Mars Entry, Descent, and Landing
by Small THz Spacecraft
via Membrane Aeroshell
A. Wachi (wachi@space.t.u-tokyo.ac.jp)
R. Takahashi. R. Sakagami, Y. Koshiro,
Y. Kasai, S. Nakasuka

1dnourgkcBa
1#Micro Deep Space Explorers

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Nano/Microsatellite Launch History andProjection (1-50 kg)

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PROCYON (Univ. of Tokyo & JAXA)• Worldʼs first deep micro space probe• Successfully demonstrated micro-spacecraft
bus system for deep space exploration• 65kg, 50cm cube

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MarCO (NASA/JPL)• Two 6U CubeSats which are planned to be launched torelay communication between InSight and Earth© NASA/JPL

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SLS-EM1 mission
Orion and 13 CubeSats will be launched at the same time.

©NASA©Lockheed Martin

©NASA

©NASA

©NASA

©JAXA

©NASA

©NASA

©NASA

©Argotec

3 additional CubeSats are TBD
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6rgkcBadnou#2Mars Entry, Descent, and Landing

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What is your memorable Mars EDL mission?

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3839 kg

890 kg©ESA© NASA4332 kg
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2328 kg9

Launch mass of conventional Mars EDL
missions has been large.
If we reduce the launch mass, many scientists
could launch their own Mars landers

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Olasoporp
urMicrosatellites

Mars EDLLower the threshold of Mars EDL
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11Univ. of Tokyo

National Institute of Information
and Communication Technology

Micro Satellites

Scientific Instrument

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Small Satellites in University of Tokyo and Automation Challenges

12Small Sats of Univ. of Tokyo• World’s first CubeSat
XI-IV, XI-V • 10cm cube, 1kg• World’s first micro deep space explorer
PROCYON • 50cm cube, 65kg
• Planned to be launched by SLS in 2019
EQUULEUS • 6U (10cm x 20cm x 30cm), 14kg

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Geoscience of NICT
NICT possesses strong heritage on THz sensing.
© NICT© NICTEarth THz observation from ISS

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Jupiter or Europa observation
via THz sensor on JUICEAIAA Space Forum and Exposition

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Then, what kind of Mars landing mission
will we do via a micro satellite?

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Background
Observation by Herschel Space
Observatory via Terahertz (THz)wave suggests the large amount ofoxygen near the Mars surface.
This observation contradicts the conventional theory(Chemical transport model)
Is there any source which generates oxygen near theMars surface?

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Scientific objective
Observe the profile of molecules against heightusing THz receiver equipped with a Mars lander

CO2O2O2OH
THz waveTHz sensor

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Premise & Assumption• Our Mars lander will be launched as asecondary payload of a Mars lander or orbiter→ The launch mass should be less than 150 kg• Scientific device mass is quite small (< 10kg)

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Our Mars Landing Project• Our Mars EDL system consists of only two components• Membrane aeroshell (inflatable structure)• Vented airbag
Lander bus system or• Launch mass: < 80 kg
scientific instrument

Membraneaeroshell

3.5 mMembrane aeroshell
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VentedAirbag

Landing phase

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Our Mars EDL approach

No heat shield
No parachuteNo powered descent
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20Mars Entry via Membrane Aeroshell
Conventional heat shield

Membrane aeroshell

Entry to the denseatmosphere at high velocity

Decelerate in the thin,upper atmosphereWe can construct light and simple Mars entry system.
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21Mars Entry via Membrane Aeroshell• Membrane aeroshell is proved to be effective for
Earth entry in EGG spacecraft released from ISS [1].

[1] http://www.isas.jaxa.jp/topics/001003.html
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22Mars DescentTerminal velocity can be obtained by:
Our landerʼs configuration

80 m

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23Mars Landing• Terminal velocity of 40m/s is too large.
• Additional mechanism for landing is needed© NASA/JPL, U. of Arizona

Thruster
2017/9/13© NASA© NASA/JPL

Non-vented
AirbagAIAA Space Forum and Exposition

Vented Airbag

Small Satellites in University of Tokyo and Automation Challenges

24Mars Landing© NASA/JPL, U. of Arizona

Non-vented
AirbagThruster••••

Robust to wind
Flight proven
Large mass
Safety review
2017/9/13© NASA© NASA/JPL•••

Robust to rocks
Large mass
Sensitive to wind

Vented Airbag•••

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Robust to rocks
Small mass
Not flight proven

Small Satellites in University of Tokyo and Automation Challenges

25Justification of our proposal

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Conclusion
1. Propose a concept of Mars landing mission
by micro-spacecraft
2. Propose a novel Mars EDL system which consistsof membrane aeroshell and vented airbag
3. Our proposal could have a potential of lowering
the threshold of Mars EDL mission

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27Thank you very much!
Akifumi Wachi (University of Tokyo)
E-mail: wachi@space.t.u-tokyo.ac.jp

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