Asteroid explorer, Hayabusa2,
reporter briefing

March 5, 2019
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2:
Future operations objectiveResult of the touchdown operation

2019/03/05

Hayabusa2 reporter briefing

2

Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. Future operations policy
3. Result of the touchdown operation
4. Images from CAM-H
5. Science comment on the touchdown
6. Future plansReference material
2019/03/05

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

Mission Flow
Launch3 Dec 2014

Earth returnlate 2020

Sampleanalysis
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Earth swing-by
3 Dec 2015

Arrival at asteroid
June 27, 2018
Examine the asteroid
by remote sensing
observations. Next,
release a small lander
and rover and also
obtain samples fromthe surface.

Depart asteroid
Nov–Dec 2019

Releaseimpactor
Create artificial
craterAfter confirming safety,
touchdown within the craterand obtain subsurface samples
Hayabusa2 reporter briefing

Use an impactor to create an
artificial crater on the asteroid’s
surface(Illustrations: Akihiro Ikeshita)51. Current project status & schedule overview
Current
status9

Schedule
overview
Event– Touchdown operation was performed from February 20 – 22. Touchdown was successful.
– In the week beginning February 28, BOX-C observations were carried out that included
observations from an altitude of about 5km.
– In the week beginning March 4, we will conduct a survey descent operation to observe
the region around S01.
2015
12

3

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2019/03/05

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Hayabusa2 reporter briefing

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6

2. Future operation policy
Following the success of the first touchdown operation (TD1-L08E1), the future operation policy
will be as follows:• The next event is the experiment to form an artificial crater using the Small Carry-on Impactor(SCI).
• The second touchdown will be done inside or outside the artificial crater formed with the SCI.
Alternative sites at a different location will also be considered. (It will be decided after the SCI
operation whether we will actually execute the second touchdown or not.)• There is a high probability that a third touchdown will not be performed.
Reasons for prioritizing the SCI collision experiment• The first touchdown has been judged to have collected a sufficient sample.
• During the first touchdown, some of the optical sensors in the spacecraft base received a reduced
amount of light. There is no problem during normal operations, but this effect means that careful
preliminary investigation is necessary ahead of touchdown operations. As this preparation takes
time, the SCI operation will be performed first.
2019/03/05

Hayabusa2 reporter briefing7

2. Future operation policy
Future Schedule

Date & time

Operation

Event

Mar. 68

Descent operation DO-S01

Acquire information for touchdown at this new location.

Mar. 2022

Descent operationCRA1

Preliminary observations near the planned crater
formation site with the SCI.

Apr. week of 1st

SCI operation

Crater formation experiment with the SCI

Apr. week of 22nd

Descent operationCRA2

Observation of the crater created by the SCI.

After May

2nd touchdown

Sampling

After July

MINERVA-II2 separation operation

MINERVA-II2 operation

Nov.  Dec.

Depart Ryugu

End of 2020

Earth return

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Hayabusa2 reporter briefing8

2. Future operation policy
Region S01: site of the SCI operation                                  (Image creditJAXA
2019/03/05

Hayabusa2 reporter briefing

93. Results of the touchdown operation
Summary• Touchdown operation
February 20  22, 2019
Touchdown time
February 22, 2019, 07:29:10

Time is JSTonboard time• Touchdown location
L08-E1, within a circle of radius 3m
Accuracy of guidance control1m
Sample collection point also identified• Method
Pinpoint touchdown method using the
dropped TM-B.

Image captured around the touchdown point at approximately
07:30 JST (onboard time) on February 22, 2019 immediately
after touchdown. Taken with Optical Navigation Camera – Wideangle (ONC-W1), at an altitude of about 25m.
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 briefing10

3. Results of the touchdown operation
6m

6m
The planned touchdown point (circle diameter 6m)
superimposed on the image captured immediately
after touchdown. The white dot at the arrow tip isthe target marker.

For comparison, this is an image taken before touchdown.
The circle at the planned touchdown point is 6m in diameter.
X indicated the position of the target marker. The size of thespacecraft picture is on the same sclae as this image.

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 briefing11

3. Results of the touchdown operation
Touchdown point

Sampling point                          Target marker
Target marker

Green circle is the planned touchdown point. The deviationfrom the circle center to the center of the spacecraft (bluedot) is 1m (Background is from the shape model).
2019/03/05

©JAXARed circle is where the sampler horn is thought to havetouched the surface. Green circle is the planned
touchdown site. Background is a real image of Ryugu.

Hayabusa2 reporter briefing12

3. Results of the touchdown operation
Duringdescent
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Note$ Touchdown
detected by change
in attitude.

10cm/s
65cm/sValue of speed isapproximate
2019/03/05

2/21
06:00

2/21
09:00

2/21
12:00

2/21
15:00

2/21
18:00

2/21
21:00

2/22
00:00

Time#JST"onboard time$
Hayabusa2 reporter briefing

2/22
03:00

2/22
06:00

2/22
09:00

#image credit%JAXA$
13

3. Results of the touchdown operation
Low
altitude

Antenna change
HGA→LGA

TM capture with GCPNAV guidance system!$%"



Antenna change
LGA→HGA



45m



Time is JST on
February 22(onboard time) $$%#%"$

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horizontal motion
LIDAR→LRF
takeover$"
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Hover at TM relative
offset point

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Image credit JAXA

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Hayabusa2 reporter briefing

14

3. Results of the touchdown operation
Low altitude

Doppler data

Direction towards
the asteroid

Accelerated decent after LRF
began taking measurements
instead of LIDAR

Hovering at 8.5m altitude

Descending at 10cm/s

Directionaway fromthe asteroid

Twice the value ofthe line-of-sightvelocity of thespacecraft, relative tothe asteroid

Hovering at
45m altitude

Final descent

Touchdown and rise
Descent from 45m
altitude
RisingTime on horizontal axis is UTC on
the ground (February 21).

07:07
07:10:31

07:19:44

Times with underlines are the onboard time in JST

07:27:29
07:29:10
Image creditJAXA

2019/03/05

Hayabusa2 reporter briefing15

3. Results of the touchdown operation
During ascent)#'#$%' "
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 !%' $#+ '% "%!$& '' '(/&$!%$% #'' $# '(%#'$+ '' '(/%'$% #'' $# 

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 -image credit/JAXA.

2019/03/05

By suddenly reducing the speedof the spacecraft, materialcaught on the teeth at the tip of
the sampler horn is transferred
into the catcher.

dust guard

Rotating cylinder (red part inright-hand figure) was turned
to close chamber A and open
chamber B.
Hayabusa2 reporter briefing16

3. Results of the touchdown operation
About sampling
After ascending after touchdown and checking thetelemetry on the ground, it was confirmed from thestatus and temperature change of the projector thatthe projectile had been fired.
In order to float the sample that was collected in the
inverted horn tip upwards, a ΔV of -1cm/s wasapplied at 10:40.

Projector temperature sensor position

Confirm temperature rise from 07:29

To allow time for the floating sample to enter thecatcher and settle in the chamber, the rotation
mechanism of the catcher was employed 40 minutes
later at 11:20 and the lid of chamber A was closed.
The change of status confirmed that the rotation
mechanism was performed normally.
Time JST, onboard time on Feb. 22
image credit JAXA
2019/03/05

Confirm the rotation mechanism operated
normally and becomes “Done”
Hayabusa2 reporter briefing 
17

3. Results of the touchdown operation
Reason for the delay in the descent start timel On February 21 at around 07:15 JST, when the descent preparation process for the spacecraft began theGate 1 check, it was found that the position information recognized by the spacecraft differed from theassumed position.
l Therefore, we delayed the judgement of whether to begin the descent to check the situation,
confirming that the spacecraft condition was normal. It was found that this event was due to slightdifference in the operation timing of the descent guidance program.
l We adjusted the timing and confirmed that the descent sequence could operate without problems.
l Procedures such as delaying the descent start time and generating a new descent trajectory at the Gate
1 check are part of the training. The new descent plan was ready and confirmed in about 5 hours.
l Since the touchdown time had been decided, we decided to increase the descent speed. As previous
ground training had used a descent speed of about 1 m/s down to an altitude of several kilometres, thiswas no problem.

2019/03/05

Hayabusa2 reporter briefing18

3. Results of the touchdown operation
The nickname for the touchdown point:
The point of the Hayabusa2 touchdown has been
named
“Tamatebako”
This is a nickname, not an official name.
Reason• Proposed name was the most popular suggestion whenrequesting names from Project Members.
• In the story of Urashima Taro (where Ryugu takes its name),smoke emerges from the tamatebako (treasure box) which islike the ejector flying upwards at touchdown.
• Also because this is the point where the sample (= treasure of
Ryugu) was collected.
2019/03/05

Hayabusa2 reporter briefingimage creditJAXA
19

3. Results of the touchdown operation
Place names on Ryugu (updated)

Note: Tritonis (landing site for MINERVA-II1), Alice’s Wonderland (MASCOT landing site), Tamatebako (first touchdown point) are nicknames
and not recognised by the International Astronomical Union (IAU). Other places names are official names recognised by the IAU.
image creditJAXA

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Hayabusa2 reporter briefing20

4. Images from CAM-H
CAM-Hsmall monitor camera• Camera built and mounted using money fromdonations.
• Images the sampler horn
Location of CAM-H

Sampler horn

Direction andarea that CAM-H
can observe

The rocket coupling ring isalways in the upper-right of
CAM-H images as it is within
the line-of-sight.

Image creditJAXA
2019/03/05

Hayabusa2 reporter briefing21

4. Images from CAM-H

Continuous image sequence plan with CAM-H
p Hayabusa2 moves to the final descent position using
the TM, while maintaining the immediate below point
altitude of 8.5m. ⇒⇒
Before alignment

directly above TM

After alignment directly above TM
TD descent start
before alignment
TD descent start
after alignmentp At the final descent position, after changing theattitude of the spacecraft (tail up) ( in the figure), thefinal descent ⊿V (about 7cm/s downwards) is
performed, then free-fall to touchdown.
p Continuous imaging with CAM-H starts from 59s
before the final descent ⊿V.

p Automatic sequence capture at 0.2fps (85 sec) ⇒1fps(86 sec)⇒2fps (25 sec)⇒1fps (64 sec)⇒0.2fps(85 sec)
fps = frame per second

2019/03/05

Image creditJAXA

Hayabusa2 reporter briefing22

4. Images from CAM-H
Prediction of the view from continuous imaging with CAM-H at touchdown

Field of view atfinal descentpositionTarget marker

Field of view attime of TD
Image creditJAXA
2019/03/05

Hayabusa2 reporter briefing23

4. Images from CAM-H
Successful imagining before and after touchdown with CAM-H
LRF-S2 reflected lightTarget Marker
image creditJAXA
2019/03/05

Before final descent during hoveringTime2/22 07:26(Time: onborad, JST)
Altitudeapprox. 8.5m
Hayabusa2 reporter briefing

During descentTime2/22 07:28
Altitudeapprox. 4.1m
24

4. Images from CAM-H
Successful imagining before and after touchdown with CAM-H

image creditJAXA
2019/03/05

Moment of touchdownTime2/22 07:29
Altitude approx. 1.0m

(Time: onborad, JST)Hayabusa2 reporter briefing

Immediately after the rise ⊿VTime2/22 07:29
Altitude approx. 2.9m
25

4. Images from CAM-H
Successful imagining before and after touchdown with CAM-HImage creditJAXA
2019/03/05

During ascentTime2/22 07:29
Altitudeapprox. 8.0m

(Time: onborad, JST)Hayabusa2 reporter briefing

During ascentTime2/22 07:30
Altitudeapprox. 49.6m
26

4. Images from CAM-H

Successful imagining before and after touchdown with CAM-H (animation)
p Continuous imaging beganfrom 59 seconds before thefinal descent and images
were taken for 5 minutes and
40 seconds while varying theimaging frequency.
p TD moment captured at 1 fps
timing.
p Final altitude is about 117m

(Animation plays at 5x speed)Image creditJAXA
2019/03/05

Hayabusa2 reporter briefing27

4. Images from CAM-H
ReferenceRyugu-simulant target and the projectile in the experiment to simulate the results of the
projectile firing. From the projectile firing experiment carried out on December 28, 2018

Fired projectile

Simulated Ryugu gravel target
after the projectile fired.
Simulated Ryugu gravel iscreated at the Universityof Tokyo & TeNQ
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Examples of the Ryugu simulated gravel after fragmentationby the projectile.

Is the shape similar
to gravel on thesurface of Ryugu?

Image creditJAXAUniversity of Tokyo
Hayabusa2 reporter briefing28

5. Science comment on the touchdown•••

Scientific analysis is in progress, but the following describes initial impressions from the images.
ONC-W1 images immediately following touchdown– There seems to be an area containing a lot of debris / particle scattering / floating material just above
the surface.
– There also seems to be abrasions on the ground made with the sampling bullet and thruster firing.
– A large quantity of scattered particles / debris can be seen: the potential for sample collection is high.
– Fine particles may have adhered to the lens of the ONC-W1 camera.
Images from CAM-H– The sampler horn seemed able to make contact with the ground without striking any large rocks.
– Surface images are similar to those captured by the landers: the surface is covered with rocks ofaverage size about 10cm.
– After touchdown, rocks reaching sizes of several tens of centimetres in diameter were ejected.
– Many chips of this released debris are flattened plate-shaped and appear to reach quite a high altitude.

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Hayabusa2 reporter briefing29

6. Future plans
Scheduled operations• Mar. 68Descent operation DO-S01
• Mar. 2022Descent operationCRA1
• Apr. week beginning 1st Small Carry-on Impactor SCI operation
Overseas presentations• LPSCThe 50th Lunar and Planetary Science ConferenceMar. 1822,
Texas, USA. There will be a Hayabusa2 session and an explanatory meetingfor local media is planned.
Press and media briefings• Mar.18 15:0016:00 regular press briefing session @ JAXA Tokyo Office
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Hayabusa2 reporter briefing

30Reference material

2019/03/05

Hayabusa2 reporter briefing

31

Touchdown Position
The approximate position of touchdown will be the red square in the figure below.

image creditJAXA
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Hayabusa2 reporter briefing

32

Touchdown Position

The approximate position of touchdown will be the red square in the figure below.

image creditJAXA / University of Tokyo / Koichi University / Rikkyo University / Nagoya University / Chiba Institute of Technology / Meiji University / University of Aizu / AIST)

2019/03/05

Hayabusa2 reporter briefing

33

Touchdown Position
The approximate position of touchdown will be the red square in the figure below.

image creditJAXA / University of Tokyo / Koichi University / Rikkyo University / Nagoya University / Chiba Institute of Technology / Meiji University / University of Aizu / AIST)

2019/03/05

Hayabusa2 reporter briefing

34

Touchdown Position
Area around thetarget marker

L08-B1 and L08-E1
were selected as
candidates for
touchdown.
↓
Finally L08-E1 wasselected.
Image creditJAXA
2019/03/05

TM indicates the position of the target marker

TM-B position and touchdown
candidate site.
Hayabusa2 reporter briefing

Touchdown planned area35

Touchdown operation plan
L08-E1 area
Wide region with scatteredrocks about 60cm in size.
Relatively far from TM.

Narrow but all rocks lessthan 60cm in size.
Relatively close to TM.

A DEMDigital Elevation Map near the touchdown candidate site
2019/03/05

Hayabusa2 reporter briefingimage creditJAXA
36

Touchdown operation plan
L08-E1 area

animation
A DEMDigital Elevation Map near the touchdown candidate site
2019/03/05

Hayabusa2 reporter briefingimage creditJAXA
37

Touchdown operation plan
Touchdown operation plan concept••••

During the landing sequence, the spacecraft autonomously monitors whether thesequence is progressing normally. If it is judged as abnormal, abort (urgent rise)is performed automatically.
If abort occurs, the safely of the spacecraft is ensured.
The design of this touchdown operation strictly sets the abort condition to not
impair safety (in particular, monitoring at check points  in the low
altitude sequence).
If an abort occurs, the back-up period will be used to re-execute the touchdown
operation.

Touchdown operation plan = a series of operation groups up to the completion oftouchdown, including re-implementation.
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Hayabusa2 reporter briefing

38

Touchdown operation plan
Touchdown operation points
Initial plan

Reality→ Assumed 100m2 possible touchdown area

→ For a touchdown area about 6m widel Hayabusa touchdown methodl Pinpoint touchdown method

horizontal component of thespacecraft’s motion to the velocity of
the asteroid surface.
l In addition to measuring the altitudewith the LRF, the spacecraft attitude
will be rotated parallel to the asteroid
surface by the measurement of LRF.

position of the target marker on theasteroid surface.
l LRF is used for altitude measurement andsafety confirmation but not for attitudecontrol.
l Attitude set based on planned values.

l Target marker is used to adjust the

2019/03/05

l Control the spacecraft relative to the

Hayabusa2 reporter briefing

39

Touchdown operation plan
Hayabusa2 pinpoint touchdown feature

rotation“Hayabusa” method• By tracking the descending
TM after its separation, we
can land with a zero ‘relative
speed’ to the ground.
• By recognising the TM rightafter separation, tracking isrelatively easy.
• Altitude is lowered while
always keeping the TM inthe center of the field of view.
• Only one TM can be tracked
at a time.
• Landing accuracy isdetermined by the TM
dropping accuracy. TMtarget marker
2019/03/05

In order to reliably find thedropped TM, it is necessary to
guide Hayabusa2 from highaltitude exactly above the TM

It is possible to land at a position
offset relative to the TM. For
accurate landings, an accurate
grasp of the topography isessential.

Hayabusa2 reporter briefing

rotation“Pinpoint touchdown” method• Capture the already dropped TM
and land at position specified
relative to this TM (it is possible
to offset the TM from the screen
center)• It is possible to recognise thearrangement of multiple TMs.
• The landing point can be specificregardless of TM dropping
accuracy.
• In this touchdown, pinpoint
touchdown using one TM will be
carried out.

40

Touchdown operation plan

Measures implemented to achieve high precision landing High accuracy of asteroid model Tuning of autonomous controls Expansion of landing safety margin
One example

One example

Accuracy of gravity model

Adopt tail-up posture during landing
t
orbi
ent
desc

L08-E1 has moreboulders to the east
than to the west.

Ryujin ridge
When approaching a big
mountain, the gravity
becomes stronger
5~10

West

White areas = places where gravity is stronger or weaker than normal

As Ryugu is not spherical, the effect of orbital bending due tothe mass concentration at the equatorial edge is considered.
2019/03/05

East

Avoid high boulders by intentionally tilting slightly
rather than keeping a straight-down landing posture.

Hayabusa2 reporter briefing

41

Touchdown operation plan
Motion of the spacecraft directly before touchdown (animation, speed x10)

Since we are
currently tuning theposition and posture,these will change inthe future.

image creditJAXA
2019/03/05

Hayabusa2 reporter briefing42