Asteroid explorer, Hayabusa2,reporter briefing

April 2, 2019
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2,
Descent operation results
Small Carry-on Impactor (SCI) operation

2019/04/02

Hayabusa2 reporter breifing

2

Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. Descent operation results
3. Small Carry-on Impactor (SCI) operation
4. Other topics
5. Future plansReference material
2019/04/02

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 furtherscientific findings through comparison and investigation of the results from both missions.

2019/04/02

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.

4Mission Flow
Launch3 Dec 2014

Earth returnlate 2020

Sampleanalysis
2019/04/02

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’ssurface(Illustrations: Akihiro Ikeshita)51. Current project status & schedule overview
Current
status9– Three journal papers were published in ‘Science’ (March 20 JST)– In preparation for the impactor experiment, the ‘Crater Search Operation(Pre-SCI)’ (CRA1) was performed from March 20 to 22 (altitude 1.7km).
– Preparation for the Small Carry-on Impactor (SCI) operation progressed.
2015

Schedule
overview

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2. Descent operation results
Results from the Crater Search Operation (Pre-SCI), CRA1
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maintaining an altitude ofabout 1.7km.
,Acquire detailed data inadvance about the area
where a crater will begenerated with the small
carry-on impactor (SCI).
↓Observations were made asscheduled.

#$&("&$)#("-Image credit/JAXA.
2019/04/02

Hayabusa2 reporter briefing7

2. Descent operation results

Area observed by the CRA1 operation
Image creditJAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute, Meiji University, University of Aizu, AIST.)

2019/04/02

Hayabusa2 reporter briefing8

3. Small Carry-on Impactor operation
Outline and purpose of operation• The impact device generates an artificial crater on the surface of Ryugu.
• Collect information about the interior of the asteroid by examining the crater
formation and generated crater.
• At a later date, touchdown at or around the generated crater and try to collectsubsurface material. However, if the condition of the surface of Ryugu isdangerous for touchdown, the touchdown will not be attempted.

Operation schedule• SCI operationApril 46• Crater generation date & time April 5 at 11:36onboard time, JST.
2019/04/02

Hayabusa2 reporter briefing93. Small Carry-on Impactor operation
SCI operation sequence• SCI separation height is 500m
• From SCI separation toexplosion: about 40 minutes• Return to home position: about
2 weeks( &  '   " $) "  *     !#%!!

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2019/04/02

Hayabusa2 reporter briefing,  ! 
 

-image credit/JAXA.
10

3. Small Carry-on Impactor operation
How to avoid debris and ejector(a)(b)(a) High speed debris(b) High speed ejector(c) Slow speed ejector

Ryugu

(c)

image creditJAXA
2019/04/02

Hayabusa2 reporter briefing Avoid debris
Debris that scatters during the detonation of
the small carry-on impactor is avoided in
the shadow of the asteroid.
 High-speed ejector avoidance
Collision with high speed ejector at the timeof impact. Avoid in the shadow of theasteroid as with .
 Slow ejector avoidance
Low speed ejector sent into an orbit
trajectory is avoided by increasing thedistance from the asteroid. The impact fromcollision is small as the speed of the slow
ejector thrown to ultra-high altitudes is low
and collision probability is small.
11Small Carry-on Impactor operation

Selection of impact target point and reason for choice

Impact target point(6.00, 303.00)

Constraint
Target point at a subearth latitude (~6∘N during the SCI collision (predicted collisionarea has a radius of about 200m = latitude / longitude 30 ∘ in 3σ .

S01(5.13, 303.39)Selection criteria for target points

1st priority Area where a generated crater can be found.
2nd priority

Area which is suitable for landing.

L12→ Flat areas with a layer of sand are desirable.
Collision target point latitude and longitude (6.00 ∘, 303.00 ∘)Flat areas are scattered around the vicinity of the flat region L12 (where the next
touchdown candidate, S01, is located).
Possibility to collect a sample from areas other than TD1 (Horai Fossa and the eastern
hemisphere).
This is a geological area very similar to TD1 and the depth distribution of matter andstructure can be discussed by comparing with the TD1 sample with an excavated sample.

Captured by the ONC-T, hoveringfor MASCOT deployment(approximately 3km altitude)

Image creditJAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute, Meiji University, University of Aizu, AIST.)

2019/04/02

Hayabusa2 reporter briefing12

3. Small Carry-on Impactor operation
S01CRA1crater generation area

Impact target point(6.00, 303.00)
S01(5.13, 303.39)

L12
Note: The observation area for the CRA1 operation is thesame as that of the crater generation area with the SCI.

Crater generation area

Image creditJAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute, Meiji University, University of Aizu, AIST.)

2019/04/02

Hayabusa2 reporter briefing

133. Small Carry-on Impactor operation
From home position to separation of the SCI
HP-Z coordinate

HP-Z coordinate

Altitude change over time
GCP-NAV
Auto. OFF

Movement in space

GCP-NAVhovering

GCP-NAV
Auto. ON

JST

20km

on-board t ground t

20km

4/4 13:00

13:17

5km

4/4 23:20

23:37

1km

4/5/ 10:44

11:01

5km

LIDAR

V = -0.4 m/s
Descent deceleration ΔV
V = -0.1m/s

        1km

TargetaltitudearrivalSCI separation

0On-board time JST)
Ground time

2019/04/02

4/4
13:00
13:17

4/4
23:20
23:37

4/5
10:44
11:01

4/5
10:56
11:13

Hayabusa2 reporter briefing

Time(JST)

0HP-X coordinateimage creditJAXA
14

3. Small Carry-on Impactor operation
%" &#%'"!'"" #"&'"!

HP-Z
coordinate

20km

4/16
HP return ΔV4
HP return

4/13
HP return ΔV3W2 imaging 4
4/15
Sun orientated Spin

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4
+ZΔV

-ZΔV1

90s later+XΔV

0-3.5km-20km

4/11
HP return ΔV2

W2
imaging 2

5 mins later
asteroid shadow
avoidance ΔV(+XΔV)

blue/time from SCI
explosion

4/10
Sun oriented Spin

red/ time from SCI separation

15 mins later-XΔV
18 mins later
DCAM3 separation

4/8
Sun orientedSpin

19 mins later-ZΔV2

100 mins laterstop evacuation
ΔV(+ZΔV)-time/on-board JST)
2019/04/02

SCI separation 6 mins later
4/5 10:56

W2imaging 3

100km1km

Movement inspace

4/12
Sun oriented Spin

SCI explosion
4/5 11:36
40 mins later
10 mins later
lessen evacuation
ΔV(+ZΔV)

HP-X coordinate

W2 imaging 1

4/5 17:14
340 mins later
HP return riseΔV(+ZΔV)

4/5 15:44
250 mins later
begin return to HP ΔV(+XΔV)

Hayabusa2 reporter briefing

4/9
HP return ΔV1

4/6
to asteroid search operation ΔV(+ZΔV)
4/6
deceleration ΔV for return(-XΔV)-image credit/JAXA.
15

3.Small Carry-on Impactor operationHP
coordinatesystem

SunDistances approximate

Hop o mesi t
io nEarthEarthSunm


Ryugu

16km

HPHP

-Z-X

Zodiac side

100km

Ryugu

 


4.5k



ion1kmexp a n s19km

image creditJAXA
2019/04/02

Hayabusa2 reporter briefing16

3. Small Carry-on Impactor operationDecision points during operation)3%-

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7 8 / .  " / ! 1 $ 3 )- %Gate 1 %'). *4$'%-%.3 3/ "%'). $%2#%.3  +-Gate 2 %'). *4$'%-%.3 !2 3/ 5(%3(%1 3/ #/.3).4% $%2#%.379+-Gate 3 %').&).!,2%0!1!3)/.*4$'%-%.37GO/NOGO
judgement 2%0!1!3)/.

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2%0!1!3)/.

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SCI operation   %60,/2)/. 3)-%!3%  0!#%#1!&3 23!342 #(%#+Gate 6 

0!#%#1!&3 23!342 #(%#+Transmission ofinformation
Spacecraft altitude, operation
status, etc.

Status of spacecraftetc.

/3%!3%./3$%&).%$
 Time shown are not fixed and are subject to change depending on the final plan and situation on the day of operation.
The time stated on the Gate is the time to begin judgement. It may take some time before the judgement result is decided.
2019/04/02

Hayabusa2 reporter briefing17

3. Small Carry-on Impactor operation
Crater searchbasically, search by eye••(a) mosaicC13DCAM3 imaging → estimate impact position

C11

C07

Comparison with pre/post low altitude ONC & TIR imaging(CRA1,2) → impact position, crater identification.

• ONC-T resolution17cm/pix altitude 1.7km

C08

C04

– Low altitude image scan of predicted impact area twoweeks prior and three weeks after impact.

C17

C10

M01
C06

M02

C05

• TIR resolution1.7m/pix altitude 1.7km••

2 (267 m)

Image of SCI separation with ONC-W1 etc. → SCI
separation confirmation, explosion location estimations.
In addition, dust observations after SCI impact with TIR andLIDAR → Collision confirmation

2019/04/02

Hayabusa2 reporter briefing

C09C033 (400 m)

C12

From crater exploratory training(ONC-T image mosaic
18

4. Other topics
Overseas presentations

At the 50th Lunar and Planetary Science
Conference (LPSC) --a research
conference in the US– there was both a
special session (oral 3/19, poster 3/20)
and local media briefing (3/19).

Date & place: March 18 – 22, The
Woodlands, Texas, USA.
 Hayabusa2 special session: 13 oralpresentations (3/19), 28 poster
presentations (3/20).
Several additional announcements
regarding Hayabusa2 were also in othersessions.
Science team meeting (3/20, 3/21)
2019/04/02

TopHayabusa2 special session(3/19)LeftHayabusa2 poster
presentation corner (3/20)
Photo creditHayabusa2 Project
Hayabusa2 reporter briefing19

4. Other topics

Group photograph of the Hayabusa2 Joint Science Team (HJST) meeting held at LPSC
(March 21, 2019). (Photo credit: Hayabusa2 Project.)
2019/04/02

Hayabusa2 reporter briefing20

5. Future plans
Operation plans• April 46Small Carry-on Impactor (SCI) operation• Week of April 22Crater Search Operation (Post-SCI) (CRA2)
Press and Media Briefings• April 5, 8:30 Press Center opens  JAXA Sagamihara Campus
Hayabusa2 Small Carry-on Impactor (SCI) control room live broadcast 4/5
around 10:1512:15
JAXATV http://fanfun.jaxa.jp/jaxatv/detail/14343.html
YouTube https://www.youtube.com/watch?v=bv2ykuJDcBo
Englishhttps://youtu.be/Lh4iFyMRWZg
2019/04/02

Hayabusa2 reporter briefing

21Reference material

2019/04/02

Hayabusa2 reporter briefing

22Small Carry-on Impactor
SCISmall Carry-on Impactor
u Shape: conical (diameter 300mmweight 14kg, explosive: ~9.5kg)
u Liner (impactor part): Pure copper (2kg), thickness ~5mm

u Explosive: HMX based PBX (Plastic bonded explosive)!
u Explosive
accelerates liner to 2 km/s in about 1/1000 seconds.
!
!
!

          
2019/04/02

Image creditJAXA

Hayabusa2 reporter briefing     23

Deployable camera
Outline of the deployable camera (DCAM3)• Deployable camera has a cylindrical Φ80 mm  78 mm
shape, excluding the protruding lens and antenna.
• There are two built-in cameras; one analog camera that cantransmit images in low resolution but in real time, and one
digital camera for digital communication of high resolution
images.
• There is also an analog and a digital transmitting antenna
for sending images.
• The battery enables imaging and wireless datatransmission for up to 3 hours (depending on conditions).
• Images can be transmitted to the mothership wirelessly
even at distances of 10km or more.
• A small monitor camera (MCAM) is mounted on theseparation mechanism to try and capture images of how
DCAM3 separates and leaves.
2019/03/18

DCAM3 = Deployable Camera 3
Successor to DCAM 1 and 2, mounted on
the solar sail IKAROS
Analog imaging
transmission antenna

Analog camera optics system
Digitalimaging
transmission
antenna

Digital camera
optics system

Hayabusa2 reporter briefingSeparation
mechanism(Image creditJAXA)
24

Deployable camera
Outline of observations from deployable camera(DCAM3)• Observe the impact from about 1km distance:- Ryugu- Scattered material generated during the collision- High speed debris (digital only- Low speed dust (digital only- SCI main body before explosion (digital only)• Analog system: color, viewing angle 71ºx53º,720x526 pixels, resolution about 10m.
Digital system: Monochrome, viewing angle
74ºx74º, 2000x2000 pixel, resolution about 1m.
• Analog system can send data to the mother shipin real time. Digital system is delayed beforesending.

Near field(Digital system)

Far field(Digital system)

Sunabout  (Ogawa et al., Space Sci. Rev. 208, 125-142, 2017)

SCICamera
viewing
direction

DCAM3about 1 km(Radius~ 500m)

mother ship

(Image creditKobe Univ.)

2019/03/18

Hayabusa2 reporter briefing25Crater excavation depth• Depth of the excavation region is about 1/10 of the crater diameter.

Pre- impact

Crater formation

Excavation region
Rt

Excavation model

An example of numerical simulations of crater formation impacts on a
granular layer (sand). Color corresponds to the depth prior to collision.
(Provided by Koji Wada)(Image creditChiba Institute of Technology)
2019/03/18

Hayabusa2 reporter briefing

26

Ejector seen during collision experiments
Large blocksGranular (sand) layer

Basalt: P=0%

strength

Glass beads (100µm): P=40%

Porosity

Mortar: P=20%

Impact speed: 4km/s
Φ7mm, nylon

2019/03/18

Perlite (3mm): P=80%
Impact speed: 90 m/s
Φ3mm, aluminum

Hayabusa2 reporter briefing

Powder layer

Plaster: P=50%

Strength

P: PorosityφProjectile diameter

Porous silica dust:
P=65%
Impact speed: 3.2km/s
Φ2mm, nylon

Courtesy of Kobe University
Arakawa Laboratory27

Impactor Experiment ScienceTo understand the repeated collisional growth and destruction of celestial body evolution• What kind of impact crater can / cannot form on the surface of Ryugu?
–Observation of the crater formation process and measurements of the formed crater size and shape.
• Construction of a impact physics model (scaling laws) based on the impact experiment in real asteroid material andenvironment.
• Construction of scaling rules for Ryugu’s collisional history on the surface and surface age estimation (crater chronology)
Scaling law: a universal equation connecting impact conditions andthe properties of the formed crater.

• What’s going on below Ryugu’s surface?
–Exposure and collection of subsurface material via crater formation → Assessment of the impact of space weathering andsurface flow.

–

In-situ observation of ejecta motion → Estimate subsurface conditions (porosity, particle size distribution etc.)• Does Ryugu’s surface move easily?
–

principal role of DCAM3

Measurement of terrain changes caused by the impact → Understand the effect of impact vibrations, the presence of few smallcraters.

• In case we hit a boulder…
–
2019/03/18

Crater on boulder measurement or measurement of fragments from boulder destruction → Estimate strength of asteroid
material
Hayabusa2 reporter briefing

28