1. Mission and Spacecraft Design
MarcoPolo-R
Mission and Spacecraft Design
Lisa Peacocke – 19th June 2013
IPPW 2013, San Jose, USA

2. MarcoPolo-R Mission ESA Cosmic Vison M-class candidate
Aim: To return a sample from a primitive near-Earth asteroid
Currently Phase A, down-selection in Feb 2014
Target is primitive asteroid 2008 EV5
MarcoPolo-R Assessment Study and CCN
Demonstrate technical and programmatic feasibility of the mission
Achieve a cost-effective and consolidated mission design
Astrium team kicked off in February 2012
Team of 18 engineers currently working on the study 2

3. 1996 FG3 Primary and Secondary
Mission Design
Launch on Soyuz-Fregat to 2008 EV5
Launch years 2022, 2023, 2024
All outward trajectories require an Earth GAM
Mission durations years
2008 EV5 DeltaV’s relatively low
Plasma propulsion architecture becomes feasible
Reduced return velocities for Earth re-entry
Other benefits of 2008 EV5
Smaller asteroid => less surface area to map
Less extreme orbit with more consistent Sun distance
Lower mass asteroid => lower gravity environment
1996 FG3 Primary and Secondary
2008 EV5 3

4. Science Operations Operations phases give ~140 GB data
8 hours data downlink per day is feasible
ESA’s 35 m ground stations 4

5. Spacecraft Design 5

6. Spacecraft Design Mechanical Propulsion Thermal AOCS Electrical
Solar Orbiter derived structure, modifications to support plasma thrusters
Propulsion
Three Snecma PPS1350 plasma thrusters (1.5 kW) with pointing mechanisms and PPUs – SMART 1
Two Xenon tanks and a high pressure regulator – BepiColombo MTM
Aeolus derived monopropellant system with 20N thrusters and hydrazine tanks
Thermal
‘Standard’ design with heaters and MLI, detailed analysis ongoing
One panel with embedded heat pipes to aid PPU heat dissipation
AOCS
Off-the-shelf European IMU, star tracker, reaction wheels and sun sensors
Electrical
Two rotating solar array wings (7.5 m2 each) with drive mechanism – Sentinel 1 & 2
Lithium-ion battery and TerraSAR-X2-based 50V PCDU
Mars Express 1.6 m high gain antenna; MGA and LGAs with 80 W RF TWTA and deep space transponder – BepiColombo/Solar Orbiter/LISA Pathfinder
Gaia-based on-board computer with mass memory, and Solar Orbiter RIU 6

7. Spacecraft Design 7

8. Payload Accommodation
All instruments mounted on same structure panel
Facilitates integration and mutual alignment
Accommodated inside spacecraft with views through cutouts 8

9. Key Technologies Proximity GNC
Visual navigation uses Wide Angle Camera based on NPAL development and a Radar Altimeter
Simulations performed for descent/touchdown
Sample Acquisition, Transfer and Containment
Rotary brush sampling mechanism developed and tested
Touchdown damping from boom back-driven motor
Minimal forces at 10 cm/s
Earth Re-entry Capsule
Hard landing, no parachute or beacons/battery
Hayabusa-shape aeroshell 9

10. Proximity GNC/AOCS 10

11. Touchdown Dynamics 11

12. Sampling and Transfer 12

13. Sampling Mechanism Early Testing13

14. Sampling Mechanism 14

15. Earth Re-entry Capsule
Main requirements
Maximum entry velocity = 12 km/s
Maximum heat flux = 15 MW/m2
Maximum total pressure at stagnation point = 80 kPa
Fully passive, no parachute – cost and MSR demonstration
Ensure impact loads to sample are less than 800 g
No beacon or battery on board
Land at Woomera, Australia
Entry flight path angle of degrees selected
Based on entry dispersion and appropriate landing ellipse
Hayabusa aeroshape selected
Stable and meets g-load, aerothermo requirements
θc = 45 deg, RN/D = 0.5
4‑3 Dispersion at impact as a function of the FPA dispersion
Huygens aeroshape can be considered if g-load limit is relaxed to 2000 g
3 June

16. Earth Re-entry Capsule
Design Properties
Diameter = m, Mass = 45.6 kg, Centring = 28.75% D (Max ~33% D)
TPS: 56 mm ASTERM on frontshield (low density carbon phenolic, 280 kg/m3)
11 mm Norcoat Liége on backcover (low density cork phenolic, 470 kg/m3)
170 mm Aluminium foam crushable material, PU foam surrounds container
Aluminum panels with lateral stiffeners
ensure a free path for sample container, even with an impact at 20 degrees
Using a stroke efficiency factor (70%) and a safety margin (15%) the absorbing material thickness is 170 mm.
An interface material is necessary to link the TPS onto the structure and to stuff the empty joints between the Norcoat liege tiles. The silicone glue ESP495 is proposed (ExoMars material).
3 June

17. Earth Re-entry Capsule
2 rpm min spin-up
3 June

18. Earth Re-entry Capsule
Landing ellipse is 68 km along longitudinal axis
3 June

19. Conclusions Phase A study finishing at the end of July
Preliminary Requirements Review in Oct/Nov
Selection will occur in February 2014
Astrium’s mission & spacecraft design is feasible
Key technologies are well into development
Extensive unit re-use or modification
Keeps development costs to a minimum, reduces cost risk
MarcoPolo-R is a very promising M-class mission candidate
New target has simplified engineering & design significantly
Serendipitous short mission trajectories – right time for asteroid sample return 19

20. Questions? MarcoPolo-R Team:
Steve Kemble, Héloise Scheer, Jean-Marc Bouilly, Antoine Freycon, Steve Eckersley, Brian O’Sullivan, Jaime Reed, Martin Garland, Mark Watt, Marc Chapuy, Kev Tomkins, Howard Gray, Bill Bentall, Andrew Davies, Chris Chetwood, Andy Quinn, Alex Elliott, Mark Bonnar, David Agnolon, Remy Chalex, Jens Romstedt
3 June