The Rover Concept for the ESA ExoMars Mission

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The Rover Concept for the ESA ExoMars Mission
G. Gianfiglio, M. van Winnendael, J. Vago, P.
Baglioni (European Space Agency) F. Ravera
(Alcatel Alenia Space Italia) L. Waugh - EADS
Astrium Ltd (UK)

• IEEE-ICRA 2007 workshop on Space Robotics
• Rome, 14 April 2007

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Automation and Robotics Section (TEC-MMA)
The Rover Concept for the ESA ExoMars
Mission Complementary Remarks By L. Joudrier
ESA-Robotics Section
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Forewords

• Presentation of Rover see proceedings for the
  mission details
• All material presented is subject to change due
  to the on-going and coming industrial studies.
• Additional pieces of information aiming to be
  potential seeds for discussions during this
  workshop.

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Presentation Outline

• Forewords
• ExoMars Mission
• Objectives
• Status
• Overview
• ExoMars Rover
• Current baseline
• Vehicle overview
• Payload Support Equipment
• Pasteur Payload
• Surface Operations
• RHUs Planetary Protection
• Considerations about the ExoMars Rover
• Locomotion subsystem
• Navigation
• Autonomy
• Planetary Protection

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Presentation Outline

• Forewords
• ExoMars Mission
• Objectives
• Status
• Overview
• ExoMars Rover
• Current baseline
• Vehicle overview
• Payload Support Equipment
• Pasteur Payload
• Surface Operations
• RHUs Planetary Protection
• Considerations about the ExoMars Rover
• Locomotion subsystem
• Navigation
• Autonomy
• Planetary Protection

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Mission Objectives

• ExoMars is the first ESA led robotic mission of
  the Aurora Exploration Programme, combining
  demonstration of key enabling exploration
  technologies with major scientific investigations
• Main technology demonstration objectives
• Safe Entry, Descent and Landing of a large size
  payload (Descent Module)
• Surface mobility (Rover) and access to the
  subsurface (Drill)
• Main scientific objectives
• Search for traces of past and present life and
  characterize Martian chemistry and water
  distribution
• Improve the knowledge on Martian environment and
  identify surface hazards to future human missions

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Mission Status

• Phase B1 on-going
• Started in October 2005 with AAS-I as Prime
  Contractor
• Extended to consider several options.
• Selection of Major sub-contractors is completed.
• ASTRIUM UK responsible for the rover
• Selection of sub-contractors completed soon
• SRR just completed
• Implementation Review is next (May 2007)
• Phase B1 to be completed by end of 2007
• Integrated Locomotion-Navigation Rover Prototype
• Launch date 2011 unlikely so target is 2013 with
  back up 2015/2016 launch opportunity.

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Mission Overview

• Launch a Descent Module to Mars with supporting
  spacecraft infrastructure for LEOP and Cruise
  Phase
• Baseline (Carrier DM Rover) Soyuz from
  Kourou MRO
• Option 1 additional Soyuz for a relay orbiter
  (MRO back-up)
• Option 2 Ariane5 for ExoMars carrier upgraded
  as orbiter (MRO back-up)
• Release Descent Module into Mars atmosphere for
  automatic Entry, Descent and Landing (EDL) on
  Mars surface
• Latitudes between 15º and 45º, all longitudes
  / Altitude 0 m relative to the MOLA zero level
• Option vented / non-vented airbag landing
  system
• Egress of the Rover from the landed module
• Accomplish Rover surface operations
• 180 sols minimum, 10 experiment cycles, 1km
  distance between experiment locations

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Presentation Outline

• Forewords
• ExoMars Mission
• Objectives
• Status
• Overview
• ExoMars Rover
• Current baseline
• Vehicle overview
• Payload Support Equipment
• Pasteur Payload
• Surface Operations
• RHUs Planetary Protection
• Considerations about the ExoMars Rover
• Locomotion subsystem
• Navigation
• Autonomy
• Planetary Protection

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Rover Current Baseline

• Mass 180 kg (including Drill, SPDS and 8kg
  Pasteur Payload)
• Average Power 120 W (by Solar Array assuming
  RHUs availability)
• X-band communication link for DTE and UHF band
  for Proxi-link with MRO
• Two Thermal Control solutions still under
  trade-off with and without RHUs

Concept with RHUs Concept without RHUs
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Rover Vehicle

• Navigation
• Cameras (Nav. Cam, Haz. Cams)
• Navigation sensors
• Navigation Software (CNES)
• Structure
• Integrated units
• Deployable mast for Cameras, IR Spectrometer and
  sensors
• SA support and mechanisms

• Locomotion
• 6 wheels chassis
• TTC
• X-band for DTE
• 2 redundant transponders
• 2 redundant SSPA
• 1 RFDN
• 1 Small HGA (30cm dish, 24dBi gain)
• UHF band for data relay with MRO
• Internal redundant Proximity-1 compliant
  transponder
• 1 LGA (quad helix)
• 1 RFDN
• Power
• Solar Arrays
• Battery (Rechargeable, Li-Ion)
• PCDU
• Thermal Control System (TCS)
• Two options under trade-off (with and without
  RHUs)

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Payload Support Equipment

• Sample Acquisition System To obtain surface and
  subsurface samples for analysis includes a
  subsurface drill with rod exchange and
  positioning mechanism a sample delivery
  mechanism, plus a surface rock corer (TBC)
• SPDS To prepare and present samples to all
  analytical lab instruments includes distribution
  mechanisms and a milling station

Subsurface drill includes a miniaturised IR
spectrometer for borehole investigations (Ma_Miss
DIBS)
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Rover Scientific Payload Pasteur
CONTEXT - PanCam - IR Spectrometer - Ground
Penetrating Radar - Close-up Imager -
Mössbauer - Raman-LIBS external optical
heads - Microscope IR - Raman - LIBS
Spectrometers - XRD

• The instruments development is under the
  responsibility of relevant National Agencies
• The current total mass of the Pasteur Payload
  Instruments exceeds the 8 kg allocation if
  necessary instruments de-scoping will be
  implemented in line with the available resources
  (Payload Confirmation Review)

INSTRUMENTS SUPPORT EQUIPMENT Drill
System (Surface and 2 m depth) Includes Borehole
IRS Sample Preparation Distribution System
(SPDS)
ORGANICS/LIFE - MOD/MOI - GC-MS - Life
Marker Chip
ENVIRONMENT - Dust H2O Vapour Suite - Ionising
Radiation - UV Spectrometer - Meteo Package
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Rover Surface Operations
The Surface Mission is composed of a sequence of
Experiment Cycles (up to 10)
An Experiment Cycle consists of Identifying the
location at which to perform the Measurement
Cycle (from Ground Control) Traveling to the new
location (distance about 1 km between
locations) Performing a full Measurement Cycle
using all instruments Transmitting scientific,
housekeeping and navigation data to the Relay
Orbiter/Earth (Data volume 1Gbit per Experiment
Cycle)
During night the Rover goes into a sleep mode and
resumes operations the following day
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Planetary Protection Radio-isotope Heating
Units

• RHUs Accommodation/location inside the internal
  enclosure is subject to trade-off between easy
  late access, proper heat distribution and
  interfaces with the Rover TCS
• Planetary Protection ExoMars is a class IVc
  mission allowing to search for past life and
  organic molecules in special regions. This is a
  major driver of the mission design, AIV,
  especially considering possible need of late
  access due to RHUs.
• The sterilization concept is under study.
• The PP mission class may be revised into IVb
  class (TBC).

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Presentation Outline

• Forewords
• ExoMars Mission
• Objectives
• Status
• Overview
• ExoMars Rover
• Current baseline
• Vehicle overview
• Payload Support Equipment
• Pasteur Payload
• Surface Operations
• RHUs Planetary Protection
• Considerations about the ExoMars Rover
• Locomotion subsystem
• Navigation
• Autonomy
• Planetary Protection

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Locomotion Subsystem 1/2

• ExoMars current baseline is the RCL-type E with
  formula 6644W
• ? Simple and light weight design passive
  articulated suspension
• ? No internal averaging mechanism
• ? Wheel-walking/peristaltic mode possible
  allowing highest mobility (Reuse of the motors
  necessary for deployment)
• BUT
• ? Static stability issue depending of CoG (40
  deg requirement)
• ? Eventually less performing compared to other
  concepts (Type D, Crab, R-bogie)
• Possible improvements
• Formula 6664W or 6666W

RCL Type-E
RCL Type-D
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Locomotion Subsystem 2/2

• ExoMars mobility requirements
• 25 cm step obstacle
• 25 deg slope on specific soil
• 40deg stability any direction
• Improvement of traction obstacle crossing
  capabilities
• Use of terramechanics to define optimum wheel
  design (Single Wheel Testbed built within RD
  activity Rover Chassis Evaluation Tools)
• Possible use of flexible wheels Richter ASTRA06
• Improved design of articulated suspension via
  simulation tools and prototyping.
• Optimising the mass and power requirements
  remains a challenge at the expense of the
  scientific payload and desirable higher
  locomotion capabilities.
• Locomotion risks due to unknown rough terrain
  are mitigated by high locomotion capabilities and
  (conservative) navigation.

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Navigation
Baseline is the use of the CNES Autonomous
Navigation Software. Accurate
localisation is key. Visual Odometry target
tracking are required. Solutions to definition
target coordinates on ground by PIs to be
experimented.
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Autonomy

• ExoMars will require high degree of autonomy
  Ground Control Staffing, amount of Telemetry to
  download, large distance traverses.
• At least level E3 on the ECSS E70 autonomy scale
  (event driven reactive systems with some
  re-planning).
• ESA Relevant RD Activities (non exhaustive)
• ESA Functional Reference Model (FRM) based on a
  3-layered controller architecture
  (Mission-Task-Actions) equivalent to
  deliberative-executive-functional layers.
• MUROCO Formal specification and verification
  Tool Kapellos-ASTRA06. Use ESTEREL formal
  language to specify/Verify the rover behaviour
  (state machine composing the actions and tasks).
• MMOPS On-board planning/re-planning and
  scheduling tool Woods-ASTRA06
• On-board model checking (just started) will
  allow advanced FDIR.
• 3DROV (on-going) full planetary rover simulator

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Planetary Protection

• Based on the facts that
• During AIV process, 80 of the bio-burden is
  brought by the AIV operators.
• Sterilisation kills the spores but does not
  remove the bodies that may trigger organic
  molecule sensitive sensors designed to detect
  traces of past life.
• ESA has initiated a feasibility study on
  Robotized AIV that would allow to reduce to the
  minimum the number of operators in the AIV clean
  rooms.
• Robotized AIV is very challenging activity where
  space robotics and Earth state of the art
  robotics would be joined.

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Conclusion
ExoMars mission and rover current baselines have
been briefly presented. They will evolve along
with the industry work. Some relevant ESA RD
activities about rover have been presented to
provide inputs to the discussion

• Questions ?