Asteroidlanding - Scilab conference 2019 Keynote

1. 1www.esi-group.com Copyright © ESI Group, 2019. All rights reserved.Copyright © ESI Group, 2019. All rights reserved. www.esi-group.com Keynote: Scilab Application for Space Exploration Mission (MASCOT) Operations T Martin, L Lorda, E Canalias, R Garmier, A Lamy thierry.martin@cnes.fr Scilab Conference 2019

2. 2www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Scilab and Space Exploration Introduction • Scilab used for iconic space missions • ATV (Jules Verne 2008) • Philae / Rosetta (2014) • Presented at SciLabTec 2015 • Mascot / Hayabusa 2 (2018) • … • How do we use scilab? • https://www.scilab.org/about/community/scilabtec/scilabtec-2015/philae-landing-comet- churyumov-gerasimenko-%E2%80%93-scilabtec

5. 5www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Flight Dynamics tools at CNES • Mission design (preliminary studies: phases 0, A, advanced concepts) • Scilab and CelestLab • Link to Java / Patrius through Scilab • Flight Dynamics Systems in operational Control Centers • Java -> Patrius / Sirius product line

6. 6www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Mission design at CNES • Iterative process to: • Definition of the mission • Prove its feasibility • Exhibit the key elements Mission objectives, Hypotheses Technical Solutions (satellite, instrument, constellation,…) PASO Thermics Space dynamics Electrical architecture Attitude control On-board Instruments … • At CNES mission analyses are carried out within a dedicated structure: PASO that: • Coordinates all specialists • Animates the Concurrent Design Facility sessions

7. 7www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Which tools for mission analysis ? What is the best answer for all theses activities ? • Completely new study • Develop specific tools, • Reuse (partly). • Recurrent study • Reuse tools, but adaptations / adjustments are often required. • Flash analysis • No time for heavy /risky developments (essential tools must be available) • Immediate answers • Anything in-between …

8. 8www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Which tools ? • Not so easy. Compromise between: - Flexibility (easy adaptation) - Robustness (reference, reliable tools) - Efficiency (simple / classical problems must be answered easily) - Consistency between tools • Scilab appears to fulfill our needs scilab • This Scilab environment designed for advanced studies may also be used in the context of operational missions (for example Mascot)

9. 9www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Foundation = CelestLab • Scilab flight dynamics library, pure scilab code • Open source (same license as Scilab) • Available on Atoms web site since end of 1999. Number of downloads close to 70000 • http://atoms.scilab.org/toolboxes/celestlab • Contains ~250 functions (~20000 lines of code) • Functions dealing with main aspects of flight dynamics Coordinates & Frames, Trajectory and maneuvers, Orbit properties, Interplanetary, Geometry & events, Relative motion, Models, Utilities • Thoroughly tested Reference data from JPL, SOFA, CNES.... • Many of examples, demos (~100), tutorial pages • Can be used as starting points when you have to do something close to what already exists. • Provides immediate answers to common/recurrent questions => simple problems are generally easily solved.

10. 10www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. CelestLabX: CelestLab’s extension • CelestLabX • Provides scilab interface to public tools and libraries • The additional features are made available through CelestLab (CelestLab then contains either pure Scilab code or calls to functions from CelestLabX) • Reasons for this extension toolbox • Open-source code / freeware libraries exist and we would like to use them through Scilab -> Saves (long) coding / testing time -> Useful features become easily available • Sometimes efficiency implies calling native code • Separate toolbox => keeps CelestLab simple • Contents • interface to STELA Java code https://logiciels.cnes.fr/content/stela • Interface to MSIS2000 C code from https://www.brodo.de/space/nrlmsise (next version) • Interface to TLE C code from http://celestrak.com/software/vallado-sw.asp

12. 12www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Scilab applications through AMS Tools (sce, sci…) and data organized in directories « navigator » Low level lib. (CelestLab / CelestLabX) Higher level lib. (+ interfaces with C, Fortran, Java) Scilab « extension » Additional features to make the tools easier to use User area … dir dir dir dir dir data tree .sce .sci .scd …

15. 15www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. • Hayabusa2: a Japanese asteroid sample return mission • Target : Ryugu, C-type Near Earth Asteroid • Launch : 3 December 2014 • Arrival at Ryugu on June 2018, departure December 2019 (18 months) • Return to Earth by the end of 2020 • Landers on-board: o Minerva-II (1A, 1B, 2) o MASCOT Hayabusa2 and MASCOT

17. 17www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Mascot • Antenna and RF harness • Power unit (PCDU) • Batteries • Mission Analysis/Flight dynamics • Mass ≈ 10 kg, dimensions 30 x 30 x 20 cm • German French collaboration. • Payload: o MARA: infrared radiometer o MASMAG: magnetometer o MASCAM: wide angle camera o MircrOmega: near infrared hyper- spectral microscope • No thrusters, no anchoring system • Autonomous surface operations • Battery lifetime 12h-15h • Mobility arm to perform MASCOT up-rigthening and to hop to different sites

18. 18www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Mascot Flight Dynamics • Preliminary Mission analysis • Support to Landing Site Selection • Only possible when enough data on Ryugu is available • Very constrained period of time • Team of 4 engineers in shift work • Flight Dynamics System (FDS) includes • 2 linux workstations • all necessary software (including scilab) • 2 portable laptops (clone of FDS) • FDS is installed in a dedicated room • Two test campaigns: • Summer of 2017 (including JAXA) B • Beginning of 2018 (MASCOT teams internally) • Creation of operational procedures (Wiki page) • Trajectory reconstruction

19. 19www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. MASCOT Delivery • Hayabusa-2 follows Ryugu at Home Position: • At 20 km altitude from the asteroid center • Located on the line center asteroid – center of Earth (ZHP of Home Position frame) • The orientation is such that: • The antenna is pointed toward the Earth • The solar panels are oriented as far as possible toward the Sun • MASCOT release scenario: • Hayabusa-2 descent from Home Position to the Freefall position. • At Freefall position: Hayabasu-2+MASCOT start a 140s freefall • After 140s, release of MASCOT by Hayabusa-2 toward the ground , later Hayabusa-2 returns to 3km altitude • MASCOT falls to the ground and bounces until immobilization Ryugu X Home Position Freefall disk Mascot Release Freefall position

20. 20www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Ryugu • Spinning top shaped asteroid, quite close to spherical shape, with prominent equator • Rotation • Steady, with a period of 7.63 h • Spin axis nearly perpendicular to the ecliptic plane ☺ Full shape observed from the Hayabusa2 Home Position  No seasonal variation in reachable latitude range from the Home Position  Day/night ratio close to 50% on the whole surface • Gravity / density: very close to reference ground based estimations • GM ~ 30 m3s-2, density ~1.27 g/cm³ • Relatively homogeneous rocky surface, no visible regolith plain….

21. 21www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. • Operational constraints: for a correct operations of MASCOT and its instruments • Illumination constraints (thermal issues): daylight during 40% to 70% of the asteroid period • Radio-Frequency (RF) link constraint: link with HY2 during at least 40% of the asteroid period • Constraints imposed by Hayabusa2 operations design: Constraints of the Landing Site Selection • Zones pre-reserved by JAXA for Hayabusa2 touchdowns • Release Epoch Ranges allowed by JAXA

22. 22www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. MASCOT Team activities Overview of MASCOT landing site selection process 22 CNES Flight Dynamics Team activities Refinement of retained candidates for ranking JAXA data package (Ryugu shape, mass, spin axis, allowed release epoch, zones reserved for Hayabusa2 operations) Agreement in MASCOT Team on retained candidates Comprehensive exploration MASCOT ranking meeting Update of JAXA data package HY2 / MASCOT combined landing site selection Engineering and science teams analyses Candidates for ranking Retained candidates Ranked candidates characteristics Final ranked list for combined selection with HY2 touchdown zones Engineering and science teams analyses Pre-selected candidates in reachable areas

23. 23www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. The 10 pre selected sites and final site MA-9 Candidates final settlement areas projected on a 3D representation of Ryugu MA-9 in orange in the center of the plot.

24. 24www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Mascot: a successful mission Hayabusa 2: an amazing mission! • Mascot was released on October 3rd • Released at 2:00 am (UTC) and reached the MA-9 site • Worked for about 17 hours (~3 asteroid days) as planned for • Hayabusa 2 • First sampling February 21 2019 • Second Sampling July 11 2019 • Return to Earth December 2020

26. 26www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Specificities but common features with advanced project context • modest budget and quick development Small exploration mission • But many differences Experience of Philae / Rosetta • Asteroid barely characterized before arrival • First operations with JAXA • Specifications not defined at the beginning Many unknown factors • Operational shifts • Procedure to be written • Dispositions to reduce the risk of error Landing site selection process A couple of weeks! • Scilab • Fortran for trajectory propagation • JAVA (AMS) Multi Language system Flexibility required Securisation required

27. 27www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Scilab Libraries for Mascot • CelestLab • CatLab • Specific small bodies : complex shapes • Handling of polyhedrons • Ray tracing • Forces • MascotLab • Specific Mascot • Plots • Files generation

29. 29www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Scilab Application for Mascot AMS allows for all applications: • Edit: • Input data • Results • Code (if needed) • Run the application • Save • Input data • Results • Plots • Code (if modified) • Load previous simulations • Import data with CL_path • …

30. 30www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Scilab Application for Mascot • Input data file is edited with Scinotes • Files are saved as data files: xxx.scd • But it is scilab code

31. 31www.esi-group.com Copyright © ESI Group, 2019. All rights reserved. Conclusions • The operations of the Mascot Landing Site Selection were carried out successfully • Scilab an asset in order to: • Improve flexibility • Reduce development cost and duration • The Flight Dynamics eco system around scilab have proven to be efficient and versatile • CNES supports Scilab from early ages and for future developments: • Numerous actions for Quality improvement: • Code robustness, test coverage, bug report,… • Strategic orientation • Roadmap to share within the community