Asteroid explorer, Hayabusa2,reporter briefing

May 22, 2019
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2,
Results from the low altitude descentobservation operation (PPTD-TM1)
Future operations

2019/05/22

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 operation (PPTDTM1) results
3. Future operation plans
4. Upcoming eventsReference material
2019/05/22

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.

2019/05/22

Hayabusa2 reporter briefing(Illustration: Akihiro Ikeshita)

Hayabusa 2 primary specifications
MassApprox. 609 kg
Launch3 Dec 2014
MissionAsteroid returnArrival
27 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
Earth swing-by
Dec 3, 2015

Ryugu arrival

MINERVA-II-1 separation
Sep 21, 2018

June 27, 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)

2019/05/22Hayabusa2 reporter briefing

5 April, 2019

completed →First touchdown5

1. Current project status & schedule overview
Current
status9– From May 14 ~ 16, the low altitude descent observation operation (PPTM-TM1) wasperformed. At an altitude of about 50m, the spacecraft autonomously aborted (andascended).
– The spacecraft return to the home position on May 17.
– Results from PPTD-TM1 are being analyzed and future operations considered.
2015

Scheduleoverview

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2. Low altitude descent observation operation
 PPTD-TM1 results• The low altitude descent observation operation (Pinpoint Touchdown – Target
Marker 1: PPTD-TM1) was performed between May 14 16.
• Preparations were made for the descent (May 14) which began on May 15, 12:31
JST (on-board time) and continued to an altitude of about 50m.
• On May 16 at 11:25 JST, when the altitude was about 50m, the descent wasstopped by autonomous judgement of the spacecraft and the spacecraft began torise (normal abort procedure).
• On May 15 at 11:00 JST, the spacecraft returned to the home position. The
spacecraft has no abnormalities.
• The cause of the normal abort turned out to be due to an issue with the LIDAR
measurement.
• Although it was not possible to drop the target marker, low altitude imaging near
the artificial crater site was successful.
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Hayabusa2 reporter briefing7

2. Low altitude descent observation operation
 PPTD-TM1 results
altitude

PPTD-TM1 operation
Home position return

Home position

20km

Deceleration
ΔV5km•eutoralut
AcRising ΔV~35m•

Could notimplement•

Normal abort at an altitude
50m.
The target marker was planned
to be dropped in the S01 area,
but separation could not beperformed.
Successful imaging near theartificial crater from low
altitude.

time
on-board time
Ground time
2019/05/22

5/15 12:31
5/15 12:47

22:51 5/16 11:25
23:07 5/16 11:41
Hayabusa2 reporter briefing

5/17 11:00
5/17 11:16(JST)image credit: JAXA
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2. Low altitude descent observation operation PPTD-TM1 results
The normal abort

Event• The spacecraft detected an anomaly in the altitude value received from LIDAR and autonomouslytransitioned to the normal abort state (stopped the descent and began to rise).
– The ‘normal abort’ is a mode that is triggered when a minor abnormality occurs (e.g. sensor output abnormality etc).

Cause of altitude anomaly• The received sensitivity of LIDAR light can be adjusted according to the altitude. In this operation,
the received sensitivity was adjusted during an automatic sequence when the spacecraft passed
50m altitude. Due to noise data being mixed in at that time, the LIDAR output returned an
unusually high altitude value.
– This is the first time that the received sensitivity change has been performed at low altitude. As the descent accuracy of
Hayabusa2 was higher than originally expected, this measure was introduced to prevent the LIDAR from going crazy with astrong reflection, even when the LIDAR light hit the target marker.
– It was difficult to predict in advance how the noise data would affect the signal, as is changes on a case-by-case basis
according to the environment of Ryugu and the situation of Hayabusa2.

 Future measures• After this event occurred, we found a adjustment method that could reliably prevent noise mixing.
This will be adopted from now on.
2019/05/22

Hayabusa2 reporter briefing92. Low altitude descent observation operation
 PPTD-TM1 results
Imaging during the spacecraft ascent• Spacecraft operation was set to image the surface of the asteroid, even if
the spacecraft ascended due to an abort.
• The region of the surface imaged depended on the abort situation, but
fortunately we were able to image near the artificial crater.
• The acquired data is valid for the assessing the possibility of a future
touchdown.
• Although the target marker could not be dropped due to the abort, as thevicinity of the artificial crater was imaged, there will be no delay in thefuture operation plans.
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Today’s
release

2. Low altitude descent observation operation PPTD-TM1 results
Imaging during the spacecraft ascent

From about 0.6 km altitude

From about 0.5 km altitude

Image timeMay 16, 2019, 11:36 JST on-board time

Image time May 16, 2019 2019, 11:39 JST on-board timeimage credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, Aizu University, AIST

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2. Low altitude descent observation operation
PPTD-TM1 resultslabelled

Imaging during the spacecraft ascent

From about 0.6 km altitude

From about 0.5 km altitude     
Image time May 16, 2019, 11:36 JST on-board time

Image time May 16, 2019 2019, 11:39 JST on-board time

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

2019/05/22

Hayabusa2 reporter briefing

123. Future operation plans Operation plan concept from May ~ July
• Currently, Ryugu is approaching the Sun (perihelion in September). It will only be possible to land onRyugu until the end of July, after which the asteroid temperature will rise.
• By the middle of June, the crater and state of the spacecraft will have been examined and it will then be
decided if a second touchdown operation will be performed between the end of June and start of July.
• Target point: Area where there is ejected material from the artificial crater.
• Operation name: “Pinpoint touchdown” (PPTD).
• 2 or 3 low altitude descent observations will be performed in May and June before the PPTD operation.
While performing detailed topographical observations of the landing point candidates, a target marker
will be dropped as a guide for landing in this region.
• 1st 5/145/16
Operation namePPTD-TM1      • 2nd 5/285/30
Operation namePPTD-TM1A• 3rd week of 6/10
Operation name: PPTD-TM1B (provisional)• During PPTD-TM1A, a target marker will be dropped at one of the candidate landing points. At thistime, C01 is thought to be the best area among those shown in the detailed image obtained during thelast operation.
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3. Future operation plansNo change from the explanation in the May 9 press briefing session
Outlook for future touchdown operations
The decision to perform a touchdown operation will be based on consideration of the following
points: Scientific & engineering value of the 2nd touchdown• Is the risk during the touchdown operation small enough and the expected value of thesecond touchdown high enough?
• Is It highly likely that artificial crater ejecta can be collected?
 Feasibility of the touchdown operation• Can the terrain information necessary for touchdown be obtained and a sufficiently safe
touchdown sequence be designed?
• Can the target marker be dropped close to the touchdown target point?
 Spacecraft condition• During the 1st touchdown, the optical system became cloudy due to dust. Can we confirm
that a second touchdown can be performed without any problems given this situation?
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3. Future operation plans

PPTD-TM1A operation         

altitudeHome position return

Home position

20km

Deceleration
ΔV

5km

Targetmarker
separation~35m

Rising ΔV

5/29~12:002019/05/22

Closest target point
target marker
drop point
||C01 area

5/29
~22:00

5/30~11:00
Hayabusa2 reporter briefingtime
5/31(JST)image credit: JAXA
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3. Future operation plans

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    0m*image credit: JAXA+

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Hayabusa2 reporter briefing16

4. Upcoming events
Operation plans• May 2830Descent and target marker separation operation
PPTD-TM1A
Press and media briefings• June 11 15:00 Press briefing session @ Tokyo office

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Hayabusa2 reporter briefing

17Reference

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Low altitude descent observation operation PPTDCurrently identified touchdown candidate points
L14 area
L14-CL14-A
L14-B

C01 area
C01-C
C01-A
C01-B

S01 area

Near SCI
collision L12-A2
point

L12-A4

L12-A3
L12-A1

L12-D• CO1 is the area where the artificial crater wasgenerated.
• S01 is that area that was observed in March thisyear as a backup candidate site for TD2.
• L14 was identified at the time of the landing
point selection for the first touchdown, that wascarried out in August last year.
• The yellow circles (approximate position) denotecurrently identified touchdown candidate points(all are 6 ~ 12 m in diameter)(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 briefing

19Terrain change before and after the SCI collision
Before SCI collision 2019/03/22

After SCI collision 2019/04/25

Comparison before & after (blink 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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