MarcoPolo-RMission and Spacecraft Design

Lisa Peacocke – 19th June 2013

IPPW 2013, San Jose, USA

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

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Astrium Satellites Ltd

Study Prime, Systems Engineering, Mission Analysis, Sample Handling,

Platform Subsystems, Payload Interface, AIV/Programmatics

Astrium ST S.A.S.Earth Re-Entry Capsule

Astrium ST GmbHLanding/Touchdown System

Astrium Satellites S.A.S.GNC for Proximity Operations

Mission Design Launch on Soyuz-Fregat to 2008 EV5

Launch years 2022, 2023, 2024 All outward trajectories require an Earth GAM Mission durations 4.5-6.5 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

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1996 FG3 Primary and Secondary

2008 EV5

30

Sun

S/C

305km altitude

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Science Operations

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Proximity Phases

Distance to surface (km)

Duration (days)

Arrival at Asteroid 500 0

Close Approach Trajectory 500 to 100 7

Transition to Far Global Characterisation Phase 100 to 10 10

Far Global Characterisation Phase (FGCP) 10 5

Transition to Radio Science (RSE) Phases 10 to 5 7

Gravitational RSE Phase 1 to 2 20

Bistatic Radar RSE Phase 1 to 5 TBC 5

Transition to Global Characterisation Phase 5 1

Global Characterisation Phase (GCP) 5 16

Selection of 5 sampling sites plus transition to LCP 5 7

Local Characterisation Phase (LCP) 0.25 15

Selection of best sampling sites + transition to sampling rehearsal 5 7

Sampling Rehearsals 5km to 100m 7

Transition to SAM Phase 5 7

Descent/Sampling (SAM) Phase 5km to surface 21

Transition to safe high orbit or FF position 10 7

Post Sampling Local Characterisation Phase (PSLCP) 0.25 3

Margin TBC 27

Preparation for return cruise TBC 7

Departure from Asteroid Far distance 1

Total

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

Spacecraft Design

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Spacecraft Design Mechanical

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

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Spacecraft Design

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Payload Accommodation All instruments mounted on same structure panel

Facilitates integration and mutual alignment Accommodated inside spacecraft with views through cutouts

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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

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Proximity GNC/AOCS

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Touchdown Dynamics

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Sampling and Transfer

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Sampling Mechanism Early Testing

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Sampling Mechanism

25mm

Container Volume

Cone Structure

Sampler ejected cover

Rotary Bristles PrimarySampling system

Sample Container

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 -10.8 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

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0

20

40

60

80

100

120

-16 -14 -12 -10 -8 -6

Nominal Flight Path Angle (deg)

Lan

din

g E

llip

se M

ajo

r A

xis

(km

)

DFPA=+/-0.4

DFPA=+/-0.2

DFPA=+/-0.1

DFPA=+/-0.08

Earth Re-entry Capsule Design Properties

Diameter = 0.880 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

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Lid TPS Lid structure (Clip door)

Front energy absorbing material

FrontShield Structure

FrontShield TPS

Rear energy absorbing material

Internal structure

Sample

BackCover structure

BackCover TPS

Container

Margin crushable thickness

Earth Re-entry Capsule 2 rpm min spin-up

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Arm Drive Mechanism

ArmSpin-up & Eject Mechanisms

Mechanicalfuses

Earth Re-entry Capsule Landing ellipse is 68 km along longitudinal axis

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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

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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

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