positive work-atmosphere.

This work also would not have been possible without the grant from the NASA

Revolutionary Aerospace Concepts program. They supported the work here at the Colorado School of Mines through the former Institute for research in Applied and Numerical Mathematics, Computer Science and Fluid Mechanics at NASA

Langley Research Center and The Center for Commercial application of

Combustion in Space here at the Colorado School of Mines. During the course of this work I got help and information from many experts in the field like Mr. B.

Blair, Dr. J. van Cleve, Dr. R. Christenson, Dr. M. Duke, Dr. R. King and many others. Also a fellow student, Yuki Takahashi joined the project for a little while before moving to Berkeley, he did most of the work for the appendix. Further I would like to thank my family for supporting me in all I do, including the move to the USA to do this project. And of course my friends here in the USA, Birgit

xviii Braun, Brenda Mulac, Mark Kerr, Kevin Smith, Kate Robertson and many others.

Thank you all for your support.

xix 1

Chapter 1

INTRODUCTION

For millenia, human beings have wondered about the heavens. Sailors have used the stars for navigation, some have worshipped the heavens, others tried to read the future in it and again others studied the movements of the planets and stars from a scientific perspective. The contact with the stars in daily life has been greatly diminished by our fast-moving city-society. Scientists however, are as eager as ever to learn more about the universe. Progress in technology, new tools and instruments, like the recently completed Very Large Telescope (VLT) in the Chilean Atacama desert (See Figure 1.1), have given them tools to observe details in many wavelengths and to see sharper and further than ever before. They are trying to answer several of mankinds' oldest questions: "Where did we come from?", "Are we alone?" and "Where are we going?". We can best find answers to most of these important questions by telescope observations in the wavelength range spanning submillimeter, infrared, and visible light. This is because stars, and the interstellar medium from which stars form, emit most of their radiation at these wavelengths. Most of the photon energy density in the Galaxy is in this wavelength range (See Figure 1.2).

2

Figure 1.1: The Very Large Telescope (VLT) in Chile, all four 8.2 meter mirrors have been operational since 2000. Image courtesy: ESO

Figure 1.2: Spectrum of our galaxy. Image courtesy: NASA

3

In addition, this range includes the molecular signatures of almost all chemical elements important to life as we know it. Unfortunately, the Earth’s atmosphere absorbs large parts of these interesting wavelengths (See Figure 1.3). Absorption (%) f(Hz)

Figure 1.3: Atmospheric transmissivity of the Earth's atmosphere. Image courtesy: NOAA

Next to the wavelength issue there is the fact that astronomers want more telescope surface area to collect more photons to get better images. This is because the detectors have reached maximum sensitivity that can be achieved with present day technology, so the only option is to increase the size of the mirrors. To best answer the questions, the telescope has to be placed in a vacuum environment to eliminate the issue of atmospheric absorption. Since the next large space infrared telescope, the James Webb Space Telescope (JWST) (See Figure 1.4), has already been chosen and the timeframe for developments for these kind of projects has to be measured in decades, it is necessary to start looking at the possibilities for the successor of the JWST now. Based on prejudice, denial and a lack of lunar knowledge, some scientists and engineers 4

would not even consider the Moon as a location to build such a telescope. Nevertheless the Moon has been considered by others (Burke 1990, Stafford, 1991, Battrick 1995, Arnold 1996) as an ideal location for astronomy. Especially since the discovery of permanently-shadowed areas in the polar regions of the Moon, the interest for exploring the lunar polar areas has increased tremendously as can be seen by the fleet of international missions planned to explore the Moon, not only because of the possible presence of water-ice, but also because these very cold areas may make excellent locations for infrared astronomy. The temperatures in those regions are suspected to reach very low, constant temperatures close to 40 K.

Figure 1.4: Artist impression of the James Webb Space Telescope. Image courtesy : NASA

5

This study was conducted to find out what the possibilities are for infrared astronomy in those lunar cold traps, how a telescope could be built using humans and robots, and how it could be operated there. In this report the appropriate mix of humans and robots will be evaluated, a possible construction design will be analyzed and the required infrastructure will be analyzed. The main questions to answer will be: what will be needed in terms of infrastructure, robot and human workforce and what effects does this have on the elements of the telescope, its construction and operation. The study was sponsored by the NASA Revolutionary Aerospace System Concepts (RASC) program, managed by the former Institute for research in Applied and Numerical Mathematics, Computer Science and Fluid Mechanics (ICASE), located at NASA Langley Research Center. The work advances the Masters thesis of the author done at the Delft University of Technology (TU-Delft) and sponsored by the education office of the European Space Agency (ESA). That thesis is called “Design and construction study of a lunar south pole infrared telescope”. This new work is based on the work done for that thesis and extrapolates it from an 8-m primary mirror to a 25- m diameter primary segmented mirror while looking at many other aspects of such an undertaking. Most of the work done in The Netherlands was aimed at the foundation design and general telescope design. The emphasis of the work done at the Colorado School of Mines (CSM) was to analyze the construction tasks and to define the appropriate human/robot workforce. The work was mainly done from May to November 2002 at the Division of Engineering of CSM and was concluded with a final presentation and discussion of the findings at NASA Langley Research Center. Some of the results have been published by Van Susante (2003). 6

Chapter 2

SUPPORT INFRASTRUCTURE

An infrastructure will be required to support construction and operation of the telescope. This infrastructure needs to be emplaced early in the construction process. Because many of the construction tasks need to be described in terms of the infrastructure it will be described here.

2.1 Transportation to the lunar surface

A large telescope project will require large quantities of materials to be transported to the lunar surface. Therefore, a transportation infrastructure is needed. In this thesis, it will be assumed that there is a lunar-propellant production facility present that can resupply spacecraft in Cislunar space (defined as the gravitational sphere of influence of the Earth-Moon system) through a fuel- depot in Earth-Moon Langrange point 1 (L1) (See Figure 2.1), which makes transportation costs considerably lower compared to directly launched cargo from Earth (Blair 2003a). Lagrange points are areas in space where the gravitational influences of two bodies are balancing each other so staying in that area does not cause an object to fall to either body. Only a small station-keeping "fee" has to be paid in the form of a few meters per second impulse per year. Each two body system has 5 Lagrange points (See Figure 2.1). The infrastructure in L1 will be assumed to resemble the outpost that has been described by the NASA 7

Exploration Team (NEXT) in combination with a propellant depot as described by (Martin 2002, Cooke 2002, Duke 2003, Blair 2003b)

E-M L5 Orbit of the Moon E-M L2 around Earth Moon E-M L1 Fuel depot 384.000 km Earth

E-M L4

E-M L3

Figure 2.1 : The Earth-Moon system to scale with the Lagrange points indicated. These locations are fixed with respect to the Earth and Moon positions.

8

Precision landings will be essential for the communication relay and power generation areas which are relatively small (in the order of a square with sides of a few hundred meters long) but critical to the success of the project. For this project, four different landing sites / destinations are envisioned on the lunar surface, on Malapert Mountain a precision landing without beacon, on the Peak of Eternal Light a precision landing without beacon, a landing in the plain for the lunar base location, this landing will use beacon assistance, the last location for landing will be in Shackleton crater, and it also will use landing beacon assistance. (See Figure 2.2, Figure 2.3 and Figure 2.4) . All single landings will happen before the telescope will be constructed to minimize the dust production and gas deposition. To prevent contamination of sensitive parts once the telescope is being constructed, all subsequent landings will take place more than 10 km from the telescope site and preferrably on a landing pad close to the lunar base.

2.2 Power generation

Power generation of the estimated 5-10 KW required to operate and construct the telescope on the Moon is limited with no fossil fuels, water or wind to generate power. Solar energy, however, is abundant at many places on the Moon and power can be produced by converting heat into electricity (Stirling engine) or light into electricity by means of photovoltaic cells (PV-cells). The solar energy delivered by direct sunlight perpendicular to the solar rays is 1.3 KW/m2 (Eckart 1999). For operation in shadowed areas or at night, energy storage or transportation is required. Because the estimates are that the sun never sets for longer than approximately 60 hours, that is the maximum storage time required. 9

Another option is nuclear power generation. Several options for nuclear power generation exist and suitability of use depends on the power demand.

Malapert Mountain outline

120 km

Lunar Base Site

Shackleton Crater outline

12.5 km

Figure 2.2: On the right a schematic indication of landing site locations on the lunar surface on the same scale as the image on the left. The intersection of the dotted lines is the approximate location of the lunar South Pole. The white box indicates the area displayed in Figure 2.3

10

"Peak of Eternal Light " Shackleton Crater

Lunar Base Site Telescope construction site

Cable lift system

12.5 km

Figure 2.3: Shackleton crater and the lunar base site

Peak of Eternal Light (PEL) Lunar Base Site

Landing pad To crater bottom

Cable lift system Lunar Base Modules

Figure 2.4: Lunar base location and the lift system 11

Radio-isotope thermo-electric generators (RTG's) are suitable for small power demands over long periods of time. They powered the Pioneer spacecraft which have travelled out of our solar system and already functioned for over 25 years. A new generation of RTG's with higher efficiency is under development. Nuclear fission can deliver more power, but requires larger systems. These do not require sunlight, but could represent a political hurdle. Nuclear space power systems are perceived by most environmental protection activists as a threat to the environment. This threat consists mainly of the risk of explosion of the rocket during launch while it is in the atmosphere. Containers have been designed and tested that can withstand this explosion and the fiery re-entry through the atmosphere and the impact on land or sea. Nevertheless they are considered by many people as unsafe and hence there are not many politicians that would like to explain this issue or lose voters over it. In the United States the rule is that nuclear space systems can only be used if there are no viable alternatives. The need for nuclear power must be proven by an extensive and expensive process before it can be used. This is why solar power generation is considered the most politically and economically acceptable choice for systems with a limited power demand in the order of several kilowatts that will have to function between the Sun and the orbit of Mars. Since the telescope itself will be in permanent shadow a careful choice is necessary. Because places exist, on or close to the rim of Shackleton crater, where there is almost always sun, it is chosen to use PV-cells to generate the required power. The power will be generated using one of the almost permanently sunlit areas (See figure 2.5) from where the energy will be transported to the telescope.

12

Table 2.1: Power generation options. * indicates chosen system option remarks PV-cells * efficient, but requires sunlight and limited in maximum power output Stirling engine needs a large difference in temperature in close proximity of eachother Nuclear fission if need exists possible, but expensive and not reasonable option for small power requirements RTG's possible, but generate heat, then electricity, not very efficient for larger power requirements

Figure 2.5: Black and white version of the illumination chart of the lunar South Pole with the central crater being Shackleton. The rectangles contain the areas with more than 80% illumination per month. (Bussey 1998) 13

2.3 Power storage

For periods when there is no sun visible at the power generation site (maximum 60 hours), there is need to store power. The method of storage varies and depends on the size and mass of the required capacity. Batteries are very inefficient systems and they can only be considered for short duration missions with small power consumption. Battery storage systems have a high specific mass, their efficiency is highly correlated to the operating temperature and they are bulky. Fuel cells are an alternative that can store energy in the form of chemicals like hydrogen (H2) and oxygen (O2) . When the energy is needed the

H2 and O2 react to form water and electricity. The water then can be electrolyzed during the times when power is generated. The fuel cell is less sensitive to low temperatures, less bulky and less massive per amount of energy stored. A problem with fuel cells is the large amount of reactants necessary and their leakage over time. Great progress is being made presently on fuel cell technology due to research on fuel cells for automobiles. So fuel cells will be chosen for this project.

2.4 Power transmission

Because the telescope and power generaton site are separated by several kilometers, power will need to be transmitted. Laser and microwave power beaming options both require a line of sight and the erection of an antenna or dish structure but do not need a cable (Henley 2002). A cable does not require line of sight, but needs to be deployed and has significant mass. The cable has advantages over power beaming options because a cable allows a combination of functions like communication, power and transportation. Research is needed, 14

but it might be possible to have a partly superconducting cable because of the cold temperatures, which could significantly reduce power transfer losses in the cable system. Another option could be to physically transport the fuel cells or tanks with H2 and O2 from the charging station to the location where they are needed. This is a less efficient system and periodic replenishment could generate dust. The cable system has been chosen here because of the combined needs for power and communication that can be integrated into a single system. The cable also integrates well with the proposed surface transportation system.

Table 2.2: options of power transportation. * indicates chosen option

Options Sub option Main issues Comments Power beaming laser requires line of sight, maybe small installation communication is possible one way. microwave requires line of sight, could heat up surroundings in crater Cable * large mass, no line of adds transportation sight required, mitigates and communication dust generation by eliminating the need for ground transport Physical transport fuel cells requires road or other means of infrastructure and connections H2 , O2 bulky, large tanks, tanks resealable connections required

15

2.5 Communication

For all activities on the lunar surface, communication is essential. For data-transfer, tele-operation and information exchange between astronauts and colleagues on Earth or in a lunar base. For some operations, periodic contact is sufficient; for others continuous contact is necessary. For simple spoken comments, only small bandwidth is required, but for virtual reality and tele- operation, a real-time, very high bandwidth is necessary. It is not feasible to build a complex instrument such as a telescope completely autonomously, it requires continuous tele-operation and control. During operation of the telescope, large quantities of data (on the order of Mbytes/sec) are gathered and need to be transmitted to scientists on Earth. This does not need to be real-time but can be done in so-called data-bursts. To be able to meet all the requirements during all phases of the preparation, construction and operation, one or more relay stations for communications are necessary. Those relays can be lunar orbiting satellites or ground relay stations, spaced in intervals that can see each other, and of which the last one will be able to see the Earth continuously. In case an E-M L2 station exists, that could be used as a relay link when Earth is not in view. Gemmink (1999), showed that in the South Pole area on the Moon, two ground- based relay stations are sufficient to give the telescope site continous communications with the required bandwidth. One relay station would have to be placed ont Malapert Mountain from where it can view both the Earth and the lunar South Pole continuously. From Malapert Mountain the bottom of Shackleton crater is not visible and thus a second relay station is required that can view both the crater bottom and Malapert Mountain. The second relay station thus would have to be placed on the rim of Shackleton crater. From the perspective of building infrastructure, this option is assumed. The Malapert mountain station could form the start of a base of operations there while the 16

station at the rim of Shackleton crater is necessary for continuous communication between the telescope and the lunar base. The communication relay station on the crater rim can be combined with the solar power generation plant, so only one mission and construction location is required. The other part of the relay-link is to be placed on the top of Malapert Mountain.

2.6 Lunar base

The lunar base will be sited close to the landing pad, while the telescope will be at least 10 km from the landing pad and situated in the permanently shadowed Shackleton crater (See Figure 2.4). The lunar base will have a storage area where telescope elements and robots can get acclimatized to the lunar environment and where they can stay till the outgassing is completed. Part of this storage area will have to be environmentally controlled since some electronic telescope elements need to stay above 220 K and need to have access to power to heat themselves or be stored in a temperature controlled room. The lunar base itself will consist of several parts such as living/working module, storage/acclimatization module, technical systems module for lifesupport and robot maintenance and the landing pad. The construction outpost will be a simpler version of the lunar base, but will also have the acclimatization area and storage area required for sensitive telescope elements because the lunar base site is not as cold as the construction outpost site.

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2.7 Lift system

This system will provide the necessary ground transportation from the lunar base to the bottom of Shackleton crater. It will consist of pylons placed on the surface that will support the cable. Once this system is installed it will assure dust free transportation from the lunar base into the crater. About 50 trips with the transport robot are needed to transport all telescope elements from the landing pad to the construction site. This trip is about 15 km long in one way and covers roughly 5 km altitude difference. The energy required to build a road in such terrain is higher than to construct a lift system. The road would, even after completion, still produce dust at elevations higher than the telescope. No matter how well made, a road would generate dust. The crater needs to be accessible even after the telescope has become operational for inspections, maintenance, upgrading and for the construction of multiple telescopes after the first one is completed. Dust production by activities on the crater floor is much easier to control and easier to shield from, than activities that take place at higher elevations than the telescope. The cable system allows accessibility while not generating any dust above the height of the telescope. It will also be the power transfer cable and the communication link. This system is simpler to make and maintain than the construction of a road up and down the crater wall. It will not need heavy machinery or the displacement of large quantities of regolith on a crater slope. The maintenance of a cable system is relatively easy if done on time because each location can be reached using the cable system and the cable itself rotates so that every centimeter can be inspected from one location. The cable system installation will begin with the landing on the PEL. After deployment of the solar arrays and checkout of the communication system, the robot that will lay the cable will be deployed. This robot will mainly use gravity to roll down to the lunar base site while unrolling the cable from its body. While 18

rolling down it will spot locations along its path that are suitable for placing the lift pylons. Once the lunar base elements, the pylons and the pylon-placing robot have arrived, the pylons can be placed in their designated positions. Once all the poles have been placed, the cable will be hoisted to the top of the pylons by an automated system integrated in the pylons. This system consists of a built-in rails and a sheave wheel set over which the cable will run. Once a pylon is placed, the cable will be placed on the sheave wheels while they are in their low positions close to the surface. Once all pylons are placed and the cable is placed on all the sheave wheels, the sheave wheels will be slowly lifted up while carrying the cable in place till they are at their desired height and locked in place. The first leg of the total system consists of the stretch from the lunar base to the PEL (See Figure 2.6). This first leg will allow easy access to the crater rim for robots and astronauts which will allow maintenance and expansion of the power generating PV-cells, communication link and maintenance to the lift- system. The second leg of the lift system will be constructed in the same manner using a second robot to deploy the second cable into Shackleton crater rolling down from the PEL (See Figure 2.7). If, indeed, as suggested in this study, a cable system is chosen, this cable needs to be significantly different from the regular steel cable systems on Earth. First, a lighter material would be beneficial since it would lower the mass significantly. Second, present cable systems on Earth contain lubrication between the different cable strands to keep them from rusting and wearing too much from rubbing against each other. This lubrication should be avoided in the cable design. Third, the cables are very long and they need to be practical to work with. At the same time this cable would need to be able to transmit data and power and withstand the huge temperature differences between the top of the crater rim and the permanent shadow. All this needs to be carried out in a vacuum environment. This has never been attempted, but would elegantly solve 19

PEL Cable being lifted in place

Pylons ~1.5 km Lunar base location

~4 km Figure 2.6: Layout and deployment of the first leg of the cable transport system

PEL Cable being lifted in place

Lunar base Pylons ~1.5 km location

~4 km To crater bottom

Figure 2.7: Installation of the second leg of the lift system into the crater

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the problem of transferring power from one place to another while also solving the pressing issue of limiting dust production by minimizing surface transport. This trip is about 3 times as long as the longest gondola system on Earth so challenges lie ahead in adapting that system for the Moon (See Figure 2.8).

Second leg First leg

PEL

Lunar base ~1.5 km location

~4 km ~3.5 km

Telescope ~11 km construction site

Figure 2.8: The lift system completed

2.8 Transportation on the lunar surface

Once landed on the lunar surface, the elements for construction need to be transported to their storage places or the construction site. In this project there are three possible destinations for the materials and elements once landed at the lunar base landing pad. They can be brought to the lunar base storage facility, 21

the storage facility at the construction outpost in the crater, or directly to the construction site (See Figure 2.3 and 2.4 and 2.9). While transporting it is essential that the construction elements not be contaminated with dust. To achieve this, elements will be transported from the landing pad to the lunar base storage / acclimatization facility in a special automated truck that is hermetically sealed against dust and will drive very slowly, such that dust will not fly high or far. There, the elements will be stored, or the special truck will board the lift to be transported into the crater. This manner of transportation fits well with the cable that will go from the top of the rim to the lunar base, and from the top of the rim into the crater.

Malapert Mountain, communication node

Peak of Eternal Light, power generation communication and transportation node

Crater rim Telescope Lunar Base

bottom ~ 7.5 km diameter ~120 km

Figure 2.9: Cross-section of surface infrastructure (not to scale)

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2.9 Construction site

Before the actual construction can begin some preparations will be required. A road will have to be established from the construction outpost to the telescope location, by compaction of a top-layer, removal of rocks and possibly filling of small craters. By doing this, and limiting the speed of travel, dust production will be limited in amount and travel distance. The surface of the construction site will have to be compacted as well so the robots will not stir up more dust than is unavoidable. The laser range finder poles will also have to placed before any digging or construction takes place so the relative locations can be measured and all elements can be placed accurately.

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Chapter 3

STATE OF THE ART OF ROBOTICS IN SPACE & CONSTRUCTION

The telescope designed here is too large to be emplaced as a single unit and will require construction / assembly. In order to provide a basis for the design details, an evaluation of the present state of the art of robotics for Earth-bound (construction) applications was required. Mining and construction automation and current capabilities of space robotics and space construction were also reviewed. A few of the most important reasons for the use of robots are: relief from repetitive tasks, execution of dangerous tasks, inspection where humans can not go, gathering of quantitative data and observation in different wavelengths. The field is too broad to list all of the robotics currently being researched, but some relevant fields will be discussed.

3.1 Earth construction robotics

Most construction robotics research has been aimed at relief from repetitive tasks or eliminating the need for humans in dangerous places (Kochan 2000, Gatton 1989). Some goals have been more ambitious and strive to eliminate the human worker totally from the worksite. Autonomy has proven to be extremely difficult and is as yet not feasible. Robot functionality, mobility, weight, size, accuracy and operations of the robots are not developed to such a level that 24

they can be applied in construction (Warszawski 1999, Zuk 1985). Some specific projects have been succesful, like an automated shot-crete machine and a concrete repair system. Other projects include the development of an automated bridge maintenance system (Lorenc 2000), a road construction and maintenance system, automated prefab-building construction, some types of building inspection and an automated steel-construction welding system (Nagao 2001). Many of these systems are expensive to operate and have not met the economic demands or the required efficiency. They are in some cases able to eliminate the need for humans in dangerous situations or locations. Construction robots are often very specialized and can only perform one or two types of operations. They are, for instance, specialized in climbing spider- like horizontally or vertically over pipes, walls or steel mesh where they perform measurements. Overall there are many improvements being made, but a construction site is inherently cluttered with material, equipment and activities. This is a hard environment for robots, but today's building process is not designed for the use of robots. Neither planners nor the construction workers are used to working with robots.

3.2 Earth mining automation

Mining operations have reduced cost by automating some repetitive processes and removed operators from dusty, dangerous and cramped mine environments which also improved safety (Stentz 1999, Hainsworth 2000). Quite a few automated mining operations are in use, but the level of automation varies per project. In the mining industry, automation so far has been quite succesful. Most operational systems are run by tele-operation while some are almost 25

completely autonomous and only supervised by a human controller like in INCO's Stobie mine or Kali und Salz's Werra Mine. A general overiew of intelligent control of mining equipment and systems can be found in King (King 1996).

3.3 Space robotics

In space, the use of robotics is very important because of the high costs and high risks that are involved with human Extra-Vehicular-Activity (EVA). One of the biggest challenges is the imitation of the functionality and versatility of the human hand. Even though in a space suit the hands and fingers of the astronauts are nowhere near as flexible and dexterous as without gloves, they are still very flexible and hard to imitate by robots. Quite a lot of progress appears to have been made in this area recently by several research groups (Bicchi 2002, Okamura 2000, Bonivento 1999, Matsuhira 1999), especially with regards to robotics for the International Space Station (ISS) (Rezapour 1996). The Special Purpose Dexterous Manipulator (SPDM) for the robotic arm is a specific ISS project (Bassett 1999). Other research is more general aimed towards developing robot hands for space applications. A special case is the Robonaut hand that is being developed in combination with the robot itself (Lovchik 1999). Separately, a hand or a dexterous manipulator would not be of much use. So platforms and means of transport are also being researched. Some examples are: the mobile servicing system for the ISS and the European Robotic Arm also for the ISS (Stieber 1999, Verhoeven 1999, Schoonejans 1999). Another succesful robotic arm that has seen considerable use, is the CanadArm that is installed on the Space Shuttles. Lunar and Mars rovers have been studied for mining purposes and general exploration (Putz 2002, Aizawa 1999, Costes 1998, Muff 2000). 26

Some space robot control methods use virtual force reflection (Penin 1999), others use techniques for augmented and virtual reality payload processing (Bentley 1998). Of great interest to this study is the work done by Nelson (Nelson 1998), about long delay control of lunar mining equipment. The 4-10 seconds delay has significant impact on the way in which machines can and should be operated. The research was not completed at the time of that publication, but it appears possible to operate remotely with delay up to 10 seconds. The project would have been considered succesfull by the researchers if this delay time caused the task to take at most twice as long to complete as without the delay time. Proof of concept of remotely controlling the Mobile Servicing System (MSS) at the ISS has been presented by Dupuis et al. (Dupuis 2002, 2001). Another demonstration of application has been given by Dupuis et al. for operations of space robotics in LEO and some tools for controlling an excavator in an open-pit tar sand mine (Dupuis 1999). Gillett (Gillet 1999) describes an infrastructure for interacting with remote equipment for operating satellite surface mines. This infrastructure includes communication strategies and data visualization for performance measurements,diagnostic monitoring and operator assistance systems.

3.4 Space construction

Because there is a need to minimize extra vehicular activities of the astronauts, robots are being developed to take over or assist with certain activities. Among those activities are inspection, maintenance and construction. On the construction front, work has been done recently on the robotic construction of truss structures (Doggett 2002). Also a more general purpose 27

robot called Skyworker has been developed and ground tested (Staritz 2001). Further, studies of robotic construction of large diameter telescopes in orbit have been conducted (Muller 2000a, Muller 2000b, Lake 2001). In these studies, Muller suggests that a 20-meter class telescope could be assembled at the ISS by the ISS robots and then in three months transported to E-S L2 using low thrust. Another option he suggests is that the construction could take place during the trip to E-S L2 by a 7 degree-of-freedom robot similar to the arms on the ISS.

3.5 General research

Next to these specialized areas of research there are several studies where the aim is to generally increase the abilities of robots. The results can be applied in many fields including telescope construction. The laser distance sensor is recently being applied for multiple uses in construction and many other fields in combination with pocket personal computers (pc’s) (Dworkowski 1998, Heinz 2001). Data gathered by these sensors allows the real-time updating of a 3D model of the construction site and its surroundings while getting immediate feedback on pocket personal computers that allows the supervisors on-site to compare reality with the design. Technical advances are being made in this area and research is being done at the National Institute of Standards and Technology (NIST) This technique is commercially available in an early version from a company called 'ArcSecond'. Most of the applications are based on automatic triangulation. Distances, horizontal, vertical positioning and angular measurements are all done compared to a by the user defined reference point or line. 28

A related area of research is the area of computer vision where with the use of several camera’s and other measurement devices, a computer processable “picture” of the surroundings is made from which useful information can be extracted (Gonzalez 2002, Shapiro 2001, Jasiobedzki 1998). The interpretation can be done by humans or by on-board processors. Inevitably the issue rises of who should do what and how far on-board autonomy should go. Wimmer (1998) addresses this issue in his paper but no clear answer can be given. Melchiorri (1998) studied multifunctional grippers to emulate the human hand for use inside or in space as discussed in paragraph 3.3. Where humans and robots work together, several forms of communication are possible. Humans often express themselves using facial expressions. For some situations it could be useful for a robot or automation system to be able to read those facial expressions and interpret them to adapt the way to work. For example in very complex or stressful operations, the human operator could be monitored for signs of stress or fatigue (Buiel 1998, Langton 2001). A multi-media environment is being developed as a tool to help with complex design and construction projects (Dureigne 2001). This tool has as its goal to use multiple sensory inputs for use with design and construction interfaces. This so far is mostly used in the design and prototyping of cars and in the aerospace industry where the digital prototyping saves a lot of time and money and where the products consist of very complex systems that can contain up to hundreds of thousands of parts. With some of the ailings of modern society, such as Repetitive Strain Injury (RSI), and to keep productivity at a good level, it is essential to keep in mind that ergonomics in the automation of systems is a high priority. The category of ergonomics includes controls, displays, body posture and other factors (Lagrange 2001). Next to asking experienced operators how they would like to see an operator station designed, a way to test these systems before 29

operator stations are built is by using virtual humans (Robertson 1997). These models of human beings can simulate the human body and its reactions or stresses to a certain workload or work situation. Another use of virtual reality is the training of personnel before they work with the real hardware. Several levels of reality can be achieved, from heads-up displays to full immersive 3D virtual reality (Logan 1998). All kinds of scenario’s that might occur during operation of the system can be simulated without crashing or damaging the hardware while at the same time giving the operator experience in all kinds of situations. Other than the ergonomics involved with the controls themselves (Wilson 2002), and the actual feedback to the displays and other control devices (Mae 2001), there is another important human aspect involved with remote control. It appears that the human return to reality, after having operated in Virtual reality or tele-operation for a couple of hours, is difficult for a while and can cause motion sickness symptoms (Takahashi 2001).

3.6 Supervised autonomy and teamwork

For complex projects and object handling it is often necessary to have more people or robots working together for transport, placement or handling. With a group of humans, this typically is done instinctively, although it is more efficient if the group is trained for the specific task. Research is being done where multiple robots handle one object (Sun 2002). The experiments have been succesful with two robots handling one rigid payload. These, however, are laboratory circumstances and do not represent a real operational environment. Training and planning for operations in a real environment can be done in many ways. One way of planning is by performing a human demonstration on a high level where decisions need to be made with intelligence, while local decisions 30

can be made by the robot. An example is path planning, where the human operator indicates a route by dots on a digital map, the robot then moves from mark to mark while avoiding obstacles locally (Tzavestas 2001). This system can be used for tele-operation, or in case where humans and robots work together in the same environment and location, the robot should be able to follow his human partner. There are many suggestions and plans on how to achieve this. One method that has been tested is to use a Light Emitting Diode on the human partner that the robot can detect and follow (Nagumo 2001). More direct interaction is possible by using voice commands, laser pointers (Trouvain 2001), and even touch in combination with the sensors that the robot has at its disposal (Grunwald 2001). Very often there will be one controller for one robot, if complex or delicate operations are being done. In some situations where multiple robots are doing similar tasks, one human can operate or drive multiple robots with the use of collaborative control and shared autonomy in teleoperation. This means the human controller can “posess” each of the robots individually while the others continue their tasks. When not controlled by the controller, the robots still need to be able to avoid collisions with each other and obstacles while at the same time they continue their assignments. This has been simulated, but not yet demonstrated (Fong 2001). A next level of difficulty comes into play when there are multiple human operators in different geographical locations, tele-operating robots that are handling one and the same object. Some experiments have been performed with this challenging mode of operations (Chong 2001, Kinugawa 2001). 31

Chapter 4

THE LUNAR ENVIRONMENT AND ITS RELEVANCE TO TELESCOPE- DESIGN AND OPERATIONS

As on Earth, in space the environment plays a significant role in planning and designing structures, and in the manner of construction. The most relevant lunar parameters will be explained and the influence on the design and construction will be discussed. A qualitative comparison between the lunar surface and free-flying telescopes in zero-G is also made with respect to the influence of the environmental parameters on the construction and operations of the telescope.

4.1 Location topography

The two most important types of terrain on the lunar surface are Mare and Highland terrains. The Highlands are the visibly lighter parts of the Moon, they are the oldest and have an age of approximately 4.6 billion years. The Highlands cover approximately 83% of the lunar surface. The Mare are younger (3.2-3.9 billion years old) and cover approximately 17% of the surface. They are the visibly dark areas. (See Figure 4.1)

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Figure 4.1: A picture of full Moon

The Mare are great flat plains, whereas the Highlands are densily cratered and rugged. Due to the longer exposure to cratering and gardening, the Highlands and Mare surfaces are relatively smooth. The regional slopes are large in the Highlands while almost absent in the Mare. The South Pole area is a special area because it is located in the largest impact basin on the lunar surface: the South Pole-Aitken Basin. This basin is approximately 2500 km in diameter and stretches from the South Pole to the crater Aitken on its far side. This basin floor generally is located below the average radius of the Moon. It is known from the Clementine mission data that the composition is different from either highland or mare samples and it is now regarded as a third type of lunar terrain. The South Pole of the Moon becomes even more interesting because of the orientation of the lunar axis with respect to the ecliptic (1.5 degrees of vertical) and the large local height differences. This generates a unique 33

environment near the lunar poles where places with permanent shadow exist in craters while the rim of the same crater can be almost permanently lit by sunlight (Kruijff 2000). It is suspected that there could be ice in the permantly-shadowed craters near the poles, which could make a valuable resource. Transportation and logistics as well as power, communication and construction need to be adapted for the location. Some locations can see Earth all the time while others can never see it. Local terrain determines whether or not the sun can be seen sometimes, never or always. This is relevant for communication, power generation and for the location of a lunar base. Lunar local terrain also determines the solid angle that the telescope can observe and its operational temperatures.

4.2 Gravity

The gravity on the lunar surface is approximately 1/6 Earth gravity (G), or 1.62 m/s2 (at the equator) (Heiken 1991).

4.2.1 Effect of zero-or micro-gravity on a large telescope

Zero- or micro-gravity is considered a great asset for large space- telescopes because of the possibility of using ultra-light-weight structures. These gossamer structures constitute a problem in other areas, such as vibration damping and stability issues that sometimes tend to be ignored. Since planning for the third generation space telescopes is starting now, it is a good time to re- address some of these issues and compare them to operations in a partial gravity field, such as the Moon. In zero-gravity, construction is complicated because of several factors. The most important ones are: getting around, 34

exerting forces, torques etc., keeping material, equipment and personel where it is supposed to stay. Most of these things can be done on the Moon in a similar fashion as they are done on Earth. Other than problems in zero-gravity during construction, there are some difficult issues during operation of a zero-gravity facility as well. First, pointing and tracking is a slow and time consuming process that generates vibrations and dynamic effects that need to die out before observations can be made, resulting in long down times and less efficient operations. Second, damping of vibrations generated by moving parts in the telescope is hard to accomplish.

4.2.2 Deformation of the mirror due to gravity

Every structure in a gravity field deforms because of that gravity field. This deformation is not a problem for most structures as long as the deflection is not perceived as disturbing by its inhabitants, or hinders the functioning of the structure by causing parts not to fit or even fail. On Earth, an example of this perception is a floor in a building that sags so much that it is visible to the eye and is perceived as unsafe (although structurally it may be fine). Another example could be elements of a house that develop cracks (glass window panes) or open and close with difficulty (jamming doors). For most structures this is effectively dealt with and it does not cause problems because of the large allowable tolerances, on the order of millimeters or even centimeters. Telescope structures are a different matter since the quality of the data over time depends for a large part on the stiffness of the structure. Thus it is important that the structure does not deflect during observations. The deflection becomes greater with the length of span. The larger the object without supports, the larger the deflection. Since the allowable tolerances on telescopes are very small, in the order of micrometers, this becomes a problem because, to get better quality 35

data, larger mirrors and structures are required. The problem has been dealt with for telescopes that exist on Earth. The largest, single mirror sizes on Earth are the 8.2 m diameter single mirrors of the Very Large Telescope Interferometer in Chile (Figure 4.3), and the 10 m diameter segmented mirrors of the Keck telescope in Hawaii (Figure 4.4). Plans exist for making even larger telescopes with the diameter of the segmented mirror of 30 m (California Extremely Large Telescope) (Figure 4.5) or even up to 100 m (Overwhelmingly Large Telescope) (Figure 4.6). The engineers and scientists that are designing these large telescopes, face great challenges to overcome the deflection by gravity of the structure, within the tolerances allowed for the scientific observations in the desired wavelengths. One advantage of gravity is that it is constant and predictable. This ensures that, if the structure is designed well within the elastic behavioral region of the materials, the same deflection will occur every time the structure is in the same position. If the desired tolerances can not be reached by material properties alone, then there is the possibility of sensing the deflection and bringing the element to the desired shape by actuators. These techniques can be adapted for the use on the lunar surface as well because gravity deformation is predictable, measurable, and constant. Since the bending moment increases with the square of the span, on the Moon it would be possible to span a length that is two and a half times as long as on Earth with the same material. If a simple supported beam is taken as an example (See Figure 4.2), then the following formula's would be applicable:

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q

1 2 θ1 θ2

wmiddle

Figure 4.2: A simple supported beam with a distributed load q generated by its own weight, deflection wmiddle and rotations θ1 and θ2. The beam has a cross- section of A, a specific mass of ρ , length L and a bending stiffness of EI.

In all these formulas g is the gravity at the beam location. gmoon = 1/6 gearth . This

results on the Moon (with everything else constant) in q,V,M, θ and Wm being 1/6 of Earth. q = A ρ g (4.1)

The forces at the endpoints will be:

V = ( A ρ g L ) / 2 (4.2)

The largest moment in the middle of the beam will be:

M = ( A ρ g L2 ) / 8 (4.3)

The rotations in the endpoints will be:

3 θ1 = θ2 = (A ρ g L ) / ( 24 EI ) (4.4) 37

The maximum deflection in the middle of the beam will be:

4 Wm = ( 5 A ρ g L ) / ( 384 EI ) (4.5)

Since the maximum stresses due to the mass of the beam will occur where the moment reaches its maximum value. This occurs in the middle of the beam length. The same beam on the Moon would have the same material properties as on Earth. However, the distributed load q is only 1/6 of the value on Earth. So if plugged in equation 4.3, this leads to:

2 L earth = 8 M / (A ρ gearth ) (4.6)

2 L moon = 8 M / (A ρ gmoon ) (4.7)

Since gmoon = 1/6 gearth equation 4.7 can be rewritten as

2 L moon = 8 M / (A ρ 1/6 gearth ) (4.8)

this leads to:

2 2 L moon = 6 (8 M / A ρ 1/6 gearth ) = 6 L earth (4.9)

or: Lmoon = 2.45 Learth (for a beam of the same material and crosssection) 38

Figure 4.3: Transportation of one of the four, 8.2 m diameter, mirrors of the VLT. Image courtesy: ESO

Figure 4.4: The 10 meter diameter segmented main mirror of the Keck telescope in Hawaii.

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Figure 4.5: Comparison between the 10 meter diameter segmented main mirror of the Keck telescope and the planned 30 meter diameter California Extremely Large Telescope main mirror.

Figure 4.6: Structural model of the Over-Whelmingly Large telescope with a 100 meter diameter segmented main mirror. Image courtesy: ESO

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4.2.3 Vibration generation and damping in the structure

Vibrations will be generated when repositioning and moving elements in the telescope. These vibrations will disturb the measurements if their amplitudes are greater than the allowable deflections. To avoid amplification of these deflections, it is very important to design a structure with eigen-frequencies as far away from the vibration frequencies as possible. The vibrations themselves will need to be damped out as quickly as possible to limit the amount of down-time, in which a telescope can not make any valuable observations. The generation of these damping forces is easier in a gravity field since there is something massive, inert and stable (a planet or moon) to absorb the forces. This makes it easier and faster to reach the required precision and stability in a gravity field than in zero- or micro-gravity where no such platform exists. Another part of the project where gravity and vibrations are linked is the cable of the lift-system. There are simplifications in the vibrations of the cable- system on the Moon because of the absence of wind and weather effects that generate vibrations as on Earth. The only generation of vibrations would be the machinery operating the system, the lift-cabin(s) going over the supports, seismic activity and possibly temperature effects. From Irvine (Irvine, 1981) it appears that the wavespeed is not influenced because it is a function of material properties that are not influenced by the gravity. However, the stiffness behavior is influenced by gravity which in turn influences the eigenfrequencies of the cable system. Equation 4.6 to 4.9 show that if an identical suspended cable system 2 would be built on the lunar surface it would have a λ moon that was 36 times 2 smaller than the λ earth .

41

2 2 λ = (m g L / H ) L / ( H Le / EA ) (4.6)

2 2 λ moon = ( m 1/6 gearth L / H ) L / ( H Le / EA ) (4.7)

2 2 λ moon = 1/36 ( m gearth L / H ) L / ( H Le / EA ) (4.8)

2 2 λ moon = 1/36 λ earth (4.9)

The parameter λ2 can be thought of as if resembling the stiffness of 2 springs in series. In the case of the suspended cable there is geometric and axial stiffness. The eigenfrequencies are related to this parameter.

From table 3.1 in Irvine (1981) a few values are extracted to illustrate the effect of changing λ2 on the eigenfrequencies of the first eight symmetric in-plane modes. The resulting Earth values and Lunar values are shown in Table 4.1.

Table 4.1: Natural frequencies of the first eight symmetric in-plane modes as a function of λ2 .

2 λ earth ω1/π ω2/π ω3/π ω4/π ω5/π ω6/π ω7/π ω8/π 256 π2 2.86 4.91 6.93 8.93 10.93 12.91 14.81 16.00

2 λ moon 70.18 2.35 3.23 5.03 7.01 9.01 11.01 13.00 15.00

This means that for a cable behaving equally stiff on the moon, the cable should be six times as long as on Earth. The deflection still is related to L4 so only 1.56 times as long a cable on the Moon will give the same deflection as on Earth. 42

4.2.4 Pointing and tracking of the telescope

One of the activities that generate vibrations in a telescope is the repositioning of the telescope to observe and track objects for the duration of the observation. However, the pointing and tracking itself is not trivial. The required speed is very low due to the rotational speed of the moon, however the required precision is very high while at the same time the vibration generation must be kept to a minimum. To move the telescope to its position it is very convenient again to have this massive, stable and inert platform because of Newton's third law (An action results in an equal but opposite reaction). This makes the movements easier and faster to accomplish compared to zero-gravity, while at the same time not generating excessive amounts of vibrations that lead to long down times. In zero- or micro-gravity, the pointing and tracking is very cumbersome with large structures, due to the complex systems (reaction wheels, thrusters etc.) required to accomplish the movements. At the same time in zero- or micro-gravity the dynamics and vibrations generated by this movement are complex and hard to damp out, which leads to long down-times, during which no observations can be made. A super-conducting magnetic bearing appears to offer a unique solution because of the gravity on the Moon, the low temperatures (See section 3.4), the required speed and precision and the dust. These bearings can give enough precision, fast movement for pointing or slow movement for tracking as is desired, they generate almost no vibrations due to stiction or friction, and as a bonus they are impervious to wear and tear by dust. Laboratory research done at the University of Houston shows that they operate at temperatures lower than 90 K and have achieved low rotational speeds of 23 millirad/sec, which is still about 3 orders of magnitude too fast, but it is expected that the desired speeds can be reached with further research. The positioning and repeatability are so far in the 43

order of 0.1 arcsec. The behavior of the bearings appears to be that of a spring with low stiffness but with high damping. From a private discussion with Dr. T. Wilson (Johnson Space Center) and Dr. K. Ma (University of Houston) it appears that, for a telescope with this mass and size, about 5% of the total mass would consist of the bearings. The forces in 1/6 Gravity would easily be supported by the bearings. Great care, however, should be given to preventing the damaging of the ceramic parts during launch, landing and construction. Distance holders will be required during construction to prevent the ceramic surfaces from damaging each other. These distance holders then can also be used during maintenance in case the power needs to be shut down. (Ma 1993, Wilson 1994) In zero- or micro-gravity, positioning thrusters could speed up the pointing and tracking of the telescope, however this would result in stronger dynamics and in clouds of particles that might condense on the mirror surfaces degrading the performance. The use of thrusters and the required propellant would limit the lifetime of operations because of the limited supply of the propellant. All in all, a light gravity environment is beneficial for the operations of pointing and tracking.

4.2.5 Construction

Gravity makes transporting, placing and installing of telescope elements easier. Low force or torque connections do not require special instruments or special consideration, from a force transfer perspective. Special torque-free tools are required in zero-G because of Newton's second law. An astronaut trying to turn a bolt using a conventional screwdriver would result in the astronaut spinning around while the bolt may not have moved at all. It might not be as easy as in zero- or micro-gravity to reach all the spots on a construction site without the use of large cranes because a robot or astronaut can not just float to where it/he/she needs to be. Another asset for the Moon is that no tethers are needed 44

to keep tools, astronauts, robots and construction elements from getting lost in space which simplifies operations. A disadvantage is that the instruments and cranes must be designed stronger to withstand the continuous moments generated by their own mass in the gravity field. The structural support mass of the telescope will be larger on the lunar surface than in zero- or micro-gravity. In zero-G the need for high-precision control of the structure will require a higher mass and higher complexity of actuators and monitoring equipment. To what extent exactly will need to be researched in greater detail. A direct comparison of masses will not be possible and must consider the lifecycle of a lunar telescope that has easy access to maintenance and upgrading will be very different from a telescope located in E-S L2 where travel times of up to 6 months to and from there to E-M L1 will severely limit maintenance and upgrading. The efficiency of such an operation should be included in the comparison and will warrant the expenditure of the transportation of the extra mass.

4.2.6 General influences on engineering

The influences of a change in Gravity are not studied well. In this paragraph an attempt is made to address some of the arising issues. There are many more issues and more study towards these influences on the design and engineering practices is required. Research in this area will increase the understanding of all the effects and will allow optimization of design and engineering practices which now are mostly based on Earth based practice and experience. Millions of dollars could be saved by designing in an optimized way for the environment (lower gravity) the design will have to function in.

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4.3 Vacuum

On the Moon, a very high quality vacuum exists. The concentrations of atoms is about 105 cm-3 during the lunar night and 104 cm-3 during the lunar day, which is about 14 orders of magnitude less than on Earth. Because of this extreme difference, it is said the Moon does not have an atmosphere, which can be assumed for many purposes (Heiken 1991).

4.3.1 No atmospheric absorption

The reason to go outside the Earth's atmosphere is because the Earth atmosphere absorps radiation in the wavelengths this telescope is supposed to observe. So no atmosphere is a must. The vacuum on the lunar surface is somewhat better than that of free space, but both are suitable for astronomical observations in the infrared wavelength. (Hodge 1973, Potter 1988)

4.3.2 Contamination of the vacuum

The lunar vacuum, however, is easier to disturb (temporarily) than in space due to the amounts of atoms that can be released in gaseous form by landing and launching and other activities that produce gases. All activities in the neighborhood of the telescope need to be carefully monitored and controlled as to not to disturb the vacuum resource. Landing and launching operations are especially crucial since they produce so much exhaust gas that they can double the tenuous lunar atmosphere temporarily (Hoffman 1973, Johnson 1971, Vondrak 1974, Burns, 1988). Because particles on the Moon travel in balistic trajectories they quickly spread over the entire Moon and settle down or escape into space if their velocity is higher than 2.38 km/sec. 46

4.3.3 Thermal heat rejection

During operation and construction in a vacuum, (in space or on the Moon), the only way to get rid of excess thermal energy is by radiation. This is a very inefficient process compared to conduction or convection and requires large surfaces. The best way to address this problem is to produce as little thermal energy as possible. Eventually all energy generated and used by the telescope or its construction will “decay” to thermal energy. This can be used to warm certain elements that will not function when they become too cold, but eventually all the energy must be radiated away. Thermal design is an important issue in any space project, but even more so for an infrared telescope.

4.4 Dust

The lunar dust, which is part of the crushed surface layer on the Moon called regolith, is very fine with an average grain-size of 70 µm and 10-20% is smaller than 20 µm. Because the primary soil forming mechanism is meteoroid impact and there is no liquid water present on the Moon, there is only a limited range of minerals present. No clay minerals or organic materials can be found. Due to the process of micrometeoroid impact which produces partially melted, very irregular particles, and the absence of water or atmosphere to erode the particles, the grains remain coarse and sharp. The layer of dust covers the entire lunar surface and can be several meters thick. Because of the continuous shaking by meteoroid impacts during billions of years, the dust is very densily packed below the first 15 cm of the surface. At approximately 30 cm depth the relative density reaches 90% (Heiken 47

1991, Perko 1998). The dust is also electrostatically charged due to solar wind and the breaking of electron bonds in vacuum conditions. This means that the dust particles cling to every surface they contact (Perko 2001). Due to the lack of an atmosphere to brake the velocity of particles or to keep very small particles floating for a long time, the travel trajectories of stirred-up particles will be purely ballistic trajectories, no matter the mass of the particles. Thus, their movement on the surface is related to the force that lifts them off the surface. Attention should be paid to limiting contact of objects to the surface and to low momentum events.

A dust transportation mechanism is suspected at the terminators where the dark and sunlit areas of the Moon border each other. These two terminators travel over the lunar surface with the speed of rotation. This mechanism would cause the particles to be levitated up to a couple of meters above the lunar surface. It has been observed in pictures taken during the Apollo missions (Rennilson 1974, Sickafoose 2001). As the mechanism requires the boundary between sunlit and dark areas, it is not expected to occur in the permanently- shadowed regions.

4.4.1 Contamination of surfaces and sensitive elements

Lunar dust can be a valuable resource for mining and construction but can cover sensitive elements of a telescope and contamination of surfaces of elements, like mirrors, would degrade the performance of the telescope. Dust contamination needs to be avoided during construction and during operations. This can be achieved by restricting the speed and angles of the dust particles that do get stirred by transportation and other activities. In other words, do everything slowly and make sure the particles do not travel higher than the bottom of sensitive parts and are not propelled in the direction of the telescope. 48

Maybe the natural contamination issue of surfaces has been overestimated because even on the equator after 30 years, the retroreflectors placed during the Apollo missions show no measurable evidence of major deterioration (Smith 1988).

4.4.2 Wear and tear of moving parts

The coarse and sharp dust particles can degrade bearings, seals and other moving parts and even render them immobile (Gies 1996). From private discussions with Dr. H. Schmitt (Apollo 17 astronaut) it appears that there were significant amounts of deep scratches on the aluminum cuffs of the connections between the gloves to the spacesuit. They were all in the radial (screw) direction and did not seem to hamper the functioning of the spacesuit. However, the visit of Apollo 17 lasted only a couple of days and can not be compared with long duration stays and rigorous work outside. Every moving part that is to be operated on the dusty lunar surface for a prolonged period of time needs to be carefully designed to prevent dust from entering the moving parts or in certain cases the issue can be avoided by using specific technologies such as magnetic bearings.

4.4.3 Foundation design

Due to the very dense packing of the regolith it is possible to build the telescope foundation in the regolith withouth having to resort to finding bedrock or constructing deep pile foundations. This same characteristic can make digging quite difficult. (Perkins 1996, Lally 1996, Klosky 1996, Willman 1995, Charlie 1996, Lin 1994) A foundation for the telescope has been designed by Van Susante (Van Susante 2001). This design minimizes required digging while 49

maximizing the stability and capacity for transportation of the static and dynamic loads to the underground.

4.5 Temperature

The sources of thermal energy are the sun (direct and reflected) and the internal lunar heat flow that is believed to be generated by the decay of radioactive elements in the lunar mantle. The heat flow from inside the Moon is very small, on the order of 30 mW/m2. As there is no sensible atmosphere on the Moon, the temperatures discussed here are surface temperatures that vary greatly with location and with solar illumination. Because the Moon rotates so slowly, a lunar day lasts for approximately 350 hours and the lunar night also lasts for about 350 hours. The axis of the Moon is tilted only 1.5 degrees from the axis of the Sun and they are in the same plane; consequently normal equatorial temperatures are as low as 120 K during the lunar night and 400 K in direct sunlight during the lunar day. Because of the orientation of the axis, there are polar regions where the sun never shines. The only light that reaches these places of permanent shadow is occasional reflected sunlight from crater rims that do receive sunlight, these areas can be relatively small. In these permanently shadowed places, the temperature is expected to drop to a constant 40-70 K (Vasavada 1999, Carruba 1999) and even to 30 K if shielded from the reflected sunlight. There are no temperature measurements of the polar regions, so the exact temperatures are not known.

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4.5.1 Absolute temperature must be very low

Because sensitivity of instruments has reached the quantum or theoretical limit and can detect single fotons it is necessary to decrease background contributions to the signal. In case of an infrared telescope that means maintaining a low temperature for the telescope and its surroundings. To function optimally, an infrared telescope needs to be extremely cold (~30 K). Some rules of thumb (equation 4.10 and 4.11) derived for infrared telescopes have been discussed with Dr. J. van Cleve (Ball Aerospace) who is involved in the Space Infrared Telescope Facility (SIRTF) that was launched on August 25 2003.

λ*Ttelescope<600 (4.10)

Where λ is the wavelength (µm) for observation and Ttelescope is the temperature (K) of the telescope. Adhering to this rule of thumb makes the telescope 'dark' in thermal emission and also increases performace at longer wavelengths. The improvement at longer wavelengths is a bonus but falls out of the range of wavelengths of design interest and is not discussed here. Another rule of thumb for detector temperature is:

λ*Tdetector<200 (4.11)

Where Tdetector is the temperature (K) of the focal plane. Adhering to this rule of thumb makes sure that the detectors can function at their maximum sensitivity.

Dr. van Cleve provided figure 4.7 to compare telescopes at different temperatures. 51

293 K Jy µ 50 K 5*nefd, 20 K

Figure 4.7: Noise Equivalent Flux Density (NEFD) (sensitivity) for different telescope temperatures and sizes.

Figure 4.7 shows the sensitivity of four telescopes. A 25 meters filled aperture at 20 K, 50 K and 293 K and the SIRTF 85 cm mirror at 20 K. This shows that a huge sensitivity gain can be accomplished by a cool 25-meter diameter filled aperture telescope. In a permanently shadowed crater, where the temperature is very low (~ 40 K) to start with, direct cooling of the telescope may only have to deal with local heat sources to provide the best environment for an infrared telescope. Active cooling for the telescope itself may not be necessary with careful design and shielding.

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4.5.2 Thermal gradients

Next to a low absolute temperature it also is important to have very small thermal gradients over the telescope mirror and structure (Dr. van Cleve, recommends a 10 K maximum variation over the entire mirror). Fortunately, in the polar areas, the thermal gradients are very small and they change very slowly due to the slow rotation of the Moon and hence the change in illumination of the crater rim. To decrease the thermal gradients even more it is possible to face away from the warmer (brighter) sunlit areas on the crater rim or use MLI shielding.

4.5.3 Thermal control

Thermal control is an important issue, especially when the structure needs to be so cold while other elements (e.g the computer elements) operate at higher temperatures (>220 K). As radiation of energy is more efficient with larger temperature differences (radiation efficiency changes with T4), time plays a role in these considerations. If a structure is heated up, it will take time to cool back down to the required very cold temperatures. Since the cooling process becomes less efficient and takes more time for each degree as the telescope becomes colder, this can take several hours to days. This would result in lower observing efficiency and is not desirable. A stable, inherently cold area is very beneficial for operations of an infrared telescope.

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4.6 Lighting conditions

Lighting effects on the lunar surface can be somewhat complex. The lack of atmospheric dispersion, the surface reflective capacity leads to very high contrast between shadowed and sunlit areas. Since the light is not dispersed, a lit surface may be unbearably bright to look at while its shadow is perfectly black. Shadows can hide things very effectively. The reflection of the surface also is a function of the illumination angle. Light coming from within 30 degrees of normal will not reach the eye or sensors as most of it will simply reflect back (back scattering effect). This may cause the observer to miss objects until he/she is almost on top of them. On the other hand, if the light comes from very low angles (< 30 degrees of horizontal) it causes very long shadows that can hide craters and boulders. If light comes from behind, a similar effect occurs, and up to 10 degrees to either side, the landscape appears featureless (Heiken 1991). These lighting conditions, as well as the areas in permanent shadow, pose challenges for construction and operations. How does one see and operate safely in the dark areas? How will artificial light scatter? Would laser, or radar sensors be more efficient than visible light cameras? More research on the exact effects, and how to deal with them, is necessary.

4.7 Seismicity

Seismic information from Heiken (1991) and Eckart (1999) shows that the total seismic energy on the moon is about seven orders of magnitude lower than that of Earth. There are four identified sources of lunar seismicity:

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* Monthly deep-focus moonquakes caused by Earth-Moon tidal stresses * Shallow moonquakes that are fewer but stronger and may be due to tectonic processes. They account for most of the seismic energy released in the Moon. * Thermal moonquakes that may be due to thermal degradation of young lunar surface features. They can last for over an hour. * Moonquakes caused by meteoroid impacts that vary widely in energy. Meteoroid impacts of all energies tend to be most common when meteoroid showers peak. Overall the moon can be considered seismically and tidally stable. A study done by ESA (ESA 1996) suggested that the moon would have a disturbing seismic event that would create a disturbance greater than 22.5 nm every 6 seconds. This would render the moon useless for large baseline interferometry. In a reaction to this report, Mendell (1998) took another look at the seismic data gathered during the Apollo era and concluded that a disturbing event of 22.5 nm occurred only once a year, so this would not be an issue for the Lunar South Pole Infrared Telescope because there are no elements that will be linked simultaneously and are kilometres apart. For a future expansion that involves interferometry it might be relevant. For this design, it can be assumed that once a year the telescope could encounter a seismic event that could disturb an ongoing observation.

4.8 Meteoroid impacts

Over time, meteoroid impacts will degrade the mirror surfaces of the telescope. Researchers have developed an average annual cumulative 55

meteoroid model from studying the bombardment and impact history of the Moon (Cour-Palais 1974, Heiken 1991).

For meteroroid mass m (grams):

-6 6 10

2 Where Nt is the number of particles per m per second of mass m or greater to hit a surface of 1 m2 on average cumulative in one Earth year.

According to the above model, a micrometeoroid of 1 * 10-12 grams or larger would hit 1 m2 every 382 minutes. This means that a telescope with a dish surface of 490 m2 would be struck every 47 seconds by a micrometeoroid of 1 * 10-12 grams or larger if the telescope was aligned with the normal. Because these models are based on the long-term bombardment history of the lunar surface and because meteoroid impacts were much more frequent in earlier time, the present risk of being hit by a meteoroid on the lunar surface is not known and more research is required before any accurate estimates can be made. The Moon’s gravity-well doubles the flux of meteoroids hitting the surface compared to free space but that does not mean that a structure on the lunar surface would be hit twice as many times as a structure in free space. The Moon itself shields the structure from at least half and often a larger part of the sky, so the lunar meteoroid flux is equal to or less than in free space. The damage done by small impacts can be repaired by polishing, re-coating or replacing the mirror elements. The amount of impacts will influence the amount of maintenance needed for the mirror segments and their replacement rate. To repair damage to the mirror elements, it is a wise decision to have some spare elements available 56

so damaged ones can be replaced. An example of a larger impact is shown in Figure 4.8. This impact is one of many that were found on the old photovoltaic arrays of the Hubble Space Telescope that were brought back by the space shuttle during a maintenance mission in 1993. The impacts found, ranged in size from 3 micrometer to 6-7 millimeter. This is the size of the zone of influence which is 10-20 times larger than the size of the particle. The Hubble Space Telescope is positioned in Low Earth Orbit which is a very 'dusty' environment with a much higher impact frequency than would be expected on the lunar surface.

1.25 mm

Figure 4.8: Impact of a micrometeoroid on the Hubble Space Telescope's old photovoltaic arrays. image courtesy: ESA 57

Chapter 5

TELESCOPE DESIGN & DESIGN DECISIONS

From the review of robotics technology and an understanding of the lunar environmental conditions to be considered, a telescope design was developed. This section discusses the design and construction of a 25-meter telescope that can be assembled in a permanently-shadowed crater at the Lunar South Pole.

5.1 Relevant general parameters for a telescope & its construction

The major factors of influence on the location choice for a large infrared telescope are listed in Table 5.1. In Table 5.2 a qualitative comparison is made of these many factors that influence a large telescope location choice. Many factors that are of influence on the telescope design are listed and compared in a qualitative way based on a table from Van Susante (2001). Each factor is described to indicate its relevance to telescope design and operation. Possible locations for a telescope which determines the nature of these factors are defined.

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Table 5.1: Description of factors of influence on telescope factor description resolution the smallest detail that can be distinguished vacuum atmospheric density background radiation interference and noise seismicity location stability force sink ease of telescope rotation rotation speed of axial rotation of the location artificial disturbances disturbing human originated activities gravity the amount of gravity weather effects classical weather on Earth vs. space weather thermal environment thermal range and variability radiation harmful radiation for operation meteoroids frequency and magnitude of meteoroid impact dust amount and mitigation of dust attitude knowledge and stability of celestial position maintenance maintenance feasibility observation duration maximum observation time communication ease of communication with Earth cost relative cost compared to Earth transport how to get to the location of the telescope construction ease of telescope in-situ construction expansion/upgrading feasibility of future improvements re-use can the hardware or infrastructure be used or recycled for other purposes

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Resolution of a telescope is determined by the observed wavelength and the diameter of the main mirror. Resolution is also influenced by the stability of the atmosphere (if any). Since the wavelength of interest for this telescope lies in the infrared it means that an atmosphere is a negative factor for the location choice while a larger main mirror is positive in general.

Vacuum is a major factor in the quality of telescope observations as light is absorbed and refracted by atmospheric gases. Dust suspended in the atmosphere may cause problems like on Earth or in extreme cases on Mars in dust storms. Vacuum is a positive factor for the quality of telescope observations. No atmosphere also means no wind and weather effects, but it also diminishes protection against micro-meteoroids.

Background radiation. Dark, cold sky is necessary to eliminate the influence of unwanted background radiation, such as the infrared radiation coming from the Earth’s atmosphere, stray-light from civilizations cities, or from surrounding “hot” terrain on the lunar surface.

Seismicity is an important factor concerning the construction of the telescope and the stability during observations. If seismic events with amplitudes larger than the required precision occur frequently, then a particular site might not be the most efficient location to build a telescope. If events are not frequent, and / or very small, then seismicity is less relevant because only the ongoing observation will be influenced. If that does not happen more than a few times a year, that is no problem. Seismicity itself does not prevent the siting of a telescope. In California and Hawaii there are many good telescopes while the region is quite seismically active.

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The presence of a force sink is of relevance because it can have significant influence on the efficiency of the telescope. If the pointing to a new observing target takes 2 hours, that is 2 hours of lost observation time. So faster pointing capability is a positive feature. On the other hand, the vibrations and other dynamic effects can disturb the observations for a long time and need to die out before detailed observing can start. So it is important to find an optimum between speed and the amount of vibration generated. If there is a Force-sink, like a planetary body, that is considered positive for telescope efficiency due to the fact that the pointing can go much faster and the vibrations will decay faster below the limits.

Rotation of the location site around the axis of the planetary body it is located on is important because it determines the maximum observation time of a target in one session. It also influences the required tracking speed. Rotation of the location varies the part of the sky that will be available for observation, except in polar areas. On Earth, observation time is limited by its 24 hour rotation which means that there is a maximum observation time of a couple of hours per object. On the Moon, this time is multiple days, while at the polar areas it is almost unlimited.

Artificial Disturbances can influence the quality of a telescope site in a negative way. Stray-light from cities, or radiowaves for radio telescopes are examples. Also vibration or dust production from industry near a telescope site can influence the quality of observations.

Gravity, facilitates construction, the previously mentioned pointing/tracking, and vibration damping. A little gravity is an asset, for some like thermal properties, it does not matter and for others it is a slightly negative aspect like the deflection of 61

the telescope structure (although that is predictable and repeatable). After studying this project it seems that gravity can be a positive factor on the lunar surface because the benefits from the positive construction and operation aspects outweigh the negative deformation aspects.

Weather effects on Earth in the classical sense with rain, snow, mist, etc. disturb telescope operations and observations. It requires an enclosure to protect the telescope and weather can make the atmosphere extra opaque. The absence of classical weather is positive.

Thermal environment is important because thermal gradients and changes in temperature deform the mirror and structural elements which disturbs the observations. Also an absolute low temperature is positive for infrared telescopes because it lowers the background noise. Low temperature, small temperature range and very slow gradients are positive factors.

Radiation quantitiy, type of radiation that the location receives from the sun is important for the detectors and other electronics, since they need to be shielded from most of the radiation. Solar flares can knock electronics offline or damage them permanently. Galactic radiation is present everywhere except where there is a large magnetic field or an atmosphere that functions as a shield that reduces its effects significantly, like on the Earth’s surface.

Meteoroid impact density is assumed uniform in space. A gravity well like the Earth or the Moon attracks meteoroids so the impact density is higher there. Earth is shielded by the atmosphere and no small meteoroids reach the ground but not so on the Moon where there is no atmosphere to shield against meteoroids. Even though the flux in lunar space is larger than in free space, a 62

location on the lunar surface is also protected by the Moon itself which reduces this higher flux by about half. So the meteoroid flux is about the same or lower than in free space.

Dust transport mechanisms exist on the Moon but are absent in free space. This is important because dust can coat the mirror elements and damage moving parts. This is described in more detail in section 4.4.

Attitude is important for the pointing and tracking. If you know where the site is, then you know where to look for your target and how to track it over time. This basically refers to the precise knowledge about the telescope location and its movements through space with respect to the rest of the universe. The Moon has a very well known location and orbit whereas other points in space need station keeping and adjustments after which the exact location will have to be determined again. This is of great relevance for precise and long duration measurements.

Maintenance is crucial for the lifetime of a telescope. If maintenance is possible, it will greatly extend the lifetime of the facility and justifies different kinds of investments.

Observation time is determined by the rotation speed and the duration of day and night times. In most places on a planetary body these two parameters are linked, however, in the South Pole area of the Moon there is no day/night rhythm. This allows continuous observations. In space, the pointing of the telescope changes the orientation of the telescope continually with respect to the Sun.

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Communication determines the way the data will get back to the scientists. Options are (1) direct, (2) relay links, (3) store and transmit later. Direct or relayed links are required for the phases prior to operations. Depending on the amount of data and the available bandwidth it may be necessary to have a direct or relay-link during regular operations as well. This depends on the setup of the instruments and how much data they gather. If required data rates are small enough, store and transmit strategies might work.

Cost is a parameter of considerable importance. The total cost, the period over which the money can be spent, and the value of data in proportion to cost are useful parameters. A longer lifetime for a higher cost may be warranted. It is hard to qualify certain factors in the cost, like the building of infrastructure that is useful for other activities and parties. The cost can be qualitatively compared to a telescope of similar size on Earth.

Transport to the telescope location, includes space transportation as well as surface transportation. This parameter defines how much effort and infrastructure is required for the transportation of the telescope (elements).

Construction in the location where the telescope will be operated. This parameter assesses the difficulty of construction, assuming that the telescope is too large to deploy as a single element

Expansion / upgrade, like maintenance, is very important for the life expectancy of the telescope facility. If expansion / upgrading is possible, that is positive.

Re-use of hardware in case the telescope is decommissioned. If reuse in part or as a whole of hardware or infrastructure is possible, that is a large positive point. 64

Table 5.2: Qualitative comparison of important factors for telescope locations

Earth Low Earth Orbit Moon Moon Lagrange point Deep space South Pole Sun-Earth L2 Resolution Limited by Diffraction limited Diffraction Diffraction Diffraction Diffraction atmosphere limited limited limited limited Vacuum None Solar wind Solar wind Ultra high Solar wind Solar wind Background None, best in Reflecting of Reflected light Crater rim Needs shield Yes, maybe radiation dry high satellites and of earth, sun reflects, rest shield mountain atmosphere glow dark necessary regions Seismicity Depends on None Very little Very little None None location, but strong events Pointing / Easy, but can Requires Easy, but can Easy, but can Requires Requires tracking generate complicated generate generate complicated complicated vibrations system of gyros vibrations vibrations system of gyros system of and reaction and reaction gyros and wheels etc. wheels etc. reaction wheels etc. Rotation 24 hours Choice but limited 28 days 28 days Choice except Choice by earth orbit orbit except orbit Artificial Many Many Near side None, except From direction of From Disturbances many, far side the ones self earth direction of none produced earth Gravity 1 g Gravity gradient 1/6 g 1/6 g None None Weather effects Full scale Expanding None None None None residual atmosphere Thermal Fast Stable Space if Extreme Stable Stable Space if Stable environment changing, shielded differences, shielded Space if seasonal as stable if shielded well as daily shielded Radiation Low Medium Medium Low Medium Medium Meteoroids Low High Medium Medium High High Dust Present Very little Careful Possibly only Only cosmic Only cosmic engineering if disturbed Attitude Known Known Known Known Not stable Not exactly known Maintenance Easy Possible Possible Possible Not easy/not Not possible possible Observation Variable 24/24 hours 14/28 days 28/28 days 28/28 days 28/28 days time possible, depends Maybe more on observations Communication Always easy Complicated with Near side Relatively Requires Deep Requires satellites easy, far side easy Space Network Deep Space complicated Network Cost Relatively low Medium High High High High Transport Relatively Medium Complicated Complicated Difficult Difficult easy Construction Easy Relatively easy Possible but Possible but not economic Not possible Complicated Complicated Expansion / Easy Difficult Relatively Relatively moving back to Not possible upgrade easy easy E-M L1 Re-use of Easy Difficult Relatively Relatively moving back to Not possible hardware easy easy E-M L1

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5.2 Requirements for a large lunar telescope

Minimum requirements for a state of the art lunar telescope in the middle of the 21st century have been established by analyzing the best telescopes planned for 2020 (See Appendix A) and matching the capabilities with those (See Table 5.3). A lunar telescope would need to gain at least an order of magnitude of sensitivity in the infrared spectrum compared to the JWST. Since this set of requirements is not necessarily unique, some are chosen based upon the experience of the author and discussions with other experts.

Table 5.3: Minimum requirements

Angular resolution Better than 0.01” Instruments 50 m3 volume ,imager, spectroscope Stability Minimal observation disruption (downtime less than in space) Wavelength 5-25 micron Temperature 30 K for telescope, 4 K for some instruments Aperture size Surface 10 times JWST => 332 m2 => radius >21 m Optical design f/2 (mirror diameter is 1/2 of the focal length) Lifetime “Infinite” upgrading, maintenance and possible expansion Commissioning Done robotically, but access by astronauts required Maintenance Done by robots in most cases , access by astronauts must be possible. Operations Remotely controlled Mirror elements Light, stiff, thermally stable, sized optimal for production Dust Prevented from contaminating any sensitive elements Micrometeoroids Equal or better situation than in space 66

In order to simplify the complex engineering characterization of the telescope, a reduced set of assumptions has been adopted (See Table 5.4). These are based on the minimum requirements in Table 5.3.

Table 5.4: Design parameters for a 25 m lunar Infrared telescope. type Chosen design parameters Primary mirror 25 m diameter segmented primary mirror Secondary mirror 3 m secondary mirror Optical design f/2 (50 m distance between primary and secondary mirror) Observation Infrared 5-25 micron wavelength wavelength Location Location inside lunar permanent shadow but close to abundant sunlight. Shackleton Crater is chosen. Bearings Super conducting magnetic bearings for azimuth and altitude bearings Mirror elements Mirror elements are hexagons with its six outlying points on a circle with a radius of 1.15 m. Total required : 492 Sky-coverage Sky-coverage is determined by the location but assumed to be sufficient (approximately 1/3 of total sky in Shackleton) Temperature Low telescope operating temperature is required (~30 K) Temperature Slow and low temperature fluctuations are required (inside fluctuations Shackleton this is met)

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5.3 Space transportation influences on elements

It is assumed from a discussion with Mr. B. Blair (CSM) that the maximum payload that can be transported to the lunar surface in a single flight is 10 metric tons. This number is based on using a new architecture to determine payload on the lunar surface. The architecture consists of a launch from Earth to lower earth orbit (LEO) where the spacecraft will be re-fueled and launched to E-M L1, where another re-fueling will take place, then the spacecraft will land on the Moon in its designated location on the landing pad near the lunar base or in Shackleton Crater. This architecture would appear to minimize transportation costs for large payloads going to the Moon (Blair et al., 2002) The maximum size payload fairing of an Ariane 5 rocket is approximately 15 meters long and 4.5 meters in diameter for the first 10 meter after which it tapers off (See Figure 5.1). During launch the payload will have to be able to withstand extreme vibrations, sounds and shakings. To avoid any damage to the cargo, all payloads must be completely tested on the ground. Because it is exactly known what environment the cargo has to withstand, the testing can be done in such a way that it can be assumed that there is no damage to the cargo when it is launched. Special attention can be paid to the packaging since there is no need for automatic deployment. The limitations on size of individual payloads and the launch vibrations must be considered in designing the telescope and its construction sequence.

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Figure 5.1: Ariane 5 payload fairing dimensions. Image Courtesy: Arianespace 69

5.4 Optimization of construction elements, transportation and robots

Robots will have to do most of the work, automatically under supervision or tele-operated from the lunar base or Earth. To make sure there is no overcapacity and that the available resources are efficiently used, all elements and actors in the construction process need to be carefully integrated. For example, the sizes of the payload fairings determine the maximum sizes of telescope elements and equipment that can be sent in one piece. However, the lifting capacity of the robots that will do the construction work will determine the mass of the elements. It would be most efficient if all elements had approximately the same size and weight when they are shipped and handled so there is only need for one type of transporter and crane-robot. Of course, lighter and smaller elements are possible but the fewer connections that need to be made, the better. This optimization process will reduce the complexity of the construction and reduce the risk while optimizing the use of robots.

5.5 Phases in the construction process

Several phases are defined for the construction process, on the basis of their operational characteristics. In phase I, the infrastructure outside the crater is built to provide power and communications for lunar base construction. The support infrastructure within the crater is built in the second phase to prepare for telescope construction. The third major phase is the telescope construction itself, where all elements are assembled and all cables and supporting elements are connected. Once the telescope is completely assembled, the commissioning phase (phase IV) starts. This is the phase where all elements are aligned and every aspect of the telescope's operation is tested and corrected, if required. If all 70

is checked out according to the requirements, full-scale observations can begin. Every so often, a maintenance check is required or upgrades will become available (Phase V). It also might be desirable to expand the facility by adding more telescopes and / or to make an interferometer. In theory there is another phase (Phase VI), if it would ever occur, the de-commissioning phase where the telescope(s) is (are) dismantled. This phase is not discussed in this thesis. On Earth this is not very common because telescopes (even if they are very old and not top of the line anymore) can still be used for major scientific discoveries. However, if upgrading and expansion are possible and it can be assured that the telescope stays up to date and top of the line, scientific work may continue for decades or even a hundred years or more.

5.5.1 Main phases

In total, five main project phases exist as described in the previous paragraph, that can be divided in sub phases. The major phases are: I) Support infrastructure outside the crater II) Support infrastructure inside the crater III) Telescope construction and assembly IV) Commissioning phase and operations V) Expansion, maintenance, and upgrading

5.5.2 Subphases

Eleven subphases can be distinguished as is shown in Figure 5.2. Main phase I can be split in four subphases : three unmanned subphases and one manned subphase. The first three unmanned subphases will take place in three different locations : Malapert Mountain (1), Shackleton Crater rim (2) and the 71

lunar base site (3a and 3b). Because the fourth subphase is more an extension of the third they are called 3a (unmanned lunar base part) and 3b (manned lunar base part).

Main phase II can be split in two subphases. One (4) where the cable is laid down into the crater and where a robot will function as a landing beacon for the next subphase. The second subphase (5) will consist of the landing of the construction outpost and other materials in Shackleton Crater, using the robot as a landing beacon. The first human inspections of the crater can start at the end of this phase.

Main phase III has four subphases. The first subphase (6) consists mainly of groundwork where digging is required and dust is generated. The second subphase (7) consists of the construction of the two parts of the main azimuth ring and the placement of the telescope robots on it. The third subphase (8) is the rest of the “rough” construction, or completion of the structure of the telescope. The fourth subphase (9) consists of the placement of all delicate elements such as the mirror segments and the instruments.

Main phase IV has two subphases, where the first (10) consists of the commisioning of the telescope, and the second (11) is the actual operation.

Main phase V has no subphases distinguished in this thesis.

In Figure 5.2 the type of lines in the subphases indicate where humans are needed. The dotted lines indicate activities mainly in Shackleton crater and thick lines indicate activities mainly near the lunar base. Humans are mainly needed in 72

phases 3b, 5, 6, 7 where they remotely control and supervise the robots and inspect the work that has been done.

5.6 Timeline

In total 19 launches over a timeframe of 104 to 124 weeks will be required to finish this project. In Appendix B the timeline can be found in an overview version (See Table B-1) and an expanded version (See Table B-2a and Table B-2b). The listed duration times are estimates by the author and are a first approximation based on the types of tasks to be done. A light arrow on a darker background indicates possible overtime. The launch schedule is quite agressive and this could mean that the launch rate is the determining factor for this project and not the duration of activities. 73

I Support 1) Landing on Malapert Mountain (communication relay) infrastructure outside crater 2) Landing on PEL (communication relay, power generation and transport of ROCADI I & II)

3a) Unmanned part: Lay cable down, prepare lift system first leg, prepare landing pad and setup landing beacon for lunar base, land base modules

3b) Manned part: inspection of base facilities, inspect lift system, expand power generation at PEL, start human exploration and research, propellant production

II Support 4) Use ROCADI II to lay cable into crater, inspect construction site infrastructure and function as landing beacon inside crater

5) Bring construction outpost, make lift system second leg operational, prepare for first human visitors in crater.

6) Land foundation elements at manned lunar base, transport them to crater, prepare construction site, prepare road surface, dig holes and place foundation poles, check by humans and lay power-data III Telescope cables. construction and assembly 7) Land elements at lunar base. Put them in storage if necessary, start assembly of first ring and second ring, connect temporary power and data lines and place telescope robots on the telescope to do the rest of the assembly

8) Assemble main support struts and temporary axis, assemble main axis, build the primary mirror support structure and the secondary IV Commissioning phase & operations mirror support struts. 9) Place secondary mirror, the primary mirror segments and the instruments, connect permanent power and data lines

10) Test all functions and operations. Telescope robots will move to V Expansion, their permanent home on the telescope. Fix and inspect anomalies maintenance & or diversions from specifications. upgrading 11) Operational phase

Figure 5.2: Overview of main- and subphases of the telescope construction process. 74

Chapter 6

TELESCOPE DESIGN AND CONSTRUCTION SEQUENCE

This chapter describes the elements of the lunar telescope, which have been defined in the course of this study. It provides a construction sequence for their installation on the Moon. This integrated view of the project provides the main basis for an evaluation of the roles of humans and robots that will be discussed in chapter 7.

6.1 Communication

To establish continuous communications between Earth and the lunar south pole region a communications relay station is established at the peak of Malapert Mountain. This will ensure communication to very large areas at the lunar south pole, however, it will not be able to cover all terrain due to the large elevation variations, particularly, it can not directly view the telescope in Shackleton crater. Therefore it is necessary to land a second communication relay that can see both Malapert Mountain and the floor of Shackleton crater. Such locations exist on the rim of Shackleton crater, where a specific location, the PEL has the advantage of near-continuous access to sunlight. It is believed that a single robotic lander, placed with high precision on Malapert Mountain and the rim of Shackleton, could provide the required communication infrastructure as described in chapter 2. At the PEL, a single 75

lander may be able to fullfill three functions: communication relay, power generation station and function as pylon in the surface transportation system for humans, robots, and construction elements. It is possible to use multiple landers instead of one lander to decrease the complexity.

6.2 Energy / transportation system installation

The second lander will also carry one Rolling Cable Distributors (RoCaDi I). After the landing on the PEL, RoCaDi I will be deployed and guided down to the location of the lunar base by remote control from Earth. This probably will be a couple of kilometers from the future landing pad. While rolling down, RoCaDi I will lay the cable and mark any sites for lift towers, till it reaches the lunar base site. See Figure 6.1. Here it will remain and function as a powered landing beacon for landers that will bring the lunar base elements and lift-system- towers. The towers will be placed by a special "Tower robot". These robotic systems will be described in more detail in chapter 7.

6.3 Lunar Base

After RoCaDi I arrives, the landing of lunar base elements can start, and the construction / assembly can take place. There are many options for lunar base configuration depending on the technology chosen, and other functions, such as mining, processing and science on the Moon, that will be carried out there. That is not the subject of this thesis. More information about recent lunar base designs and important factors can be found in Eckart (1999) and in Mohanty (2003). If only the telescope facility is supported, the lunar base would 76

consist of a landing pad, a living / working place for four astronauts, a technical area for life-support, robot maintenance and technical work and a storage / acclimatization area.

Figure 6.1: The first rolling cable distributor as it has arrived at the possible lunar base site. Original image courtesy: NASA

6.4 Transportation etc. into crater

RoCaDi II will be deployed and guided down in the same way as RoCaDi I. RoCaDi II will need to be flown in separately and transported to the PEL by the first part of the cable system. RoCaDi II then will go down into the crater where the telescope will be constructed. Along the way down, it will also mark locations 77

for lift towers, and once down it will function as a powered landing beacon for precision landing(s) in the permanently-shadowed crater. (See figure 2.7)

6.5 Landing of construction outpost

It is necessary to have a shelter for astronauts and a storage area for construction elements at or near the telescope construction site in Shackleton Crater (See Figure 2.5). The construction outpost and storage facilities will be landed inside the crater using the landing beacon provided by RoCaDi II. The construction outpost will have to be assembled, then powered through RoCaDi II and checked if it is operational. The towers for the lift system will be flown in at the lunar base. These towers will be transported to their locations by the same robot that did the first leg of the lift system, so the lift-system can become operational (See Figure 2.8). When this phase is complete, there will be power, communications, transportation into the crater and shelter for visiting astronauts.

6.6 Site preparation

After the basic transportation system has been installed, more site preparations are necessary. The final site inspection can be done by astronauts and the construction location can be confirmed. A road will have to be established from the construction outpost to the telescope location, by compaction of a top-layer, removal of rocks and possibly filling of small craters. The "Dirty" robot will perform this and by doing so, and limiting the speed of travel, dust production will be limited in amount and travel distance. A laser range finding grid will be installed to determine the positions of all elements relative to each other, as depicted in Figure 6.2. 78

~55 m

Lower super conducting magnetic bearing Laser Rangefinders

~55 m

Foundation poles

Figure 6.2: A depiction of how laser range finders could assist in the correct placement of elements during the telescope construction. For simplicity it only contains six foundation poles rather than 15.

6.7 Foundation construction

The construction will start with the digging of holes for the foundation poles in a circle with a diameter of 25 meter. If problems are found, the digging will shift a little untill all holes are dug. After all holes have been completed the poles are placed and aligned with the circle. The holes will be filled with the excavated regolith and compacted. Then a pre-determined pre-load will be applied by stacking up regolith on the poles and compacting it. (See figure 6.3) The operational maximum load on the foundation has to be surpassed so that all 79

settlements happen in this phase and not during operation. One pole is shown in figure 6.3. The bottom surface of the foundation plate exists of sharp cones pointing downward to maximize the contact surface, the flanges on the bottom-part of the pole function to distribute the load more equal over the base and to support a higher side-stability against torsion and sagging to one side. The main axis has two arms to support the ring-segments at smaller intervals to minimize the deflection and to form a stiff triangular shape once in place. These arms are folded in their upright position during transportation and placement.

1.7 m 1.7 m

2.5 m

1.5 m

0.5 m

Figure 6.3: Placement sequence of a foundation pole. First the placement, then the compaction and application of the pre-loading and finally the deployment of the support-arms.

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6.8 First ring construction

Once all the foundation poles are in place and the arms deployed, the elements of the lower, superconducting magnetic azimuth bearing can be placed. (See Figure 6.4) Each ring-segment has one foundation-pole with three arms, supporting it. The ring-segments are interlocking, but have space for adjustments. Once all elements of the ring are in place, the fine adjustments can take place to make sure the completed ring meets the required precision positioning and is placed within the tolerances. (See Figure 6.5) An line drawing of the size of a human being is added for scale references.

12.5 m

First super conducting magnetic ring segment

Figure 6.4: Placement of the first element of the lower super-conducting azimuth ring. In this figure the layer of regolith covering the foot of the foundation poles is not shown.

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6.9 Power-, data-, communication-line to first ring

After the ring is complete (See Figure 6.5), checked and fixed in position, the power-, data- and communication-line can be connected to test if all has gone well and if everything works before the rest of the telescope is constructed.

Figure 6.5: The lower azimuth ring is complete, positioned and fixed. The power and data line can now be connected.

6.10 Second ring construction

The second half of the superconducting magnetic azimuth bearing will be placed, element by element, on the first ring. Built-in distance holders will keep a 82

small distance between the two ring halves, so that the delicate ceramic surfaces do not damage each other. In case of a shut-down for maintenance, the same distance holders will perform that function. The elements are loosely fitted at first, and when all elements are placed, they will be tightened to the required precision fit.

6.11 The on-telescope robots

Once the second ring is complete, the telescope construction and on-telescope robots will be placed on top of the second ring which will function as a fixed reference frame. The two robots will receive the rest of the telescope elements from the dust protected, "clean" transport robot, and then assemble the elements in their location.

6.12 Main support struts installation

The construction continues with the assembly of the main support struts that will hold the main axis. These will be placed in their prepared location on the second azimuth ring. (See Figure 6.6)

6.13 Main axis installation

The rest of the telescope depends on the installation of the main axis. Since the axis has a length of approximately 25 m, it can not be transported in one piece. A solution for this is using a temporary axis that is strong enough to 83

carry the main axis elements and the robots, until the main axis is placed. The temporary axis could be a telescopic beam that can be transported in one piece. Once the temporary axis is in place the robots can move over it and place the main axis elements, connect them and ensure the structural integrity of the whole assembly.

Temporary and main axis 25 m

Counter weight 17 m and instrument Main support struts housing

Figure 6.6: An impression of the telescope structure after completion of the second part of the azimuth ring, the main support struts, the main axis and the housing for the counter-weight and instruments. 84

6.14 Instrument and counter weight housing

Once the main axis is in place, the counter weight and instrument housing can be assembled by attaching the elements to the main axis. While this is done, the main axis will be locked in place so it will not be able to rotate. This housing will also contain the garages for both the telescope robots. The counter weight mass will be installed as well now, before any delicate instruments will be placed in the housing. (See Figure 6.6)

6.15 Main mirror support structure

The most voluminous part of the telescope is the main mirror support structure which will be attached by the robots to both sides of the axis. This will be a frame construction (light and stiff) inside a cover of multi-layer insulation (MLI). Inside the massive looking closed structure as depicted in Figure 6.7 will be a truss structure.

6.16 Secondary mirror support struts installation

This may be the most complicated part of the telescope construction process. The three secondary mirror support struts need to be built up from their elements till they touch, 50 meter high, above the middle of the main mirror support structure (See Figure 6.8). The stiffness of this structure is determined by the connection of these struts into large triangles. During construction however, the struts will not be connected in a structural way. One solution is to use a temporary structure to guide the three struts to the top where they can be 85

connected to form one structure. This temporary structure could then be converted to hold the secondary mirror in the top of the telescope. Another option is that it already contains the secondary mirror in a protected enclosure.

Main mirror support structure shielded with MLI

Figure 6.7: The main mirror support structure is in place. This is a truss structure covered in a layer of MLI.

6.17 Secondary mirror installation

After the support struts are in place, (See Figure 6.8) the secondary mirror can be hoisted in place by the robots. Another option could be that the mirror is 86

already attached to the temporary support structure that guides the three struts. This would eliminate the need to hoist it up in one piece in the end. Instead it would be slowly moved into place with the speed of the strut construction.

6.18 Instrument installation

The only parts left to install at this point are the delicate parts. First the instruments will be placed in their housing and checked, connected etc. by astronauts wearing special “telescope” suits. They will travel in the special "clean" transport robot that keeps them and also the telescope elements dust- free at all times.

6.19 Main mirror panels installation

As the last part of the telescope, the main mirror elements will be installed by the robots. This is to make sure that no other construction or assembly activities can damage, or contaminate the mirror elements. The hexagons will be placed from the center spiraling outwards to the edge of the main mirror support structure. (See Figure 6.9)

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57 m

Figure 6.8: The entire telescope structure is complete except for the most delicate elements. 88

6.20 Commissioning phase

During the commissioning phase each element of the telescope is tested and determined if it functions as it should or whether it requires adjustment, alignment or replacement. This can not be planned well since it is never known exactly which parts will need to be adjusted or replaced. It will require robots and humans on site that will test and adjust if necessary. This is a delicate and lengthy procedure that could take up to several months to complete. For the JWST the team is planning for 6 months of commissioning. Since the lunar telescope will be larger, this phase may take a while longer, up to one year. However, a lot of commissioning can possibly be done during construction. Observations may start during this phase, but the quality will not yet be optimal.

6.21 Operational phase

Occasional maintenance, checks and adjustments, monitoring of health of the structure will be necessary, but once the commissioning phase is complete, the telescope can start operations and the answering of questions can begin. (See Figure 6.10) The telescope now will be turned over to the control of the scientists on Earth who will remotely control the telescope observations using the communication relay stations that have been put in place.

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50 m

Figure 6.9: The telescope is completely assembled and the commisioning phase can begin.

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Figure 6.10: The telescope in operational position after the main axis is unlocked. 91

Chapter 7

ROLES OF HUMANS AND ROBOTS

The telescope design has been discussed previously. This chapter will discuss who and/or what will actually build the telescope and the required infrastructure. What capabilities will be required and who or what can supply those.

7.1 Unique qualities / capabilities

Human presence on the Moon will be limited because of expenses and safety hazards, so telerobotics will be used as much as possible. However, humans have capabilities that have not yet been duplicated by telerobotics, so humans will be necessary for certain tasks.

7.1.1 Unique for humans

The human brain is capable of complex thought processes. It can access a lifetime of experience and learned knowledge instantaneously, it can make abstract predictions that are based upon experience and decisions can be made based on both facts and desired outcomes. Humans not only observe using different inputs simultaneously, but also interpret, can apply imagination and strategic thinking, and have the ability to set or change priorities. Instant re- 92

“programming” is possible with changing situations and humans have intuitive problem solving capability. Besides the capabilities of the human brain, a human has complex motor / computer skills, and once learned and trained, motor skills do not require conscious thought. Humans have good eye-hand coordination and multiple tasks can be done simultaneously without much effort.

7.1.2 Unique for robots

Robots have different virtues; including a programmed, logical response; parallel processing; detailed, accurate, massive computational capabilities; and can make precise and quantifiable measurements, which all can be exactly repeated. Apart from that, robots can easily surpass human reach and strength, movements can be duplicated exactly and robots can be designed to posess many mechanical abilities. A robot can have different sensors and may be expendable or easily repairable so they can be sent into more dangerous environments.

7.1.3 Advantages of one over the other

Robots do not need oxygen and they can operate in a wider thermal range than humans who need to wear spacesuits that limits their flexibility. Humans are infinitely more flexible in functioning in different situations than are robots. Robots, on the other hand, don’t get tired, don’t need food or air or showers, they don’t get bored and don’t make mistakes because of any of the aforementioned reasons. Instead, they need power, regular maintenance and replacement parts. If the environment and tasks are known in advance (within certain limits), robots mostly can usually be designed to do the job. Human intervention is required , however, if on-site judgement or interpretation is required. 93

7.2 Robots required

In total, for this project, five different robots are needed. They can be described as follows:

RoCaDi: Two Rolling Cable Distributors, will deploy the cable for communication and power transmission. The same cable also has to function as a load bearing structural element in the lift system. The RoCaDis will also function as landing beacons once they arrive at their final position. They will roll down mainly using gravity as driving force. The halves of these spherical shaped robots can rotate separately and give them the capability to steer (See Figure 7.1). in case a flat or slightly up-slope area needs to be crossed, a counterweight will be placed off balance that will use the gravity pull to roll it further. On this pole with counterweight, also the camera and sensor system will be mounted. Since it is connected to the cable it will roll out, and that same cable is connected to the power generation station, this robot will get its power via the cable.

“Dirty” ground work robot: This robot is needed to perform “dirty” operations which includes the preparation of the landing pad, the digging of the foundation holes and other operations that require working with the regolith directly. See Figure 7.2. This robot receives its power from plugging into a recharge station to recharge its batteries or fuel cells at the lunar base or the construction outpost. This robot will construct the landing pad, the roads and the foundation of the telescope.

"Tower" robot: This robot will probably have to perform the most challenging task. It will need to be able to carry the lift towers, transport them to their locations identified by both the RoCaDi's, dig foundation holes similar to the 94

ones required for the telescope, erect the tower and finally hang up the cable. It will be able to get extra power from the cables while it works, so it does not need solar cell arrays.

“Clean” Transportation robot: This robot will transport telescope elements, and/or humans from the landing pad to the lunar base/outpost. It can also use the lift-system to travel into the crater, where it can deliver cargo to the construction outpost, or the telescope construction site. This robot needs to be equipped with a dust-free cargo space, in which sensitive telescope elements can be transported in safely and it will need a crane to load and unload the elements at the lunar base, the construction outpost or the construction site. Also this robot will transport the humans when they have to work on the telescope in special telescope suits so they will not be exposed to dust. The power will be recharged at the lunar base, or the construction outpost.

On-telescope robot: Two of these robots will be placed on the telescope after both halves of the super-conducting magnetic azimuth bearings are complete. They will assemble the rest of the telescope, while never leaving the structure to avoid dust contamination. Once the telescope is complete they will move to their garages on the telescope, where they will remain until needed for maintenance, repair, or other tasks. These two garages, one on the left side and one on the right side, contain the robot rechargers and store more end-effectors and instruments. See Figure 7.3 and 7.4.

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Table 7.1: Overview of robots needed for telescope construction process. robot number of robots arrives in phase RoCaDi 2 2 "Tower robot" 1 3a "Dirty work robot" 1 3a "Clean transport robot" 1 6 On-telescope robot 2 end of 7

7.3 Humans required

Human tasks in the crater during the telescope construction are limited to the sub-phases shown in Figure 5.2 with the dotted (activities mainly in crater) and thick lines (activities mainly near the lunar base) in phases 3b, 5, 6, 7 where they remotely control or supervise the robots. During the construction phase, at most two people will have to be present at one time. They can stay in the construction outpost for up to 14 days Which is the expected maximum stay untill an emergency rescue from Earth can arrive but help from the Lunar base probably could arrive earlier. Normal residence times would be in the order of a few days. To keep delay times low and speed up the construction process, the robots can be controlled from the lunar base. This lowers the delay control time and thus increases the safety for the astronauts on-site while also minimizing the required residence time in the crater. If the construction time is less important or if there are no humans on-site, the robots can be controlled from Earth with longer delay times. 96

Mobility weight Observation system

Cable

Figure 7.1: A rolling cable distributor as it could look, to deploy the cable from the top of the crater rim to the bottom of the crater.

Observation system

Different end- effectors

Figure 7.2: A sketch of the "dirty" work-robot.

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Different end- effectors and instruments Legs

Observation system

extended lenght ~ 7.5 m

Figure 7.3: A first sketch of one of the two, on-telescope robots. It has multiple end-effectors and can thus perform multiple operations with different tools. It also has three legs to move around with and to hold onto three points when lifting heavy loads.

Structure

Rails

Grapple

Figure 7.4: A sketch of how rails might be incorporated (if necessary) into the structure such that the robot need not worry about umbilical cords or grapple- points. 98

During the commissioning phase, a few specialists need to have access to the crater to help with element check-out, calibration and repair-activities. This is a relatively uncertain and poorly defined phase, because it is not known which elements will need some adjustment or replacement. Because it is a safety measure in case of solar flares, it should be possible to reach a safe shelter in 20 minutes. This means that the lift system has to be capable of transporting a human from one side to the other in 20 minutes. The distance between lunar base and telescope construction site is about 15 km so the lift will have to operate at a speed of approximately 12.5 m/s . This is quite fast for a lift-system since most ski-lifts operate at speeds of 4-6 m/s. According to the manufacturer of aerial tramways, Leitner, systems are possible that operate at 12 m/s. For the system at the lunar surface it is assumed to be possible in emergency situations, and probably also in normal operation mode.

7.4 Tasklist and workforce role

In this section, the different phases and subphases are described and determined is who will do what tasks. It will be defined what robot is necessary and how many humans will be required for certain tasks.

7.4.1 Main Phase I: Infrastructure Outside Shackleton Crater

Subphase 1 This subphase consists only of one landing on Malapert Mountain. There is no need for robots or humans in this mission. If deemed worth sending, an exploration robot could be included to explore the mountain region, but this is not 99

required and would not be part of the telescope mission. Once landed, the lander will deploy its communication antennas and solar cells. Except for landing in this specific location, this type of mission has been done before with the Viking landers on Mars and the Surveyor missions to the Moon.

Table 7.2: Activities in subphase 1

Activity (1) in what way/by whom Soft-Landing on Malapert Mountain Robotic Lander Deploy power generation devices Automatic Deploy data relay equipment Automatic

Subphase 2 Subphase 2 is a complex robotic mission that consists of several parts. The lander will execute a precision landing on the Peak of Eternal Light (PEL) on the crater rim of Shackleton Crater and mechanically deploy solar power arrays and the communication equipment. For this deployment only relatively simple mechanisms are required. It may be necessary to be able to move a few hundred meters to the best location for the lift system or solar exposure. The lander and its structure will form the lift tower on top of the crater rim and the mid-lift-station. It will also bring RoCaDi I which will have to be deployed so it can roll down to the lunar base location, lay the cable, identify lift-tower locations and function as landing beacon for the first lunar base landings.

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Table 7.3: Activities in subphase 2

Activity (2) in what way/by whom Soft-landing on PEL Robotic Lander Deploy solar cell arrays Automatic Deploy data relay equipment Automatic Release RoCaDi 1 Automatic Erect lift tower on rim Automatic

Subphase 3a Both RoCaDi’s are robots that will roll down the crater slope, in a controlled way, under power of gravity and supported by the cable they will be deploying. They will be tele-operated, and along the way down they will mark relatively flat boulder-free and crater-free locations for lift cable support towers. The RoCaDi's can steer by rotating both halves of their body with different speeds. By using a moving-weight that deliberately unbalances the spherical-shaped robot, it can move through small craters or up a moderate slope. Once down, near the location of the lunar base or construction outpost, they will function as initial landing beacons. Then, the first transports will arrive with the lunar base elements and lift-towers. Through the cable that RoCaDi I deployed, immediate power is available for the lunar base elements. The landing pad construction by the "dirty" robot can begin and the lunar base can be prepared. The lift towers can be put into place by the "Tower" robot and the first leg of the lift system made operational.

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Table 7.4: Activities in subphase 3a

Activity (3a) in what way/by whom Roll RoCaDi 1 down Remotely guided (Earth) Select tower locations RoCaDi controllers Mark tower locations with beacon & virtual RoCaDi controllers Soft-landing in lunar base area Robotic Lander Unload modules & robot Automatic Prepare landing pad "Dirty" work robot Setup permanent landing beacon "Dirty" work robot Connect modules "Dirty" work robot Connect power/data to modules "Dirty" work robot Erect lift towers "Tower robot" Hang up lift cables "Tower robot" Tighten cables by loading them "Dirty & Tower robot" Hook up the lift-cabin "Dirty & Tower robot" Test cable system part 1 remotely from Earth

Subphase 3b Once Subphase 3a has been completed, the first manned landing can take place. The lunar base will be made operational, and all the facilities will be activated and they will be inspected by astronauts. The lift system inspection and the expansion of the solar cell arrays on the PEL will complete this phase. The access by humans to the crater rim will allow remote inspection of Shackleton Crater by humans from the rim by means of night-vision binoculars and camera’s to confirm the telescope construction site and assess the crater in general.

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Table 7.5: Activities in subphase 3b

Activity (3b) in what way/by whom Soft-landing on landing pad Lander with 2 humans Inspection of all base facilities 2 Humans Hookup of backup power 2 Humans & "dirty" robot Internal setup of base 2 Humans Inspection of lift system 2 Humans Expand power on PEL 2 Humans & "dirty" robot Start human exploration and research 4 Humans & robots

7.4.2 Main Phase II: Infrastructure inside Shackleton Crater

Subphase 4 In this subphase RoCaDi II will land close to the lunar base and transported to the top by the lift system, after which RoCaDi II will be deployed. It will roll down, tele-operated from the lunar base, into Shackleton Crater while deploying the second cable. Along the way it will determine and mark suitable locations for the lift towers in the same way as RoCaDi I did. Once down it will confirm the suitability of the chosen location visually and survey for a new site closeby in the rare case unsuitable parameters are detected, such as a new crater impact. This is a similar procedure as locating potential tower locations. Then it will remain where it is and function as landing beacon for the next lander(s) in Shackleton crater.

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Table 7.6: Activities in subphase 4

Activity (4) in what way/by whom Land lift elements at lunar base Robotic Lander Bring RoCaDi II to top of PEL RoCaDi II + first Lift leg Connect cables to top lift tower "Dirty" robot RoCaDi II rolls down Remotely guided Find tower locations RoCaDi II controllers Find pre-determined construction site RoCaDi II controllers

Subphase 5 In subphase 5 the construction outpost and the lift towers will be landed in Shackleton crater under guidance from the landing beacon on RoCaDi II. Power can be connected to the construction outpost immediately through RoCaDi II. The lift towers will be put in place and the lift system made operational in the same way the first leg was put into place. The two sections of the lift system need to be connected at the PEL. After the lift system has been thoroughly tested for all operational loads and situations, and confirmation has been received that the construction outpost is operating as expected, the first humans can visit the bottom of Shackleton Crater using the lift system. A last check of the telescope construction site can be performed by humans. Once the site is confirmed, the laser rangefinder grid will be put installed and calibrated by the "dirty" robot. This grid makes sure that all elements are placed in the right positions with respect to each other locally, as there is no absolute lunar coordinate system and no lunar GPS system.

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Table 7.7: Activities in subphase 5

Activity (5) in what way/by whom Soft-land in crater Robotic Lander Unload construction outpost Automatic Hook it up to power/data lines RoCaDi II & Lander Activate robot recharging stations Automatic Place lift towers Tower Robot Hook up the cables Tower Robot Put tension on cables Tower Robot Test ski-lift system Remotely Couple both parts of lift system on PEL Tower Robot & 2 Humans First human visitors in crater 2 Humans Check out construction outpost 2 Humans Start of crater research 2 Humans & Robots Land more humans and supplies Lander & humans

7.4.3 Main Phase III: Telescope Construction and Assembly

Subphase 6 Subphase 6 is the dusty and thus “dirty” phase where all digging takes place for emplacing the foundation poles and pre-loaded with regolith, so uneven settlements that occur, will occur then and not during operations, so corrections can still be made if required. This will be done by the special, “dirty” robot, that also made the landing platform and compacted the short road from the lift end station to the telescope. After a few days the pre-load will be removed. Since this 105

is a very important phase, and a phase where the robots work in a less structured environment with unstructured material, it is closely supervised and inspected by humans. See Table 7.8 for list of activities.

Subphase 7 Subphase 7 is the first phase where the telescope elements are delivered that need to be kept totally clean from regolith particles. They will be landed at the lunar base landing platform and then part will be transported to the storage facilities at the lunar base and part to the construction site, by the “clean” transport robot, using the lift system to get in the crater. The lower and upper azimuth super-conducting ring will be assembled and fixed. After the rings are complete, the two special on-telescope robots will be put on the telescope, where they will remain for the rest of their operational life while constructing the rest of the telescope and assisting in the commisioning phase and during maintenance and replacement of parts. See Table 7.9 for activities.

Subphase 8 Since the two telescope robots now are operating on a fixed reference frame (the upper azimuth ring), the laser range finder system is not necessary anymore but can be used as an independent check on positioning. The on-telescope robots will take the telescope elements from the “clean” transport robot and assemble the rest of the telescope while never leaving it. After subphase 8, the entire telescope support structure is complete. 106

Table 7.8: Activities in subphase 6

Activity (6) in what way/by whom Soft-land elements at base landing pad Robotic Lander Deploy "Clean transport robot" Automatic Unload telescope elements "Clean transport robot" Transport elements to storage "Clean transport robot" Transport elements to crater "Clean transport robot" Transport elements to construction site "Clean transport robot" Transport humans to crater in lift On foot or in Rover Transport humans to construction site rover or "Clean trans. robot" Transport robots to crater remotely controlled Prepare road surface "Dirty" robot Prepare telescope construction site surface "Dirty" robot Place laser range finders "Dirty" robot Dig holes for foundation poles "Dirty" robot Check position 2 Humans & range finders Place foundation poles "Dirty" robot Check orientation 2 Humans & range finders Fill holes "Dirty" robot Apply pre-load "Dirty" robot Lay cables for data/power "Dirty" robot Compact the loose regolith "Dirty" robot Remove the pre-load after certain time "Dirty" robot Deploy foundation arms "Dirty" robot or humans Check if all positions are within margins 2 Humans & range finders

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Table 7.9: Activities in subphase 7

Activity (7) in what way/by whom Soft-land elements Robotic Lander Transport elements to construction site "Clean" transport robot Place primary 1st level ring segments on poles "Dirty" robot Adjust position to match margins Automatic & "Dirty" robot Connect individual segments to form a ring "Dirty" robot Check positions and adjust if necessary 2 Humans & automatic Fixate to form a solid ring Automatic Connect power and data to this ring 2 Humans Check integrity and functioning 2 Humans Place individual secondary ring segments "Dirty" robot Check precision and shape 2 Humans & range finders Then fixate into solid ring Automatic Connect power/data to this ring in temporary form 2 Humans Confirm operation and integrity 2 Humans Clean top ring elements from dust 2 Humans Bring 2 telescope robots "Clean" transport robot Place them on the secondary ring "Clean" transport robot

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Table 7.10: Activities in subphase 8

Activity (8) in what way/by whom Soft-land elements near base Robotic Lander Transport elements to construction site "Clean transport robot" Hand elements to telescope robots "Clean transport robot" Telescope robots move over telescope telescope robots Telescope robots place elements telescope robots Attach elements within margins telescope robots Check position and fixate Automatic & robots Repeat till support struts are finished telescope robots Including magnetic altitude bearings telescope robots

Subphase 9 Subphase 9 will be done in the same way as 8 but now all the delicate elements will be placed, starting with the secondary mirror, the instruments and then the hexagonal main mirror segments. Once this is done, all elements will be in place, and the two on-telescope robots can take their standby position in their garages on either side of the telescope in the counterweight and instrument housing near the main axis.

7.4.4 Main Phase IV: Commissioning and Operations

Subphase 10 This subphase is called the commisioning phase and operations phase. First, all elements of the telescope need to be aligned and tested as a whole. 109

Table 7.11: Activities in subphase 9

Activity (9) in what way/by whom Transport temporary axis "Clean transport robot" Install fixed temporary axis telescope robots Transport main axis elements "Clean transport robot" Hand elements to telescope robots "Clean transport robot" Telescope robots will transport to desired location telescope robots Attach element in place telescope robots Check location before fixating automatic & robots Repeat till main axis and main mirror support telescope robots structure are done Attach elements of counterweight and instrument telescope robots room Place counterweight telescope robots Place elements of secondary mirror support struts telescope robots Use temporary support to connect the 3 struts telescope robots Slowly move upwards till connection is made telescope robots & support Then fixate struts after position control automatic & robots (Haul up the secondary mirror and fix in place telescope robots) Install the mirror segments of the primary mirror telescope robots Install the instruments and calibrate the telescope robots & humans counterweight Remove temporary power and connect humans permanent power Robots go to garage telescope robots

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Malfunctions or aberrations need to be addressed by either robots or humans. Most likely it will be a combination, because on-site observation and interpretation are necessary, while at the same time, problems may not clearly be defined or the solutions may be complex. Elements may be misaligned, wiring damaged or The telescope robots are capable of transporting humans to any place on the telescope. However, the humans must be wearing special suits that are “clean” and reserved for use only on the telescope. This is to prevent dust contamination by “dirty” suits that have been used in exploration trips. Once all is working according to the requirements, the scientific operations can commence.

Table 7.12: Activities in subphase 10

Activity (10) in what way/by whom Test observations telescope functions and operation remotely Calibrate and commission mirrors and instruments remotely Fix or replace if not meeting specifications humans and telescope robots

Subphase 11 This is the operational phase and operations will be done remotely from Earth using the communication relays that have been built. Occasional checks and maintenance will be necessary and mostly done by the telescope robots, unless they can’t find or fix the problem. 111

Chapter 8

CAPABILITIES / CAPACITIES TO DEVELOP

From all previous information it can now be distilled what capabilities and capacities need to be developed to make this possible or could be improved to increase the effectiveness or efficiency of a project such as this. Not all changes and improvements are related to technology, some are related to attitude of decision makers and the way in which projects are chosen. In current space programs, long term vision is often missing and there is no investment in infrastructure.

8.1 Technology

A large part of the developments will have to come from the improvements of technology. Most technologies are either available in early forms or similar technology is being developed for other purposes but can be used for this telescope project.

8.1.1 Precision

In the present state of the art of robotics and construction techniques, it is not common, possible or necessary to have precision up to micrometer scale. For this telescope project, however, it is necessary to achieve that level of 112

precision. The robots that will assemble the telescope need to be able to precisely align and connect elements in three dimensions. The robots are not capable at present of reaching the required micrometer scale precision. According to a discussion with some experts from MD-Robotics it is not expected that robots will posses that capability in any foreseeable timeframe. This would mean that other means of reaching the required precision need to be developed. A way to do this would be to develop "intelligent" building blocks or elements that have actuators and sensors built in to them so they can adjust their position at macro and micro level. Since the telescope can not be built and tested on Earth, the elements need to be designed in such a way that they would achieve their final desired shape in their operating environment. This means that materials need to be chosen and developed of which it is exactly known what shape and behaviour they will have at 40 K and in a vacuum in 1/6th G. To allow for acclimatization there will be storage areas where the elements can achieve the right temperature and finish their outgassing process.

8.1.2 Power

The permanently-shadowed areas are very interesting for several reasons, but also pose significant operational problems. One of the most important ones is the power generation and transportation. In case no nuclear power can be used, the project will depend on solar power which is assumed in this thesis. Since only 5-10 KWatt is required (based on other telescope instruments and extrapolating them to the larger sizes required for this telescope) the dependence on solar power poses no real problem as far as power generation since less than a 100 m2 of solar arrays are required. The techniques for transporting this power from the place where it is generated at the top of the crater rim into the crater and to the telescope are challenging. 113

Improvements in the area of mass required for power storage for periods of time up to 3 days (duration of longest possible shading of PEL) are also important to minimize the mass for power storage. Good progress is being made with fuel cells, so they should be available at the time this telescope could be constructed. The fuel cells being developed by General Motors for use in cars can at present deliver over 100 KWatt at a mass of 82 kg and can function for

3000 hours.This mass excludes the storage for the fuel and oxidizer (H2 and O2).

8.1.3 Communications

The amounts of data required for live full 3D virtual reality for operational purposes is huge, on the orders of tens of gigabytes. This can be optimized by having the model on Earth and only transfering the changes in position of elements and equipment etc. from the Moon. However, the model needs to be updated continuously as construction progresses. For operators on Earth to form an acurate image of what is happening on the Moon, 385,000 km away, it is essential that good situational awareness is generated. Also, the laser range finders produce huge gigabyte-size data-clouds which need to be processed. Most of the pre-processing can be done on site, or at the lunar base, after which the remaining useful information can be sent to Earth. This requires computing power at the lunar base. This will need new techniques of compression and increases in data transfer rates. The available internet speeds via satellite have increased tremendously recently. Several Mbit per second is soon available according to providers such as optistream. For the lunar telescope application it is envisioned that also high bandwidth is required, in the order of 10-100 Mbit/sec. This will require slightly more advanced satellites, but the developments are going fast in this area so it is anticipated that the required speeds can be reached in the next few years. 114

8.1.4 Flexibility in command

Flexibility in command is defined as the case when several sources are able to command robots, have access to and are able to interact with the live operational data. The support team on Earth, the astronauts at the lunar base and the maximum of two astronauts on-site will all have control possibilities and will require different types of data in different time frames and formats. In cases where parts of the network are off the "air", all parties must be able to respond to possible errors or uncontrolled movements or actions. However, there are many issues with time-delays between the different participants and the level of detail that is desirable for each person. An astronaut on site in his space-suit doesn't need to see the smallest details of the operation that a support team would want on Earth. The astronaut only wants to see what is relevant for him/her, like where the robot is planned to go next and which elements will be targeted for use or where it will be placed, so they can go out of the way if they happen to be near it. A support team on Earth on the other hand will have access to the exact element data as well, like temperatures, internal checks, etc. Also checks with the construction plan, tolerances and measured values should be possible for all parties involved. In-situ checks and calibration of data will occasionally be required. Another issue is the situational awareness of the robots and the astronauts on-site. It is of high importance to make sure that every participant in this complex operation knows at all times who is where and if there is any danger of unwanted interaction. With GPS on Earth, one knows exactly where one is on this planet. Interaction in the form of different units that all are equipped with GPS units is possible since they can compare their positions and headings and evaluate if potential collisions are about to happen. On the Moon, no such system exists. Similar situational awareness can be achieved in several ways, 115

with radio transmitters, locator devices that use an external system like the laser range finders to determine where the locators are, or a visual (or infrared) scene generation where the actors can be recognized from their features. These systems are not now adequately developed. The systems need to become capable of real-time response and need to be made compatible with the lunar environment. Every team member, whether robot or astronaut or support team on Earth, needs to be able to see where all the active participants on the telescope site are located and what they are doing. As the situation on the construction site will be in a constant state of flux, this system needs to be highly flexible and allow for quick changes in actors and operators. This requires a very fast and flexible but complex operating system in which all parts work together and can be plugged or unplugged as is required in real time without the need for restarting or restructuring the whole system. This system will increase the safety of astronauts and robots working together while they are operated by different operators while at the same time increasing the speed with which can be operated. This capability will be important not only for the telescope project, but also in exploration of mining projects that involve human-robot teams, where the robots are operated remotely controlled from a different location.

8.1.5 Versatility

The robots that will be required, especially the on-telescope robots, will need to have great versatility in their operational capabilities. They will need to have several observational tools and sensors, dexterous manipulation tools, lifting and placement tools of high precision, path-planning and decision-making software. They will need to operate under extremely cold conditions for a prolonged period of time without recharging. To date, no space-system has been designed or has operated under such extreme temperature conditions (40-300 K) 116

as can be encountered at the lunar South Pole. And, preferably, they will need to be able to refurbish each other with certain elements like new fuel-cells or end- effectors or new camera's or sensors. Current robotic systems are not designed to be able to do this. Mostly because on Earth there is no need for it. Possibly on the Lunar surface, humans could maintain or refurbish the robots. The on- telescope robots however will need special care from the humans since they will not be allowed to leave the telescope and the humans can only access the telescope in special suits. This requires modular design approaches for the robots and easy connections as to minimize the time required for replacing parts of several kilograms and modest sizes while at the same time making sure the system is robust enough so it can withstand the local environment.

8.1.6 Environmental operations

The working environment is far from ideal for standard robotics. Even regular robust space robotics have never been designed or have operated in the extreme range of temperatures that will be encountered at the lunar South Pole. In the extremely cold craters (40 K) where there is a vacuum and no light they will have to function, but the same robot may have to function at the top of the crater rim where it can get real warm (300 K) and the sun can blind the sensitive instruments. So far, space robotics have been designed for operational temperatures ranging from 120K - 300K. The robots, however, are never constantly in the cold areas since in space, one side of the spacecraft is in the sun and the other side is in shadow. For robots that will have to function at low temperatures and on the dusty lunar surface, the use of superconducting magnetic bearings could be explored. This would prevent the bearings from getting clogged with dust and frequent maintenance requirements. It probably also would extend the lifetime of all the moving parts. These could prove the 117

ideal bearings for the telescope, but for the robots as well. Small several-inch- sized super conducting bearings for telescope operations have been tested under laboratory conditions and functioned well. At the same time, magnetic bearings are applied in commercial large scale magnetic levitation trains. So bearings exist now that can handle the forces. There is, however, need to scale the systems up to the required 25 meter size and it is required that an improvement of three orders of magnitude in positioning accuracy is achieved. This area of research could prove very beneficial for space operations in general but specifically for applications in very cold regions. While it is extremely cold outside the robot hull, the electronics inside the robot need to be kept in their optimal temperature range (220K-350K). This will require a thorough thermal design of the robot systems. Possibly some of the warmth required for the electronics can then be used to keep the joints at a higher (150K instead of 40K) and more desirable temperature during operations.

8.1.7 Teamwork

An area where great improvements will be required is the area of teamwork. This area is closely related to the flexibility in command. If humans and robots are going to form teams, the understanding and cooperation must be on a much more intuitive level where a mix of commands can be given in different ways, than controls offer today. Systems nowadays allow input through keyboards, pre-programmed sequences, pre-defined voice-commands. These need to be combined so any one can be used to give the same command. Other options need to be added, like laser pointers and arm-gestures. At the same time, the person giving the orders should be able to see the interpretation of the orders on their screens such that it is clear that the interpretation of the robot matches the intended order. Communication on several levels and engineering 118

details need to be exchanged easily as mentioned in the previous sections. This communication should be possible, even if the human changes location, say from the construction outpost to a spacesuit. During all these situations and activities, information will be exchanged, it is of high importance that no data will be lost. A robust system will be needed so no teammember will be looking for the requested data in a wrong location.

8.1.8 Human tool improvements

For humans on other moons, planets and asteroids, it is very important to provide capabilities that are as close as possible to those humans have on Earth. In other words, the space-suits that humans have to wear should not hamper these capabilities. In fact, the proper development of suits should improve human capabilities. Sensors in the suit can activate artificial muscles in the suit so movement of the arms and legs is easier. The gloves have certainly improved since the days of Apollo, but still they are bulky and require quite some force to be able to use hands and fingers. The main issue is temperature control versus dexterity. Thinner, less pressured gloves will give more dexterity but will provide less insulation against the extremely low temperatures. Adding enhancements in the form of artificial muscles would increase dexterity while allowing for better insulated gloves. At the same time those sensors could relay information to a robot that would imitate those movements. In case a certain operation could be done by a robot, but has never been programmed or done by a robot, it could be demonstrated by the human while the robot records the movements such that the robot learns the movements from the human. This way it would be easy to change pre-programmed procedures to ones that appear to work better in the real lunar environment. Helmet visors could improve vision in the permanently shadowed areas, by adding infrared vision or sensors at other wavelengths such 119

as UV or ultrasound, that extend the usefulness of the human visual system. The helmet should be designed with projection capability, so the visor can function as screen. Activation of the hands and arms could allow suited astronauts to manipulate objects and type things, similar to using a 3D-virtual mouse and keyboard. During construction projects, the needs may arise to look up a detail in an engineering drawing or to give the robot a command to do something by clicking at it on a drawing or a map of the location. This is not far from present capabilities but the interface is usually done with computer screens or touchpads and not done by astronauts in suits. During a construction project it is desirable to compare the real progress or situation with the plans that were made to check if all tolerances are met and if no mistakes have been made. In this case projection capability of the real site and the plan would be beneficial if also can be shown on that overlay where errors or deviations are so they are easy to find and identify.

8.2 Telescope parts

The telescope parts are elements of the structure, and thus often considered to be inert or "dumb" objects. Many of these elements probably need to get "smart" built-in position sensors and actuators that can precisely adjust their position within micrometers to within the required tolerances. However, both macro (centimeter) and micro (micrometer) range adjustments will be required. This will be a challenge for designers and engineers. After the desired location has been achieved, the actuators need to have sufficient strength and stiffness to function as a structural element as well. The actuators only need to be located at the connection points and thus it is beneficial to keep that number low. However, to keep the amount of adjustment space large, more actuators is better. An 120

optimum needs to be found between complexity and capacity for adjustments. Built-in temperature sensors, tensiometers and accelerometers could provide information on the health of the telescope parts and thus the health of the telescope. A capability for an individual element to identify itself and where it should be placed would speed up the construction process.

8.3 Integration and commitment

A change in philosophy will be required to construct a large lunar telescope. The lunar surface is far from a standard construction site and, as such, standard Earth developed techniques should not simply be assumed to work on the Moon. Things that would never work on Earth might be perfectly suited for use in lunar conditions, while things that work perfectly on Earth could fail or would not be possible on the Moon. The whole process from the start of planning to operation should be considered as one project. The level of integration between the different actors, like transportation from Earth to the lunar surface, the telescope designers, and robot operators, will need to be at an unprecedented level. Another change in the way of thinking is required in the area of overall mission design. Much more integration between space missions is required while at the same time, the "use-it and then discard-it" way of working needs to change. Building of infrastructure for prolonged use should be the goal and not one-shot missions. For some specific missions, such as deep space exploration missions, this is unavoidable but for relatively near space projects such as the Hubble Space Telescope, a more durable approach is beneficial. The larger the projects, the larger the benefit of sharing infrastructure. For real progress, it is 121

required to build up capabilities and with each step improve them. Then, real growth becomes possible using the so-called bootstrap method.

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Chapter 9

POSSIBLE PRECURSORS AND RESEARCH REQUIRED

Based on an evaluation of the stated requirements and the state of the art in knowledge, technology and operations, a set of recommendations has been developed to allow for a telescope such as this to be constructed on the lunar surface in about 15 years from now. There are three types of knowledge that will have to be gathered; (1) knowledge about the location itself, its environment and the influences of human presence on the unique environment; (2) what kind of equipment and material will function as required in the environment and (3) what operational organization works best. Some activities will have to take place on Earth, others can only be performed, or learned about, on or near the Moon.

9.1 Experiments on Earth

Many tests can be performed on Earth to test operational strategies and tests that lead to better understanding of the influences of the lunar environment on the construction and operation on the lunar surface.

9.1.1 Knowledge about the location

Dust research can be partly done on Earth using lunar regolith simulant and once techniques have been developed, using real Apollo lunar regolith 123

samples. In a vacuum chamber, the statically charged particle behavior can be studied and its affinity for certain materials. Tests of mitigation measurements such as the anti-charging of the structure, can be performed in such a test setup as well. Possible temperature relations can be addressed too, but reaching the required 30K-range temperatures on a large scale will be difficult. Once such cold temperatures can be reached, material behavior can be studied. A vacuum chamber from the Apollo days currently in posession of CSM might be used to perform such tests.

9.1.2 Equipment and material testing

Tests on gas-leaking of equipment can be performed under vacuum and real lunar temperature conditions as well, an example is the space suits for the astronauts and lunar base seals and airlocks. One of the most important tests is the effect of dust on all moving parts of space-suits, robots, equipment and lunar base elements. Another required study is the deformation of materials due to the large temperature changes from 400 K to 30 K. This needs to be completely understood for the materials that will be used in the telescope construction, since the tolerances are in the order of nano- or micrometers. This will allow design of elements that will only reach their final and intended shape on the lunar surface.

9.1.3 Operational testing

Operational testing also is needed to test the operations of the robots in circumstances like those of the lunar surface. Particularly in lunar-like terrains. In this operationally similated environment, setting up of the lift towers, laying of the cables using a RoCaDi prototype, construction operations, positioning using laser range finders and the human-robot teams all need to be tested and evaluated so 124

that improvements can be made. By doing this it will become clear which operations will work and which will not. However, the results will need to be extrapolated using the environmental characteristics on the lunar surface as well. This can be tested using ever increasing reality in operations. First operating in a laboratory, then in a less structured outside environment, a simulated lunar site and finally in a vacuum chamber in near real situations. Maybe even in a KC-135 simulating lunar gravity. The operations testing includes all possible operations to be done by robots and humans. Driving, digging and constructing without stirring up much dust while keeping it close to the ground need to be tested. Connecting components of the lunar base and all telescope element connections need to be designed, tested and practiced to achieve the required sub-millimeter precision. Transportation and the handing over of all elements will have to be practiced in all situations, using the lander-transports, the storage areas, the lift system and the "clean" transport robot who then will hand some of the elements to the on- telescope robots. The supervision by humans, interaction between robots and humans, and on-site inspection while other work progresses by autonomous or remotely controlled robots needs to be tested in all conceivable situations.

9.2 Activities at a lunar outpost or base

Activities that could be performed at a lunar outpost will be described. These activities, that would benefit the understanding of the lunar environment in general, and the effects of the presence of humans and activities on the environment, that might influence the operations of the telescope, are described in this section. Questions are listed to which answers will be required.

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9.2.1 Knowledge about the location

More understanding is required in the areas of dust behavior, atmospheric composition and the effect of human presence on it, the exact temperatures in the polar areas, much higher spatial resolution topographical information, and local seismic information. Dust, atmospheric and seismic measurements will have to take place on the lunar surface while the temperature and topography measurements can be partly done from orbit. Another important issue is whether ice is present or not because this could influence the choice of activities that should take place first in the crater, for example; ice-mining before building telescopes for observation of the universe.

9.2.2 Environment measurements

Dust Movement: What size particles come near the telescope during operations? How much natural movement is occuring and how high above the ground does this occur?. This should be studied using dust catchers in different locations. Statically charged properties: How much charge do the particles have? Is it only positive or negative or mixed? How strong is the adhesion once in contact with surfaces? Does it react differently to different materials? Can it easily be wiped off or flushed off or is it effective to charge the surface area? How quickly does it accumulate? Is there an equilibrium after which no new particles will collect? This can be researched on Earth in vacuum chambers using lunar soil simulant or even real apollo samples, even though the charging will have to be simulated. Some of these tests will 126

have to be repeated on the lunar surface in the real environment, to verify and calibrate. Secondary debris: How much secondary debris from impacts in other places on the lunar surface will periodically reach the telescope site? How much damage can it possibly inflict? How high are the probabilities of such events? This data can only be collected on the lunar surface, but it will be hard to distinguish primary impacts from secondary ones.

Atmosphere Density: How dense is the lunar atmosphere in the polar areas? Is it lower in the permanently shadowed areas than in sunlit areas as expected? A special instrument will have to be designed to measure the tenuous atmosphere. Perhaps a gaschromatograph can be used. Composition: Is there a difference in composition in the polar areas compared to the Apollo measurements? Do certain elements have a higher affinity to condense on certain material surfaces? If the lunar conditions based on Apollo measurements could be mimicked well on Earth this could be tested in a lab or on the KC-135 lunar-G simulation missions. The exact composition has to be acquired on the lunar surface though. Changes over time: Are there periodic changes in the atmospheric density and composition? How significant are these changes? This requires long duration continuous or periodic measurements on and above the lunar surface.

Temperature and lighting In permanently dark craters: How cold does it really get in permanently shadowed craters? How much light is reflected from the crater walls? Is 127

this sufficient to work by? What illumination frequencies would be the most efficient to use? This can only be found out on the lunar surface by measuring the temperature and testing different lights, robot receptors, the reaction of human eyes or similar reactive devices. Changes over time: How large are the variations over a month, during the lunar summer and winter? How quickly do the changes in temperature and illumination occur? This requires camera's operating and mapping over a whole year basically to map summer and winter illumination, this can be done from lunar orbit, but the temperature will have to be measured on the surface periodically in different locations. Local variety: Are there local variations in temperature? Are they due to differences in illumination or do they originate from the inner heat flux of the Moon? As in the previous subsection, temperature measurements in different locations on the surface in the area of interest over a long period of time are required to answer these questions.

Topography Steepness of the terrain: How steep are the slopes? Are there large local differences? Are there fissures or faults? How stable are the slopes? Are there flat areas? Topography can be measured from lunar orbit, but fissures, slopes and their stability need to be measured on the surface using seismic and other in-situ tests. Total elevation differences: How large are the differences? The required spatial resolution needs to be better than a meter. This will take a long duration lunar orbiter mission at low altitudes. How rough is the terrain: How many craters and boulders larger than 50 cm are there per unit area? Are there areas with bare rock? Are there nice flat areas as expected? These questions probably only can be answered 128

from surface pictures taken from very closeby and probably will require a surface reconnaisance mission of the target location.

Seismic activity Natural (tidal, meteoroids, seismic activity): How much seismic activity exists in the lunar polar areas? Does it match the Apollo data? How much is generated by meteoroids? This will have to be researched by a surface mission requiring seismometers. Part of the information may be found by the Japanese LUNAR-A mission. Duration: How long do these events "ring"? Magnitude: How large are the amplitudes of the seismic events? Will they disturb the observations? For how long will they disturb the observations? How often do disturbing events occur? Does it match the expectations deducted from the Apollo data? Origins: How much of the seismic activity originates in the Moon? How much is generated by meteoroids? Can a periodicity be detected? For the seismic measurements a seismometer (network) in and near the telescope construction site would be required.

Next to increased knowledge about the location and its environment, it is also necessary to determine the effectiveness of the equipment.

9.2.3 Equipment tests

Different types of materials need to be tested such as carbon composites, metals, ceramics that can be applied in the telescope, at the lunar base or in the infrastructure elements. Long duration exposure tests to test weathering effects on materials such as the cable for the lift-system, the structural elements, the 129

mirror segments and basically every other element exposed to the local environment. This has high correlation with the research to dust behavior and is also related to the temperatures and the differences in temperature. Material behavior in extremely cold areas (down to 40 K) is not often tested because there are almost no applications for materials that need function in such an environment. The only area that has been researched under laboratory conditions is the super-conductivity of materials at such low temperatures. Next to material research to find effective and durable materials, in-situ research on a small scale proto-type telescope is important before the large version will be constructed, to make sure there are no design or material flaws. A small, maybe a hundred meter long, local version of the cable system would need a shake-out test to detect any critical design flaws before the large, kilometers long version is constructed. The cable manufacture and lubrication issues need to be tested, perhaps a different type of cable, or a different way of weaving the strands together, will be required. The functioning of robots under real lunar environmental conditions needs to be tested. Mainly the wear and tear of the robot due to the dust and the low temperatures and testing of the expected behavior in precision, efficiency, design life of batteries, end-effectors and operations must be understood. Another important test-item are new space-suits that can function for long periods of time on the lunar surface and don't have to be replaced after 5 uses because the dust has made it un-usable. The last item that needs to be tested is the efficiency of different radiator types for thermal control of all systems. Different shapes, locations and shielding mechanisms have to be tested.

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9.2.4 Operations tests

Before each subsequent landing or step in the process can be started, the previous step needs to be tested and confirmed to be operating as planned. The first essential parts are the communication relay stations at Malapert mountain and the PEL. Once operational, the next phases can start. Tests with remotely controlled robots to determine the functionality and possible areas without reception will have to be done, after which possible changes in the schedule or plans can be made. The local effectiveness of digging and other dust related activities need to be tested to see if they meet the scheduled performance. Possible design alterations in shape of end-effectors or wheels for better grip can be introduced in the next generation of robots after lessons have been learned from operating in the real lunar environment. It may be necessary during operations with robots and humans to include certain commands that only were thought of while working on the lunar surface, while others that have been thought of on Earth, may be ineffective in practice. The human influence on the local lunar environment, particularly the dust generation, vibration generation and exhaust gases of landing and take-off can only be tested in-situ. There need to be studies using sensors that are located at different distances around sites of activity to measure the changes in those parameters over time. Some reference sensors will be required to make sure these changes are indeed of local origin.

9.3 Design and engineering optimization

Theoretical studies are required to the effects of the influence of the change of Gravity. These will bring to light which changes in the design will have the most optimization effect on the product. Standard Earth-based practices and 131

design guidelines will overdimension the design. By optimizing the design specifically for 1/6 G mass, and thus money, can be saved. A change in Gravity will also change behavior of elements such as explained in paragraph 4.2. This is only one example of how behavior can change in a different Gravity environment. Every science and engineering discipline will have to find out what kind of effect a change in Gravity will have on processes or behavior. Some aspects will hardly be influenced, while others may be significantly changed. It is crucial to study and know this in advance such that not only disasters can be prevented, but also the design can be optimized and money can be saved and risk reduced. 132

Chapter 10

CONCLUSIONS

In this study a possible design and construction scenario for a 25-meter diameter lunar inrared telescope was analyzed and the feasibility of construction of the telescope and the required infrastructure in a lunar South Pole crater studied. The required workforce, consisting of humans and robots, was chosen based on an analysis of current and expected capabilities, the lunar environment and the construction tasks required. The study shows that such a large telescope can be built using 4 astronauts and 7 robots while using the environment in such a way that the positive aspects are fully utilized and the negative aspects mitigated or avoided. The infrastructure and its construction has been analyzed and described. This study, while the second in a series by the author points to the need for a commitment for further study. The project proposes ways to deal with the perceived negative aspects of the Moon such as dust, gravity, temperatures, etc. However, the choice between free space (Sun-Earth L2) and the lunar surface for a large infrared telescope is not immediately clear. Both locations have advantages and disadvantages. The major advantage of S-E L2 is the possibility to observe the whole universe, while the major advantage of the lunar South Pole is the possibility to operate for many years longer and at the same time allowing easier maintenance and expansion than possible in S-E L2. For a final choice it is not only important to look at the possible astronomy, but also to the 133

construction, operations and other factors such as maintenance options, efficiency, expansion possibilities and the support of a larger infrastructure. Many improvements will be required in many technological areas dealing mostly with the capabilities of robots, the extension of operational environment into the extremely cold regions of 30 K, remotely operated performing delicate construction tasks, the creation of infrastructure, the superconducting magnetic bearings in a much larger version than currently in existence and their required three orders of magnitudes increase in precision, but none seem unacceptably far in the future. More theoretical studies will be required to the influence of 1/6 G on processes and behavior of systems to optimize design, minimize costs and reduce risk. Next to technology improvements, there is also the need to know more about the lunar local environment such as the dust behavior, the topography with a vertical and horizontal spatial resolution better than one meter, absolute temperature measurements and the temperature fluctuations. Some of these measurements will be done by lunar missions that will reach the Moon in the coming years such as SMART-1, LUNAR-A and SELENE. It is concluded that most activities and construction can be performed with robots, but the in-situ checks by humans will be required at certain stages in the project to make sure the rest is not built upon a faulty or misaligned part. Human presence will also speed up solving problems and evaluating or suggesting improvements in procedures. As far as humans are concerned it will require augmentations in the space-suits of the astronauts, such as enhanced sensors, artificial muscles in the suit and display capabilities in the helmet, to make sure the humans are optimally equiped to handle all situations during the construction process. A prerequisite for an extensive project like this would be the presence of the transportation infrastructure to transport all the elements to the lunar surface 134

at a lower cost as presently possible. This requires scientists and other involved partners to commit to, build and invest in an integrated long-term infrastructure. This change in philosophy might prove to be the most difficult of all steps forward. The Moon is an excellent platform for operations for astronomical purposes while at the same time it is possible to combine such scientific activities with exploration and resource utilization. A small lunar base will be required for this telescope project and combining different activities will greatly increase the value of such a base.

"Ad astra per aspera"

135

REFERENCES CITED

J. Aizawa, N. Yoshioka, M. Miyata, Y. Wakabayashi, Designing of Lunar Rovers for High Work Performance, pp. 61-68, iSAIRAS '99, Proceedings of the Fifth International Symposium on Artificial Intelligence Robotics and Automation in Space, ESA-SP-440, ESA, 1999

L. Arnold , A. Labeyrie and D. Mourard, A Lunar Optical Very Large Interferometer (LOVLI) with Simplified Optics, pp. 1149-1158, Advances in Space Research. Vol. 18, No. 11, COSPAR, 1996

D.A. Bassett, A.Abramovici, Special Purpose Dexterous Manipulator (SPDM) Requirements Verification, pp. 43-48, iSAIRAS '99, Proceedings of the Fifth International Symposium on Artificial Intelligence Robotics and Automation in Space, ESA-SP-440, ESA, 1999

B. Battrick, C. Barron (editors), Mission to the Moon, ESA-SP-1150, ESA, 1995

M.T. Bentley, Augmented & Virtual Reality Payload Processing, pp. 409-416, Space 98, The Sixth International Conference and Expostion on Engineering, Construction and Operations in Space, ASCE, 1998

136

A. Bicchi, Hands for Dexterous Manipulation and Robust Grasping: A Difficult Road Toward Simplicity, pp. 652-662, IEEE Transactions on Robotics and Automation, Vol 16, No. 6, December 2000, IEEE, 2000

B. Blair, An economic rationale for lunar mineral exploration, to be published in the proceedings of the International Lunar Exploration Working Group 5 meeting in Hawaii, November 2003a

B. R. Blair, J. Diaz, P. van Susante, T. Muff, B. Ruiz, L. Johnson, P. W. Keaton and M. B. Duke, Lunar propellants and "gateway" space transportation architectures, to be published in the proceedings of the International Lunar Exploration Working Group 5 meeting in Hawaii, November 2003b

C. Bonivento, C. Melchiorri, G. Vassura, G. Ferretti, C. Maffezzoni, G. Magnani, G. Beccari, S. Caselli, F. Zanichelli, A Dexterous Gripper for Space Robotics, pp. 637-642, iSAIRAS '99, Proceedings of the Fifth International Symposium on Artificial Intelligence Robotics and Automation in Space, ESA-SP-440, ESA, 1999

E.F.T. Buiel, Design and Evaluation of a Human-Machine Interface for a Teleoperated Space Manipulator, Delft University Press, PhD thesis, Delft, 1998

B.F. Burke, Astrophysics from the Moon, pp. 1365-1370, Science, Vol. 250, no. 4986 , 7 dec. 1990

137

J.O. Burns et al., Artificially Generated Atmosphere Near a Lunar Base, Lunar Bases and Space Activities in the 21st Century Symposium, Houston TX, LBS-88-024, 1988.

D.B.J. Bussey, P.D. Spudis, S. Nozette and C.L. Lichtenberg, Analysis of the Lunar Polar Lighting Conditions as seen by Clementine, Lunar and Planetary Science Conference XXIX, Houston, 1998

N.Y. Chong, T. Kotoku, K. Ohba, K. Komoriya, K. Tanie, Exploring Interactive Simulator in Collaborative Multi-Site Teleoperation, pp. 243-248, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

D.R. Cooke, B.K. Joosten, M.W. Lo, K.M. Ford, R.J. Hansen, Innovations in Mission Architectures for Human and Robotic Exploration Beyond Low Earth Orbit, Proceedings of the International Astronautical Congress, IAC- 02-Q.6.04, Houston, 2002

N.C. Costes, S. Sture, a Mobility Concept for Martian Exploration, pp. 301-318, Space 98, The Sixth International Conference and Expostion on Engineering, Construction and Operations in Space, ASCE, 1998

B.G. Cour-Palais, The current micrometeoroid flux at the Moon for masses <10-7 g from the Apollo window and Surveyor 3 TV camera results, pp. 2451-2462, Geochim. Cosmochim. Acta, Vol. 3, 1974.

138

W. Doggett, Robotic Assembly of Truss Structures for Space Systems and Future Research Plans, IEEE 0-8703-7231-X/01, IEEE, 2002

M.B. Duke, J. Diaz, B.R. Blair, M. Oderman, M. Vaucher, Architecture Studies for Commercial Production of Propellants from the Lunar Poles, pp. 1219- 1226, American Institute of Physics, Conference Proceedings, Vol. 654(1), 2003

E. Dupuis, G.R. Gillett, P. Boulanger, E. Edwards and M.G. Lipsett, Interactive, Intelligent Remote Operations: Applications to Space Robotics, Conference Proceedings of SPIE Telemanipulator and Telepresence Technologies VI, 1999

E. Dupuis, R. Gillett, Validation of Ground Control Technology for International Space Station Robot Systems, iSAIRAS 2001, Proceedings of the Sixth international Symposium on Artificial Intelligence Robotics and Automation in Space, Montreal, Canada, 2001

E. Dupuis, R. Gillett, J. Piedboeuf, L. Gregoris, Ground Control Technology For International Space Station Robot Systems, Proceedings of the 23rd International Symposium on Space Technology and Science, Matsue, Japan, 2002

M. Dureigne, Multimedia Environment in Complex Aerospace Engineering, pp. 390-395, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

139

R. Dworkowski, P. Wojcik, Modeling the Geometry of the Laser Distance Sensor, pp. 111-114, Space Robotics, A Proceedings Volume from the IFAC Workshop St-Hubert, Quebec, Canada, IFAC, 1998

P. Eckart, The Lunar Base Handbook, McGraw-Hill, New York, 1999

ESA, Kilometric Baseline Space Interferometry, European Space Agency, SCI(96)7, 1996

T. Fong, S. Grange, C. Thorpe, C. Baur, Multi-Robot Remote Driving with Collaborative Control, pp. 237-242, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

T.M. Gatton, F.W. Kearney, Automation and Robotics in Construction: Japanese Research and Development, US Army Corps of Engineers, USACERL Technical Report M-90/03, Oct. 1989, USACERL, 1989

H.O. Gemmink, Future Communication Infrastructures on the Moon, a Case Study for an Infrared Telescope on the Lunar South Pole, Masters Thesis, TU-Delft, Delft, 1999

J.V. Gies, The Effect of the Lunar Surface Environment upon Machinery, pp. 639-645, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96, Vol. 1, ASCE, 1996

140

G.R. Gillet, M.G. Lipsett, P. Boulanger, Interactive Intelligent Remote Operations, Proceedings of Computers in Manufacturing 1999, Birmingham, 1999

G. Grunwald, G. Schreiber, A. Albu-Schaeffer, G. Hirzinger, Touch: the Direct Type of Human Interaction with a Redundant Service Robot, pp. 347-352, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

D.W. Hainsworth, Teleoperation User Interfaces for Mining Robotics, ICRA2000, International Conference on Robotics and Automation, Workshop San Francisco, California, IEEE, 2000

I. Heinz, F. Haertl, C. Froehlich, Semi-Automatic 3D CAD Model Generation of AS-Built Conditions of Real Environments using a Visual Laser Radar, pp. 400-406, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

M.W. Henley, J.C. Fikes, J. Howell, J.C. Mankins, Space solar power technology demonstration for lunar polar applications, Proceedings of the International Astronautical Congress, IAC-02-R.4.04, Houston, 2002

R.R. Hodge, J.H. Hoffman, F.S. Johnson, D.E. Evans, Composition and dynamics of lunar atmosphere, pp. 2855-2865, in Proceedings of the fourth lunar science conference, Geochim. Cosmoschim. Acta 3, Suppl. 4, 1973

141

J.H. Hoffman et al., Lunar Atmospheric Composition Results from Apollo 17, pp. 2865-2875, Proceedings of the 4th Lunar Science Conference, 1973

M. Irivine, Cable Structures, Dover Publications, Inc., Meneola, N.Y. 1981

P. Jasiobedzki, C. Anders, Computer Vision for Space Robotics: Applications, Role and Performance, pp. 95-102, Space Robotics, A Proceedings Volume from the IFAC Workshop St-Hubert, Quebec, Canada, IFAC, 1998

F.S. Johnson, Lunar Atmosphere, Reviews of Geophysics and Space Physics, Vol. 9, No.3, pp. 813-823, 1971

R.H. King, A survey of intelligent control of mining equipment and systems, International Journal of Intelligent Control and systems, Vol. 1, No. 1, pp 101-117, 1996

K. Kinugawa, H. Noborio, A Shared Autonomy of Multiple Mobile Robots in Teleoperation, pp. 319-325, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

J.L. Klosky, S. Sture, H.Ko, F. Barnes, Vibratory Excavation and Anchoring Tools for the Lunar Surface, pp. 903-911, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 2, ASCE, 1996

142

A. Kochan, Robots for Automation Construction - an Abundance of Research, pp. 111-113, Industrial Robot: an International Journal. Vol 27, No. 2, MCB University Press, 2000

M. Kruijff, The Peaks of Eternal Light on the Lunar South Pole: How they were found and What they look like, pp. 333-336, ESA-SP-462, 2000

V. Lagrange, An Ergonomic Perspective on Automation, pp. 396-399, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

M.S. Lake, Launching a 25-meter Space Telescope "Are Astronauts a Key to the Next Technically Logical Step After NGST", IEEE Aerospace Conference, IEEE Paper No. 460, IEEE, 2001

M.J. Lally, S.P. Mackey, L.R. Gaskins, Considerations for Realistic Lunar Excavation, pp. 896-902, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 2, ASCE, 1996

J.C. Lane, C.R. Carignan, D.L. Akin, Advanced Operator Interface Design for Complex Space Telerobotics, ICRA2000, international Conference on Robotics and Automation, Workshop in San Francisco, California, IEEE, 2000

143

S.R.H. Langton, How the Eyes Affect the I: Gaze Perception, Cognition and the Robot-Human Interface, pp. 359-365, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

A.I. Logan, Training Beyond Reality, pp. 183-189, Space Robotics, A Proceedings Volume from the IFAC Workshop St-Hubert, Quebec, Canada, IFAC, 1998

S.J. Lorenc, B.E. Handlon, L.E. Bernold, Development of a Robotic Bridge Maintenance System, pp. 251-258, Automation in Construction 9, 2000, Elsevier, 2000

C.S. Lovchik, M.A. Diftler, The Robonaut Hand: A dexterous Robot Hand for Space, pp. 907-912, Proceedings of the 1999 IEEE International Conference on Robotics & Automation, IEEE, Detroit Michigan, 1999

K. B. Ma, C. K. McMichael, M. A. Lamb and W. K. Chu, Application of HTS’s on Levitation Bearings, Torque Transmissions and Vibration Dampers, IEEE Transactions on Applied Superconductivity 3, pp. 388, 1993

Y. Mae, T. Arai, K. Inoue, I. Kurosaki, View Controls in Environment Presentation for Robot Tele-Operation, pp. 332-337, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

144

G. L. Martin, The NASA Exploration Team: Recent Accomplishments, Proceedings of the International Astronautical Congress, IAC-02-Q.6.03, Houston, 2002

T. Muff, R. H. King, and M. B. Duke, Preliminary Analysis of a Small Robot for Martian Regolith Excavation, Proceedings of the Space Resources Roundtable II, #7035, Colorado School of Mines, 2000

N. Matsuhira, M. Asakura, Y. Shinomiya, K. Machida, K. Tanie, H. Nishida, H. Bamba, K Akita, A Wire Handling Experiment Using a Teleoperated Advanced Robotic Hand on ETS-7, pp. 397-402, iSAIRAS '99, Proceedings of the Fifth International Symposium on Artificial Intelligence Robotics and Automation in Space, ESA-SP-440, ESA, 1999

C. Melchiorri, G. Vassura, Design of a Three-Finger Gripper for Intra-Vehicular Robotic Manipulation, pp. 7-12, Space Robotics, A Proceedings Volume from the IFAC Workshop St-Hubert, Quebec, Canada, IFAC, 1998

W.W. Mendell, Effect of the Lunar Seismic Environment on a Moon-Based Optical Interferometer, pp. 451-461, Space 98, The Sixth International Conference and Exposition on Engineering, Construction and Operations in Space, ASCE, 1998

S. Mohanty, B. Imhof, P.J. Van Susante, European Lunar Base Concepts, International Conference on Environmental Systems 2003, Society of Automotive Engineers, Vancouver, Canada, 2003

145

R.M. Muller, Orbital Assembly and Servicing of a 20-meter Diameter Space Telescope Using the International Space Station, The QSS Group, Inc, QSS, 2000a

R.M. Muller, Robotic Assembly of a 20-meter Space Telescope, with Extension to 40-meter Space Telescopes, The QSS Group, Inc, QSS, 2000b

Y. Nagao. H. Urabe, F. Honda, J. Kawabata, T. kawamura and N. Miyamoto, Development of a Teachingless Robot System for Welding a Large-Sized Box-Type Construction, pp. 287-291, Advanced Robotics, Vol. 15, No. 3, VSP and Robotics society of Japan, 2001

Y. Nagumo, A. Ohya, Human Following Behavior of an Autonomous Mobile Robot Using Light Emitting Device, pp. 225-230, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

T.J. Nelson, M.R. Olson and H.C. Wood, Long Delay Telecontrol for Lunar Mining Equipment, pp. 477-484, Space 98, The Sixth International Conference and Exposition on Engineering, Construction and Operations in Space, ASCE, 1998

A.M. Okamura, N. Smaby and M.R. Cutkosky, An Overview of Dexterous Manipulation, pp. 255-262, Proceedings of the 2000 IEEE International Conference on Robotics & Automation, IEEE, 2000

146

L.F. Penin, K. Matsumoto, S. Wakabayashi, ETS-7 Space Robot Teleoperation Through Virtual Force Reflection, pp. 389-396, iSAIRAS '99, Proceedings of the Fifth International Symposium on Artificial Intelligence Robotics and Automation in Space, ESA-SP-440, ESA, 1999

S.W. Perkins, C.R. Madson, Scale Effects of Shallow Foundations on Lunar Regolith, pp. 963-972, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 2, ASCE, 1996

H.A. Perko, Surface Cleanliness Based Dust Adhesion Model, pp. 495-505, Space 98, The Sixth International Conference and Exposition on Engineering, Construction and Operations in Space, ASCE, 1998

H.A. Perko, J.D. Nelson, W.Z. Sadeh, Surface Cleanliness Effect on Lunar Soil Shear Strength, pp. 371-383, Journal of Geotechnical and Geoenvironmental Engineering, april 2001, 2001

A.E. Potter and T.H. Morgan, Discovery of Sodium and Potassium Vapor in the Atmosphere of the Moon, pp. 675-680, Science 241, 1988

P. Putz, Space Robotics, pp. 421-463, Report on Progress in Physics 65 (2002), Institute of Physics publishing, IOP publishing limited, 2002

J.J. Rennilson and D.R. Criswell, Surveyor observations of lunar horizon glow, The Moon, No.10, pp. 121-142, 1974

147

A. Rezapour, Overview of International Space Station ExtraVehicular Robotics, pp. 490-496, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 1, ASCE, 1996

B. Robertson, Virtual Humans at Work, pp. 33-39, Computer Graphics World, July 1997, 1997

P. Schoonejans, M. Oort, ERA, The Flexible Robot Arm, pp. 49-53, iSAIRAS '99, Proceedings of the Fifth International Symposium on Artificial Intelligence Robotics and Automation in Space, ESA-SP-440, ESA, 1999

L.G. Shapiro, G.C. Stockman, Computer Vision, Prentice-Hall, Upper Saddle River, New Jersey, 2001

A.A. Sickafoose, J.E. Colwell, M. Horányi, and S. Robertson, Experimental investigations on photoelectric and triboelectric charging of dust, pp. 8343, Journal of Geophysical Research 106, 2001.

H.J. Smith, Future astronomical observatories on the moon, pp. 37-42, NASA conference publication 2489, Washington, DC, 1988

T. Stafford, America's Space Exploration Initiative, U.S. Government Printing Office, Washington D.C. 20402, 1991

148

P.J. Staritz, S. Skaff, C. Urmson, W. Whittaker, Skyworker: A Robot for Assembly, Inspection and Maintenance of Large Scale Orbital Facilities, pp. 4180-4185, ICRA2001 Proceedings, Proceedings of the 2001 IEEE International Conference on Robotics and Automation, IEEE, 2001

A. Stentz, M. Ollis, S. Scheding, H. Herman, C. Fromme, J. Pedersen, T. Hegadorn, R. McCall, J. Bares and R. Moore, Position Measurement for Automated Mining Machinery, pp. 299-304, Proceedings of the 1999 International Conference on Field and Services Robotics, 1999

M.E. Stieber, D.G. Hunter, Overview of the Mobile Servicing System for the International Space Station, pp. 37-42, iSAIRAS '99, Proceedings of the Fifth International Symposium on Artificial Intelligence Robotics and Automation in Space, ESA-SP-440, ESA, 1999

D. Sun, J.K. Mills, Manipulating Rigid Payloads with Multiple Robots Using Compliant Grippers, pp. 23-34, IEEE/ASME Transactions on Mechatronics, Vol. 7, No. 1, March 2002, IEEE, 2002

Y. Takahashi, A. Murata, Change of Equilibrium Under the Influence of VR Experience, pp. 642-647, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

149

B.A. Trouvain, F.E. Schneider, D. Wildermuth, Integrating a Multimodal Human- Robot Interaction Method into a Multi-Robot Control Station, pp. 468-472, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

C.S. Tzafestas, Tele-planning by Human Demonstration for VR-Based Teleoperation of a Mobile Robotic Assistant, pp. 462-467, ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication : IEEE catalog number : 01TH8591, IEEE, 2001

P.J. Van Susante, Design and Construction study of a Lunar South Pole Infrared Telescope, MSc. Thesis, TU-Delft, july 2001, Delft, Department Of Civil Engineering, 2001

P.J. Van Susante, Study Towards Construction and Operation of Large Lunar Telescopes, pp. 2479-2484, Advances in Space Research, Volume 31, issue no. 11, Elsevier, 2003.

A.R. Vasavada, D. A. Paige, Near-Surface Temperatures on Mercury and the Moon and the Stability of Polar Ice Deposits, pp. 179-193, ICARUS 141, 1999

D. Verhoeven, Space Mechanisms and Tribology for the Joints of the European Robot Arm (ERA), pp. 335-340, Proceedings of the 8th European Space Mechanisms and Tribology Symposium, ESA-SP438, ESA, 1999

150

R.R. Vondrak, Creation of an Artificial Lunar Atmosphere, pp. 657-659, Nature 248, 1974

A. Warszawski, Industrialized and Automated Building Systems "A Managerial Approach", pp. 364-396, E&FN Spon, Routledge, New York, 1999

B.M. Willman, W.W. Boles, Soil-Tool Interaction Theories as They Apply to Lunar Soil Simulant, pp. 88-99, Journal of Aerospace Engineering, Vol. 8, No.2 april 1995, ASCE, 1995

J.R. Wilson, UAVs and the Human Factor, pp. 54-57, Aerospace America, AIAA, July 2002, AIAA, 2002

T. L. Wilson, W. K. Chu and P. C. Chen, Advanced Technology Lunar Telescope, Lunar and Planetary Science XXV, Vol. 3, pp. 1501, Lunar and Planetary Institute, Houston, 1994

W. Wimmer, Robotics and On-Board Autonomy : For What and How Far Can We go?, pp. 51-57, Space Robotics, A Proceedings Volume from the IFAC Workshop St-Hubert, Quebec, Canada, IFAC, 1998

W. Zuk, Final Report "Robotics in Construction", Virginia Highway and Transportation Research Council, Charlottesville, Virginia, 1985

151

SELECTED BIBLIOGRAPHY

D.S. Acton, P.L. Wizinowich, M. Divittorio, T. Gregory, Lessons Learned in the Design, Construction, and Implementation of the W.M. Keck Observatory AO System, pp. 14-25, Adaptive, Optical Systems Technology, Proceedings of SPIE Vol. 4007, part 1, SPIE, 2000

T. Anderson, A. Ardeberg, R. Gilmozzi, Proceedings of the Backaskog Workshop on "Extremely Large Telescopes", ESO Conference and Workshop Proceedings no. 57, ESO, Garching, 1999

D. Bedini, Self-Constructing Space Systems, pp. 1032-1037, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 2, ASCE, 1996

H. Benaroya (editor), Lunar-Based Astronomy, pp. 65-108, Journal of the British Interplanetary Society, London, UK, 1995

H. Benaroya, L.Bernold, K.M. Chua, Engineering, Design and Construction of Lunar Bases, pp. 33-45, Journal of Aerospace Engineering, April 2002, ASCE, 2002

152

E. Brunetto, F. Koch, M. Quattri, OWL: Further Steps in Designing the Telescope Mechanical Structure and Assesing its Performance, SPIE Vol. 4004, Munich, March 2002

J.O. Burns, Astronomy from the Moon, pp. 242-251, Robotic Telescopes, ASP Conference Series, Vol. 79, 1995, Astronomical Society of the Pacific, 1995

V. Carruba, A. Coradini, Lunar Cold Traps: Effects of Double Shielding, pp. 402-413, ICARUS 142, 1999

W.A. Charlie, T.Taylor, K.C. Brownell, Model Studies of Effects on Lunar Soil of Chemical Explosions, pp. 601-602, Journal of Geotechnical Engineering, July 1996, ASCE

D. Danesy (editor) ESA Publications Division, Proceedings of the 8th European Space Mechanisms and Tribology Symposium, ESA-SP-438, ESA, 1999

L.T. De Witt IV, Construction Metrology Beyond Earth, a White Paper, pp. 357- 360, Space Manufacturing 12, Challenges and Opportunities in Space, Proceedings of the Fourteenth SSI/Princeton Conference on Space Manufacturing, Space Studies Institute (SSI), 1999

F. Didot, M. Bavdaz, J. Schiemann, U. Knoop, H. Petersen, Assembly of Large Spacecraft: the XEUS Mission, pp. 55-60, iSAIRAS '99, Proceedings of the Fifth International Symposium on Artificial Intelligence Robotics and Automation in Space, ESA-SP-440, ESA, 1999

153

P. Eckart, Lunar Base Model, pp. 601-607, Space 98, The Sixth International Conference and Exposition on Engineering, Construction and Operations in Space, ASCE, 1998

A. Ellery, An Introduction to Space Robotics, Springer / Praxis, UK, 2000

R.G. Galloway and S. Lokaj (editors), Space 98, pp. , The Sixth International Conference and Exposition on Engineering, Construction and Operations in Space, ASCE, 1998

B., Greber (editor), Space Manufacturing 12, Challenges and Opportunities in Space, Proceedings of the Fourteenth SSI/Princeton Conference on Space Nanufacturing, Space Studies Institute (SSI), 1999

J.R. Gustafson and W. Sargent, The Keck Observatory : 36 Mirrors are Better Than One, pp. 43-53, Mercury, Vol. 17, No. 2, 1988

S.W. Johnson (editor), Engineering, Construction, and Operations in Space V, Proceedings of the Fifth International Conference on Space '96 vol 1 and 2, ASCE, 1996

S.W. Johnson, K.M. Chua M. Schwartz and J.O. Burns, Architectural Considerations In Design Of Lunar-Based Astronomical Observatories, pp. 871-880, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 2, ASCE, 1996

154

A. Labeyrie, Hypertelescopes and Exo-Earth Coronagraphy, ESA-SP-514, ESA, 2002

M.S. Lake, L.D. Peterson, M.M. Mikulas, J.D. Hinkle, L.R. Hardaway, J. Heald, Structural Concepts and Mechanics Issues for Ultra-Large Optical Systems, Ultra Lightweight Space Optics Workshop, Napa Valley California, March 1999

C.P. Lin, D.J. Goodings, L.E. Bernold, R.D. Dick, W.L. Founey, Model Studies of Effects on Lunar Soil of Chemical Explosions, pp. 1684-1703, Journal of Geotechnical Engineering, Vol 120, No. 10, ASCE, 1994

J.L. Margot, D.B. Campbell, R.F. Jurgens and M.A. Slade, Topography of the Lunar Poles from Radar Interferometry: a Survey of Cold Trap Locations, pp. 1658-1660, Science, Vol. 284, 1990

S. Matsumoto, N. Isome, K. Oishi, H. Kanamori, K. Takagi, Y. Kay, M. Suzuki, S. Suzuki, Construction System for Lunar Bases, pp. 140-144, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 1, ASCE, 1996

D.S. McKay, C.C. Allen, Concrete -- A Practical Construction Material for Mars, pp. 566-570, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 1, ASCE, 1996

J. Nelson, The Keck Telescope, pp. 170-176, American Scientist, Vol. 77, No. 2, 1989 155

J. Nelson and T. Mast (editors), Conceptual Design for a Thirty-Meter Telescope, CELT report 34, CELT Report Number 34, June 2002, California Extremely Large Telescope, University of California and California Institute of Technology, 2002

S.B. Niku, Introduction to Robotics, Analysis, Systems, Applications, Prentice Hall, Upper Saddle River, NJ, 2001

S. Nozette, P.D. Spudis, M. Robinson, B. Bussey, C. Lichtenberg, R. Bonner, Integration of Lunar Polar Data Sets, Lunar and Planetary Science Conference XXX, Houston, 1999

M. Perry (editor), iSAIRAS '99, Proceedings of the Fifth International Symposium on Artificial Intelligence Robotics and Automation in Space, ESA-SP-440, ESA, 1999

R. Richard Hodges Jr., Lunar Cold Traps and their Influence on Argon-40, pp. 2463-2477, Proceedings of the 11th Lunar and Planetary Science Conference, 1980

S. Rondeau (editor), Space Robotics, A Proceedings Volume from the IFAC Workshop St-Hubert, Quebec, Canada, Pergamon, 1998

W.Z. Sadeh and M.E. Criswell, Lunar Base Development Stages, pp. 912-919, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 2, ASCE, 1996

156

T. Sato, S. Matsumoto, H. Namba, K. Takagi, H. Tadokoro, H. yamakawa, T. Oura, K. Nozaki N. kaya, Self Deployable Mechanisms for Large Disk- Antenna Using Centrifugal Force., pp. 1155-1161, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 2, ASCE, 1996

S.B. Skaar, C.F. Ruoff (Editors), Teleoperation and Robotics in Space, Progress in Astronautics and Aeronautics, Vol. 161, AIAA, 1994

A. Sogame, H. Furuya, Construction With Cylindrical Deployable Space Structures, pp. 74-78, Space 98, The Sixth International Conference and Exposition on Engineering, Construction and Operations in Space, ASCE, 1998

N.J. Stacy, D.B. Campbell andP.G. Ford, Arecibo Radar Mapping of the Lunar Poles: a Search for Ice Deposits, pp. 1527-1530, Science, vol. 276, 1997

L.A. Taylor, D.S. Taylor, Location of a Lunar Base : A Site Selection Strategy, pp. 741-755, Engineering, Construcion and Operations in SPACE V, Proceedings of the Fifth International Conference on Space '96 vol 2, ASCE, 1996

G.T. van Belle, From PTI to the Keck Interferometer, pp. 450-461, From Extrasolar Planets to Cosmology

157

T.J. Waters, M.T. Waters, Hyperboloidal Deployable Solar Space Mirrors, Hyperboloidal Deployable Space Antennas, Hyperboloidal Spacecraft Structures, pp. 227-233, Space Manufacturing 12, Challenges and Opportunities in Space, Proceedings of the Fourteenth SSI/Princeton Conference on Space Manufacturing, Space Studies Institute (SSI), 1999

D. Woody, D. Vail, W. Schaal, Design, Construction and Performance of the Leighton 10.4-m-diameter Radio Telescopes, pp. 673-686, Proceedings of the IEEE, Vol. 82, No. 5, May 1994, IEEE, 1994

ROMAN '01 Proceedings of 10th IEEE International Workshop on Robot and Human Interactive Communication, IEEE catalog number : 01TH8591, IEEE, 2001 158

APPENDIX A

Requirement definition of a future infrared telescope.

Some questions have sparked curiosity through the ages. These questions; "Where did we come from?" and "Are we alone?", have been the topic of many discussions and convictions of large groups of people. Nowadays we have developed the technical means to try to find some clues through astronomical observations. Ever larger and more complex telescopes are designed and built for this purpose. Many organisations of internationally cooperating universities and research institutes have been formed because the projects have become too large, too costly and too complex to be done by one party. An example of such a cooperation is the European Southern Observatory (ESO), which exists of cooperating institutions all over Europe and who have recently completed the construction of the Very Large Telescope Interferometer (VLTI) in Chile. The VLTI exists of four, 8.2 m diameter, telescopes and when the light of the four is combined it is at present the largest telescope in the UV-VIS-IR wavelength region.

To find clues about the answers of these fundamental questions, many phenomena are being studied. Some of these phenomena are: galaxy formation, galaxy evolution, planet formation, planetary system evolution and life detection. To study these phenomena it is most efficient to look in the visual, infrared and submillimeter wavelengths. The mid- and far-infrared is of special importance 159

because of three reaons. First because of the redshift that occurs over time in starlight, the original visible light is now red-shifted to the infrared part of the spectrum. Second because of the large dust clouds surrounding starformation that block the visible light but allow infrared light to pass. And third because of the ratio of brightness between a star and its planets is three orders of magnitude more favorable in the infrared region (106:1) than in the visible light region (109:1) , for detecting and studying planets.

Other telescopes are planned in different wavelengths to succeed the present state of the art telescopes. The leading telescopes that will be operational in twenty years, are being planned now. To make sure that the telescopes do not have exactly the same capabilities and do complement each others observations, it is necessary to compare to other plans for telescopes who will be operational in the twenty year timeframe (See Table A-1).

Table A-1: Planned leading telescopes available in 2020

telescope start year size of mirrors baseline wavelength ALMA 2010 24 m (64x) 12 km Sub-MM SAFIR 2015 8 m N/A Far-IR SPECS 2015 4 m (3x) 1 km Far-IR JWST 2010 6.5 m N/A Mid-IR TPF/Darwin 2015 3m (5x) 40-1000 m Mid-IR OWL 2020 100 m N/A Near-IR , Vis SUVO 2015 8 m N/A Vis, UV

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The question remains, what telescope would be required to follow on and improve the discoveries made by the planned telesopes. The James Webb Space Telescope (JWST) will reach its designed end of lifetime around 2020. Plans for its successor are being made but all plans are in the early feasibility study phase. Most of these plans consider similar designs as the JWST, but then assembled at the space station and launched to Earth-Sun Lagrange point 2 from there. An option that in general is being overlooked is that for such large (larger than 20 m diameter) telescopes the lunar surface may make an excellent site to emplace an infrared telescope. Another thing to keep in mind is that the permanently shadowed regions in the South Pole area of the Moon are most favorable for infrared astronomy. Since most other wavelengths will be covered well around 2020 by other telescopes, this leads to the conclusion that a successor of the JWST in the infrared is required to complement the other planned observatories. What size would then be required to improve the observations of the JWST and as far as resolution and sensitivity is concerned, match the other leading observatories.

In the mid-infrared the leading observatories will be the single-aperture JWST and the TPF/Darwin interferometer, while in the far-infrared the SAFIR and SPECS interferometer will respectively provide the sensitivity and resolution. By ~2020, the JWST will be reaching its operational lifetime, while TPF/Darwin will be continuing its search for more extra-solar planets and utilizing its angular resolving power for astrophysical observations. A much larger next generation telescope optimized for the mid-infrared will be in the highest demand to succeed the JWST for solving the remaining mysteries.

The minimum requirement to determine the size is that it is larger than both the JWST (6.5 m) and the SAFIR (8 m) to surpass the available sensitivity 161

and efficiency. The minimum detectable flux density (S) improves proportionally to the collecting area (A) and the square root of integration time (t):

S ~ 1 / A sqrt(t).

For spectroscopy, the available spectral resolving power is proportional to the collecting area for a fixed integration time and a certain signal-to-noise ratio (S/N). In general, the required integration time shortens with the collecting area squared. So, in theory, a continuously operating 25-meter telescope will be able to complete all the observations done during the 10-year lifetime of the JWST in only about 17 days. This is considered to be enough orders of magnitude improvement for the successor of JWST while keeping the technological challenges achievable in the next 20 years.

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APPENDIX B

Timeline of the telescope construction

-overview version (See Table B-1) -expanded version (See Table B-2a and Table B-2b)

*please be aware of the compressed time-axis *light arrows on dark background indicate overtime for certain tasks

week launch activity 1349101718232429303738414247485152555659606263666774757879848592939697104105108109120121124 1a landing on Malapert mountain 1b landing on Peak of Eternal light 2 landing near RoCaDi I at lunar base site 3 landing near RoCaDi I at lunar base site 4 landing on landing pad near lunar base 5 landing on landing pad near lunar base 6 landing on landing pad near lunar base 7 landing near RoCaDi II in Shackleton Crater 8 landing on landing pad near lunar base 9 landing on landing pad near lunar base 10 landing on landing pad near lunar base 11 landing on landing pad near lunar base 12 landing on landing pad near lunar base 13 landing on landing pad near lunar base 14 landing on landing pad near lunar base 15 landing on landing pad near lunar base 16 landing on landing pad near lunar base 17 landing on landing pad near lunar base 18 landing on landing pad near lunar base 19 landing on landing pad near lunar base Table B-1: Overview version of the construction timeline

163 week launch activity 1349101718232429303738414247485152555659606263666774757879848592939697104105108109120121124 1a landing on Malapert mountain 1b landing on Peak of Eternal light deployment of RoCaDi I roll down and locate tower locations find lunar base location function as landing beacon at lunar base site 2 landing near RoCaDi I at lunar base site deploy "dirty" and tower robot transportation of lift tower for 1st leg make landing pad by "dirty" robot place towers & hookup of cable by tower robot possible first element of lunar base & power hookup 3 landing near RoCaDi I at lunar base site landers of 2 & 3 form part of the lift anchor system assemble the lunar base elements hoist entire cable of first leg in place check lift system & power 4 landing on landing pad near lunar base assemble the lunar base elements transport humans check & activate all systems of the lunar base visit PEL via the lift system for inspection 5 landing on landing pad near lunar base bring more lunar base elements & RoCaDi II assemble the lunar base elements transport RoCaDi II up to PEL with lift hook cable up to existing lift tower on PEL roll down and locate tower locations find lunar outpost location & telescope site function as landing beacon in Shackleton Crater 6 landing on landing pad near lunar base transport the towers for the 2nd leg bring solar cell expansion for PEL place towers & hookup of cable by tower robot bring expansions and supplies for lunar base 7 landing near RoCaDi II in Shackleton Crater assembly of lunar outpost elements the lander functions as lift anchor in the crater hoist cable of lift system leg 2 in place test the 2nd leg finish the outpost and connect power human inspection of outpost & crater 8 landing on landing pad near lunar base deploy "clean" transport robot transport more lunar outpost elements transport laser range finders and setup grid by dirty dig foundation holes by dirty robot place foundation poles inspect placement of poles & orientation by 2 humans apply preload by dirty, and then remove Table B-2a: Expanded version of the construction timeline I

164 week launch activity 1349101718232429303738414247485152555659606263666774757879848592939697104105108109120121124 9 landing on landing pad near lunar base transport elements of lower super conducting magnetic ring install the elements under supervision in crater inspection or ring before fixation 10 landing on landing pad near lunar base transport elements of upper half of super conducting magnetic ring transport of the 2 on-telescope robots install the upper half of the ring and place the 2 on-telescope robots 11 landing on landing pad near lunar base bring elements for the main support struts to site by "clean" robot hand to on-telescope robots installation of elements 12 landing on landing pad near lunar base transport temporary- and main axis elements the "clean" transport robot brings them to lunar base of outpost install the altitude bearings install the temporary axis install the main axis elements 13 landing on landing pad near lunar base transport main mirror support structure elements install the elements by the on-telescope robots 14 landing on landing pad near lunar base transport main mirror support structure elements install the elements by the on-telescope robots 15 landing on landing pad near lunar base bring counterweight & instrument housing elements transport to lunar base or telescope site install the elements by the on-telescope robots install the counter weight (made of local material) 16 landing on landing pad near lunar base bring secondary mirror support strut elements & secondary mirro transport to lunar base or telescope site install the elements by the on-telescope robots install the mirror 17 landing on landing pad near lunar base transport instruments to lunar base or telescope site place instruments under human supervision & by humans 18 landing on landing pad near lunar base bring main mirror segments to lunar base or telescope site install segments test installation of segments and actuators as soon as installed 19 landing on landing pad near lunar base bring main mirror segments to lunar base or telescope site install segments test installation of segments and actuators as soon as installed Table B-2b: Expanded version of the construction timeline II

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