Asteroid explorer, Hayabusa2,
reporter briefing

June 25, 2019
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2,
 Results from the low altitude descent observation
operation PPTD-TM1B
 Decision on the 2nd touchdown operation
 The 2nd touchdown operation

2019/06/25

Hayabusa2 reporter briefing

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Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. Low altitude descent observation operationPPTD-TM1B results
3. Decision on the 2nd touchdown operation
4. The 2nd touchdown operation
5. Upcoming eventsReference materials

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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.

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Hayabusa2 reporter briefing

Hayabusa 2 primary specifications(Illustration: Akihiro Ikeshita)
Mass
Approx. 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.

4

LaunchDec 3, 2014

Mission flow
Earth swingby Dec 3, 2015

Ryugu arrival

MINERVA-II-1 separation

June 27, 2018

Sep 21, 2018

MASCOT
separation

March 10, 2018

Ryugu departure

Feb 22, 2019NovDec, 2019

Earth return
End of 2020

After confirming safety,
touchdown at or near crater area
to collect subsurface material.

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

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Hayabusa2 reporter briefing

5 April, 2019

completed → First touchdown5

1. Current project status & schedule overview
Current
status9– From June 11 ~ 13, the low altitude descent observation operation (PPTM-TM1B) was
performed.
– The spacecraft descended to an altitude of about 9m above the CO1 area, and observed
the surface of Ryugu.
– Preparation is now underway for the second touchdown.
2015

Schedule
overview

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2. Low altitude descent observation operation(PPTD-TM1B) results• The low altitude descent observation operation (PPTD-TM1) was performed
between June 11 13.
• Preparations were made for the descent (June 11) which began on June 12 11:40
JST (on-board time) and reached an altitude of about 35m on June 13 at 10:34 JST.
The spacecraft then hovered around this altitude.
• The descent began again at 10:43 JST and reached an altitude of 9m at 10:53 JST,after which the spacecraft began to rise (PPTD-TM1B did not separate a target
marker).
• The spacecraft returned to the home position on June 14.
• In this operation, we observed near the area CO1 and the crater generated with the
SCI.
• We also acquired data for the spacecraft operation checks at low-altitude.
2019/06/25

Hayabusa2 reporter briefing7

2. Low altitude descent observation operation(PPTD-TM1B) results
altitude

PPTD-TM1B operation

Return to home position

Home position

20km

Descent target point||
C01

Deceleration
ΔV

5km
~35m

On-board time 6/12 11:40
Ground time 6/12 11:54

Rising ΔV
22:00
22:14

6/13 10:34 10:57
6/13 10:48 11:07

time
6/14

(JST)

image credit: JAXA
2019/06/25

Hayabusa2 reporter briefing8

2. Low altitude descent observation operation(PPTD-TM1B) results
Low altitude sequence for PPTD-TM1B
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$image credit: JAXA%
2019/06/25

Hayabusa2 reporter briefing92. Low altitude descent observation operation(PPTD-TM1B) results
Image taken on June 13, 2019 during the PPTDTM1B operation. This is a composite of 28 images
taken at 7 second intervals from 10:58 JST, onboard time (upper left) to 11:01 (lower right) using
the Optical Navigation Camera – Telescopic (ONCT). The altitude is about 52m at the beginning of thecomposite and 108 at the end. The white point in theupper-left-center is the target marker. This showsdetailed images can be acquired continuously fromthe target marker to the edge of the artificial craterin the lower right of the screen.
Image creditJAXAChiba Institute of Technology, University of Tokyo, Kochi
University, Rikkyo University, Nagoya University, Meiji University, University of
Aizu and AIST)
2019/06/25

Hayabusa2 reporter briefing10

3. Decision on the 2nd touchdown• Based on the detailed study of the results from the Hayabusa2 project, JAXA/ISAS
have decided to conduct the second touchdown.
• Touchdown operation will be performed from July 9 11 (touchdown on July 11).
• The back-up week for the touchdown operation will be the week of July 22 (Note 1).
• Judgement considerations for touchdown:Ø High scientific value of a subsurface sample collection
Ø Confirmation of the feasibility of a sufficiently safe touchdown operation by the spacecraft inits current condition.
Ø Confirmation that there is no hindrance to subsequent operations even if the amount of lightreceived by the optical system is further reduced during the second touchdown.

Note 1 The temperature conditions on the asteroid were investigated in detail, particularly at the touchdown
point. It was determined that touchdown was possible for solar distances more than 1au (about 150
million km) → touchdown is possible until the end of July.

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Hayabusa2 reporter briefing11

3. Decision on the 2nd touchdown
Project judgement for whether to perform the second touchdown operation

Scientificandengineeringvalue

Operation
feasibility

Spacecraft
status2019/06/25

Judgement items

Current status

JudgedIs there a high probability in collecting artificial craterejecta?

For sites is close to the artificial crater, it is very likely
ejecta is on the surface.

Is the scientific value high enough?

Subsurface collection, multiple collection andincreased collected volume are all very valuable.

Is the engineering value high enough?

There is high engineering significance indemonstrating the world’s first multi-sampling andsubsurface sampling.



Do we have the terrain information needed fortouchdown?

Terrain information necessary for touchdown was
obtained from PPTD-TM1 and PPTD-TM1A.



Proximity of the target marker to the touchdown
target point.

Target marker landed 3m from the center of C01-C.



Can we design a sufficiently safe touchdown
sequence?

Confirm that a sufficiently safe touchdown sequencecan be designed Is there any problem with the optical system where
the amount of light received has decreased due to dustin the first touchdown?

Confirm that the reduction in received light in the
optical system does not affect touchdown operation Hayabusa2 reporter briefingUpdate from last press briefing (6/11)

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4. The 2nd touchdown operation• 2nd touchdown operation July 911
• Touchdown date: July 11around 11 JST• Touchdown locationC01-Cbtarget marker drop area We refer to this as the ”2nd touchdown” but the operation is denoted PPTD.

2019/06/25

Hayabusa2 reporter briefing

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4. The 2nd touchdown operation
PPTD-TM1 image

PPTD-TM1B image

TM
H=140cmm
2.6

C01-CbRadius 3.5m

Styx boulder
H=55cmRock
mass
H=65cm

C01-Cbcenter

H=39cmTM

H is the highest
estimatedheight value(worstscenario)

Small
H=44cm Styx Boulder names are nicknames, not official names
image creditJAXAUniversity of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.)

2019/06/25

Hayabusa2 reporter briefing

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4. The 2nd touchdown operation
C01-Cb area

C01-Cb

C01-CbTM

TM

Ar

Artificial crater

t

al

i
ific

er
t
a
cr

DEM Digital Elevation Map near the touchdown candidate pointimage creditJAXA
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Hayabusa2 reporter briefing15

4. The 2nd touchdown operation
New

Images taken with the ONC-T while rising during PPTD-TM1A

1m

2019/05/30 11:26 JST (onboard timeAltitude: 71 72m
2019/06/25

Image creditJAXAChiba Institute of Technology, Universityof Tokyo, Kochi University, Rikkyo University, Nagoya University,
Meiji University, University of Aizu, AIST

Hayabusa2 reporter briefing16

4. The 2nd touchdown operation
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4. The 2nd touchdown operation
Low altitude sequenceTM capture with GCPNAV guidance system.
Vertically descent
while tracking TM.

30m

Mid-descent towards 8.5m,
altitude control switched to LRF.
TM relative
horizontal motion.
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   %$ " checkpoints for autonomous judgements as to whether Hayabusa2 continues to the next sequence.

2019/06/25

Hayabusa2 reporter briefing0mimage creditJAXA
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4. The 2nd touchdown operation
Changes from the 1st touchdown sequence•

To counter the cloudiness of the optical system at the base of the spacecraft, the altitudes to begin
tracking the TM and using LRF were set lower than in TD1.
̶•The safety design either maintains or strengthens the level of TD1. As a result, the sampling achievement
probability is slightly reduced.

To shorten the sequence, the spacecraft attitude will switch to tail-up immediately after reaching an
altitude of 8.5.
̶•This is streamlined based on experience from TD1. In TD1, tail-up was just before the final descent.

As the TM and landing point are very close this time, the final descent for touchdown will be a
vertical descent.
̶This improves landing accuracy. As the TM was further away during TD1, the final descent had to bediagonally downwards.

For other touchdown sequence design highlights, please refer to press briefings before the
1st touchdown (February 6 & 20, 2019)http://www.hayabusa2.jaxa.jp/en/enjoy/material/

2019/06/25

Hayabusa2 reporter briefing

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5. Upcoming events
Operation plans• July 911 2nd touchdown operation

Press & media briefings• July 9 Regular press briefing @ Tokyo office• July 11: Press Center Opened @ Sagamihara Campus

2019/06/25

Hayabusa2 reporter briefing

20Reference material

2019/06/25

Hayabusa2 reporter briefing

21

Hayabusa2 Mission Success Criteria
Mission goal

Minimum success

Full success

Extra successScience goal
Investigate the material sciencecharacteristics of C-type asteroids.
In particular, clarify the interaction
between minerals, water andorganic matter.

Provide new insights on thesurface material of C-type
asteroids by observations in thevicinity of the asteroid.

Obtain new findings on mineralwater-organic interactions from theinitial analysis of the collected
samples.

Integrate astronomical & microscale
information to create new scientificresults regarding materials for Earth,sea and life.

Science goal
Investigate the formation processof asteroids by direct exploration of
the asteroid’s reaccumulation
process, internal structure andsubsurface material.

Provide insights on the internal
structure of the asteroid byobservations in the vicinity of
the asteroid.

Obtain new knowledge on thePresent scientific results on asteroidinternal structure and subsurface
formation based on new findings
material of the asteroid byregarding the collision destruction &observing the phenomena caused byreaccumulation process.
collisions with an impacting body.
New scientific results from the
exploration robots on the surface
environment of asteroids.

Engineering goal
Improve robustness, accuracy andoperability of the new technology
implemented in Hayabusa, andmature it as a technology.

Rendezvous with a target orbit
Drop the exploration robot to theusing ion engines for deep spaceasteroid surface.
propulsion.
Take a sample of the asteroid
surface.
Collect the re-entry capsule on
Earth.

Engineering goal
Demonstrate impact object
colliding with a celestial body.

Construct a system to allow animpact device to collide withthe target object and performthat collision with the asteroid.

2019/06/25

Make the impact device collide in a
specified area.

Hayabusa2 reporter briefing

Achieved
Awaiting
achievement
confirmation

N/A

Collect a sample of asteroid
subsurface material exposed during
the collision.

Currentaim
22

Engineering value• Multi-sampling (sampling from multiple points on one celestial body) andsubsurface sampling (collection of artificial crater ejecta) are challenges
that humanity has not yet achieved. It is a technology that candramatically increases the freedom of space exploration.
• The main technologies related to sample return (electric propulsion
navigation, optical navigation, sampling, re-entry) were achieved by
Hayabusa, but multi-sampling and subsurface sampling are unexploredtechnologies that were planned with Hayabusa2, along with artificial
crater generation.
• Multi-sampling is an operation that requires comprehensive reliability andtechnology accumulation, including hardware and software reliability forthe spacecraft and operation technology (human skill).
2019/06/25

Hayabusa2 reporter briefing

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Science value• The second planned touchdown point (C01-C) is close to the SCI crater and there is a high possibility that
subsurface material excavated by the crater has been deposited on the surface.
• Subsurface material is a valuable sample as through comparison with the first surface sample collected, it canbe used to evaluate the impact of the solar wind and cosmic ray generation on the asteroid surface.
• If degeneration is weak, information regarding the formation period of the Solar System should be can beacquired in detail. Subsurface materials are particularly valuable for sensitive organics.
• The mixing process and its timescale on the asteroid surface can be constrained.
• The extend of regional heterogeneity of celestial bodies can be clarified from the comparison of multiple point
samples.
• OSIRIS-REx excels at sample volume, but only from a single point. If Hayabusa2 can obtain samples frommultiple points, it will be an qualitatively unmatched outcome.
• This can be expected to be a valuable sample that will be the key to directly connected Hayabusa2 science(remote observation, collision experiment, returned sample analysis).
• Collecting several samples successfully will prove that the sampling operation of Hayabusa2 has been
established with high reliability.

by Sei’ichro Watanabe

2019/06/25

Hayabusa2 reporter briefing24Ejecta from the SCI near C01
30m
20m

C01-C



• Ejecta from the SCI crater (darker colors than
the surface) is distributed all over the PPTD
candidate site, C01-C.
• The average thickness of the ejecta in C01-C
is estimated at about 1cm, based on the spatial
distribution of the darkening. C• The C01-C ejecta is thought to be a mix of
excavated material from depths of 0m to about
1m.  Layers of several 10s cm or more are
predicted from space weathering, solar heating andcosmic rays.

Change in reflectance before and after SCI impact
CRA1 → CRA2Contrast emphasized. Black
areas darkened after collision
2019/06/25

by Seiji Sugita 

Terrain created by adjusting lighting conditions in the ONC image.

(JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya
University, Chiba Institute of Technology, Meiji University, University of Aizu,
AIST)
25
Hayabusa2 reporter briefing

SCI crater observation by NIRS3
reflectivity

New
Outside crater

Inside crater

Relative reflectancenormalised at awavelength of 2.0µm

NIRS3 reflection spectrum inside and outside the SCI crater(data from TM1A) image creditJAXAUniversity of Aizucredit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya
NIRS3 footprintPPTD-TM1A)

University, Chiba Institute of Technology, Meiji University, University of Aizu,
AIST)• Part of the SCI crater was successfully observed at high resolution during the PPTD-TM1A/B operations.
• Similar to with the ONC, the reflectivity of the crater tends to be lower than the surroundings.
• No significant difference in the characteristics of the 2.7µm absorption, which indicates the presence of hydrated
minerals, inside and outside the crater.
by Kohei Kitazato)
2019/06/25

Hayabusa2 reporter briefing

26

Expectation for the second touchdown frommaterial analysis science Reveal the cause of the “black substance” characteristic of Ryugu•
The reflectance of the Ryugu surface is lower than that of any known meteorite and various possibilities have been
speculated as to its origin (organic carbon composition, iron sulphide / iron oxide composition, modification by heatand space weathering, particle size etc). The fact that the reflectivity is lower in the artificial crater than at thesurface suggests that the black material may be a component before being subjected to surface modification, or it
may be a product of the SCI collision experiment. Chemical analysis of a second sample is essential to clarify thecause.
 High quantity of (possibly) organic chemical information•
Amino acids, carboxylic acids, hydrocarbons, nucelobases etc, are hardly detected (reported in the 80-90s) in
carbonaceous meteorites that that undergone heating (similar in spectrum to the surface material of Ryugu). This isin addition to thermal decomposition and carbonization of insoluble high molecular weight organic compounds.
Therefore, if a weakly modified sample can be collected during a second touchdown, the type and quantity oforganic molecules obtained will increase, and the acquisition of clues to clarify the origin of the Solar System andlife will be overwhelmingly improved.
•
From the surface sample collecting in the first touchdown, we may discover new kinds of organic molecules that canbe synthesized (not only decomposed) by solar heating and space weathering. Analysis of a subsurface sample will
be very important as a comparison to understand the formation process.
•During observations, organic matter has not been identified. For Hayabusa2, sample analysis is the only means oforganic matter characterization.

by Hikaru Yubata

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Hayabusa2 reporter briefing

27

Touchdown candidate sites
L14 area
L14-C

L14-A
L14-B

C01 area
C01 area
C01-C

L14 area

C01-A
C01-B

S01 area

Near SCI
collision L12-A2
point

L12-A4

L12-D

L12-A3
L12-A1

S01 area(image credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya
University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST)

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Hayabusa2 reporter briefing28