Asteroid explorer, Hayabusa2,reporter briefing

February 20, 2020
JAXA Hayabusa2 ProjectTopicsRegarding Hayabusa2,
Current operation status
Ion engine operation results

2020/2/20

Hayabusa2 reporter briefing

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Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. Ion engine operation results
3. Outreach
4. Future plans

2020/2/20

Hayabusa2 reporter briefing

3Overview of Hayabusa2
Objective
We will explore and sample the C-type asteroid Ryugu, which is a more primitive type than the S-type asteroid
Itokawa that Hayabusa explored, and elucidate interactions between minerals, water, and organic matter in theprimitive solar system. By doing so, we will learn about the origin and evolution of Earth, the oceans, and life, andmaintain and develop the technologies for deep-space return exploration (as demonstrated with Hayabusa), a field
in which Japan leads the world.
Expected results and effects
By exploring a C-type asteroid, which is rich in water and organic materials, we will clarify interactions between
the building blocks of Earth and the evolution of its oceans and life, thereby developing solar system science.
 Japan will further its worldwide lead in this field by taking on the new challenge of obtaining samples from acrater produced by an impacting device.
We will establish stable technologies for return exploration of solar-system bodies.
Features:World’s first sample return mission to a C-type asteroid.
World’s first attempt at a rendezvous with an asteroid and performance of observation before and after projectile
impact from an impactor.
Comparison with results from Hayabusa will allow deeper understanding of the distribution, origins, andevolution of materials in the solar system.
International positioningJapan is a leader in the field of primitive body exploration, and visiting a type-C asteroid marks a newaccomplishment.
This mission builds on the originality and successes of the Hayabusa mission. In addition to developing planetaryscience and solar system exploration technologies in Japan, this mission develops new frontiers in exploration ofprimitive heavenly bodies.
NASA too is conducting an asteroid sample return mission, OSIRIS-REx (launch: 2016; asteroid arrival: 2018;
Earth return: 2023). We will exchange samples and otherwise promote scientific exchange, and expect further
scientific findings through comparison and investigation of the results from both missions.

2020/2/20

Hayabusa2 reporter briefing

Hayabusa 2 primary specifications(Illustration: Akihiro Ikeshita)
MassApprox. 609 kg
Launch3 Dec 2014
MissionAsteroid return
Arrival27 June 2018
Earth return2020
Stay at asteroid Approx. 18 months
Target body
Near-Earth asteroid Ryugu
Primary instruments
Sampling mechanism, re-entry capsule, optical cameras, laser
range-finder, scientific observation equipment (near-infrared,thermal infrared), impactor, miniature rovers.

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LaunchDec 3, 2014

Mission flow
Ryugu arrival

Earth swing-by
Dec 3, 2015

MINERVA-II-1 separation

June 27, 2018

Sep 21, 2018

MASCOT
separation
Oct 3, 2018

Ryugu
departure
Earth return
End of 2020

Nov 13, 2019

MINERVA-II2
separation
Oct. 3, 2019

(image credit: illustrations including spacecraft by Akihiro Ikeshita, others by JAXA)

2020/2/20

Secondtouchdown

Impactor (SCI)
5 April, 2019

July 11, 2019

Hayabusa2 reporter briefing

First touchdown
Feb 22, 20195

1. Current project status & schedule overview
Currentstatus8Schedule
overview
Event– The ion engines began operation on December 3, 2019 and were temporarily stopped onFebruary 5 to allow for the determination of a precise orbit. Based on the results, a minor
modification to the ion engine injection was made from Feb. 18 to today (February 20)
and the first phase of the ion engine operation in the return phase was completed.
– Journal papers have been written and submitted by the science team.
2015
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2. Ion engine operation results
After departing from Ryugu on November 13 last year and a trial run of the ion
engines, the first phase of the ion engine operation for the Earth return wasimplemented.
After February 5, the ion engines were shut-off to implement a precise trajectory
estimation. After this, a trim operation was performed between February 18 – 20 andthe ion engines were stopped today at 8:01 JST. This completed the first-stage ion
engine operation.
 Navigation time powered by ion engines is 7396 hours (return: 881 hours). The speed
increase on the return trip is about 100 m/s. Remaining Xenon is a little less than 60%.
Details of the trail run will be described separately.
2020/2/20

Hayabusa2 reporter briefing7

2. Ion engine operation results

Ion engine operation history after leaving Ryugu (2019.11.20 – 2020.2.20)

Average generated thrust (mN)

11/13
Good-bye Ryugu

2020/2/20

Commissioning
11/20~28

1st return phase
IES operation 12/3~2/3

3 engine operation

Commissioning Orbit determination
2/4
trim operation

2 engine 1 engineDecrease in number due to increase in solar distance

Hayabusa2 reporter briefing82Ion engine operation results•

Total impulse, Ns

250000200000Spacecraft calculated value of total impulse
ITR-A
ITR-B
ITR-C
ITR-D

150000cumulative
operation time, hour•

As of Feb. 20, 2020, 27kg of Xenon propellent have been
consumed. 39 kg remain.
Cumulative operation times:
A: 6638 h, B: 33 h, C: 6024 h, D: 7106 h,IES (powered navigation) : 7396 h
Plasma ignition - extinguishing cycle
A: 84 times, B: 5 times, C: 77 times, D: 99 times, IES: 114 times

10000050000

On/Off Cycles•

Cumulative operation time and on-off cycle history

8000
IES
7000
ITR-A
6000
5000
ITR-B
4000
ITR-C
3000
ITR-D
2000
1000
0Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul
2014201520152016201620172017201820182019201920202020
120
100
80
60
400

Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul
20152015 20162016 20172017 20182018 20192019 20202020

2020/2/20

ABCumulativeC
operation time (h)
D
IES
A
B
Total impulse
C(MNs)DIES
A
B
Maximum thrust
C(mN)
DIES

IES
ITR-A
ITR-B
ITR-C
ITR-D

 Hayabusa2 Hayabusa
6638
733
12809
6024
11989
7106
14830
7348
25590
19753
39635
0.22580.00010.00090.32210.20400.26390.24470.36130.67380.9474
10.03
7.42
9.90
8.36
10.16
8.30
10.16
7.95
29.67
24.12

 Including operation tests. “IES” refers to one or more engines.
 Hayabusa data for the entire mission.

200Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul
2014201520152016201620172017201820182019201920202020

  Hayabusa2 reporter briefing

9Details of trial run
1.

Operation check of all combinations of ion engines
A,C,D 3 ACDs 2 each for AC/AD/CD 1 for A/C/D•
After a long pause, operation check of all thrusters
and combinations.

 2. Ion engine operation results
ABC

D

2.

Performance check on back-up ion engine B•Confirm that ion engine B functions as a back-up during the most critical second
stage ion engine operation.

3.

Confirmation of automatic control of ion engine gimbal (controls the thrust axis withrespect to the center of gravity).
•The handling and confirmation of the position of the center of gravity has changed
during the near-asteroid operations.

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Hayabusa2 reporter briefing10

2. Ion engine operation results

1. Operation check for all combinations of ion engines A, C, D (2019.11.2028)
Concern• Given the potential exposure to regolith during touchdown, can a high voltage be applied
properly to accelerate the ion beans after no use for a year and a half?
• Are operations successful with all engines in use?

2. Performance check of back-up ion engine B (2020.2.34)

Concern• Not used since check in 2014. The total operation time has been about 11 hours. Does theplasma still ignite? Is ion beam acceleration possible?

3. Confirmation of automatic control of ion engine gimble (control of thrust axis
relative to the center of gravity).
Concern• The location of the spacecraft’s center of gravity changed during the near-asteroid operations.
Can the gimbal still respond?

Everything is OK. The Earth return operation will be performed with all four
available ion engines.

2020/2/20

Hayabusa2 reporter briefing11

2. Ion engine operation results
Explanation for “automatic control of ion engine gimble”:
RW-C/D
RW-A

RW-B

Generatedtorque

The ion engine has a gimble that can be tilted on two axes, allowing
control of the thrust axis so that it always passes through the center ofgravity.
Additionally, torque can be intentionally generated by shifting the thrust
axis from the center of gravity and automatically keeping the number ofrevolutions of the reaction wheels constant (IES unloading function).
This feature eliminates the need to unload the two reaction wheels via
chemical propulsion during the ion engine operation, contributing to fuelpreservation.

Thrust axis

Ion engine gimble (2 axes)

Each reaction
wheel speed

Thrust axis control begin

target :3000 rev.

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Hayabusa2 reporter briefing12

3. Outreach
Hayabusa2 Talk Live Season 2(Project members give talks on
Hayabusa2)

The prefectures where Talk Live was/will be held• Period 2020/19• Currently 27 locations 17prefectures(Language: Japanese)  2020/2/20

Hayabusa2 reporter briefing

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4. Future plans Operation schedule2020 / 5 Phase 2 for the ion engine operation (planned)
Press briefings
2020/4 TBD)

2020/2/20

Press conference @ Tokyo Office

Hayabusa2 reporter briefing

14Reference material

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Hayabusa2 reporter briefing

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Return cruise operation plan
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2020/2/20

Hayabusa2 reporter briefing��� ��������������������H������������� ����������
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Electric propulsion (ion engine)• Name: µ10• Converts xenon* into plasma (ions), which is accelerated by applying voltage.
• A microwave discharge system is used to generate ions.
• Four units are mounted, and simultaneous operation of three generates thrusts of up to 28 mN.
• Approximately 60 kg of loaded xenon fuel, allowing acceleration up to 2 km/s.
• It is used to alter trajectories when cruising from Earth to the asteroid and back.

Injection test  a flight model ina vacuum chamber*Why we use xenon• Xenon is a monoatomic molecule, so its ionization voltage is smaller than that of gasses
comprising two or more atoms. This increases the ratio of added energy that is used foracceleration.
• Reactivity is lower than that of other substances.
• Mass (atomic weight) is large, improving the efficiency of acceleration.
Hayabusa 2 ion engine

2020/2/20

Hayabusa2 reporter briefing(© JAXA)
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Referencehow the ion engines work

Fig: Schematic diagram of microwave discharge type ion engine  
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ReferenceSpin-off ion engine technology
Applying the ion engine technology of Hayabusa2 asteroid explorer tothe development of the “microwave plasma discharge treatment system”(© JAXA)

Regardless of the type of business, the generation of static electricity at amanufacturing site that requires a high vacuum environment has an adverse
effect on product manufacturing. (For example, when manufacturing highend film material such as OLEDs or a high barrier film, an electrostatic
discharge can be generated on the film and lower the manufacturing yield).
Attachment of charged dust to a spacecraft from the asteroid or lunar
surface also has an adverse effect (e.g. camera lens dirt).
By applying the neutralizer technology developed for Hayabusa2, wedeveloped a device that can eliminate static electricity even in a high vacuum
environment through plasma emission. With manufacturer Kasuga Electric,
we commercialised this with domestic parts in FY2019. (The main feature isa large amount of static electricity can be removed without breaking the highvacuum environment).
For inquires, please refer to the JAXA press release: http://www.jaxa.jp/press/2019/10/20191008a_j.html
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Hayabusa2 reporter briefing

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2019/11/13 Commemorative photo of Ryugu departure

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Hayabusa2 reporter briefing

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