Asteroid explorer, Hayabusa2,reporter briefing

July 22, 2020
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2,
Extended mission

2020/7/22

Hayabusa2 reporter briefing

2

Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. Extended mission proposal: background
3. Extended mission: review process
4. Extended mission: plan outline
5. Future plans

2020/7/22

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.

2020/7/22

Hayabusa2 reporter briefing(Illustration: Akihiro Ikeshita)

Hayabusa 2 primary specifications
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.

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Mission flow
LaunchDec 3, 2014

Earth swing-by
Dec 3, 2015

MINERVA-II-1 separation
Sep 21, 2018

Ryugu arrival
June 27, 2018

Target marker
separation
Oct 25, 2018

Ryugu
departure
Nov 13, 2019

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

Earth return

2020/7/22

MASCOT
separation
Oct 3, 2018

Secondtouchdown
July 11, 2019

Targetmarker
separation
May 30,2019

Hayabusa2 reporter briefing

Impactor (SCI)
5 April, 2019

First touchdown
Feb 22, 20195

1. Current project status & schedule overview
Currentstatus<– The 2nd ion engine operation and work for the return of the re-entry capsule to Earth isongoing.
– Discussion and consideration for an extended mission.
– Scientific papers have been submitted and published.
2015

Schedule
overview123

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Hayabusa2 reporter briefing62. Extended mission proposal: background• After leaving the Earth, Hayabusa2 can continue deep space flight with an orbit
control capability equivalent to 1.7 km/s.
• All initial objectives of the mission will have been meet, and extended operation
would provide a rare opportunity to hone challenging on-orbit operation techniques.
• When aiming for another celestial body, it is possible to reach new scientificachievements at much better cost performance than when designing a new mission.

Propose a mission afterleaving Earth(“extended mission”)

Capsule atmosphere re-entry (December 6, 2020)
Change of orbit to leave Earth

Extended mission

TCM-4
TCM: Trajectory
Correction Maneuver

2020/7/22

Capsuleseparation

Remaining trajectory
control ability1.7km/s

TCM-5

Hayabusa2 reporter briefing    7

3. Extended mission: review process
Examples from the study of orbits after Earth departure.
Earth→Earth→AsteroidAsteroid flyby/impact

Earth→Earth→Mars→Mars→MarsMars multi-flyby

Hayabusa2

Earth→Venus→Earth→Earth→towards Jupiter
Venus flyby observations and distant flightdemonstration.
    22030    12028

   2026

Earth→Asteroid→Earth→Earth→Asteroid
Asteroid flyby and asteroid
rendezvous
Hayabusa2

Hayabusa2  2032

1998 KY26
2001 CC21

2020/7/22

Mission typeFly-by exploration Passing by celestial bodies at high speed.
Trajectory design is relatively easy.
Rendezvous exploration Arrives and stays at the celestial body.
Trajectory design is difficult.

Hayabusa2• Hayabusa2 enters into an orbit between Venus and the Earth due tothe influence of the Earth’s gravity (swing-by effect) after leaving
the Earth.
• After that, celestial bodies were identified that could be reached with
the ion engines and planetary swing-bys (Earth, Venus etc.).
Search for target celestial bodies
Venus, Earth, Mars, asteroids, comets (Hayabusa2 solar cells canoperate up to Mars distance)

Hayabusa2

Earth→Venus→Earth→Earth→Asteroid
Venus flyby + asteroid rendezvous• First, we searched for potential orbits from the viewpoint of orbitfeasibility (celestial mechanics) with the residue orbit control
capability of Hayabusa2.

  

Planets vs small bodiesasteroidscomets
• Only fly-by is possible for planets. Planets can be used for swing-by,
but arrival & orbit is not possible with Hayabusa2’s ability.
• Fly-by, impact & rendezvous are possible for small celestial bodies.

Hayabusa2 reporter briefing83. Extended mission: review process
Search for possible small bodies (asteroids / comets) for rendezvous

Search for candidate bodies• Search for asteroids/comets that can be reached with fuelspeeds of 1.7 km/s or less from the 18002 celestial bodies
that pass through the Earth’s orbit.
• “Rendezvous” has a priority over “fly-by” in the search.

Total reachable celestial bodies354
Required speed
increase km/s

pof o r s s ib
a n r e n le c adl dne s s e z v d idc o o us ate snsum (e ar of s
p t lie m aio n r a llo f r r iv b o df u a l ie se l) t ime

Arrival dateüüü

ItemsNoAbsolute magnitude less than 22 deg(Approximate diameter : larger than 140m)

17

Rader observation30

After the departure from the Earth : arrives within 6 years
arrives within 7 years
arrives within 8 years

21331

Binary0

Quasi-satellite, mini-moon

0Known spin period

23

Rader observation is possible in future

6

Reachable via Venus

1

There are no celestial bodies (planets or small bodies) that can be reached within a short period ( 1 ~ 5 years)
We found many rendezvous candidate asteroids around 10 year travel via an Earth or Venus swing-by in 4 ~ 10 years after Re-entry.
These candidates were further narrowed down from the viewpoint of operation feasibility and scientific value.
    
2020/7/22

Hayabusa2 reporter briefing93. Extended mission: review process•

The top two celestial bodies were selected by narrowing down the asteroids that satisfy the following
constraints and have a high score from the viewpoint of engineering and science.

Constraints
 Arrival date before 2031/12/31
 ΔVbelow 1.6 km/s
 Sun distance is not too far at arrival date.
 Trajectory is well understood.

Engineering feasibility

Science value

Certainty of asteroid orbit

size

Observability from groundSpin rate

Trajectory plan feasibility

ShapeFeasibility of spacecraft
operationType
comprehensive evaluation

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Hayabusa2 reporter briefing10

4. Extended mission: plan outline
About the 2 candidate celestial bodies

 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 type2020/7/22

Elongated, aspect ratio: ~0.5 (from light curveobservation)
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 briefing11

4. Extended mission: plan outline• Created mission plans for 2001 AV43 and 1998 KY26
• Finally choose one of these two )&("' '*$$(*"'& #%)
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2020/7/22

VenusEarth
2001AV43
S/C

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Hayabusa2 reporter briefing-1-0.500.5

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4. Extended mission: plan outline
Significance of targets 2001 AV43 and 1998 KY26(1) Progress in long-term navigation technology within the Solar System(2) Realisation of fast rotating small asteroid exploration(3) Acquisition of science and technology for planetary defense! %#&$' ,!#$' #&$!"#%! , &&%! !! %#!"#%! #$&%$!# +

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$ #!! ).

% &$!#%Venus fly-by-swing-by.→(1)(EVEEA scenario only)$%#!%% $$%#!# *'!&$+ 

Images of Earth captured by Hayabusa2
during swing-bys

Venus image credit/PLANET-C Project Team

2020/7/22

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Hayabusa2 reporter briefing-#%/  .
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4. Extended mission: plan outline
Significance(1) Progress in long-term navigation technology within the Solar System••Acquire operation technology necessary for more flexible exploration at greater distances, based on engineeringachievements until Earth-return.
– Ultra-low fuel consumption operation and ultra long-term maintenance technology for spacecraft system .
–Experience of ion engine operation technology, acquisition of long-term performance.

–Navigation technology for Solar System multi-flyby with ion engines.

Perform scientific observation during long-term navigation and at fly-by.
–

Observation of zodiacal light and exoplanets––

Observations during Venus fly-byEVEEA scenario
Observations during asteroid fly-byEAEEA scenario

–Moon observations during Earth fly-by    
2020/7/22

Hayabusa2 reporter briefing

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4. Extended mission: plan outline
Significance(2) Fast rotating small asteroid exploration•

This is an unexplored system that has never been visited so far, making an extremely attractive exploration target.
• How such asteroids form is a mystery (they could be monolithic, but an rubble pile is also possible)• On the surface of such asteroids, the centrifugal force should dominate gravity.
Descent trajectory
Monolith?

TMCentrifugal force
exceeds gravity, TM
cannot be placed

accumulation

Fast rotatingsmall asteroid    ••Comparative observations with Ryugu can further deepen the scientific knowledge obtained from Ryugu.
New asteroid exploration technology can be expected to be acquired due to the approach in a special dynamicenvironment.

2020/7/22

Hayabusa2 reporter briefing15

4. Extended mission: plan outline
Significance(3) Acquisition of science and technology that contribute to Planetary Defense
What is Planetary Defense• Activities to prevent disasters caused by celestial bodies colliding with the Earthalso called ‘spaceguard’.
• The collision between the Earth and a small celestial body about 10km is regarded asa possible cause for the extinction of many species including the dinosaurs about 66
million years ago.
• Even below the scale of the dinosaur extinction, the collision of a celestial body witha size of 10s of meters will cause great damage locally (e.g. Tunguska event in 1908,
Chelyabinsk Meteor in 2013).
• The frequency of collision with celestial bodies several 10s of meters in size is about
1 every 100 – several 100 years.
Illustration: Akihiro Ikeshita
Extended mission
• Investigate the characteristics of asteroids with a size of 10s of meters that are capable of causing great regional damage(world first).
• Refining exploration technology in the vicinity of an asteroids with size 10s m obtains knowledge to contribute toPlanetary Defense technology. (world first)• In the EAEEA scenario, ultra-close fly-by/impact technology will also be acquired.

2020/7/22

Hayabusa2 reporter briefing16

4. Extended mission: plan outline

Conclusion (summary)• Built a scientific scenario based on criteria that “celestial bodies that arereachable” and “celestial bodies that are high-value”.
• Key points:– Acquisition of Solar System navigation technology utilizing ion engines + swing-by.
– Fast Rotator– Science and technology related to asteroids approaching the Earth= Planetary Defense• Based on consideration of “operational feasibility” and “scientificsignificance”, we narrowed down the candidates to two asteroids.

– A mission plan was prepared for each of the two scenarios.
– Currently, we are finalizing the two scenarios from the standpoint of their feasibility. We
plan to select one of these by the end of this fall, whereupon it will become the final plan.

• Since this will be a long-term mission of about 10 years, the policy will be togradually accumulate results during flight.
2020/7/22

Hayabusa2 reporter briefing17

5. Future plans
Operation plans
2020/5/129
Continuation of 2nd ion engine operation until
around September.
2020/10Re-entry precision guidance
2020/12/6
Re-entryPress and media briefings
2020/8TBD
Press briefing @ onlineTBD
2020/7/22

Hayabusa2 reporter briefing

18Reference

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Hayabusa2 reporter briefing

19Return cruise operation plan
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2020/7/22

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Earth return final guidance phase
Ion engine TCM
Mid September,37M km from Earth)
Capsule reentryDecember 6TCM: Trajectory Correction
Maneuver

Small trajectory adjustment
Using RCS, same for later TCMs

TCM-2Te(O rmin
cto albe Gur idanc)ePhaEscape Maneuver

Small trajectory adjustment

TCM-1

Targeting to Woomera

TCM-3

Targefor t traTC ject
M- or0,1 y,2TCM-0

Final adjustment

TCM-4

Capsuleseparation

seTCM-5• Implementation date of each event is currently undecided.
• 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.
2020/7/22

Hayabusa2 reporter briefing

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Search for candidate objects
The search for celestial bodies that can be reached by around 2030, based on the remaining spacecraft fuel,operating conditions, and a scientific study of celestial bodies, resulted in two small body candidates forrendezvous.

               

Orbit transition
diagram of candidate
celestial bodies   !
2020/7/22

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



1Diameter km100   
2020/7/22

Hayabusa2 reporter briefing

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

1 disaster every
100 ~ 200 years!

observation 

'!$!! !!"! !$"
2020/7/22

predictionMass extinction

Average collisioninterval (years)

Approximate size of2001 AV43 and 1998 KY26

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

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

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