Asteroid explorer, Hayabusa2,
reporter briefing

September 24, 2019
JAXA Hayabusa2 ProjectTopicsRegarding Hayabusa2,
Results from the target marker separation
operation
The MINERVA-II2Rover2separation
operation Rover2 (MINERVA-II2) will also be described by Tohoku
University, representing the university consortium
2019/09/24

Hayabusa2 reporter briefing

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Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. Temporary postponement of the target marker separation
3. Target marker separation operation results
4. MINERVA-II2 (Rover2) separation operation
5. Outreach
6. Reports from international conferences
7. Future plansReference
2019/09/24

Hayabusa2 reporter briefing

3Overview of Hayabusa2Objective
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 fieldin 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.

2019/09/24

Hayabusa2 reporter briefing

Hayabusa 2 primary specifications(Illustration: Akihiro Ikeshita)
MassApprox. 609 kgLaunch
3 Dec 2014MissionAsteroid 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.

4Launch
Dec 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
NovDec, 2019

completed →July 11, 2019

Impactor (SCI)

Earth return
End of 2020

Second touchdown

5 April, 2019

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

2019/08/22

Hayabusa2 reporter briefing

First touchdown
Feb 22, 20195

1. Current project status & schedule overview
Current
status9– The target marker separation operation was conducted from September 12 ~ 17. On September
17 at 01:17 and 01:24 JST, we were able to separate two target markers as scheduled.
– After target marker separation, the spacecraft ascended to image the target marker as it orbitedfrom an altitude of about 20km. We have confirmed that the imaging was successful. In thefuture, the trajectory will be analyzed.
– An operation plan for the separation of Rover2 (MINERA-II2) has been created.
2015

Scheduleoverview

123

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2. Temporary postponement of the target
marker separation

As a rehearsal for Rover2 (MINERVA-II2) separation operation, the target marker
separation operation scheduled for September 5 was postponed until September 16.
This was due to the spacecraft being in the Safe-Hold state.
 When any abnormality is detected in the spacecraft, the solar cell panel is directed towards the Sun and the level of power
generation is held constant. The spacecraft is placed into a spin (rotation) state that stabilizes the posture and only the minimum
necessary devices are operational, such as that for communication. This prioritises the spacecraft’s safety. For Hayabusa2, thespacecraft accelerates away from Ryugu to avoid a collision with the asteroid.

Reason for Safe-HoldAn abnormal reading was detected during the testing of the spare reaction wheel.
 Hayabusa2 is equipped with four reaction wheels for attitude control, and usually three of them areused. The remaining wheel is a reserve.
On August 29, an operation test for the reserved reaction wheel was scheduled before the return toEarth. An abnormal value (increased torque) was detected, so the spacecraft autonomously entered
the Safe-Hold state. The cause of the increased torque is currently being investigated.
Entering the Safe-Hold state indicates that the functions designed to keep the spacecraft safe areoperating normally.
2019/09/24

Hayabusa2 reporter briefing7

3. Target marker separation operation results

Overview of target marker separation operation• After separating the two target markers (TM), the spacecraft rose to an altitude of 20km.
• The trajectory of the TMs descending while orbiting was optically observed at an altitude of 20kmwith the camera on the spacecraft.
altitudeObservation with sun behind HP Box-A return

HP:20 [km]Slow descent

Descent speed
020cm/s

Separation altitude
1km

ONC-T,W1 ONC-T,W1

2 TM separation
Separation interval is about 5 minutes(equatorial and polar directions)Image creditJAXA
2019/09/24

    
Hayabusa2 reporter briefing Time (JST)83. Target marker separation operation results
Target marker E separation

separation time2019/9/17 01:17 JST

Target marker C separation

separation time2019/9/17 01:24 JST

Separation at an altitude of about 1 km. Continuous image sequence (for about 1 minute) captured every 4 seconds. Images taken while thespacecraft is ascending at 11cm/s. Target markers separated at about 12 cm/s in the horizontal distraction (approximate direction of separation
is indicated by the red arrow). Although the descent speed is almost zero, the target marker appears to get smaller as the spacecraft is rising.
creditJAXAChiba Institute of TechnologyUniversity of TokyoKochi UniversityRikkyo University, Nagoya University, Meiji University, University of Aizu, AIST. 

2019/09/24

Hayabusa2 reporter briefing

93. Target marker separation operation results
Target marker C separation
separation time2019/9/17 01:24 JST

animation

Target marker E separation
separation time2019/9/17 01:17 JST

Animation of the target markers taken from the spacecraft. Images captured at 4s intervals. In the first image, the distanceto the target marker is about 1m, and in the final image is is about 9m (the target marker is not dropping, but thespacecraft moves away from the target marker.)creditJAXAChiba Institute of TechnologyUniversity of TokyoKochi UniversityRikkyo University, Nagoya University, Meiji University, University of Aizu, AIST. 

2019/09/24

Hayabusa2 reporter briefing

104MINERVA-II2 (Rover2) separation operation•••

At the press briefing on 2018/11/8, Tohoku University announced the status of the MINERVA-II2: “Study with
JAXA to acquire meaningful results”.
Study meetings were held involving the Hayabusa2 Project, Tohoku University, Kyushu Institute of Technology
and Colorado University, USA.
Consortium plan
“Landing on the asteroid surface: Acquire useful scientific results while descending to the surface of the asteroid”– Expected outcomes
Scientific results Contribution to higher accuracy estimations of Ryugu’s gravitational field.
Engineering results Separation and landing of a small space probe from high altitude, flight trajectory
analysis.
– Operation plan in agreement with Tohoku University• Separate Rover2 at high altitude (~1km) in an equatorial orbit.
• From information from Tohoku University, the separation device will give a separation speed between
13 cm/s ~ 17 cm/s.
• The separation sequence has been assembled under these conditions, and the separated Rover2 will betracked as much as possible through optical observations by Hayabusa2

2019/09/24

Hayabusa2 reporter briefing

114MINERVA-II2 (Rover2) separation operation
HP return
HP:20 [km]Slow descent

Observation
altitude810km
ONC-T,W1

separation
1km

ONC-T,W1

Rover2
separation

Towards equator

9/28
9:00JST
2019/09/24

10/3
0:00~2:00JST
Hayabusa2 reporter briefing

By 10/8

Time

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5. OutreachExchange of opinions meeting on outreach and educational
activities with Hayabusa2 Part 2.
Held on August 25 at the Sagamihara City Museum. About 30people outside the project participated.
Various opinions were exchanged regarding data released fromthe project and future activities.
The next meeting will be held on September 29 at the Osaka
City Science Museum.

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Hayabusa2 reporter briefing13

5. Outreach Hayabusa2 Talk Live Extra Sagamihara City Museum8/2514:00 ← Finished ~170 participants
 Osaka City Science Museum 9/2817:30 ← First event outside Sagamihara City Museum
http://www.sci-museum.jp/
Itami City Children’s Science Museum 9/2914:30
http://business4.plala.or.jp/kodomo/ Hayabusa2 Talk Live Season 2 The second series of Talk Live will be held from January to October 2020 during theReturn to Earth Phase.  The first series was 14 talks that ran from February 2016 toApril 2016, held at the Sagamihara City Museum)
NationwideLooking for venues
 Details (Japanese) http://www.hayabusa2.jaxa.jp/topics/20190807_TalkLive/2019/09/24

Hayabusa2 reporter briefing

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6. International conference reportEPSC-DPS Joint Meeting 2019

• EPSCEuropean Planetary Science Congress
• DPSAAS Division for Planetary Science• Sept. 15-20, 2019, Geneva International Convention Center• Hayabusa2 and OSIRIS-REx joint session was held on September 17 (16 oral presentations related toHayabusa2)• A press briefing for Hayabusa2 was held on September 17. About 10 people from the media participated.
The large venue
where theHayabusa2
presentations wereheld (Hayabusa2Projectphotograph)

2019/09/24

Hayabusa2 reporter briefing

Press briefing(Hayabusa2Project
photograph)157. Future plans
Operation schedule
9/28Sat. 9:00 Begin descent for Rover2 separation
10/3Thurs. 0:002:00 Rover2 separation
Separation status will be announced on the Hayabusa2 official twitter:@haya2_jaxa/@haya2e_jaxa
Press briefing
10/2Wed. 14:00 Regular press briefing @ Sagamihara Campus
Study results from the MASCOT team, with simultaneous interpretation
Late OctoberTBD Regular press briefing @ Tokyo office

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Hayabusa2 reporter briefing

16Reference

2019/09/24

Hayabusa2 reporter briefing

17Hayabusa2 reaction wheels

The reaction wheel is a device used to control the attitude of satellites andspacecraft. It contains a metal disk that rotates at high speed.
As an example, imaging playing with a toy spinning top. As it spins in the air,the top always faces the same direction. A reaction wheel takes advantage ofthis property so that if the disk is kept rotating in the spacecraft, thespacecraft will continue to point in the same direction. Furthermore,
accelerating or decelerating the disk results in the spacecraft rotating orstopping due to the reaction force. This allows the spacecraft to take thedesired attitude.

   

Hayabusa2 reaction wheels  

CG image of Hayabusa2 (left) and schematic diagram of reaction wheel layout (right). The spare reaction wheel that wastested this time is located in red on the right figure.
Video about the reaction wheels (JP): https://fanfun.jaxa.jp/c/jaxaclub/cgi-bin/index3857.html?MODE=NEWS_DETAIL&ID=821
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Target marker• Body (ball) size: about 10cm diameter• Retroreflective film on the surface• 4 bar rolling prevention• Many polyimide small balls inside• Separation orderB→A→E→C→D• 2018/10/25: B dropped• 2019/05/30: A dropped• 2019/09/17 E and C dropped
2019/09/24

Hayabusa2 reporter briefing

ABCDE

Image creditJAXA
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