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Yuichi Tsuda,Hayabusa2 Project Team

Institute of Space and Astronautical ScienceJAXA

Hayabusa2 MissionHayabusa2 is the 2nd Japanese sample return mission to a small body. JAXA launched Hayabusa2 in 2014 which is now exploring the C-type asteroid Ryugu, and will return back to the Earth in 2020.

• Round-trip mission– High specific impulse ion engine for

continuous-thrust trajectory control.• In-situ science at “Ryugu”

– 1.5year proximity operation at Ryugu– Four landers, four remote science

instruments.• Touch down & sample collection

– Two normal touch down, one pin-point touch down (to an artificial crater) are planned.

• Artificial crater forming– Kinetic impact on the asteroid surface to

create a 2m-class crater.– Investigating Sub-surface structure of the

asteroid2

Ryugu arrival

3June 27, 2018

This is Ryugu

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The surface is very dark. The axis of rotation is nearly perpendicular to orbital plane.Features include craters, numerous boulders (including rocks up to 130m in size)

and a grooved terrain.

UTC 2018-06-26 03:50

Scientific Features of Ryugu

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• Top shape with a very circular equatorial bulge• Radius: mean 450 m

equatorial 500 m polar 440 m• Mass: 450 million ton GM 30 m3s-2 )• Rotation axis: (λ, β) = (180 , -87 ) • Obliquity: 8• Rotation period P = 7.63 hours• Reflectance factor v-band 0.02• Crater number density: as much as those on Itokawa and Eros• Many boulders: the largest near the south pole is ~130 m across• Optical spectra: flat spectra, bluer in equatorial bulge and poles• NIR spectra: uniform flat (slightly redder) spectra with weak water absorption• brightness temperature strong roughness effect (flat diurnal Temperature

variation), higher thermal inertia in the equatorial bulgeThe gravity at the equator is eighty-thousandth of the Earth and a few times of

Itokawa)

©JAXA University of Tokyo & collaborators

Approved Names on Ryugu

6Theme: names from children’s stories

“Landing Site Selection”

• Held on August 17, 2018• 109 participants including DLR/CNES/NASA.• Three s/c landing sites (1 primary, 2 backups), MINERVA-II-1 site, MASCOT site

were selected based on safety and scientific value.

7©JAXA

“Landing Site Selection”

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Touch-Down site analysis MINERVA site analysis MASCOT site analysis

MASCOTHayabusa2

MINERVA-II1

MINERVA-II-1 Operation

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2018

Sep 20

04:08 Gate1 Decision (Descent Start = Go)

05:08 Altitude 20km, Descent rate -0.4m/s

15:46 Gate2 Decision (5km Check-point = GO) Descent rate -0.1m/s

Sep 21

01:17 Rover Power On

03:25 Gate3 Decision (Spacecraft autonomous & rover sepration = Go)

04:06 Rover Separation

04:07 Ascent Delta-V, Ascent rate = +0.4m/s

04:11 TX Switched to LGA-A (for scanning observation maneuver)

04:28 Gate4 Decision (Ascent confirmation = Confirmed)

04:47 TX Switched to HGA (Back to Earth pointing attitude)

05:05 Gate5 Decision (Scan sequence completion = Confirmed)

05:36 HP return Delta-V

06:36 Gate6 Decision (HP return confirmation = Confirmed)

(5) MINERVA separation

Time

Altitude

HP:20 [km]

Separation Altitude 50 ~

55m(TBD)

(Not to Scale)

(Not to Scale)

(1) GCP-NAV

(2) GCP-NAV altitude control off(3) FF ΔV to decelerate descent

velocity

free fall

[Event]

Trigger Altitude:60 [m] (TBD)

(4) Wait for attitude control convergence

constant descent velocity e.g. 10 [cm/s]

(7) Ascent ΔV

Ascent Altitude30 + β [m] (TBD)

Point A:MINERVA Separation

Point B:1st Contact on Surface

(9) MINERVA landing

(8) Attitude scan

ONC-W1

ONC-T

ONC-W2

(10) HP Keeping

(6) Additional free fall for preventing plume contamination

Point C:Final settlement Point

Candidate of Simulation Epoch

at LIDAR Alt. 60m“Lateral dV1 (Before

Separation) ”“GCP-NAV end”

After 350sec of “Lateral dV2 (After

Separation)”

HP: Home Position

↓↓

↓

↓

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Surface Exploration by MINERVA-II1

Image credit JAXA

Two rovers hopped, collected data, and constantly sent data back to the spacecraft.

Two MINERVA-II-1 rovers have become the world first robots which successfully performed mobile activity on the small body surface.

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Image captured by Rover-1A on September 22 at around 11:44 JST. Color image captured while moving (during a hop) on the surface of Ryugu. The left-half of the image is the asteroid surface. The bright white region is due to sunlight. (Image credit: JAXA).

MINERVA-II1 imagesInitial images from falling and hopping rover

Image captured by Rover-1A on September 21 at around 13:08 JST. This is a color image taken immediately after separation from the spacecraft. Hayabusa2 is at the top and the surface of Ryugu is bottom. The image is blurred because the shot was taken while the rover was rotating.

Image credit JAXA Image credit JAXA

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Sep 23, 2018, before hop of Rover-1B

MINERVA-II1 images

Images credit JAXA

pin

antenna

Sep 23, 2018, Rover-1A on surface

Sep 23, 2018, Rover-1A on surface with self shadow

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15 frames captured on September 23, 2018 from 10:34 – 11:48 JST

MINERVA-II1 movie

credit JAXA

Scenery of Ryugu surface observed by Rover-1B

animation

MINERVA-II-1 Result

• Separation: Sep 21 04:06UT.• MINERVA-II-1A: – Last telemetry reception was on Oct 26 (113 sol)–Weak carrier signal had been received until recently.

• MINERVA-II-1B: – Last telemetry reception was on Sep 24 (10 sol)–Weak carrier signal had been received until recently.

World first robots which performed mobile activity on the small body surface!

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MASCOT Operation

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Oct 201:50 Gate1 Decision (Descent Start = Go)02:50 Altitude 20km, Descent rate -0.4m/s13:29 Gate2 Decision (5km Check-point = GO) Descent rate -0.1m/s23:48 MASCOT Final ConfigurationOct 300:50 Gate3 Decision (Spacecraft autonomous & lander separation = Go)01:57 MASCOT Separation01:59 Ascent Delta-V, Ascent rate = +0.4m/s02:03 TX Switched to LGA-A (for scanning observation maneuver)02:21 Gate4 Decision (MASCOT sep & Ascent confirmation = Confirmed)02:40 TX Switched to HGA (Back to Earth pointing attitude)02:58 Gate5 Decision (Scan sequence completion = Confirmed)05:29 Arrival at 3km Hovering altitude06:29 Gate6 Decision (Low-Alt hovering = GO)19:30 Mission Completion Announcement by MASCOT project teamOct 411:30 Home Position Return delta-V +0.3m/s

↓↓ ↓ ↓

↓

MASCOT Operation Result

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Sol1• MASCOT separated.• Settled on ground with the upside-

down orientation.• Observation executed at night.Sol2• A “big hop” commanded from ground

to flip the MASCOT orientation.• Observation executed at night.Sol3• Small relocation hop commanded

from ground to change camera and microscopic spectrometer FOVs.

• Fall into power save mode.• Final data downlink.• Battery depleted after 17 hrs of on-

surface operation.

CNES (Toulouse) DLR (Cologne)

JAXA/SSOC(Sagamihara Space Operation Center)

JAXA UDSC(Usuda Deep Space Center)

NASA DSN(Deep Space Network)

ESA ESTRACK(ESA Tracking

Station Network)

300 million km

Hayabusa2(Relay)

MASCOT

Largest lander on Ryugu.Perfectly successful collaboration among DLR/CNES/NASA/ESA/JAXA.

Images by MASCOT

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Oct. 3, 2018, During free fall Oct. 3, 2018, Right before initial bounce

Increased Accessibility to Surface

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MINERVA-II1 Descent

MASCOT Descent

TD1-R1A, TD1-R3

Low Altitude (

Decided Landing Sites and Accomplishments

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LSS Decision Meeting on Aug 17, 2018Touchdown L08 backup L07, M04 To be conducted next year!MASCOT MA-9 Landed on Oct.3!MINERVA-II-1 N6 Landed on Sep.21!

MINIERVA-II-1 SeparationAccuracy 3.3m, +50s

MASCOT SeprationAccuracy 30m, -60s

TD1-R1-A Touch Down RehearsalAccuracy10.8m, -55sec

TD1-R3 TM Release)Accuracy15.4m, -64sec

Candidate Landing Zone L08-B

100m

L08-B

L08-B

6m

20m

Toward Spacecraft’s Touch Down

• The original design assumes TD accuracy of 50m.• L08 area (100x100m width) has been selected as the

target landing site in the LSS decision meeting on Aug.17.• Further observations revealed that there is only

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Touch Down (Rehearsal) Sequence

25m

20m

0m

Key technology of TD

GNC accuracy

Terrain safety

LRF performance

TM tracking control reliability

TD operation

TD Rehearsal on

Oct.25, 2018

Target Maker has landed!

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L08-B

TD1-R3 ONC-W1 image

TM1

10m

15m

5m

Only 15.4m off from L08-B center.

TM autonomous tracking in TD1-R3 (with Target Control Box)

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CAM-H movie in TD1-R3

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Touch Down Target

TM

15 m

L08-B

12m

6m

L08-B1Area

L08-E1 Area

L08-B1

L08-E1TM

Wider but farther from TM

Narrower but closer to TM

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Touch Down Operation is scheduled in the week of Feb.18 (Feb.18-24)

Mission Accomplishments

Ryugu ArrivalCharacterization of Ryugu, Mapping, Gravity Measurement.Delivering Two MINERVA-II1 Rovers to Asteroid SurfaceDelivering MASCOT Lander to Asteroid SurfaceSpacecraft Touch-DownCrater FormingSpacecraft Touch-Down to Crater* (if situation allows)Delivering MINERVA-II2 Rovers to Asteroid SurfaceEarth Return

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Thank you

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