Operation status for the asteroid explorer,
Hayabusa2, in the vicinity of Ryugu

August 2, 2018
JAXA Hayabusa2 ProjectTopics
Regarding Hayabusa2:
RCurrent mission status
RScienceSLIDARQNIRS3Qshape modelT
RMission schedule
RCooperative research

NoteTLIDAR\laser altimeterQNIRS3\near-infrared spectrometerContents
0UHayabusa2 & mission flow outline
1UProject status & overall schedule
2UInitial observational results with the laser altimeter
3UInitial observational results with the infrared spectrometer
4UShape model of Ryugu
5UMission Schedule
6. Cooperative research
7UFuture plans

Overview of Hayabusa2
ObjectiveWe 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 the primitive solar
system. By doing so, we will learn about the origin and evolution of Earth, theoceans, and life, and maintain and develop the technologies for deep-space return
exploration (as demonstrated with Hayabusa), a field in which Japan leads theworld.

Expected results and effects
RBy exploring a C-type asteroid, which is rich in water and organic materials, wewill clarify interactions between the building blocks of Earth and the evolution of
its oceans and life, thereby developing solar system science.
R Japan will further its worldwide lead in this field by taking on the new challenge ofobtaining samples from a crater produced by an impacting device.
RWe will establish stable technologies for return exploration of solar-system bodies.

Features:
RWorld’s first sample return mission to a C-type asteroid.
RWorld’s first attempt at a rendezvous with an asteroid and performance ofobservation before and after projectile impact from an impactor.
RComparison with results from Hayabusa will allow deeper understanding of the
distribution, origins, and evolution of materials in the solar system.

International positioning[
RJapan is a leader in the field of primitive body exploration, and visiting a type-C
asteroid marks a new accomplishment.
RThis mission builds on the originality and successes of the Hayabusa mission. In
addition to developing planetary science and solar system exploration
technologies in Japan, this mission develops new frontiers in exploration ofprimitive heavenly bodies.
RNASA too is conducting an asteroid sample return mission, OSIRIS-REx (launch:
2016; asteroid arrival: 2018; Earth return: 2023). We will exchange samples andotherwise promote scientific exchange, and expect further scientific findings
through comparison and investigation of the results from both missions.

(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.

Mission flow
Launch3 Dec 2014

Arrival at asteroid#une 27, 2018P▲
Earth swing-by
3 Dec 2015

Examine the asteroid by remote sensing
observations. Next, release a small lander androver and also obtain samples from the surface.

Earth returnlate 2020

Depart asteroid
Nov–Dec 2019

Create artificial
craterSample analysis(Illustrations: Akihiro Ikeshita)

After confirming safety, touchdown
within the crater and obtain
subsurface samples

Releaseimpactor

Use an impactor to create
an artificial crater on theasteroid’s surface1. Current project status& schedule overview

Current status[– BOX-C operations were carried out between July 17 – 25. The spacecraft remained at
the lowest altitude (around 6km) for approximately one day after July 20.
– Medium altitude operations were conducted from July 31 – August 2. The spacecraft
reached a minimum altitude of around 5 km on August 1.
– From August 5, we will conduct the descent operation for a gravitational
measurement.

Schedule overview:
2015
3

12

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10 12

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2017

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2020
12

Arrival at Ryugu	
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operations (CAN/MLG)	
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 Solar conjunction	
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2. Initial observations with the laser altimeterShape measurement by LIDAR

Credit: JAXA, University of Tokyo, Kochi
University, Rikkyo University, Nagoya
University, Chiba Institute of Technology,
Meiji University, University of Aizu, AIST

(Above) Global shape of Ryugu from laser altimeter data obtained over one month between June 30 –July 25. It nearly coincides with the shape model created from image data, with the craters and megalithreadable topology. As Hayabusa2 usually hovers over the equator, there is a concentration ofobservations near that region
Credit[ NAOJ, JAXA, Chiba Institute of Technology, University of Aizu, Nihon University, Osaka University.



2. Initial observations with the laser altimeterCrater topology

Topology [m](Top) Crater provision number #6. Diameter~210m, depth ~30m. Ratio of depth to diameter isabout 0.14. The height at the crater edge if 5m or
less.
(Bottom) Crater provision number #12: Diameter~ 110m, depth ~17m. Ratio of depth to diameter isabout 0.16. Height a the crater edge is about 7m.
Distance East-West [m]Topology [m]12Distance East-West [m]Credit: JAXA, University of Tokyo, Kochi
University, Rikkyo University, Nagoya
University, Chiba Institute of Technology,
Meiji University, University of Aizu, AISTThe scatter of points in theleft-hand figures are not due
to errors, but from variationsin the crater crossing position
according to the position andattitude of the spacecraft Credit: NAOJ, JAXA, Chiba Institute of Technology, University of Aizu, Nihon University, Osaka University.

2. Initial observations with the laser altimeter

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Crater#1

Crater#2

Crater#3

Crater#4

Altitude [m]Altitude [m]Altitude [m]Altitude [m]Altitude [m]Crater topology

Altitude [m]Crater#6

With the same method, the shape for a totalof 7 craters has been measured.
From this measurement:(i) depth/diameter ratio is about 0.1 – 0.2(ii) There appear to be craters withrelatively clear edges (about 5m high?)
Regarding (i), this ratio is in good
agreement with simple craters previously
observed on asteroids and comets. On theother hand, (ii) is not a characteristic foundon Itokawa (although it is not the first
discovery for an asteroid/comet)

Altitude [m]Crater#12

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Distance [m](East-West)

Crater#15


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Credit: NAOJ, JAXA, Chiba Institute of Technology, University of Aizu,
Nihon University, Osaka University3. Initial Observations with the near infrared spectrometer
Device outline
N Observation equipment to examine the presence and distribution of moisturecontaining minerals.

Reflectance (%)N The reflection spectrum in the wavelength range of 1.8 – 3.2µm is measured,along with significant absorption at 3µm by hydroxyl groups and water.

HD5B9?B@8?D?7B1@8

Allende meteorite(water content 0.3-3 wt%)

Murchison meteorite(water content 2-16 wt%)

Wavelength (µm)

Reflectance spectrum of a carbonaceous meteoritemeasured in the laboratory.
Credit: Tohoku University, JAXA3. Initial Observations with the near infrared spectrometer

Device status & observation results
N Device is operating normally with no problems in performance.
N First observations of Ryugu were successfully made on June 21,
good quality data continued to be acquired.
N Since arrival on June 27, observations were taken at an altitude of
20km (Box-A) for four asteroid rotations, and at 12 – 7km (Box-C)
for 2 rotations.
N Scan observations were done within Box-A and Box-C for eachrotation.
N A total of approximately 54,000 spectral data points have beenacquired.
3. Initial Observations with the near infrared spectrometerObservation coverage
N Scan performed by controllingthe attitude of the spacecraft andthe rotation of Ryugu.
N More than 90% of the total surface
was successfully observed
Rotation direction

Observational
regionObs.
point
RepeatmotionEdge
point

Attitude variation
Image showing scan coverage

Credit: University of Aizu

B5AE5>3I?6?2C5BF1D9?>C?F5BD85CEB6135
?6)IE7ED1;5>?>#E<IG9D89>?H  
B1I=1B;CE>?2C5BF541B51C N
B549D,>9F5BC9DI?69JE #/3. Initial Observations with the near infrared spectrometerCurrent main results
N Absorption of water at around 3µm has currently not been detected.
N The surface of Ryugu appears to be more depleted of water than
expected.
N Two possible scientific interpretations:
S1TNo water-containing minerals were in the parent body
S2Tdehydration occurred during a secondary heating
N However, there is a possibility that water may exist in the polar
regions or below the surface and cannot be observed. Further
investigation is planned for future observations.
4. Shape Model of Ryugu
N Shape of Ryugu is estimated from the images tocreate a three dimension model.
– This also gives a highly accurate estimate of
the spacecraft position & attitude, as well as
the rotation axis direction and period of theasteroid.
N An estimate of the asteroid size is made from therelative position of the spacecraft & asteroid andthe range value from the laser altimeter.
N These two independent methods:– Mutually complement– Confirm the validity of the result bycomparison between the two.
N This allows a quantitative understanding of thevisible features in the image.
N Offers basic engineering information needed todetermine the landing site.
N And basic physical information for considering
the origins of Ryugu. (Right) CG created shape model. Viewpoint is from 0 degrees longitude, with Ryugu’s
north pole at top.

SfM model, credit
University of Aizu, JAXASPC model, credit Kobe
University, JAXA

4. Shape Model of Ryugu
N Method of shape estimation:– Three-dimensional shape estimation of objects use images from multiple
viewpoints (so-called stereo viewing)
N *tructure-from-Motion (SfM) method:– Used by the analysis group at the University of Aizu
– Almost automatic, allowing rapid processing– Process generalised in recent years and many different software packages
now exist.
N Stereophotoclinometry (SPC) method:– Used by the analysis group at Kobe University– In addition to the stereo view, shading information generated by combining
the unevenness of the terrain with the lighting conditions is also used.
– Developed in the US for analysis of lunar and planetary exploration data.
– Used in many exploration missions, including the shape estimate of asteroid
Itokawa during the Hayabusa mission.
N We have completed the creation of the shape model mainly from images taken ata distance of 20km and are currently conducting analysis using images at higher
resolution.
4. Shape Model of Ryugu

SfM model
Credit: U. Aizu, JAXASpecifications:Av. radius: ~450 m
Rotation period[~7.63 hrs
Rotation axis direction[
ecliptic long. Λ[~179deg
ecliptic lat. Β[~ -87deg(animation)

SPC model
Credit: Kobe U, JAXANorth pole of Ryugu is at the top (opposite of previously published images)

()



Ryugu North-SouthN The north & south of the asteroid
depends on the direction ofrotation.
N The direction of a right-handscrew (counterclockwise) is thenorth pole.
N The rotation is the opposite
direction to the Earth.
– Itokawa also had a reverse
rotation, in the same direction as
Ryugu.
N The north direction on the Earthis the standard of the north-southin the entire Solar System.
N Almost all of the images of
Ryugu in the presentationmaterial so far have been shownin the same way as the Earth’s
north (and that of the Solar
System), with the direction
upwards.

Ryugu’s north pole

Earth’s north pole

Ryugu’s north pole

4. Shape Model of Ryugu
Four sides of Ryugu (north pole of Ryugu is top)
Longitude: 0 deg90 deg

180 deg

270 deg

SfM model (credit: University of Aizu, JAXA)SPC model (credit: Kobe University, JAXA)4. Shape Model of RyuguMap of shade on Ryugu

Created from the SfM model(credit: JAXA. U. of Aizu)

Created from the SPC model(credit: JAXA, Kobe U.)5. Mission ScheduleCurrent operation plan
N Usual operation is from the home position of an altitude of about 20km
PPPPPPPPPPPPPPP\PBOX-A
N Operations at lower altitude
done Ø BOX-C operations[July 17-25, lowest altitude ~ 6km (July 20-21)
on-goingØ Medium altitude descent operation[July 31 – August 2, minimum altitude~ 5km (Aug. 1)
Ø Gravity measurement descent operation: August 5 – 7, minimum altitude~ 1km (Aug. 7)
N Tour operations:Ø BOX-B operations[Late August
O See reference material for BOX information.
5. Mission Schedule
Outline of BOX-C operations

AltitudeHome position

time
7/25 PPPPPPP

7/17
7/2021

5. Mission Schedule
Image from BOX-C

Ryugu from an altitude of ~6km. Image taken with the Optical Navigation
Camera
PPPPPPP –Telescopic (ONC-T) on July 20, 2018 at around 16:00 JST.
Image credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute ofTechnology, Meiji University, University of Aizu and AIST.



5U
UMission Schedule
Overview of the medium altitude descent operation
AltitudeDescentDirectobservation(during descent)

Directobservation(home positiion)

Directobs.

Return toHome Position

Aug. 2Q~07:30
Start ascentconfirmation

8/2
18

~18:00(during
ascent)

Home Position

8 hours

24 hours

Aug. 1Q~10:38
Start descentconfirmation

Aug. 1Q~20:32
Altitude ~5km reachedO Time in JST. This may change depending on adjustments in the operation plan and situation 

time


5U
UMission Schedule
Overview of the medium altitude descent operationNo

Phase

Overview

Al�tudeV Descent	
  from	  Home	   Descent	
  from	  Home	  Posi�on.	
  Use	  the	
  same	  Posi�ondescent	
  technique	
  (GCP-­‐NAV)	
  as	
  touchdown.	
  NIRS3	  is	
  ON.	
  

207	
  km

W Direct	
  Observa�ons	
  ONC-­‐T,	
  TIR	
  observa�ons	
  start.	
  Directly	
  image	  surface	
  below.	
  

75	
  km

X Direct	
  Observa�ons	
  While	
  maintaining	
  5km	  al�tude,	
  directly	
  image	  surface	
  below.

5	
  km

Y Direct	
  Observa�ons	
  

A�er	
  accelera�ng	
  to	
  ascend,	
  directly	
  image	  the	
   57	
  km
surface	
  below	
  un�l	  an	
  al�tude	  of	
  7km.

Z Return	
  to	
  Home	  While	
  ascending,	
  begin	
  the	
  data	  downlink	  (Descending)
(Hovering)

(Ascending)
Posi�on

720	
  km

OFor GCP-NAV see next slide.



5U
UMission Schedule
Comparison between medium height descent operation and BOX-C operation
Phase

Medium	  height	
  descentBOX-­‐C	
  opera�on

Descent	  �me

Half-­‐day

Descent	
  over	  several	
  days

Posi�on	  control	
  during	  descent	
  

GCP-­‐NAV

HPNAV

Posi�on	  control	
  GCP-­‐NAV	
  during	  observa�ons Hovering	
  using	  HPNAVFree	
  mo�on	  depending	  on	  advanced	  ΔV

Observa�on	
  �me

8	
  hours

About	  10	  hourObserva�on	
  angle+Z	
  towards	
  EarthScan	
  opera�on	
  implemented

Opera�on	
  concept

Reduce	  al�tude	  and	
  observe	
  at	
  a	
  
target	  point	  and	
  angle.	
  (Precisely	
  guide	
  down	  to	  a	
  target	
  point	
  in	
  the	  same	
  manner	
  as	
  landing)

Reduce	  al�tude	
  while	  hovering.	
  (Approximately	
  reduce	  the	  al�tude	  by	
  extending	
  the	
  same	  hovering	
  technology)

Note[GCP-NAV (Ground Control Point Navigation)
PPPP→ A method of finding the position & speed of the spacecraft by observing features on the asteroid surface.
PP HPNAV (Home Position Navigation)
PPPP→ A method of finding the position & speed of the spacecraft from the direction to the image center and attitude data of
the spacecraft

5. Mission Schedule
Ryugu imaged during the medium height descent operations

Aug 1 ~08:00

Aug 1 ~10:00

Aug 1 ~12:00

Aug 1 ~14:00

Aug 1 ~16:00

Aug 1 ~18:00

Aug 1 ~19:20

Aug 1 ~20:15

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UMission Schedule
Overview of gravity measurement descent operation
AltitudeHome Position

TrackKV

about

time
8/6~10:00
10


8/6
20
~20:00

8/7
7
~07:00

8/7~16:00
16

O Time in JST. This may change depending on adjustments in the operation plan and situation 



5U
UMission schedule
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*D1DEC+89CC3854E<5=1I25381>7546?B=E<D9@<5613D?BC16D5B1BB9F1<1D)IE7E (<51C5>?D5
D85B56?B5 D81DD85C9DE1D9?>9C>?D69H54 5H35@DG85B5=1B;54L?=@<5D5M 6. Cooperative research■Cooperative research with Space Exploration Innovation HubCenter of JAXA:N The technique of Visual SLAM (Simultaneous Localization and Mapping) is
being developed at the Space Exploration Innovation Hub Center of JAXA.
N We try to apply this technique to the operation of Hayabusa2.

■Research teams(1) IVIS Corp. and ViewPLUS Corp.
http://www.ivis.co.jp http://www.viewplus.co.jp(2) Concept Corp. and Morpho Corp.
https://qoncept.co.jp https://www.morphoinc.com(Please see the material in Japanese for detailed information.)7. Future Plans■Schedule of press briefings
N Aug. 23 SThursT16:30]17:30
N Sept. 5 SWedT11:00]12:00
N Sept. 27 SThursT14:30]15:30■Outreach and events (in Japanese)Ø Events for Children
N Why Hayabusa2? Any questions classroom
N Sept. 2 (Sunday) 2 – 4pm
N Sagamihara City Museum
N Online broadcast plannedReference materialHome Position Coordinate System
Earth

Sun

ZHP

YHP
Ryugu

XHP

BOX definition
Earth Sun

Home position
coordinate system
SXHP, YHP, ZHPTBOX-A

SReference materialT
BOX-B

BOX YHP-direction size
BOX-C

BOX-A operation[operations while hovering at
20km altitude. Regular operation standard.
BOX-B operation[Tour observation. Hovering
area extended horizontally to enable
observations to either side of the asteroid.
asteroid averageradiusasteroid center of mass

BOX-C operation[Hovering area extended
vertically to enable observations at low
altitude. Primary spacecraft components

Deployable camera(DCAM3)

X-band lowX-band high- gain antenna
gain antenna

Solar array paddle

X-band midgain antenna
Ka-band highgain antennaOptical navigation Laser altimeter
cameraLIDAR
ONC-T

Near-infrared
spectrometer
NIRS3

Thermal infrared
cameraTIR

Scientific observation equipment
Star trackers

Ion engineNear-infrared spectrometer(NIRS3)

RCS thrusters
Optical navigation
cameraONC-T, ONC-W1

Re-entry capsuleSampler horn

Laser altimeter(LIDAR)

Small lander & rover
MASCOT

Optical navigation
camera ONC-W2

Minerva W

MASCOT lander
Thermal infrared camera(TIR)

II-1A

II-1B

II-2

Created by DLR and II-1: By the JAXA Minerva-II team
CNES
II-2: By Tohoku Univ. & the Minerva-II
Consortium

Minerva-II rover

Small carry-on impactor (SCI)
Target markers × 5Size[ 1 ×1. 6×1. 25 m (main body)P
PPPPPPSolar paddle deployed width 6 m
Mass [ 609 kg (incl. fuel)

Remote sensing equipment
Optical Navigation Camera (ONCT

Thermal Infrared Camera (TIRT

ONC-T (telephoto)PPONC-W1,W2 (wide-angle)
Imaging for scientific observation and navigation

Near-infrared Spectrometer (NIRS3T

Infrared spectra including the 3-µm band:
investigates mineral distributions on the asteroid
surface

8–12 µm imaging: Measures asteroid surface temperature

Laser Altimeter (LIDART

Measures distance between the asteroid and the spacecraft
in a range of 30 m–25 km

Optical navigation camera (ONCTT
ONC[Optical Navigation Camera
Objective: Images fixed stars and the target
asteroid for spacecraft guidance andscientific measurements
Scientific measurements[
N Form and motion of the asteroid:
Diameter, volume, direction of inertial principal axis,
nutation
N Global observations of surface topography
Craters, structural topography, rubble, regolith
distribution
N Global observations of spectroscopic properties of
surface materials
Hydrous mineral distribution, distribution of organic
matter, degree of space weathering
N High-resolution imaging near the sampling point
Size, form, degree of bonding, and heterogeneity ofsurface particles; observation of sampler projectiles
and surface markings

ONC-­‐T
Detector

N Elucidation of features of target asteroid
N Distribution of hydrous minerals andorganic matter, space weathering,boulders
N Sampling site selection
N Basic information on where to collectasteroid samples
N Ascertaining sample state
N High-resolution imaging of sampling sites

W1
FoV
T
FoV

ONC-­‐W1

ONC-­‐W2

2D	
  Si-­‐CCD	  	  (1024	
  ×	
  1024	  px)	

Viewing	  direc�on

Downward	
  (telephoto)

Viewing	
  angle

6.35°	  ×	  6.35°�

65.24°	  ×	
  65.24°�

Focal	
  length

100	
  m–∞	  1	  m–∞

Downward	
  (wide-­‐angle)

Sideward	
  (wide-­‐angle)	
  Spa�al	  resolu�on1	
  m/px	
  	
  	
  @	
  10-­‐km	
  alt.	
  1	
  cm/px	
  @100-­‐m	
  alt.	
  

	
  	
  	
  10	
  m/px	  	
  @10-­‐km	
  alt.	
  1	
  mm/px	
  @1-­‐m	
  alt.

Observa�on	
  wavelength

390,	
  480,	
  550,	
  700,	
  860,	
  950,	
  589.5	
  nm,	
  and	
  wide	  �

485–655	
  nm



Thermal infrared camera (TIRT
T
TIR=Thermal Infrared Imager
The surface temperature of the asteroid changes overthe day, rising in sunlight and decreasing at night.
Diurnal change in surface temperature is large in finesoils like sand and highly porous rock, and small in
dense rock.
We will examine the physical state of the asteroid’s
surface by 2D imaging (thermography) of thermalradiation from the asteroid.

Large

400	
  
350	
  

Temp
(K) [K]Temperature	  : 2D uncooled bolometer: 8–12 µm: –40 to 150 °C: 0.3 °C
: 328 × 248 (effective): 16°×12°: 20 m (20-km alt.T
5 cm (50-m alt.T

Stone

GravelSandR Detector
R Observation wavelength
R Observed temperatures
R Relative accuracy
R Dimensions
R Viewing angle
R Resolution
PPPPPPPP

Small

Temperature change

Night

Night

Day

I=10

300	
  

I=50
I=100

250	
  

I=200

200	
  

I=500

150	
  
100	
  
-180

I=1000

I=2000
-135

-90

-45

0

45

Longitude	  [deg] PLongitude

90

135

180



Laser altimeter (LIDARTTLIDAR: Light Detection And RangingRPulse-type laser altimeter
R A pulse YAG laser with a 1.064-µm
wavelength is emitted toward the target
object, and the altitude is measured bymeasuring the return time of the laser
beam.
R The LIDAR aboard Hayabusa 2 could
perform measurements from 30 m–25 km.
R LIDAR is a navigation sensor used forapproach and landing at a target, and ascientific observation device used tomeasure shape, gravity, and surface
characteristics, and for dust observations.
R It also has a transponder function that canperform space laser ranging (SLR)
experiments with ground LIDAR stations.

Short-range telescopeBeam expander for illumination

Long-range Cassegrain telescope
Laser altimeter engineering model
Scientific objectives
N Terrain and gravity field observations of thetarget asteroid
N Observations of albedo distribution at various
surface points
N Observations of dust floating around theasteroid

N Asteroid form, mass, porosity, and deviation
N Asteroid surface roughness
N Dust floating phenomenaNear-infrared spectrometer (NIRS3)
NIRS3: Near-infrared Spectrometer(‘3’ from 3 µm)Infrared absorption of hydroxyl groups and watermolecules is observed in 3-µm band reflection spectra in
the near-infrared region. NIRS3 investigates distributionsof hydrous minerals on the asteroid surface by measuringreflection spectra in the 3-µm band.
OH H2O

Observation wavelength range: 1.8–3.2 µm
Wavelength resolution: 20 nm
Full field of view: 0.1 deg
Spatial resolution: 35 m (20-km alt.)
PPPPPPP2 m (1-km alt.T
N Detector temperature: –85 to –70 °C
N S/N ratio: 50+ (wavelength 2.6 µm)

Orgueil (CI)

Absorption form anddepth vary dependingon the type andamount of hydrous
mineral

1.5
ScaledreflectanceReflectance
Relative

N
N
N
N

Murchison (CM)1.0

Renazzo (CR)Near-infrared reflection
spectra ofcarbonaceouschondrites

0.5

Allende (CV)

0.0

2.0

2.5
Wavelength (µm)

3.0Wavelength (µm)

