Hayabusa2 Update
Yuichi Tsuda, Hayabusa2 Project Team
Institute of Space and Astronautical Science JAXA Hayabusa2 Mission Hayabusa2 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 asteroid 2 Ryugu arrival
June 27, 2018 3 This is Ryugu
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
4 Scientific Features of Ryugu
• Top shape with a very circular equatorial bulge • Radius: mean 450 m equatorial 500 mpolar 440 m • Mass: 450 million tonGM30 m3s-2 ) • Rotation axis: (λ, β) = (180 , -87 ) • Obliquity: 8 • Rotation period P = 7.63 hours • Reflectance factor v-band0.02 • Crater number density: as much as those on Itokawa and Eros ©JAXAUniversity of Tokyo & collaborators • 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 temperaturestrong roughness effect (flat diurnal Temperature variation), higher thermal inertia in the equatorial bulge The gravity at the equator is eighty-thousandth of the Earth and a few times of Itokawa) 5 Approved Names on Ryugu
Theme: names from children’s stories 6 “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.
©JAXA 7 “Landing Site Selection”
Touch-Down site analysis MINERVA site analysis MASCOT site analysis
Hayabusa2 MASCOT MINERVA-II1
8 MINERVA-II-1 Operation
2018 (Not to Scale) (6) Additional free fall Sep 20 Altitude for preventing plume (2) GCP-NAV altitude control off contamination 04:08 Gate1 Decision (Descent Start = Go) (3) FF ΔV to decelerate descent (7) Ascent ΔV [Event] velocity (5) MINERVA separation 05:08 Altitude 20km, Descent rate -0.4m/s (9) MINERVA landing (4) Wait for attitude control 15:46 Gate2 Decision (5km Check-point = GO) Descent rate -0.1m/s (1) GCP-NAV convergence (8) Attitude scan (10) HP Keeping Sep 21 HP:20 [km] 01:17 Rover Power On
After 350sec of 03:25 Gate3 Decision (Spacecraft autonomous & rover sepration = Go) constant descent “Lateral dV2 (After velocity e.g. 10 [cm/s] Separation)” 04:06 Rover Separation 04:07 Ascent Delta-V, Ascent rate = +0.4m/s Trigger Altitude :60 [m] (TBD) Point B: 1st Contact 04:11 TX Switched to LGA-A (for scanning observation maneuver) free fall ONC-W2 on Surface 04:28 Gate4 Decision (Ascent confirmation = Confirmed) Separation Altitude 50 ~ at LIDAR Alt. 60m Point A: 04:47 TX Switched to HGA (Back to Earth pointing attitude) 55m(TBD) “Lateral dV1 (Before MINERVA ONC-T Point C: Ascent Altitude Separation) ” Separation Final settlement 05:05 Gate5 Decision (Scan sequence completion = Confirmed) 30 + β [m] (TBD) “GCP-NAV end” Point 05:36 HP return Delta-V ONC-W1 06:36 Gate6 Decision (HP return confirmation = Confirmed) Time
Candidate of (Not to Scale) Simulation Epoch HP: Home Position
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9 Surface Exploration by MINERVA-II1
Two rovers hopped, collected data, and constantly sent data back to the spacecraft.
Image creditJAXA
Two MINERVA-II-1 rovers have become the world first robots which successfully performed mobile activity on the small body surface. 10 M IN ERVA -II1 images Initial images from falling and hopping rover
Image creditJAXA Image creditJAXA Image captured by Rover-1A on September 22 at Image captured by Rover-1A on September 21 at around around 11:44 JST. Color image captured while moving 13:08 JST. This is a color image taken immediately after (during a hop) on the surface of Ryugu. The left-half of separation from the spacecraft. Hayabusa2 is at the top the image is the asteroid surface. The bright white and the surface of Ryugu is bottom. The image is region is due to sunlight. (Image credit: JAXA). blurred because the shot was taken while the rover was rotating.
11 M IN ERVA -II1 images
Sep 23, 2018, before hop of Rover-1B Sep 23, 2018, Rover-1A on surface
Images creditJAXA
pin
antenna
Sep 23, 2018, Rover-1A on surface with self shadow 12 MINERVA-II1 movie
Scenery of Ryugu surface observed by Rover-1B
15 frames captured on September 23, 2018 from 10:34 – 11:48 animation JST
creditJAXA 13 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! 14 MASCOT Operation Oct 2 01:50 Gate1 Decision (Descent Start = Go) 02:50 Altitude 20km, Descent rate -0.4m/s 13:29 Gate2 Decision (5km Check-point = GO) Descent rate -0.1m/s 23:48 MASCOT Final Configuration Oct 3 00:50 Gate3 Decision (Spacecraft autonomous & lander separation = Go) 01:57 MASCOT Separation 01:59 Ascent Delta-V, Ascent rate = +0.4m/s 02:03 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 altitude 06:29 Gate6 Decision (Low-Alt hovering = GO) 19:30 Mission Completion Announcement by MASCOT project team Oct 4 11:30 Home Position Return delta-V +0.3m/s
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15 MASCOT Operation Result
Sol1 Hayabusa2 • MASCOT separated. (Relay) • Settled on ground with the upside- MASCOT down orientation. 300 million km • Observation executed at night. Sol2 • A “big hop” commanded from ground JAXA UDSC NASA DSN ESA ESTRACK to flip the MASCOT orientation. (Usuda Deep Space Center) (Deep Space Network) (ESA Tracking • Observation executed at night. Station Network) Sol3 • Small relocation hop commanded from ground to change camera and JAXA/SSOC (Sagamihara Space microscopic spectrometer FOVs. Operation Center) • Fall into power save mode. • Final data downlink. • Battery depleted after 17 hrs of on- surface operation.
Largest lander on Ryugu. Perfectly successful collaboration among DLR/CNES/NASA/ESA/JAXA. (Toulouse) DLR (Cologne) CNES 16 Images by MASCOT
Oct. 3, 2018, During free fall Oct. 3, 2018, Right before initial bounce
17 Increased Accessibility to Surface
N MINERVA-II1 Descent TD1-R1A, TD1-R3
MASCOT Descent S Low Altitude (<100m) Descent Operation Trajectories
• 7 GCP-NAV descents, 4 low altitude (<100m) accesses. • Latitude range of 30deg has been proved to be accessible with higher-than-expected guidance accuracy.
18 Decided Landing Sites and Accomplishments LSS Decision Meeting on Aug 17, 2018 Touchdown L08backupL07, M04 To be conducted next year! MASCOT MA-9 Landed on Oct.3! MINERVA-II-1 N6 Landed on Sep.21!
MINIERVA-II-1 Separation Accuracy 3.3m, +50s
TD1-R1-ATouch Down Rehearsal Accuracy10.8m, -55sec TD1-R3TM Release) Accuracy15.4m, -64sec
MASCOT Sepration Accuracy 30m, -60s
19 Candidate Landing Zone L08-B
L08-B L08-B
20m
6m
100m 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 <10m safe are even in L08. • The project has decided to deploy the Target Maker first to precisely evaluate the terrain-relative nav/guid accuracy, which was successful. • The project is in the final phase of assessing the landing zone safety and adjusting the landing procedure to it.
21 Touch Down (Rehearsal) Sequence
Key technology of TD GNC accuracy Terrain safety LRF performance TM tracking control reliability 25m TD Rehearsal on Oct.25, 2018 20m
TD operation
0m
22 Target Maker has landed! TD1-R3 ONC-W1 image
L08-B
15m
10m
5m
TM1
Only 15.4m off from L08-B center.
23 TM autonomous tracking in TD1-R3 (with Target Control Box)
24 CAM-H movie in TD1-R3
25 Touch Down Target
L08-B1Area
Wider but farther from TM 12m
L08-B1 L08-B
15 m 6m TM L08-E1
TM L08-E1 Area Narrower but closer to TM
Touch Down Operation is scheduled in the week of Feb.18 (Feb.18-24) 26 Mission Accomplishments
Ryugu Arrival Characterization of Ryugu, Mapping, Gravity Measurement. Delivering Two MINERVA-II1 Rovers to Asteroid Surface Delivering MASCOT Lander to Asteroid Surface Spacecraft Touch-Down Crater Forming Spacecraft Touch-Down to Crater* (if situation allows) Delivering MINERVA-II2 Rovers to Asteroid Surface Earth Return
27 Thank you
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