Asteroid explorer, Hayabusa2,reporter briefing

January 8, 2019
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2:• Results from the solar conjunction
operation• Status of the plan for touchdown• Place names on the surface of Ryugu
2019/01/08

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 from the solar conjunction operation
3. Status of the touchdown operation
4. Place names on the surface of Ryugu
5. Other topics
6. Future plans
2019/01/08

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, andorganic matter in the primitive solar system. By doing so, we will learn about the origin and evolutionof Earth, the oceans, and life, and maintain 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 a crater 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 andafter projectile impact from an impactor.
Comparison with results from Hayabusa will allow deeper understanding of the distribution, origins,and evolution 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
new accomplishment.
This mission builds on the originality and successes of the Hayabusa mission. In addition todeveloping planetary science and solar system exploration technologies in Japan, this mission
develops new frontiers in exploration of primitive 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 scientificexchange, and expect further scientific findings through comparison and investigation of the resultsfrom both missions.

2019/01/08

Hayabusa2 reporter briefing(Illustration: Akihiro Ikeshita)
Hayabusa 2 primary specifications
MassApprox. 609 kg
Launch3 Dec 2014
MissionAsteroid returnArrival
27 June 2018
Earth return2020
Stay at asteroidApprox. 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, miniaturerovers.

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Mission FlowLaunch
3 Dec 2014

Earth swing-by
3 Dec 2015

Earth returnlate 2020

Sampleanalysis
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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

Createartificial
craterAfter confirming safety,
touchdown within the craterand obtain subsurface samples
Hayabusa2 reporter briefing

Release impactor

Use an impactor to create an
artificial crater on the asteroid’ssurface(Illustrations: Akihiro Ikeshita)51. Current project status & schedule overview
Current
status9– Solar conjunction ended on December 29, 2018 and operations for 2018
were completed on December 31.
– Operations for 2019 began on January 4.
– BOX-B operation is scheduled for January.
2015

Scheduleoverview

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2. Results of the solar conjunction operation• Solar conjunction11/2312/29• Ran as scheduled.

2018.12.31
2018.11.20
Earth

12/15
SunHill coordinates
A coordinate
system in which theSun direction isconstant and Ryugu
is at the origin.

2019/01/08

12/10
12/5

12/20

TCM1
11/30

12/25
TCM2

11/23
COI Ryugu

SunHPR
12/29

Ryugu

Position of the spacecraft in the Hill coordinate systemHayabusa2 reporter briefing

Relative position of the Earth and Ryuguimage creditJAXA7

2. Results of the solar conjunction operation
Solar conjunction orbit control operations:

NameDate

Degree of orbit control

COI

2018/11/23~14cm/s

TCM1

2018/11/30~ 0.4cm/s

TCM2

2018/12/25~ 1cm/s

HPR

2018/12/29~ 14cm/s  
        

2019/01/08

Ryugu imaged with the Optical Navigation Camera– Telescopic (ONC-T) on December 11 at around
21:00 JST. The distance to Ryugu was about 110 km.
This data was transmitted to the spacecraft on
December 21. Image creditJAXA
Hayabusa2 reporter briefing

82. Results of the solar conjunction operation
Beacon operation during solar conjunctionl When the spacecraft is located in the direction of the Sun as seenfrom Earth, communication with the spacecraft becomes difficult
due to radio waves emitted by the Sun and its surrounding plasma.
l Information from the spacecraft can be transmitted by using radio
wave signal strength to express either a “0” or “1” = Beacon
operation.
l 1byte=8bit of information is repeatedly transmitted five times andthe received radio fields superimposed. The transmission takes
about 10 minutes.
l Beacon operation was performed between 2018/11/30
2018/12/21. However, we managed to receive some form oftelemetry during most operations (from using the high gainantenna).
l At the smallest SEP angle on December 11, telemetry could not bereceived, but beacon operation was still established.

2019/01/08

Hayabusa2 reporter briefing

EarthSEPSpacecraftSun

RyuguOn 12/11, the SEP
angle was about 0.5
degrees.
93. Status of the plan for touchdown• The first touchdown (TD1) isplanned for the week of February 18(backup week is March 4).
• Another target marker will not bedropped. The target marker (TM-B)
that has already landed will be used.
• Touchdown candidate sites currently
under consideration are L08-B1 andL08-E1 (see right-hand figure).
TM-B position and touchdown candidate sites
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Hayabusa2 reporter briefing10

3. Status of the plan for touchdown
Wide region with
scattered rocks about
60cm in size. Relatively
far from TM.

Narrow but all rocks lessthan 60cm in size.
Relatively close to TM.

The DEM (Digital Elevation Map) used to accurately estimate the rockshapes near the touchdown candidate site.
Image creditJAXA
2019/01/08

Hayabusa2 reporter briefing11

4. Place names on the surface of Ryugu• Place names on the asteroid surface were discussed by the IAU (International AstronomicalUnion) Division F (Planetary Systems and Bioastronomy) Working Group for Planetary
System Nomenclature (hereafter referred to as WG).
• We first proposed a theme of “children’s stories” to the WG for place names on Ryugu.
(June 28, 2018).
• This theme was accepted by the WG (September 25) and we applied to the WG to name 13
notable geographical features that have been picked up in science papers (Application date:October 12).
• After an exchange with the WG, 9 names were accepted as proposed and 4 names werecorrected and then accepted.
• 4 different features types were named:– Dorsum = peak or ridge– Crater = crater– Fossa = groove or rut– Saxum = boulder
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4. Place names on the surface of Ryugu
Official names

Image credit
JAXA

NoteTrinitas and Alice’s Wonderland are nicknames of the MINERVA-II1 and MASCOT landing sites, respectively, and not place names recognised by the IAU.

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4. Place names on the surface of Ryugu
Official names in Japanese

Image credit
JAXA

2019/01/08



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4. Place names on the surface of Ryugu

NoteTrinitas and Alice’s
Wonderland are nicknames ofthe MINERVA-II1 andMASCOT landing sites,
respectively, and not place
names recognised by the IAU.

image creditJAXA
2019/01/08

Hayabusa2 reporter briefing15

4. Place names on the surface of Ryugu
NameRyujin

Type
Terrain description
Dorsum Equatorial ridge

Original story
Urashima TaroCountryJapan

Origin of nameDragon god who is Princess Otohime’s father

Urashima

CraterBiggest crater on Ryugu

Urashima TaroJapan

Fisherman who rescued the turtle

Cendrillon

CraterOne of the biggest craters outside the equatorial ridge

Cinderella

FranceThe French name for Cinderella 1

Kolobok

CraterTypical crater on the equatorial ridge

Kolobok

RussiaA small round bread that ran away from home 2

BraboCrater

Typical crater on the equatorial ridge

Brabo and the giant

Netherlands

The brave young man who defeated a giant 3Kintarou

Crater

5th largest crater on Ryugu

Kintarou

JapanThe child with super strength who grew up on Mt Ashigara

Momotarou

Crater

4th largest crater on Ryugu

Momotarou

JapanThe boy born from a peach who fought against an ogre

Kibidango

Crater

6th largest crater on Ryugu

Momotarou

JapanFood that Momotarou gave his friends

TokoyoFossa

Ryugu’s largest groove-shaped depression

Urashima TaroJapan

Tokoyo, a faraway land across the sea, the land of eternal life

HoraiFossa

Ryugu’s 2nd largest groove-shaped depression

Urashima TaroJapan

Horai, the utopia in the sea

CatafoSaxum

Boulder that denotes the prime meridian on Ryugu

Cajun Folktales

America

Boy who cleverly marked a route to avoid losing his way. 4Otohime

Saxum

Ryugu’s biggest boulder

Urashima TaroJapan

The princess who lived in Ryugu castle and entertained
Urashima and who gave him the treasure box (tamatebako).

Ejima

Saxum

One of the boulders that holds the key to Ryugu’s formation
Urashima Tarohistory.

JapanWhere Urashima rescued the turtle and left for Ryugu Palace.

1 “Cinderella” was proposed, but modified to the original French by the WG. 2 “Peter Pan” was proposed but changed due to copyright issues. 3 “Sleeping Beauty” was proposed but it
was suggested that the character number was too long, so “Brabo” was proposed and accepted. 4 “Oz” was proposed but this is used for Charon (moon of Pluto) so was changed by the WG.

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Hayabusa2 reporter briefing

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4. Place names on the surface of Ryugu
Supplement on namingboulders
Many boulders are distributed on the surface of Ryugu,
including a huge boulder near the South Pole. The existenceof boulders is important for characterising the surface layerof Ryugu and so we decided to name these features.
There was no precedent for the naming of boulders so noestablished name type. Therefore, we proposed a name type
for the boulders along with with the place name application.
Since the type is normally given in Latin, we suggested
Saxum (meaning “rocks and stones” in Latin) as a boulder
type and this was adopted by the IAU.
Note At the time of the Hayabusa mission, boulders on the surface of theasteroid Itokawa were not permitted to be named.
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Hayabusa2 reporter briefing

Asteroid Ryugu(Image credit: JAXA / University of Tokyo / Koichi University/ Rikkyo University / Nagoya University / Chiba Institute ofTechnology / Meiji University / University of Aizu / AIST)

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4. Place names on the surface of Ryugu
Supplement on naming: Otohime
As Otohime is an important person in the storyof Urashima Taro, we wanted to use the nameas one of the places on Ryugu, whose name isfrom the dragon palace in the same story.
As there is already a place named “Otohime
Tholus” on Venus, the proposed name wasinitially refused by the IAU. However, it wasaccepted after the team appealed on thegrounds of the importance of the name ofOtohime in the Urashima Taro tale.
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Hayabusa2 reporter briefing

185. Other“Imagining Ryugu” space art contest winning entries
The winning entries announced on December 27 on the Hayabusa2 Project website.
“Ryugu Look Alike” Grand Prize“Most Fun” Grand Prize“Most Imaginative” Grand Prize/ 6th grade elementary school
student [Akashi Municipal Planetarium]/ Lower grade elementary school student,
Osaka Prefecture [Japan Young Astronauts Club]/ 3rd grade high school student / Fukushima
Prefecture [Sekizaki Kaisei Museum, Oita]

 There were a further 15 winning entry announcements for different categories and age, 6 from overseas and 6 for the best effort.
http://www.hayabusa2.jaxa.jp/topics/20181227_Contest/Image credit: each creator
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Hayabusa2 reporter briefing

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6. Future Plans
Scheduled operations• Future operations: Main focus is the BOX-B operation during
January• Touchdown Week of February 18 (backup week of March 4)
Press briefings• February 6 (Wednesday) 1500 Press briefing @ Ochanomizu

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Hayabusa2 reporter briefing

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