Asteroid explorer, Hayabusa2,
reporter briefing

February 6, 2019
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2:
Touchdown operation planTouchdown related information

2019/02/06

Hayabusa2 reporter briefing

2

Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. Touchdown operation plan
3. Projectile firing experiment
4. Scientific importance of the touchdown
5. Future plans
Amendment
Reference material
2019/02/06

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.

2019/02/06

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
2019/02/06


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– BOX-B observations were performed between January 8 – 9 and data from
opposition (the direction towards the Sun as seen from Ryugu) was acquired.
– BOX-B observations were also conducted on January 25 to make observations
around the north pole of Ryugu
2015

Schedule
overview

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2019/02/06

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Hayabusa2 reporter briefing

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6

2. Touchdown operation plan
outline• Touchdown (TD) date & timeFeb 22, 2019 about 8am• Touchdown operation
Feb 20  22, 2019
Begin descent2/21  8amAll times are in JST

• Touchdown location
L08-E1• Target marker (TM)Use pinpoint touchdown methodwith TM-B that is already
dropped.

TM-B position and touchdown candidate site
Image creditJAXA

2019/02/06

Hayabusa2 reporter briefing7

2. 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
2019/02/06

Hayabusa2 reporter briefingimage creditJAXA
8

2. Touchdown operation plan
L08-E1 area

animation
A DEMDigital Elevation Map near the touchdown candidate site
2019/02/06

Hayabusa2 reporter briefingimage creditJAXA
9

2. Touchdown operation planSequence of the touchdown operation (entire)#*"*+)%*
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2019/02/06

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fixed and may change
depending on the final
plan and situation on
the day of operation.

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Hayabusa2 reporter briefing*"$-image credit/JAXA.
10

2. Touchdown operation plan
Touchdown operation sequence (at low altitude)
TM capture with GCPNAV guidance system!"

TM relative
horizontal motion

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offset point%!#!
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~Check points of the spacecraft’s autonomous system (proceed to next operation if normal at each checkpoint)
2019/02/06

Hayabusa2 reporter briefing11

2. Touchdown operation plan
Motion of the spacecraft directly before touchdown (animation)

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

image creditJAXA
2019/02/06

Hayabusa2 reporter briefing12

2. 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

2019/02/06

l Control the spacecraft relative to the

Hayabusa2 reporter briefing13

2. 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
2019/02/06

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.

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2. 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.
2019/02/06

East

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

Hayabusa2 reporter briefing15

2. Touchdown operation plan

Decision points during operation
item

Ground time: JST

Decision item

Gate 1

2/21 07:13

Decision on start of descent

Gate 2

2/21 18:52

Start confirming whether to continue descent

Gate 3

2/22 06:02

Start final decent judgement (GO/NOGO)

HGA→LGA

2/22 07:27(07:08)

Antenna switchingTD

2/22 08:15(07:56)

Touchdown

Gate 4

2/22 08:15

Start rising check

LGA→HGA

2/22 08:22(08:03)

Antenna switch

Gate 5

2/22 08:22

Start check of the state of the spacecraft

Gate 6

2/22 18:27

Start confirmation of ΔV to return to home position.

 onboard time

Transmission of
information

Ryugu images from ONC-W1
Advanced data from LIDARConfirm the probe speed with
Doppler data.

Check with telemetry

 The indicated time is not fixed and may change depending on the final plan andsituation 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.
2019/02/06

Hayabusa2 reporter briefing16

2. 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.
2019/02/06

Hayabusa2 reporter briefing17

3. Projectile firing experiment
Sampler hornentire
2019/02/06

tip
Hayabusa2 reporter briefingimage creditJAXA
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3. Projectile firing experiment
Sample Catcher

Tantalum
Projectile
300m/ sReentry). Capusle

Sample will be stored
in the catcher0)-0
Sample Catcher

Reflector
Sampler Horn

Harness for
Latch and Seal
Mechanism

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Sample rise up to
the catcher
reflecting on theinside surface ofsampler horn

Reflector
evacuation
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Conveyerevacuation/*" 2Harness Cutter




'2&

Ejectionimage creditJAXA
2019/02/06

Sampler horn

Transport mechanism
Hayabusa2 reporter briefing19

3. Projectile firing experimentRotation Cylinder

B roomVolume:12cm3

A roomVolume:24cm3

Walls of Sample Catcher

Latch Mechanism
I/F Surface

C roomVolume:12cm3

Structure of sample catcherimage creditJAXA
2019/02/06

Hayabusa2 reporter briefing20

3. Projectile firing experiment
Folded tip of the sampler horn
Surface material caught on the folded edgeof the tip has the possibility of entering thesample catcher during the ascent of thespacecraft.
Before launch, we made a device simulating
the folded tip and confirmed thefunctionality in a microgravity experiment.
See JAXA archive:

http://jda.jaxa.jp/result.php?lang=j&id=8e3fa0b26882c
50c19b007f2b878ac64
image creditJAXA
2019/02/06

animation
Hayabusa2 reporter briefing21

3. Projectile firing experiment

Experiment Hayabusa2 sampler projector FM-equivalent ignition operation test.
Date2018/12/28
PlaceJAXA Institute of Space and Astronautical Sciences (ISAS)
Implementing group Hayabusa2 Project Sampler Team

Purpose By using an equivalent projector as that onboard the spacecraft (FM-equivalent: manufactured in the samebatch as the flight mode equipment), confirm that after a storage period of four years, ignition and planned
function can occur normally.
Shoot into a target simulating Ryugu and check the resultant behavior, such as the ejector released from theimpact.
Method:1 Create a simulated target of the surface of Ryugu based on information acquired during previous exploration.
Destroy artificial rocks created by simulating the composition and density of carbonaceous chondrite meteorites
and create targets for the gravel layer that reproduce the distribution of gravel and stones on the surface of Ryugu
that was confirmed by the landers.
2 Execute bullet firing test under vacuum conditions
Ignite Hayabusa2 sampler projector in a vacuum chamber, aiming at one pebble.
5g metal bullet injected at a speed of about 300 m/s
High-speed video captured of gravel crushing where the bullet landed and the surrounding gravel ejection.
2019/02/06

Hayabusa2 reporter briefing22

3. Projectile firing experiment

Target simulating the surface of Ryugu.
(image creditJAXAUniversity of Tokyo
2019/02/06

Projector (barrel) and projectile (bullet) used: as these areflight spares, the shape, material etc are the same as thoseonboard Hayabusa2.image creditJAXA

Hayabusa2 reporter briefing23

3. Projectile firing experiment(movie)Image taken during the experiment. This is recorded at the normal video
rate. (image creditJAXA)
2019/02/06

Hayabusa2 reporter briefing24

3. Projectile firing experiment(movie)Image taken during the experiment. The true frame rate is 420 images per second, and this isslowed to about 14 times longer than actual time. (image creditJAXA)2019/02/06

Hayabusa2 reporter briefing25

3. Projectile firing experiment
Results
FM equivalent projector works normally.
Bullets were injected and the target gravel was crushed.
Confirmed that adjacent pieces are also crushed and both small and fine particles
are released.
A large quantity of crushed gravel and particles are released even in Earth’s
gravity, confirming that a crater was formed.
Discussion
Similar behaviour is assumed for sample collection during the actual touchdown.
Since the surface of Ryugu experiences microgravity, more debris is expected tobe discharged and enter the sampler horn than during the ground experiment.

2019/02/06

Hayabusa2 reporter briefing26

4. Scientific importance of the touchdown
Touchdown = sample collection
Science can be done over a wide range of scales (12 orders of magnitude)• History of asteroid Ryugu• Origin & early evolution of the Solar System• Earth compositionbody, water, life• The environment 4.6 billion years ago in the 13.8 billion year
history of the Universe.
2019/02/06

Hayabusa2 reporter briefing27

4. Scientific importance of the touchdown
science on different scales
Km

1

m

100

10

mm

1

100

10

μm

1

100

10

nm

1

100

10

1

Remote sensing observations from the spacecraft
ONC (T, W1, W2), LIDAR, NIRS3, TIR, DCAM3

Rover & lander observations

MASCOT, MINERVA-II (1A, 1B, 2)

Sample analysis

Sampler, ground analyzer

Ryugu©JAXAUniversity of Tokyo &e.g. Itokawa particles©JAXA
collaborators
Hayabusa2 reporter briefing
2019/02/06

Molecular
structure28

4. Scientific importance of the touchdown
Galaxies

Star-forming
cloudsProtoplanetary
discs

Asteroid

Earth, life andoceansAsteroid Ryugu’s
history

Origin of the Solar
System, early evolution
Solar System material(c) ESO/S. Brunier

2019/02/06(c) NASA(c) NASA

Delivery of the Earth’s
oceans and evolutionof the materials for life(c) JAXA, U. Tokyo &collaborators

Hayabusa2 reporter briefing(c) JAXA/NHK

29

5. Future plans
Scheduled operations• Touchdown2/22FridayWeb broadcast scheduled for about one hour before and after touchdown(English translation provided)
Press and media briefings• 2/20 Wed. 15:00 Press briefing @ JAXA Ochanomizo Office• 2/22 Thurs. 05:30 Press center @ JAXA Sagamihara campus Due to limited capacity, media participation in the press center will be via a preregistration system. Notice for related information, such as the application method, will be
distributed at a later date.

2019/02/06

Hayabusa2 reporter briefing

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Correction

2019/02/06

Hayabusa2 reporter briefing

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MINERVA-II1:
correction to the landing site nameAt the press briefing on December 13, 2018, we announced
the landing site of the MINERVA-II1 rovers as “Trinitas, thebirthplace of the goddess, Minerva”. This is actually an error
and the correct name should be “Tritonis”.
incorrect Trinitas → correct Tritonis

2019/02/06

Hayabusa2 reporter briefing

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MINERVA-II1:
correction to the landing site namerevisedMINERVA-II1 rover landing site

Nickname for the landing site for
the MINERVA-II1 rovers.

Tritonis
Tritonis, birthplace of the goddess,
Minerva

2018/9/21 at 13:02 JST
Altitude 70mwith the ONC-W1
2019/02/06(Image credit: JAXA / University of Tokyo / Koichi University / Rikkyo
University / Nagoya University / Chiba Institute of Technology / Meiji
University / University of Aizu / AIST)
Hayabusa2 reporter briefing

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MINERVA-II1:
correction to the landing site name
Revised

Official names

NoteTritonis & Alice’s Wonderland are nicknames for the MINERVA-II1 and MASCOT landing sites, respectively, and not place names recognized by the IAU.
image creditJAXA

2019/02/06

Hayabusa2 reporter briefing

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MINERVA-II1:
correction to the landing site name
Official names (in japanese)

Revised

6,0,-*'0*

2019/02/06



!&&MINERVA-II1MASCOT-+(.2/IAU#%&!!$"5 

3  (1)+,6JAXA4
35

Revised

MINERVA-II1:
correction to the landing site nameNoteTritonis & Alice’s Wonderland are nicknames for the MINERVA-II1 and MASCOT landing sites, respectively,
and not place names recognized by the IAU.

2019/02/06

Hayabusa2 reporter briefingImage creditJAXA
36

Reference material

2019/02/06

Hayabusa2 reporter briefing37

Small Body Exploration Strategy
How did the Earth become rich in water and life? What is needed to maintain these conditions?
 Small bodies born outside thesnowline are initially balls of icy mud(primitive comets) but can evolve intoa variety of forms (e.g. primitive
asteroid).
Transport of volatiles such as waterand organics to the terrestrial planet
region is thought to be essential forlife.
When, which stage of evolution ofthese celestial bodies, and how waterand organic matter was brought to theprimitive Earth is explored in thefollowing missions:- HAYABUSA2 (asteroid)- MMX (Martian moons)- DESTINY+ (asteroidcosmic dust)- CAESAR (comet)- OKEANOS (Jupiter Trojans)- JUICE (Jupiter), etc.
2019/02/06

Hayabusa2 reporter briefing

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Science of Hayabusa2:
birth & evolution of the Solar System
Subjects

Cross section

Planetoid

Primitive Solar System disk
(dust + gas)

 Investigate the materials that formed theplanets

Dust → Planetoid formation

What materials existed in the primitive
Solar System disk and how did it change
before the planets were born?

Coalescence of planets
Primitive planets
Terrestrial planet formation

Investigating the formation process ofthe planets

Gas giant formation

Loss of solar disk,
completion of Solar System

How do celestial bodies grow fromplanetoids to planets?


2019/02/06

Hayabusa2 reporter briefing39 Investigating the materials that formed the planets The Universe is thought to have begun 13.8 billion

years ago. After this, numerous elements were createdduring the evolution of stars and were dispersed into
outer space. About 4.6 billion years ago, the Solar
System was born and our goal is to clarify the types ofmaterial in space at that time.
 We aim to clarify the substance distribution in theoriginal Solar System disk.
 After the initial celestial bodies were formed, we seek
to clarify how materials evolved on these bodies.
↓
Revealing the materials that eventually became theplanetary body, sea and life
2019/02/06

Hayabusa2 reporter briefing

Keywords

 Pre-solar particlesParticles inheritedfrom the interstellar molecular cloudthat are in the Solar System.
 White inclusions  CAI   Substancesthat record the initial high temperaturestate of the Solar System.
 Mineral-water-organic matterinteractionDiversification of organic
matter in the original birthplace.
 Thermal metamorphism 
space
weatheringChanges of materials in
the celestial body after its initialformation.

40

Elucidation of organics by Hayabusa2
Volatile substances, such as water and organic matter, form on dust surfaces in molecular clouds. It is thought that thesechange due to aqueous metamorphism and thermal denaturation in primitive solar system discs and planetoids, eventually
accumulating on Earth and providing materials for life. We will clarify what kinds of substance existed during this process.

Planetoid

Molecular cloud → Primitive solar discAccumulation

AsteroidMetamorphosis

EarthTransition of carbon materials on dust surfaces
Interactions
between materials,
water, andorganics
2019/02/06

mineralsorganics

Earth
OceansLifeice water in minerals

Hayabusa2 reporter briefing

Chirality of amino acids
Life on Earth almost exclusively uses
left-handed amino acids. But why?
Left-handed (L-configuration) and righthanded (D-configuration) amino acids

41

 Investigating Planetary Formation
Rubble pile bodyDust(minerals, water, organics)

Planetoids

Impact Elucidate the structure of planetoids that eventuallybecame planets.

 Elucidate what processes occurred during the collisions,coalescence, and accumulation of celestial bodies.
↓
Elucidate formation processes from planetoid to planet
2019/02/06

Hayabusa2 reporter briefing

Metal
core

PlanetDifferentiatedbody

Keywords
 Rubble pile body A celestial body formed fromaccumulated rubble
 Impact fragment and coalescence: When celestialbodies collide, the resulting fragments can
combine to form a new body Re-accumulation: Accumulation of fragments
resulting from a collision via the force of gravity
42

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

image creditJAXA
2019/02/06

Hayabusa2 reporter briefing

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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)

2019/02/06

Hayabusa2 reporter briefing

44