Asteroid explorer, Hayabusa2,reporter briefing

July 9, 2019
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2,
 2nd touchdown operation

2019/07/09

Hayabusa2 reporter briefing

2

Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. The 2nd touchdown operation
3. Scientific significance of performing the 2nd touchdown
4. Message from the JAXA/ISAS Director General
5. Upcoming eventsReference material
2019/07/09

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 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.

2019/07/09

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Launch
Dec 3, 2014

Mission flow
Earth swing-by
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)

2019/06/25

Hayabusa2 reporter briefing

5 April, 2019

completed → First touchdown5

1. Current project status & schedule overview
Current
status9– A second touchdown will be performed from July 9 – 11. Preparation for
touchdown is now complete.
– Today (July 9), the shift for the touchdown operation has begun. Today, weare making final preparations for the descent.
2015

Scheduleoverview

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2. The 2nd touchdown operation• 2nd touchdown operation7/911• Touchdown data & time7/11 10:05  10:45 JST (on-board time)• Touchdown location: C01-Cb (target marker drop area)
 The operation is named ‘2nd touchdown‘ but denoted PPTD.

2019/07/09

Hayabusa2 reporter briefing7

2. The 2nd touchdown operation

TM
H=140cmm
2.6

C01-CbRadius 3.5m

Styx boulder
H=55cmRockmass
H=65cm

C01-Cbcenter

H=39cm
TMH is the highestestimatedheight value(worstscenario)

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

2019/07/09

Hayabusa2 reporter briefing8

2. The 2nd touchdown operation
C01-Cb area

C01-Cb

C01-CbTM

TMAr

Artificial cratertali
ificertacr

DEM Digital Elevation Map near the touchdown candidate pointimage creditJAXA
2019/07/09

Hayabusa2 reporter briefing

92. The 2nd touchdown operationC01-Cb area

DEMDigital Elevation Mapnear the touchdown
candidate point
movieimage creditJAXAUniversity of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.,
Kobe University, University of Occupational and Environmental Health)2019/07/09

Hayabusa2 reporter briefing10

2. The 2nd touchdown operation    1m

2019/05/30 11:26 JST (onboard timeAltitude: 71 72m
2019/07/09

Image creditJAXAChiba Institute of Technology, University ofTokyo, Kochi University, Rikkyo University, Nagoya University, Meiji
University, University of Aizu, AISTHayabusa2 reporter briefing11

2. The 2nd touchdown operation
Operation sequence (overall)

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plan and situation on
the day of operation.
* Touchdown takes placeabout 40 minutes fromthe time shown on thefigure.

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Hayabusa2 reporter briefing The transition
from LIDAR to LRF
takes place during
the descent from30m to 8.5m.

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12

2. The 2nd touchdown operation
Operation sequence (low altitude)

Altitude 
 %

0m

Vertically descend
while tracking TM  !

Mid-descent towards 8.5m,altitude control switched to LRF

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09:40

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Hover at TM relative
offset point.

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
10:03*
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After detection of touchdown,
projectile is fired and spacecraft rises

10:05*
!# checkpoints for autonomous judgements as to whether Hayabusa2 continues to the next sequence.

2019/07/09



TM capture byautonomous function

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Times shown are on
July 11, 2019. Note that
due to autonomous
control, the times maydiffer.
8.5m
Times indicated by *are the earliestapproximate times andmay be delayed by up
to about 40 minutes
from the stated time.

10:56*

Hayabusa2 reporter briefingTimecredit: JAXA
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2. The 2nd touchdown operation
Motion of the spacecraft from an altitude of 8.5m

16x animation)

creditJAXA
2019/07/09

Hayabusa2 reporter briefing

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2. The 2nd touchdown operation
Decision points during the operation
%

 # " & !  %     $"! %) * " !  "  # %  Gate 1

Decision on start of descent (@20km)

Gate 2Start confirming whether to continue descent )+5km)

Gate 3  Start final descent judgement )GO/NOGO judgement)'

 

Antenna switching

Gate 4Confirm switch to LGA  Touchdown





Transmission ofinformation( Ryugu images from ONC-W1( Advanced data from LIDAR( Confirm the probe speed withDoppler data  !$#" #% '

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Antenna switching

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



Start check of the state of the spacecraft

Gate 6Start confirmation of ΔV to return to home position( Check with telemetry

The indicated time is not fixed and may change depending on the final plan and situation on the day of operation. The
time written by the Gate is the time to start judgment, and it may take some time for the final result to be determined.
2019/07/09

Hayabusa2 reporter briefing15

2. 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 analtitude 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 avertical 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 1sttouchdown (February 6 & 20, 2019) http://www.hayabusa2.jaxa.jp/en/enjoy/material/

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Hayabusa2 reporter briefing16

2. The 2nd touchdown operation
Closing of catcher chamber B• During the operation on 6/24, the sample
catcher was rotated to close chamber B.
• Chamber B was open immediately after the
first touchdown (2/22). After this, the impact
experiment (SCI) and a total of 7 descentoperations were conducted.
• Chamber C is currently open.
      image creditJAXA

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Hayabusa2 reporter briefing17

2. The 2nd touchdown operation
Location of the first (TD1) and second (TD2) touchdowns

Tamatebako

image creditJAXAUniversity of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.)

2019/07/09

Hayabusa2 reporter briefing18

2. The 2nd touchdown operation

Location of the first (TD1) and second (TD2) touchdowns

TD1

TD2

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.

2019/07/09

Hayabusa2 report briefingcreditJAXA
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3. Scientific significance of performing
the 2nd touchdownCollection of sub-surface material• Black material from Ryugu• Degeneration process of surface material from solar windor cosmic rays
• Mixing process on asteroid and its time scaleCollection from multiple sites• Regional heterogeneity of celestial bodies• Increase the amount of sample
2019/07/09Hayabusa2 reporter briefing20

4. Message from the Director General of ISAS / JAXA
So far, Hayabusa2 has achieved 1) asteroid rendezvous, 2) deployment ofexploration robots and acquisition of surface data, 3) 1st touchdown, 4)
artificial crater generation and from this, returned many results. We
believe that sample acquisition was achieved during the 1st touchdown.
When considering whether or not to perform the 2nd touchdown, it could
be said that cancelling the 2nd touchdown and prioritising the return toEarth was the safest option for securing the early successes. On the other
hand, if the second touchdown is successful, subsurface material can becollected and scientific results further enhanced. However, this comeswith the possibility of serious damage or a crisis that could threaten thereturn to Earth.
We therefore carefully reviewed whether the accuracy requirements of the 2nd touchdown and that of the spacecraft
performance fell within the conditions that were available at the 1st touchdown. From this, we confirmed that it wasextremely likely that we could safely secure a 2nd touchdown with the current capabilities of the Hayabusa2 team andspacecraft. Therefore, ISAS will implement a 2nd touchdown with attention to both the “challenge” and “safety” components.
We believe that success in this challenge will be a catalyst for advancing many future space science and exploration
programs.
Director General, ISAS Hitoshi Kuninaka
2019/07/09

Hayabusa2 reporter briefing21

5. Upcoming events
 Operation plans• 7/9112nd touchdown operation
 Press and media briefings• 7/11 8:3017:30 Press center opens @ Sagamihara campus• 7/11 14:0015:00
Press conference on the implemented touchdown @ Sagamihara campus
Applications for participation in the press center and press conference closed on June 25

2019/07/09

Hayabusa2 reporter briefing

22Reference material

2019/07/09

Hayabusa2 reporter briefing

23Process for judging if the 2nd touchdown was feasible• From May ~ June 2019, JAXA/ISAS discussed the scientific significance, state of thespacecraft and sequence confirmation, the reliability and risk regarding the 2nd touchdown
operation with Hayabusa2.
• By 2019/6/20, the results of the examination by Hayabusa2 were summarized and discussedby the team.
• On 2019/6/21, the decision was judged at ISAS.
• On 2019/6/25the decision was reported to JAXA management.
• Judgement of touchdown implementation:
Ø High scientific value of a subsurface sample collection
Ø Confirmation of the feasibility of a sufficiently safe touchdown operation by thespacecraft in its current condition.
Ø Confirmation that there is no hindrance to subsequent operations even if the amount oflight received by the optical system is further reduced during the second touchdown.
2019/07/09

Hayabusa2 press briefing

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Touchdown candidate sites

L14 area
L14-C

L14-A
L14-BC01 area
C01 area
C01-C

L14 area

C01-A
C01-B

S01 area

Near SCI
collision L12-A2point

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 briefing

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