Asteroidlanding - Scilab conference 2019 Keynote

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Copyright © ESI Group, 2019. All rights reserved.Copyright © ESI Group, 2019. All rights reserved.
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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

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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

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Contet
Content:
• Scilab for Flight Dynamics at CNES
• Mascot mission
• Scilab for Mascot

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Scilab for Flight Dynamics at CNES

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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

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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

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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 …

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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)

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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.

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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

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CelestLab: illustrations (demos)

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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
…

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Examples of AMS results

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The Mascot / Hayabusa 2 mission

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• 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

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Hayabusa 2 / Mascot

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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

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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

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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

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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….

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• 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

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MASCOT Team activities
Overview of MASCOT landing site selection process
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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

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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.

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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

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Scilab for Mascot Mission

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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

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Scilab Libraries for Mascot
• CelestLab
• CatLab
• Specific small bodies : complex shapes
• Handling of polyhedrons
• Ray tracing
• Forces
• MascotLab
• Specific Mascot
• Plots
• Files generation

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Scilab Application for Mascot
• Applications can be launched
through AMS

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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
• …

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• Input data file is edited
with Scinotes
• Files are saved as
data files: xxx.scd
• But it is scilab code

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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

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Thank you

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Asteroidlanding - Scilab conference 2019 Keynote