Asteroid explorer, Hayabusa2,
reporter briefing

September 15, 2020
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2,
Extended mission selection

2020/9/15

Hayabusa2 reporter briefing

2

Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. Extended mission selection
3. Scientific significance of extended mission
4. Future plans

2020/9/15

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.

2020/9/15

Hayabusa2 reporter briefing(Illustration: Akihiro Ikeshita)

Hayabusa 2 primary specifications
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
LaunchDec 3, 2014

Earth swing-by
Dec 3, 2015

MINERVA-II1 separation
Sep 21, 2018

Ryugu arrival
June 27, 2018

Target marker
separation
Oct 25, 2018

Ryugu
departure
Nov 13, 2019

TargetmarkercompleteDec. 6, 2020
MINERVA-II2 separation
separation
Sept. 17,
(image credit: illustrations including spacecraft
Oct. 3, 20192019
by Akihiro Ikeshita, others by JAXA)

Earth return

2020/9/15

MASCOT
separation
Oct 3, 2018

Secondtouchdown
July 11, 2019

Targetmarkerseparation
May 30,2019

Hayabusa2 reporter briefing

Impactor (SCI)
5 April, 2019

First touchdown
Feb 22, 20195

1. Current project status & schedule overview
Current
status<– Precise estimate of the orbit of the spacecraft was made and from today (September 15),
the fine correction (TCM-0) of the orbit by the ion engine is planned.
– Narrowed down the extended mission– Continue preparation for recovery work
2015

Schedule
overview

123

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Hayabusa2 reporter briefing62. Extended mission selection

Scenario selection result••

There were 2 candidates for the Hayabusa2 extended mission and we planned to select one scenario after confirming thetechnical feasibility
After examination, the EAEEA scenario has been selected. -The final target celestial body is 1998 KY26.

Mission significance/ (1) Advancement in long-term navigation within the Solar System (2) fast-rotating small asteroid exploration (3)Acquisition of science and technology for planetary defense.
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01998 KY26 properties1
Spherical (from radar obs.)
About 30 m
10.7 min (0.178hr)
No short-term variability
detected
Possible carbonaceous asteroid

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2020/9/15

Hayabusa2 reporter briefing7

2. Extended mission selection

Background••

Originally, the spacecraft was designed on the assumption that the solar distance is in the range 0.85 – 1.41 au. But in bothscenarios, the solar distance will deviate from the design premise.
ØØ

EVEEA Sun distance range/ 0.711.64au
EAEEA Sun distance range/ 0.771.52auØØDeviation from the allowable temperature range of the onboard equipment near the Venus orbit (0.71 au) (0.77 au is no problem)
Operation restrictions for the ion engines in a high temperature environment (3 engines can be operated up to 0.85 au but even 1 engine isdifficult to operate at 0.77 au)

Further analysis and the conducted examination highlighted further specific issues:,#%$%#"#%#%$%#"-,#%!&$#%#%$%#"-

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period before/after Venus
swing-by : 144day

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2020/9/15

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Venus
1998KY26
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2001AV43
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2. Extended mission selection

Scenario comparison and selection
Evaluation

EVEEA

Eval.

Thermalfeasibility

When attitude is changed for observing Venus, thetemperature range for onboard eqipnebts exceed
the nomal range. (Max. Sun distance: 1.64 au)

Ion engine
conditions

Ion engine cannot be used for about 140 days
before/after Venus swing-by (0.71 au)

Scenario
feasibility

If trouble occurs during the Venus swing-by, the orbit
plan for the asteroid cannot be achieved (criticaloperation required in a high-risk environment)

≪

≪

EAEEA
Even at minimum solar distance (0.77 au), thetemperature range for onboard equipment does notexceed the mormal range. (Max. Sun distance: 1.52 au)
Ion engine cannot be used for about 100 days
before/after asteroid fly-by (0.77 au)
Even if the asteroid fly-by cannot be implemented, there
is no problem with the subsequent Earth swing-by andno major changes to the orbit plan are required.

• The difference between the minimum solar distance of 0.71au and 0.77au, as well as the timing of the mission
implementation make a big difference to the mission feasibility, and EAEEA is generally more feasible.
• In addition to the thermal analysis here, the model uncertainty cannot be determined because we have no experiences.
This results in a latent risk that should be supressed by minimising the deviation from the initial solar distance range.
• Conclusion
From a comprehensive judgement and evaluation from these situations, the EAEEA scenario with less deviation fromthe design premise for the solar distance range was selected in order to reduce risk.
2020/9/15

Hayabusa2 reporter briefing92. Extended mission selection
EAEEA scenario orbit sequence
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Venus
0.85AU
S/C

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Hayabusa2 reporter briefing

Earth
Venus
1998KY26
1.41AU
S/C

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10

2. Extended mission selection
EAEEA scenario mission sequence
time

Event

Engineering achievements

Science achievements

202126/7

Cruise operation

Acquisition of long-term fuel saving / laborsaving cruise operation technology

 Zodiacal light observation
 Exoplanet observation

2026/7

Asteroid2001 CC21
Fly-byAcquisition of asteroid proximity high-speed
flyby technology
Acquisition of technology that contributes toPlanetary Defense

Observation of L-type asteroids by closerange high-speed flyby.

2027/12

Earth swing-by 1

 Multi (3rd) Earth swing-by achieved

Calibration of on-board equipment
through lunar observations during Earthswing-by

Earth swing-by 2

 Multi (4th) Earth swing-by achieved

Calibration of on-board equipment
through lunar observations during Earthswing-byTarget body 1998
KY26 rendezvous

Progress of long-term deep space navigation(completion of the final phase)Acquisition of fast rotator exploration
technology
Acquisition of knowledge contributing toPlanetary Defense technology

Elucidation of the formation andevolution of fast rotating asteroids
Acquisition of science that contributes toPlanetary Defense

2028/62031/72020/9/15

Hayabusa2 reporter briefing11

3. Scientific significance of the extended mission
The great challenges of sending Hayabusa2 to an unplanned destination•

Long cruise over 10 years– Deterioration due to radiation of the optical system for the observation equipment and sensors.
•

Evaluation of equipment through stellar observations and those of the Moon during the Earth swing-by.

– Zodiacal light and exoplanet observations can take advantage of the long cruise.

•

Proximity high-speed fly-by observations of small asteroids•

The world‘s first rendezvous with a fast rotating micro-asteroid.

– Challenging observations for equipment not designed for a fly-by, such as the fixed cameras.

– Can we rendezvous and observe a small celestial body about 1/30 the size of Ryugu?
– Rotation period is about 10 minutes. The centrifugal force > force due to gravity, so target markers
cannot be used.

2020/9/15

Hayabusa2 reporter briefing12

3. Scientific significance of the extended mission
Scheduled scientific observations and expected outcomes

Mission phase

Expected scientific observationsExpected outcomes

Cruising

Zodiacal light observation*Long-term observation constrains the spatial distribution ofinterplanetary dust
Exoplanet observation*Follow-up of exoplanet search projects

Asteroid 2001 CC21 fly-by

Observations of L-type asteroids by proximity high-speed fly-by: an unexplored spectral typeobject, determining similarity to white inclusions (CAI) found in primitive meteorites.

Earth swing-by

Moon observationCalibration of on-board equipment and examination of any changes
during long-term navigation.

Asteroid 1998 KY26
rendezvous

Visible light observation: Elucidation of the characteristics of asteroids with a diameter ofseveral tens of meters.
Near/mid-infrared observation: Elucidation of physical and thermal properties of rapidly
rotating objects.
Comparative observation with Ryugu: Details comparison using the same observationequipment.
 Acquisition of information useful for Planetary Defense.

* see p. 20 and p. 21 for zodiacal light observations and exoplanet observations)
2020/9/15

Hayabusa2 reporter briefing13

3. Scientific significance of the extended mission
Characteristics of the asteroid to be explored

From JPL Small-Body Database•(98943) 2001 CC21 fly-by•

1998 KY26 rendezvous– Semi-major axis 1.032 au, eccentricity 0.219, orbital inclination 4.81º, orbital period 383 days.
– Absolute magnitude 18.4 mag, rotation period 5.02 hours, diameter 700m assuming albedo 0.15,shape unknown, L-type [R. P. Binzel et al. 2004, Meteor. Planet. Sci. 39, 351]

– Semi-major axis 1.233 au, eccentricity 0.202, orbital inclination 1.48º, orbital period 500 days.
– Absolute magnitude 25.5 mag, rotation period 10.7 minutes, diameter 30 10 m [S.J. Ostro et al. 1999,
Science 285, 557], close to spherical lower right figure, possibly carbonaceous (radar / visible albedo
is slightly low and there are signs of water presence).
– Passed Earth at a distance of 806,000 km on June 8, 1998. At this time, the shape etc was observed with
the Goldstone X-band radar in the USA.
   

2020/9/15

Hayabusa2 reporter briefing    

14

3. Scientific significance of the extended mission
Ryugu

1998 KY26, "%'!'. ((%##)%&'* %'*(( ".  #)%&'*$$ *$ $#)%&'* *$#)%&'*$*#)%&'*  #&''('$#$!$*#)%&'*#)%&'*$ +( %'- ". ((%##)%&'* 

2020/9/15

Hayabusa2 reporter briefing15

3. Scientific significance of the extended mission
From the perspective of Earth history and Planetary Defense•

If a celestial body with a diameter of several tens of meters collides with the Earth, greatdamage is expected to occur locally.

– The Chelyabinsk meteorite that fell on the Ural region of Russia on February 15, 2013, and injured
nearly 1,500 people, is thought to have had a diameter of 17m when it entered the atmosphere.
– The frequency of impacts with meteorites with a dimeter of more than 30m is thought to be about once
every several hundred years.

•••

However, the mechanical properties such as the strength of micro-asteroids, the rotation
state and physical properties are not well understood.
The role of collisions with micro-asteroids on the Earth’s history is not well understood.
It is expected that the world’s first proximity observation of celestial bodies less than 100m
in diameter will provide useful information, not only for elucidating the history of the
Earth but also for Planetary Defense.

2020/9/15

Hayabusa2 reporter briefing

16

4. Future plans
Operation schedule
Around 2020/9/1516 Fine orbit correction with the ion engines (TCM-0)
2020/10
Final re-entry guidance
2020/12/6
Re-entryPress and media briefings
2020/10TBD
Press briefing @ online TBD

2020/9/15

Hayabusa2 reporter briefing

17Reference material

2020/9/15

Hayabusa2 reporter briefing18About 1998 KY26
4 Discovered by the US Spacewatch
Project on May 28, 1999 (theclosest distance to Earth at thetime was about 800,000 km)
4Radar observations made in June,
1998 5by S. Ostro6.
4 Approximately 30m in size,
rotation period 0.1784 hours510.7
minutes6
%,")+!"(4Semi-major axis71.23au, orbital)$" -"!&/ 00-**&1"-.&/2
period71.37 years 5500days6
  +-&$&*(!/#+-/%".%,")+!"(7./-+ "/(!-*!+,/& (+."-1/&+*.+#./"-+&!  
 &"* "    
3 

2020/9/15

Hayabusa2 reporter briefing

- ' ),7
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-"+#",/")"- )$" -"!&/

19

About zodiacal light observations
Observations from Hayabusa2

What is zodiacal light?

We aim to clarify the density and structure ofinterplanetary dust near the Earth by observing
zodiacal light at multiple points away from the Earth.

Scattering sunlight by solid
particles (interplanetary dust) withsizes about 0.1- 100 micrometeres
floating in interplanetary space.
 It is important to explore the
distribution and origin ofinterplanetary dust throughobservations of zodiacal light inorder to understand the whole
picture of material transport
through the Solar System: thescientific goal of Hayabusa2.
Zodiacal light observations ininterplanetary space beyond theEarth’s orbit have not been
observed since the Pioneer
spacecraft in the 1970s
2020/9/15

Zodiacal light

The brightness of the zodiacal light will be
determined by regularly conducting observations
with the ONC-T and measuring the ‘brightness ofouter space’ where celestial bodies such as stars are
not visible.
Test observations
were conductedduring the return trip,
confirming thatzodiacal light could be
detected with therequired accuracy.

Provided byKoji Onishi

Test observation of the Milky Way
Image creditJAXA, AIST, University of Tokyo, Kochi University, Rikkyo University,
Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu.

Hayabusa2 reporter briefing

20About exoplanet observations
Purpose– Accurate observations of the diameter and transit time of exoplanets around bright stars thatwill be targets for high-precision spectroscopic observations in the future.
– Development of exoplanet observation technology using satellite-mounted photodetectors.
Background– Expected to be the first exoplanet observation by Japanese satellites/spacecraft.
– High-precision telescopes have large apertures, so they are not well suited for observing
bright stars.
– In orbit, Hayabusa2 can take stable observations regardless of weather or temperature. Since
the ONC has a small aperture, it is suitable for observing bright stars.
MethodTransit technique– Principal: Measure the size of the planet and the distance to the host star by identifying thedimming of the host star due to the planet passing in front of the host star.
– Specific method The same star is imaged multiple times over a long period (often 3 – 10hours) to examine the temporal change in light. Basically the same as Ryugu observations
during the approach phase.
2020/9/15

Hayabusa2 reporter briefing21

2 celestial bodies in the final candidate selection for the extended mission
 Characteristics of 1998 KY26

Characteristics of 2001 AV43

small3040m
rapid rotationspin period: about 10 minutes
↓Is this a rubble pile or monolithic?
Earth approach at a distanceof approximately 300,000km
on 2029/11/11 ← Hayabusa2
rendezvous at the time of thisapproach
Shape
Av. diameter
Spin period
Tumbling motion
Spectral type2020/9/15

Elongated, aspect ratio: ~0.5 (from light curve
observation)
About 40m
10.2 min (0.17hr)
No short-term variability detected
Possible S-type, uncertain

Possible C-type asteroid,
offering interesting comparison
with Ryugu and Bennu

Shape
Av. diameter
Spin period
Tumbling motion
Spectral type

Spherical (from radar observation)
About 30m
10.7 min (0.178hr)
No short-term variability detected
Possible carbonaceous asteroid

Image credit Auburn University, JAXA

Hayabusa2 reporter briefing

22Relationship between asteroid diameter androtation period
1998 KY26

unexplored2001 AV43

Rotation period (time)0.01

         
    1

100

10000

purple NEA
blue MBAyellow >5AU

0.01



1

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2020/9/15

Hayabusa2 reporter briefing

23Prediction of asteroid collision frequency
Tunguska event " !&# "

1 disaster every
100 ~ 200 years!

observation 

'!$!! !!"! !$"
2020/9/15

pr
ed
ict
ion

Mass extinction

Average collisioninterval (years)

Approximate size of2001 AV43 and 1998 KY26

$$#%$!

Chelyabinsk meteor#!      (Hayabusa2 reporter briefing

24Return cruise operation plan
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2020/9/2

Hayabusa2 reporter briefing��� ����6����6���6������
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25

Operation plan for re-entry terminal guidance

TCM-0

Capsule separation
around 12/5 14:00-15:00 JST~220,000 km from Earth

Orbit fine adjustmentusing RCS, same for later TCMs
(around 10/20– 26, ~17M km from Earth)Orbit fine adjustment(around 11/2-19, ~12M km from Earth)

TCM-1

TCM-2

Te
(O rmin
cto albe Gu
r idanc)ePha

Targeting to Woomera(around 11/25-19, ~3.5M km from Earth)

TCM-3

Change to Earth departure trajectoryaround 12/5 15:00-17:00 JST
~200,000 km from Earth

Orbit fine adjustment(around 12/1. ~1.8M km from Earth)

TCM-4

Capsuleseparation

se

TCM-5

• May change depending on conditions.
• At TCM-0,1,2, the spacecraft will enter an orbit that passes more than 200 km away from the Earth.
• After capsule separation, the spacecraft will divert from the reentry trajectory by TCM-5.
2020/9/2

Capsule landingaround 12/6 2:00-3:00 JST 

Hayabusa2 reporter briefing

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around 9/15-21, ~36M km from Earth)TCM: Trajectory Correction Maneuver

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26