mission to earth―moon lagrange point by a 6u cubesat: …

Mission to Earth―Moon Lagrange Pointby a 6U CubeSat: EQUULEUS

(EQUilibriUm Lunar-Earth point 6U Spacecraft)

Ryu FunaseAssociate Professor,EQUULEUS project manager,Univ. of Tokyo

EQUULEUS Project Team(U of Tokyo, JAXA)

ISSL Intelligent Space Systems LaboratoryThe University of Tokyo

www.space.t.u-tokyo.ac.jp

Growing trend of nano/micro-satellites

2©SpaceWorksNow



University of Tokyo’s experience

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XI-IV (2003): 1kgThe first CubeSatStill operational (>14yrs)

Nano-JASMINE: 33kgfor Astrometry(space science mission)Awaiting launch…

XI-V (2005): 1kgfor tech. demo. Still operational (>12yrs)

PRISM (2009): 8kgfor remote sensing(20m GSD)Still operational (>8yrs)

Hodoyoshi-3 and 4 (2014)remote sensing (~6m GSD)



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6m GSD image taken by Hodoyoshi-4 satellite




Next frontier for small satellites is...

deep space!5



The First Interplanetary Micro-Spacecraft

PROCYON



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PROCYON(~65kg)

Hayabusa-2(~600kg)

H-IIA rocket

© JAXA © JAXA

Piggyback launch with Hayabusa2 on Dec. 3, 2014



Achievements of PROCYON• [Primary mission]Demonstration of the deep space micro-satellite busPower generation/management (>240W)

Thermal design to accommodate wide range ofSolar distance (0.9~1.5AU) and powerconsumption mode (electric prop. on/off,137W/105W)

Attitude control (3-axis, <0.01deg stability)

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SSC16-III-05 (2016)



Achievements of PROCYON• [Primary mission]Demonstration of the deep space micro-satellite bus (cont’d)communication & navigation in deep space

• Communication from ~60,000,000 km Earth distance• X-band GaN-based SSPA (Solid-State Power Amplifier)

with the world’s highest RF efficiency (>30%)

Propulsion system for micro spacecraft• RCS (8 thrusters) for attitude control/momentum

management• Ion propulsion system for trajectory control (1 axis,

Isp=1000s, thrust>300uN), ~220hr operation• Trajectory guidance, control, and navigation

experiment in deep space (<100km, 3σ)9

SSC16-III-05 (2016)



Achievements of PROCYON• [Secondary mission] Scientific observation

– Wide-view imaging observation of geocorona with Lyaimager from a vantage point outside of the Earth’s geocoronadistribution

– Imaging observation of the hydrogen emission around the“67P/Churyumov–Gerasimenko” comet (the target of ESA’sROSETTA mission) to evaluate water release rate from thecomet

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Hydrogen emission around 67P/Churyumov–Gerasimenko comet was observed on Sep. 13, 2015. This comet is the destination of the European Space Agency's Rosetta mission.

[Shinnaka et al., 2017]




What PROCYON demonstrated:

Out next challenge is…

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Possibility of deep space explorationby small satellite



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EQUULEUSThe first CubeSat to go to Lunar Lagrange point and explore the cis-lunar region



Why we started EQUULEUS?(The goal behind the EQUULEUS mission)

1. Going back to CubeSat “again” by downsizing our deep space bus– Adapt to as much as deep space

launch opportunities in the future

2. Enhance the mission capability in deep space– Not only obtaining the ”tricky” deep

space trajectory guidance, navigation, and control techniques itself,

– but also enhancing our overall capability to conduct deep space missions such as:

• astrodynamics, mission planning and analysis, s/c system design, and s/c operation

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Missions of EQUULEUS

1. [Engineering] (primary mission)demonstration of the trajectory control techniques within the Sun-Earth-Moon region by a nano-spacecraft through the flight to the Earth-Moon Lagrange point L2 (EML2)

2. [Science] Imaging observation of the Earth’s plasmasphere

3. [Science]Lunar impact flash observation

4. [Science]Measurement of dust environment in cis-lunar region


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Trajectory all the way to EML2...

Capture to EML2 libration orbit

SunDV1

DV2

DV3

Lunar flyby sequences

Insertion to EML2 libration orbit using Sun-Earth week stability regions

Earth-Moon L2 libration orbit

LGA1LGA2

LGA3

EarthMoon

EQUULEUS will perform ~6 months flight to EML2 with ∆V of as low as ~10m/s (deterministic), by using multiple lunar gravity assists.

*LGA: Lunar Gravity Assist, EML2: Earth-Moon L2 point


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Missions of EQUULEUS (2/4)1. [Engineering] (primary mission)

demonstration of the trajectory control techniques within the Sun-Earth-Moon region by a nano-spacecraft through the flight to the Earth-Moon Lagrange point L2 (EML2)


Metal thin film filter

Primary mirror (multilayer film optimized for He+(30.4nm)

Detector (MCP)

Mechanical shutter

10cm

0.5U


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3. [Science]Lunar impact flashes observation

10cm

10cm

5cm

0.5U


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3. [Science]Lunar impact flash observation

4. [Science]Measurement of dust environment in cis-lunar region

Dust impact sensors installed within spacecraft thermal blanket (MLI)


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Solar Array Paddleswith gimbal

Attitude control unit

Battery

Ultra-stable Oscillator

Transponder

Water resistojetthrusters

X-Band LGA

CDH & EPS

DELPHINUS (lunar impact flashes observation)

PHOENIX (plasmasphere observation)

Propellant (water) Tank

X-Band LGA

X-Band MGA

20cm

30cm



Technological challenge/advancement• Miniaturization of the deep space bus (e.g. deep space

communication transponder) into the CubeSat formfactor

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XTRP demonstrated in PROCYON (2014) XTRP being developed for CubeSat（EQUULEUS）

Digital Processing Module &Rx Module

Power Amplifier & XTx Module

* Miniaturization* Modularization* Reduction of RF output* Reduction of power consumption

*XTRP: X-band Transponder



Technological challenge/advancement• Miniaturization of the deep space bus (e.g. deep space

communication transponder) into the CubeSat formfactor

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XTRP demonstrated in PROCYON (2014) XTRP being developed for CubeSat（EQUULEUS）

Digital Processing Module &Rx Module

Power Amplifier & XTx Module

* Miniaturization* Modularization* Reduction of RF output* Reduction of power consumption

*XTRP: X-band Transponder

Spec. of our CubeSat X-band deep space transponderBit Rate: 15.625/125/1k [bps] (CMD)

8 ～262.144k [bps] (TLM)Dimension: 80×80×(<50) [mm], ~0.5UMass: < 500 [g]Power: <13 [W] (@Tx ON)RF output:1 [W] (+30 dBm)Navigation: RARR, DDOR



Technological challenge/advancement• Development of the new resistojet (warm gas)

propulsion system using water as the propellant.– Water is perfectly safe, non-toxic propellant, which is

advantageous when we consider piggyback launch.– (In-situ space resource utilization age in the future is also

in my mind...)

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Water tank

4 x RCS thrusters

2 x Delta-V thrusters Vaporization chamber

~2.5U


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Summary• University of Tokyo has started to challenge deep space

exploration by nano/micro satellite, based on the successful nano/micro satellites development and operation in Low Earth Orbit.

• The first deep space micro satellite “PROCYON” successfully demonstrated the deep space micro-satellite bus system in 2015.

• After that, we have proposed and started the development of a 6U CubeSat mission to Earth - Moon Lagrange point "EQUULEUS"in the summer of 2016.

• The primary mission of EQUULEUS is the trajectory control demonstration in cis-lunar region, and some scientific observation missions are also carried. These missions are enabled by downsizing the deep space bus system to fit the CubeSat standard and also by developing the new propulsion system.

• The development of the spacecraft started in the summer of 2016 and the engineering model integration and testing was completed. The flight model development will be completed by the spring of 2018, to be ready for the launch by SLS’ first flight in 2019. 27

mission to earth―moon lagrange point by a 6u cubesat: …

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