QB50 Sensor Selection Working Group (SSWG) Final Report 19 March 2012 Editor: Prof. Alan Smith Mullard Space Science Laboratory (MSSL) University College London (UCL) Holmbury St. Mary Dorking, Surrey RH5 6NT United Kingdom 1 SSWG Membership A. Smith (Chairman, Mullard Space Science Laboratory, UK) T. Beuselinck (RedShift BVBA, Belgium) J. F. Dalsgaard Nielsen (Aalborg University, Denmark) J. De Keyser (Belgian Institute for Space Aeronomy, Belgium) A. Gregorio (University of Trieste, Italy) D. Kataria (Mullard Space Science Laboratory, UK) V. Lappas (Surrey Space Centre, UK) F. J. Lübken (Institute for Atmospheric Physics, Germany) J. Moen (University of Oslo, Norway) S. Palo (University of Colorado, USA) R. Reinhard (von Karman Institute, Belgium) A. Ridley (University of Michigan, USA) J. Rotteveel (Innovative Solutions In Space, Netherlands) G. Schmidtke (Fraunhofer Institute for Physical Measurement Techniques, Germany) T. Schmiel (TU Dresden, Germany) 2 Table of Contents 1. Introduction ........................................................................................................................... 4 2. The QB50 Project .................................................................................................................... 5 3. Science Context ..................................................................................................................... 10 4. In‐situ measurements in the lower thermosphere – other projects ........................................ 13 4.1 Past satellites in highly elliptical orbits ............................................................................... 13 4.2 The Drag and Atmospheric Neutral Density Explorer (DANDE) ............................................ 20 4.3 Low‐Flying Spacecraft (LFSC) Daedalus ................................................................................ 21 4.4 Sounding Rocket experiments ............................................................................................ 22 4.5 Armada .............................................................................................................................. 26 5. QB50 Candidate Sensors ........................................................................................................ 28 5.1 Introduction ....................................................................................................................... 28 5.2 Ion and Neutral mass spectrometer .................................................................................... 29 5.3 FIPEX: In‐situ Atomic Oxygen Measurement in Low‐Earth Orbit .......................................... 32 5.4 Multi‐Needle Langmuir Probe ............................................................................................. 37 5.5 Magnetoresistive magnetometer ........................................................................................ 40 5.6 Accelerometer .................................................................................................................... 43 5.7 GPS receiver ....................................................................................................................... 46 5.8 Laser Retroreflector ............................................................................................................ 52 5.9 Thermistors/thermocouples ............................................................................................... 53 5.10 Q‐BOS (Bolometric Oscillation Sensor) .............................................................................. 56 5.11 Silicon Detector ................................................................................................................ 59 5.12 Spherical EUV and Plasma Spectrometer (SEPS) ................................................................ 63 5.13 WINCS .............................................................................................................................. 68 5.14 Sensor Resource Summary ............................................................................................. 70 6. QB50 CubeSat physical constraints and payload architecture ....... Error! Bookmark not defined. 7. Selection ............................................................................................................................... 71 8. Recommendations ................................................................................................................ 74 9. Baseline sensor package configurations ................................................................................. 75 10. References ......................................................................................................................... 76 11. Acronyms .......................................................................................................................... 77 12. Contributors ...................................................................................................................... 81 3 1. Introduction The QB50 Sensor Selection Working Group met on four occasions: 3 March 2011, 4 May 2011, 16-17 June 2011, and 26 July 2011. All meetings were held at the von Karman Institute for Fluid Dynamics, Rhode‐St‐Genèse, near Brussels, Belgium. The results of the working group were reported on 27 July 2011 at the 2nd QB50 workshop and then to the QB50 Steering Committee on the same day. The task of the SSWG was to identify optimal sensor package options for the network part of the QB50 mission taking into consideration: scientific objectives; potential science instruments, their availability and their heritage; the very limited spacecraft resources of CubeSats; and the limited available financial resources. The SSWG remained cognisant of the overall QB50 mission objectives and recognised that these were perceived differently by the variety of stakeholders including EC, the Science Community and CubeSat providers. The group also recognised the importance of the science context both in terms of what were the key scientific issues to be addressed, and also what missions have flown or are proposed for this area of endeavour. Given the CubeSat nature of the mission, accommodation constraints for any selected sensor package were naturally important and given high priority in discussions. A wide range of sensor options were considered with additional options being introduced as they became known to the group. Expert advice was sought where appropriate and budgetary considerations were included in the SSWG deliberations. Inputs were received from a wide variety of sources including other QB50 working groups, commercial organisations, science groups, and potential instrument providers. Meetings included teleconference sessions and presentations. This report outlines the QB50 project, provides science context, describes earlier missions and future mission proposals in this area and then goes on to describe the science instrument options that were considered. A brief description of the payload architecture and payload interface requirement is then followed by the selected payload options and other recommendations. This report was compiled from numerous inputs (attributed below) and edited by A. Smith. 4 2. The QB50 Project R. Reinhard, VKI QB50 is a network 50 CubeSats in a ‘string‐of‐pearls’ configuration that will be launched together in the first half of 2015 by a single rocket, a Shtil‐2.1, from Murmansk, Northern Russia into a circular orbit at 320 km altitude, inclination 79°. The 50 CubeSats will comprise about 40 atmospheric double CubeSats and about 10 double or triple CubeSats for science and technology demonstration. All 40 atmospheric double CubeSats and most of the 10 double and triple CubeSats for In‐Orbit Demonstration (IOD CubeSats) will carry a set of standardized sensors for multi‐point, in‐situ, long‐duration measurements of key parameters and constituents in the largely unexplored lower thermosphere and ionosphere. These multi‐point measurements will allow the separation of spatial and temporal variations. Due to atmospheric drag, the CubeSat orbits will decay and progressively lower and lower layers of the thermosphere/ionosphere will be explored without the need for on‐ board propulsion. The mission lifetime of individual CubeSats is estimated to be about three months. QB50 will also study the re‐entry process by measuring a number of key parameters during re‐entry, e.g. CubeSat on‐board temperature and deceleration. The re‐entry process will also be studied by comparing predicted (using a variety of atmospheric models and different trajectory simulation software tools and CubeSat ballistic coefficients) and actual CubeSat trajectories and orbital lifetimes, and by comparing predicted and actual times and latitudes/longitudes of atmospheric re‐entry. The initial total network size in orbit is determined by the deployment sequence, deployment speed and direction, and can be selected anywhere between 500 and 5000 km. It is currently planned to deploy one CubeSat every orbit, i.e. every 86 minutes. All deployment will preferably take place on the dayside of the orbit. The deployment speed will be 2‐3 m/s and the deployment direction will be uncontrolled. The initial distance between individual CubeSats will be between a few tens and a few hundred kilometres. Orbital modelling has shown that due to density variations along the orbit and small differences in the CubeSat ballistic coefficients the separation distance will change, eventually leading to a non‐uniform