Asteroid explorer, Hayabusa2,reporter briefing

October 29, 2020
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2,・Results of TCM-1
・Preparation status for capsule collection
・Ground observations of Ryugu
・Outreach2020/10/29

Hayabusa2 reporter briefing

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Contents
0. Hayabusa2 and mission flow outline
1. Current status and overall schedule of the project
2. Results of TCM-1
3. Preparation status for capsule collection
4. Ground observations of Ryugu
5. Re-entry open call for observations
6. Outreach / public relations
7. Future plans
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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 positioning：
・Japan 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.

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Hayabusa2 reporter briefing(Illustration: Akihiro Ikeshita)

Hayabusa 2 primary specifications
MassApprox. 609 kg
Launch3 Dec 2014
MissionAsteroid return
Arrival27 June 2018
Deoarture
13 Mov 2019
Earth return6 Dec 2020 (plan)
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-II1 separation
Sep 21, 2018

Ryugu arrival
June 27, 2018

Target marker
separation
Oct 25, 2018

Ryugu
departure
Nov 13, 2019

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

Earth return

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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 final guidance phase began in October, and TCM-1 was performed on October 22,
which corrected the orbit as planned.
– Part of the capsule recovery team have begun domestic quarantine ahead of the move toAustralia.
2015

Scheduleoverview

123

InitialoperationEvent2016
10 12EDVEGA2017

4Journey to asteroid

launchEarth swing-by(Dec 3)

ESA（MLG/WLH）
Southern hemisphere station
test operations
operations (CAN/MLG)(May 21 - 22)
OctMayJun

2019

Mar2020

6 7approach

Swing-by(Dec 3)Ion engine operations※ Mar

2018

May

12

12

Re-entry
Earth return

Asteroid proximity operations

Arrival at Ryugu

Departure from Ryugu(June 27)

(Nov 13)

Capsule re-entry(Dec 6, 2020)

Optical navigation Solar conjunction
May Jul Nov Dec
Nov

AprJanJunDec

FebMaySept.

（image credit：JAXA）
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Hayabusa2 reporter briefing62. Results of TCM-1• The first orbit control for the final re-entry guidance phase, TCM-1,
was performed on October 22, and the orbit correction was achieved
as planned（TCM: Trajectory Correction Maneuver）.
• The orbit correction was made by the chemical engines (RCS) at
around 18:00 JST. At around 19:00, an acceleration correction (trimΔV) was performed.
• The orbit control amount was about 15cm/s. The closest altitude tothe Earth has changed from about 400 km to about 330 km.
• The spacecraft condition is normal.
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3. Preparation status for capsule collection
Spacecraft operation rehearsal
The CPSL operation• As with the critical operations near the asteroid, real-time operation training using the Hayabusa2 simulator(HIL) and rehearsals with the actual spacecraft are planned.
• On September 26, real-time operation training using HIL was conducted covering the CPSL separation toTCM-5, including response to contingency cases. Based on the training results, we are updating theprocedure manual.
• A CPSL separation operation rehearsal using the actual spacecraft is scheduled for November 4, and theprocedure is currently being prepared.
The TCM operation• From September 28, a dry run of the series of work from orbit determination to orbit correction (ΔV )procedure creation was carried out as the TCM rehearsal. This confirmed the procedure and preparation
status from offline work to operation.
• TCM-1 was carried out without any delays on October 22.
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Hayabusa2 reporter briefing83. Preparation status for capsule collection
Preparation status of the capsule recovery team
• Start the move towards capsule collection.
• Capsule collection team: 73 people in total (preliminary team (14 people) and main team (59 people)).
• The coronavirus situation in Australia is calm. However, depending on the situation, interstate travel may require twoweeks of quarantine, so we will travel directly to Adelaide, south Australia by charter plane.
• Preliminary team：
10/24：
Domestic quarantine began
11/1：
Departure (Haneda → Adelaide）
until 11/15：
2 weeks quarantine in Adelaide
11/16：
Woomera arrival, preparations begin.
• Main team：
11/1：11/9：
until 11/23：
11/24：
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Domestic quarantine began
Departure (Haneda → Adelaide）
2 weeks quarantine in Adelaide
Arrive at Woomera and begin work
Hayabusa2 reporter briefing

9October – December 2020 is an opportunity to observe Ryugu at alarge phase angle (Fig. 4-1, 4-2).
Dark asteroids such as Ryugu are expected to show a high degree ofpolarization when observed at a phase angle of 90 – 100 degrees, butthere are few observations of similar objects (Fig. 4-3).
The polarization of Bennu has been measured, but only for a phaseangle of just 57 degrees (Cellino+2018).
The ground observation subgroup is planning polarized imaging
observations of Ryugu using four telescopes in Japan and overseas(Hiroshima University, University of Hyogo, Hokkaido University
and Bohyunsan Optical Astronomy Observatory. If we miss thisopportunity, we have to wait 13 years for next time.

Figure 4-1
Explanatory drawingof phase angles(Credit: KyotoUniversity)

Scattering
surface

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ObserverasteroidSun

linear polarization (%)

Overview:

predicted magnitude distance from thephase angle (deg) of V-band
Earth center (au)

4. Ground observations of Ryugu

phase angle (deg)Figure 4-3
Asteroid phase angle – polarization plot. Data
from Kuroda+2018; Ito+2018; Shinnaka+2018;
Cellino+2018; Cellino+2005;
Ishiguro+2017; Ishiguro+1997; Mukai+1997;
Kiselev+2005.
(Credit: Kyoto University)

days
Figure 4-2
Ryugu phase angle, magnitude, geocentric
distance (credit: Kyoto University)

Hayabusa2 reporter briefing10

4. Ground observations of Ryugu
Expected result:・Do dark (low albedo) asteroids truly show high polarization?
Preliminary predictions suggest Ryugu will exhibit a degree of polarization of over 30%.
・It may be possible to clarify the mechanism of polarization that occurs on the surface ofasteroids.
From previous studies, there is an expected close relationship between the degree of polarizationand the surface particle size. Ryugu is the optimal and essential target to verify this, as the surface
conditions have been well investigated. It may be possible confirm the presence of smaller
particles that were not visible in close-up images of Ryugu (Fig. 4-4) (suggested by Morota+2020).

Figure 4-4
DLR camera MASCAM on MASCOT (Grott+2019)(Credit: MASCOT/DLR/JAXA)

Progress:
In October 2020, polarized imaging data was acquired at the observatories of three universities inJapan (Fig. 4-5). Observations will continue in November and December, with the final results
expected after the end of 2020.

Collaborators:
Daisuke Kuroda (Kyoto University), Sunao Hasegawa, Makoto Yoshikawa (JAXA),
Masateru Ishiguro (Seoul National University), Hiroshi Akitaya, Koji Kawabata (HiroshimaUniversity), Jun Takahashi, Miyako Tozuka, ASoi Kawakami (University of Hyogo),
Hiroyuki Naito (Nayoro Observatory), Tomohiko Sekiguchi, Koki Takahashi (Hokkaido
University of Education), Seiko Takagi, Kiyoshi Kuramoto (Hokkaido University)

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Hayabusa2 reporter briefing

Figure 4-5
Polarization imaging data forOctober 2020 (credit Hokkaido
University / University of Hyogo/ Hiroshima University)114. Ground observations of Ryugu
Recent images to Ryugu

Observation date & time: October 18, 2020, 19:53 – 19:58 JST (exposure time: 60 seconds x 3)
Observation site : Hokkaido University Astronomical Observatory (Nayoro City, Hokkaido)
Location： Near Pegasus

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Hayabusa2 reporter briefing(animation)(Credit: Hokkaido University / Kyoto University)

125. Open call for re-entry observations
・We held an open call for participants to observe the re-entry capsule and joint research agreements are signed for the following 7 cases.
・However, the novel coronavirus made it difficult to execute observations for these joint researches.
・To the extent possible, collaborative research with Australian researchers or proxy observations by project members will be performed.
Research title

Representative （affiliation）

How to do

GNSS observations of ionospheric disturbances generated by the re-entry of Hayabusa2

ITO Takeko (Nagoya University)
Phil R. Cummins （Australian National University)

Australia
collaborative project

VLF Observation of the Hayabusa-2 Sample Return Capsule Re-entry

KOBAYASHI Miki (Nippon Meteor Society)

JAXA proxyobservation

Spectroscopic observation of meteors using a grating

MINO Shotaro/SAITO Koichiro(Furukawa Reimei High School）

JAXA proxyobservation

NUV-VIS Spectroscopy of Meteor Train and Afterglow Plasma caused by Hayabusa2
Reentry Capsule

ABE Shinsuke (Nihon University)

JAXA proxyobservation

The project to receiving the message of Hayabusa2 ! ～Research of Meteor Bursts Caused
by Atmospheric Re-entry Objects～

KAWACHI Kohei (Chubu University)
TANAKA Kouki (University of Tokyo)
KAWAMURA Tomoya (Aichi Institute of Technology)
NAKAYAMA Nao (Doshisha University)

JAXA proxyobservation

Measurement of plasma size of the re-entry capsule by high magnification video
observation
Detailed observation of overpressure (infrasonic) and induced seismic waves generated byshock waves on HAYABUSA 2 earth-reentry and its trajectory determination

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IIYAMA Ohmi (Osaka science museum)

YAMAMOTO Masa-yuki （Kochi University of Technology）「はやぶさ２」記者説明会

Not implementedAustralia
collaborative project13

6. Outreach & public relations
Ryugu & Hayabusa2 return observation campaign• Currently, there is an opportunity to observe Ryugu (brightness of Ryugu: about 17mag).
※ This is the second Ryugu observation campaign (previous campaign was conducted in2016).

• Immediately before re-entry, there is the possibility to observe the Hayabusa2spacecraft.
• Organizer： Hayabusa2 Project, Japan Public Observatory Association (JAPOS),
The Planetary Society of Japan (TPSJ)• Observers recruited from November 1• Campaign URLs:
JAPOS https://www.city.himeji.lg.jp/atom/planet/info/campaign/haya2return/index.html
TPSJ http://planetary.jp/Haya2-Special/projects/hayabusa2-serv.html
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Hayabusa2 reporter briefing

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7. Future plans■Schedule of operation
2020/11/2〜19
TCM-2
2020/11/25〜29
TCM-3
2020/12/6
Re-entry■Press and media briefings
2020/11 （TBD）
Press briefing @ online （TBD）

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Hayabusa2 reporter briefing

15Reference material

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Hayabusa2 reporter briefing

16Return cruise operation plan
Return phase orbit map

Hayabusa2 orbit
Ryugu orbit
2nd ion engine operation(May 12,2020~ Sept 17, 2020）
Earth orbit
Sun

Re-entry terminal guidance(Oct 2020～）

Earth re-entry(Dec 6, 2020)

Ryugu departure（Nov 13, 2019）（image credit：JAXA）
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Hayabusa2 reporter briefing

1st ion engine operation（Dec 3, 2019 ～ Feb 20, 2020）17

Operation plan for re-entry terminal guidance
Ion engine TCM（9/17, ~36M km from Earth)

TCM-0Done※TCM: Trajectory Correction Maneuver
Capsule separation（around 12/5 14:00-15:00 JST，~220,000 km from Earth）

Orbit fine adjustment（using RCS, same for later TCMs）
Done(around 10/22, ~17M km from Earth)

TCM-1

Orbit fine adjustment(around 11/2-19, ~12M km from Earth)

TCM-2

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

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.
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Capsule landing（around 12/6 2:00-3:00 JST ）Hayabusa2 reporter briefing（Image credit：JAXA）

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Supplementary information on polarization observation
What is polarized light?
Light (electromagnetic waves) is a transverse wave that travels due to electric and magnetic fields
vibrating (changing) on a planet perpendicular to the direction of travel. The vector magnitude anddirection bias of the electric field oscillations in this vertical plane is the polarization. There arelinearly polarized light and circular and elliptical polarized light depending on how the electric field
vibrates.
What is the degree of polarization?
The degree of polarization is the ratio of the polarized states, where one completely polarized state(fully polarized) is 1 and unpolarized is 0. States in between are referred to as partial polarization,and the degree is indicated by a value between 0 and 1. Unpolarized light (natural light) is randomly
polarized and the polarized state is unknown.

Explanatory diagram of polarized light
Credit (Miyazaki & Ikeuchi, 2008, IPSJ Journal 64-72)

Typical example
When light is reflected or refracted, the vibrational direction does not change but in order to change
the direction of travel, only the vertical component remains. This can suppress reflection intensities
such as for polarized sunglasses.

Polarization observation
The intensity of the light collected by the telescope is measured by separating the polarizing
components using a polarizing element. High-precision polarized light observations often use awave plate and polarizing element to measure two components of the polarized light at the sametime.

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Hayabusa2 reporter briefing

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Observations during Earth swing-by on 2015/12/3
Observations of Hayabusa2's Earth swing-by with ground-based telescopes → observations reported from a total of 39
locations in Japan and overseas.

Change in apparent magnitude of Hayabusa2

apparent magnitude

Position where Hayabusa2 was imaged

Plots of the observed positions of Hayabusa2. Hayabusa2
moves from left to right across the figure. At 18:48,
Hayabusa2 entered the shadow of the Earth and could not be
observed.
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Hayabusa2 reporter briefing

time（image credit：JAXA, JAPOS, TPSJ）
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