Jump to content

162173 Ryugu

From Wikipedia, the free encyclopedia
(Redirected from Ryugu)
"Ryugu" redirects here. For the Japanese folklore palace, see Ryūgū-jō.

162173 Ryugu
Color image of Ryugu taken by Hayabusa2, 2018
Discovery[1]
Discovered byLINEAR
Discovery siteLincoln Lab's ETS
Discovery date10 May 1999
Designations
(162173) Ryugu
Pronunciation/riˈuːɡuː/
Japanese: [ɾjɯːɡɯː]
Named after
Ryūgū[1]
("Dragon palace")
1999 JU3
Apollo · NEO · PHA[1][2]
Orbital characteristics[2]
Epoch 12 December 2011 (JD 2455907.5)
Uncertainty parameter 0
Observation arc30.32 yr (11,075 d)
Aphelion1.4159 AU
Perihelion0.9633 AU
1.1896 AU
Eccentricity0.1902
1.30 yr (474 d)
3.9832°
0° 45m 34.56s / day
Inclination5.8837°
251.62°
211.43°
Earth MOID0.0006 AU (0.2337 LD)
Physical characteristics
Dimensions1004 m × 876 m[3]
448±2 m[3]
Equatorial radius
502±2 m[3]
Polar radius
438±2 m[3]
Volume0.377±0.005 km3[3]
Mass(4.50±0.06)×1011 kg[3][4]
Mean density
1.19±0.03 g cm−3[3]
Equatorial surface gravity
1/80,000 g[4]
7.63262±0.00002 h[3]
171.64°±0.03°[3]
North pole right ascension
+96.40°±0.03°[3]
North pole declination
−66.40°±0.03°[3]
0.037±0.002[5]
0.042±0.003[6]
0.047±0.003[7]
0.063±0.020[8]
0.07±0.01[9]
0.078±0.013[10]
SMASS = Cg[2] · C[7] · Cb[11]
18.69±0.07 (R)[10]
18.82[8]
19.2[5]
19.25±0.03[7]
19.3[1][2]

162173 Ryugu (provisional designation 1999 JU3) is a near-Earth object and a potentially hazardous asteroid of the Apollo group. It measures approximately 900 metres (3,000 ft) in diameter and is a dark object of the rare spectral type Cb,[11] with qualities of both a C-type asteroid and a B-type asteroid. In June 2018, the Japanese spacecraft Hayabusa2 arrived at the asteroid.[12] After making measurements and taking samples, Hayabusa2 left Ryugu for Earth in November 2019[13][14] and returned the sample capsule to Earth on 5 December 2020.[14] The samples showed the presence of organic compounds, such as uracil (one of the four components in RNA) and vitamin B3.

Discovery and name

[edit]

Ryugu was discovered on 10 May 1999 by astronomers with the Lincoln Near-Earth Asteroid Research at the Lincoln Lab's ETS near Socorro, New Mexico, in the United States. It was given the provisional designation 1999 JU3.[1] The asteroid was officially named "Ryugu" by the Minor Planet Center on 28 September 2015 (M.P.C. 95804).[15] The name refers to Ryūgū-jō (Dragon Palace), a magical underwater palace in a Japanese folktale. In the story, the fisherman Urashima Tarō travels to the palace on the back of a turtle, and when he returns, he carries with him a mysterious box, much like Hayabusa2 returning with samples.[1][16]

Geological history

[edit]

Ryugu formed as part of an asteroid family, belonging either to Eulalia or Polana.[17] Those asteroid families are likely fragments of past asteroid collisions. The large number of boulders on the surface supports a catastrophic disruption of the parent body.[18] The parent body of Ryugu likely experienced dehydration due to internal heating[17] and must have formed in an environment without a strong magnetic field.[19] After this catastrophic disruption, part of the surface was reshaped again by the high speed rotation of the asteroid forming the equatorial ridge (Ryujin Dorsum), through internal failure and/or mass wasting. The geologically distinct western area ('Western bulge') is likely the result of asymmetrical internal failure.[20] It is hoped that surface samples will help to reveal more of the geological history of the asteroid.[17]

Ryugu is hypothesized to be an extinct comet.[21]

Characteristics

[edit]

Orbit

[edit]
The origin of 162173 Ryugu may be either 495 Eulalia or 142 Polana.[22]
   Sun ·    Earth ·    162173 Ryugu ·    142 Polana ·    495 Eulalia

Ryugu orbits the Sun at a distance of 0.96–1.41 AU once every 16 months (474 days; semi-major axis of 1.19 AU). Its orbit has an eccentricity of 0.19 and an inclination of 6° with respect to the ecliptic.[2] It has a minimum orbital intersection distance with Earth of 95,443.442 km (0.000638 AU), equivalent to 0.23 lunar distances.[2]

Physical

[edit]

Early analysis in 2012 by Thomas G. Müller et al. used data from a number of observatories, and suggested that the asteroid was "almost spherical", a fact that hinders precise conclusions, with retrograde rotation, an effective diameter of 0.85–0.88 km (0.528 miles) and a geometric albedo of 0.044 to 0.050. They estimated that the grain sizes of its surface materials are between 1 and 10 mm.[7]

Initial images taken by the Hayabusa2 spacecraft on approach at a distance of 700 km (430 mi) were released on 14 June 2018. They revealed a diamond-shaped body 1 km in diameter and confirmed its retrograde rotation.[23] Between 17 and 18 June 2018, Hayabusa2 went from 330 to 240 km (210 to 150 mi) from Ryugu and captured a series of additional images from the closer approach.[24] Astronomer Brian May created stereoscopic images from data collected a few days later.[25] After a few months of exploration, JAXA scientists concluded that Ryugu is actually a rubble pile with about 50% of its volume being empty space.[26]

The acceleration due to gravity at the equator has been evaluated at about 0.11 mm/s2, rising to 0.15 mm/s2 at the poles. The mass of Ryugu is estimated at 450 million tonnes.[27] The asteroid has a volume of 0.377 ± 0.005 km3 and a bulk density of 1.19 ± 0.03 g/cm3 based on the shape model.[3]

Shape

[edit]
Image sequence showing the rotation of Ryugu

Ryugu has a round shape with an equatorial ridge, called Ryujin Dorsum. Ryugu is a spinning top-shape asteroid similar to Bennu. The ridge was shaped by strong centrifugal forces during a phase of high-speed rotation, through landslides and/or internal failure. The western side, also called the western bulge, has a distinct shape. It has a smooth surface with a sharp equatorial ridge. When modeling a high-speed rotation of present-day Ryugu, subsurface material appears structurally intact and relaxed in the western bulge, while other regions are more sensitive to structural failure. This indicates past structural failure in the western bulge (only the elements that did not experience structural failure previously are now sensitive to failure).[20] The western bulge is bordered by the Tokoyo and Horai Fossae.

Surface

[edit]
Images of the asteroid's surface made with Hayabusa2

Observations from Hayabusa2 showed that the surface of Ryugu is very young and has an age of 8.9 ± 2.5 million years based on the data collected from the artificial crater that was created with an explosive by Hayabusa2.[11][28]

The surface of Ryugu is porous and contains no or very little dust. The measurements with the radiometer on board of MASCOT, which is called MARA, showed a low thermal conductivity of the boulders. This was an in situ measurement of the high porosity of the boulder material. This result showed that most meteorites originating from C-type asteroids are too fragile to survive the entry into Earth's atmosphere.[29][30] The images from the camera of MASCOT, which is called MASCam, showed that surface of Ryugu contains two different almost black types of rock with little internal cohesion, but no dust was detected. One type of rocky material on the surface is brighter with a smooth surface and sharp edges. The other type of rock is dark with a cauliflower-like, crumbly surface. The dark type of rock has a dark matrix with small, bright, spectrally different inclusions. The inclusions appear similar to CI chondrites.[31][32] An unanticipated side effect from the Hayabusa2 thrusters revealed a coating of dark, fine-grained red material.[33]

Craters

[edit]

Ryugu has 77 craters on the surface. Ryugu shows variations of crater density that cannot be explained by randomness of cratering. There are more craters at lower latitudes and fewer at higher latitudes, and fewer craters in the western bulge (160°E – 290°E) than in the region around the meridian (300°E – 30°E). This variation is seen as evidence of a complicated geologic history of Ryugu.[34] The surface has one artificial crater, which was intentionally formed by the Small Carry-on Impactor (SCI), which was deployed by Hayabusa2. SCI fired a 2 kg copper mass onto the surface of Ryugu on 5 April 2019.[35] The artificial crater showed a darker subsurface material. It created an ejecta of 1 cm thickness and excavated material from up to 1 metre in depth.[36]

Boulders

[edit]

Ryugu contains 4,400 boulders with a size larger than 5 metres. Ryugu has more large boulders per surface area than Itokawa or Bennu, about one boulder larger than 20 metres per 50 km2. The boulders resemble laboratory impact fragments. The high number of boulders is explained with a catastrophic disruption of Ryugu's larger parent body. The largest boulder, called Otohime, has a size of ~160 × 120 × 70 m and is too large to be explained as an ejected boulder from a crater.[18]

Sample analysis results

[edit]

After the initial description (phase-1), part of the sample was distributed to the Hayabusa2 Initial Analysis Team, consisting of six sub-teams, and two Phase-2 curation institutes at Okayama University and JAMSTEC Kochi Institute for Core Sample Research.[37]

In September 2022 the Hayabusa 2 initial Analysis Stone Team announced the results of their study, which includes:[38]

  • Ryugu samples contain grains that were formed at high temperatures above 1000 °C, which formed close to the Sun and were later transported towards the outer Solar System.
  • The samples are soft enough to be cut with a knife and the samples preserve the magnetic field like a hard disk.
  • A simulation of the formation was performed, which showed that the parent body of Ryugu accumulated 2 million years after the formation of the Solar System. It heated up to 50 °C over the next 3 million years, resulting in reactions of rocky material with water. In these reactions anhydrous silicates became hydrous silicates and iron became magnetite. The 100 km large parent body was then destroyed by a <10 km large impactor, with an impact speed of about 5 km/s. Ryugu then formed from material far from the impact.

Origin from the outer Solar System

[edit]

The deuterium-rich and nitrogen-15-rich isotopic compositions of fine-grained minerals and organics suggests that the parent body of Ryugu formed in the outer Solar System.[39] Titanium, chromium and molybdenum isotopic anomalies provide more evidence that ties Ryugu's origin to the outer Solar System.[40]

Based on preserved magnetism in the samples researchers concluded that the parent body of Ryugu was likely formed in the darkness of nebular gas.[38]

Volatiles

[edit]
Water
[edit]

The Hayabusa2 sample capsule was significantly upgraded from Hayabusa, to preserve water, light organics, gases, and other volatiles.[41][42] This water was successfully sampled and preserved.[43][44][45][46] Via a bulk sample (~95 milligrams), its water content was reported as 6.84 ±0.34 wt%.[47]

Independently, a research group with a far smaller allocation (particles) reported 4-7 percent water.[48]

The lower-than-expected water signature seen by Hayabusa2 instruments was the result of space weathering, producing a dehydrated rind.[49][50][51]

Liquid water and aqueous alteration
[edit]

Carbonated liquid water was discovered in one crystal. The water contained salts and organic matter. The liquid water was found inside a hexagonal iron sulfide crystal. The carbon dioxide was likely CO2-ice (dry ice) inside the parent body. The water ice melted soon after the parent body formed and the CO2 dissolved into the water.[38][52][53]

Crystals "shaped like coral reefs" were found. These crystals likely formed in liquid water, which was once present in the interior of the parent body.[38] The parent body had a dryer surface and a wetter interior. After the collision of the parent body with a smaller asteroid, the interior and surface material were mixed. Today Ryugu has both interior and parent body surface material on its surface.[38]

An international team found particles in the samples that contained small amounts of material unaltered by water. The team found about 0.5 vol% of anhydrous silicates. The isotopic analysis of the magnesium-rich olivine and pyroxene in the sample suggests that two types of high-temperature objects accreted onto the surface of Ryugu: amoeboid olivine aggregates and magnesium-rich chondrules.[54]

Gas
[edit]

Hayabusa2 recovered helium and other noble gases. Some terrestrial contamination entered the system, but the Ryugu components are still measurable.[55][56][57][48][58]

Organic molecules
[edit]

Aliphatic carbon-rich organics associated with coarse-grained phyllosilicates were found. Such an association has not been observed in any meteorite study and could be unique to the asteroid Ryugu.[39]

In samples retrieved on Ryugu from the Japanese Hayabusa2 spacecraft, scientists discovered 20 different amino acids.[59]

In March 2023, scientists announced that uracil and vitamin B3 were detected in samples retrieved from Ryugu. Unlike previous instances when nucleobases and vitamins were found in certain carbon-rich meteorites, the samples were collected directly from the asteroid and delivered to Earth in sealed capsules, which meant Earthside contamination was not possible.[60][61]

Similarities to CI chondrites

[edit]

NanoSIMS-based analysis at the Carnegie Institution found that the Ryugu samples contained grains older than the solar system. The abundance and composition of these presolar grains were similar when compared to presolar grains in CI chondrites.[62] Researchers using the particle accelerator in J-PARC, used Muon beams to analyse the chemical composition of the samples. The researchers found a similar composition when compared to CI chondrites, but a 25% lower oxygen abundance relative to silicon for the Ryugu samples. The oxygen excess in meteorites might come from contamination after they entered earth's atmosphere.[63]

Magnetic field

[edit]

No magnetic field was detected near Ryugu on a global or local scale. This measurement is based on the magnetometer on board of MASCOT, which is called MasMag. This shows that Ryugu does not generate a magnetic field, indicating that the larger body from which it was fragmented was not generated in an environment with a strong magnetic field. This result cannot be generalized for C-type asteroids, however, because the surface of Ryugu seems to have been recreated in a catastrophic disruption.[19]

Surface features

[edit]

As of August 2019, there are 13 surface features that are named by the IAU.[64][65] The three landing sites are not officially confirmed but are referred to by specific names in media by JAXA. The theme of features on Ryugu is "children's stories". Ryugu was the first object to introduce the feature type known as the saxa, referring to the large boulders found on Ryugu's surface.

Craters

[edit]
Feature Named after
Brabo Silvius Brabo[66]
Cendrillon Cendrillon
Kibidango Kibi dango featured in Momotaro
Kintaro Kintarō
Kolobok Kolobok
Momotaro Momotaro
Urashima Urashima Taro

Dorsa

[edit]

A dorsum is a ridge. There is a single dorsum on Ryugu.

Feature Named after
Ryujin Dorsum Ryujin

Fossae

[edit]

A fossa is a ditch-like feature.

Feature Named after
Horai Fossa Penglai
Tokoyo Fossa Tokoyo

Saxa

[edit]

A saxum is a large boulder. Ryugu is the first astronomical object with them being named. Two boulders have been named "Styx" and "Small Styx" unofficially by the JAXA team; it is unknown if these names will be submitted for IAU approval. Both names refer to the River Styx.[67]

Feature Named after
Catafo Saxum Catafo, from Cajun folktales[65]
Ejima Saxum Ejima, the location where Urashima Taro rescued the turtle[65]
Otohime Saxum Otohime

Landing sites

[edit]

JAXA has given informal names to the specific landing and collection sites.

Feature Named after Notes
Alice's Wonderland Alice in Wonderland MASCOT landing site
Tritonis Lake Tritonis MINERVA-II1 landing site, initially referred to as "Trinitas"; as of February 2019 this has been rectified.
Tamatebako Tamatebako Site of first sample collection
Uchide-no-Kozuchi Uchide no kozuchi Site of second sample collection

Exploration

[edit]

Hayabusa2 mission

[edit]
Main article: Hayabusa2
Animation of Hayabusa2's orbit from 3 December 2014
  Hayabusa2   162173 Ryugu   Earth   Sun

The Japan Aerospace Exploration Agency (JAXA) spacecraft Hayabusa2 was launched in December 2014 and successfully arrived at the asteroid on 27 June 2018. It returned material from the asteroid to Earth in December 2020.[68]

The Hayabusa2 mission includes four rovers with various scientific instruments. The rovers are named HIBOU (aka Rover-1A), OWL (aka Rover-1B), MASCOT and Rover-2 (aka MINERVA-II-2). On 21 September 2018, the first two of these rovers, HIBOU and OWL (together the MINERVA-II-1 rovers) which hop around the surface of the asteroid, were released from Hayabusa2.[69] This marks the first time a mission has completed a successful landing on a fast-moving asteroid body.[70]

On 3 October 2018, the German-French Mobile Asteroid Surface Scout (MASCOT) lander successfully arrived on Ryugu, ten days after the MINERVA rovers landed.[71] Its mission was short-lived, as was planned; the lander had only 16 hours of battery power and no way to recharge.

Hayabusa2 touched down briefly on February 22, 2019, on Ryugu, fired a small tantalum projectile into the surface to collect the cloud of surface debris within the sampling horn, and then moved back to its holding position.[72] The second sampling was from the subsurface, and it involved firing a large copper projectile from an altitude of 500 metres to expose pristine material. After several weeks, it touched down on 11 July 2019 to sample the subsurface material, using its sampler horn and tantalum bullet.[73]

Samples of Ryugu returned by Hayabusa2[74]

The last rover, Rover-2 or MINERVA-II-2, failed before release from the Hayabusa2 orbiter. It was deployed anyway on 2 October 2019 in orbit around Ryugu to perform gravitational measurements. It impacted the asteroid a few days after release.

On 13 November 2019, commands were sent to Hayabusa2 to leave Ryugu and begin its journey back to Earth.[13] On 6 December 2020 (Australian time), a capsule containing the samples landed in Australia and after a brief search was retrieved.[14][75]

Prior to the sample capsule return, the amount of sample was expected to be at least 0.1 g.[76] The description of overall bulk sample was planned to be done by JAXA in the first six months.[77][78][79] 5 wt% of the sample will be allocated for the detailed analysis by JAXA.[77] 15 wt% will be allocated for initial analysis, and 10 wt% for "phase 2" analysis among Japanese research groups.[77] Within a year, NASA (10 wt%) and international "phase 2" research groups (5 wt%) will receive their allotment.[77] 15 wt% will be allocated for research proposals by international Announcement of Opportunity.[77] 40 wt% of the sample will be stored unused for future analysis.[77]

After the sample capsule returned, the amount of retrieved sample turned out to be about 5.4 g. Since it was 50 times more than anticipated, the allotment plan was adjusted to: 2 wt% to the detailed analysis by JAXA; 6 wt% for the initial analysis; 4 wt% for the "phase 2" analysis by Japanese research groups; 10 wt% for NASA; 2 wt% for the international "phase 2" research groups; 1 wt% for the public outreach; 15 wt% for the international Announcement of Opportunity; and the remaining 60 wt% will be preserved for future analysis.[80][81]

[edit]

162173 Ryugu is the setting of Daniel Suarez's novel Delta-V, describing the adventures of eight space miners who explore near-Earth asteroid Ryugu.

See also

[edit]

References

[edit]

Citations

[edit]
  1. ^ a b c d e f "162173 Ryugu (1999 JU3)". Minor Planet Center. Retrieved 30 October 2018.
  2. ^ a b c d e f "JPL Small-Body Database Browser: 162173 Ryugu (1999 JU3)" (2016-08-09 last obs.). Jet Propulsion Laboratory. Retrieved 30 October 2018.
  3. ^ a b c d e f g h i j k l Watanabe, S.; Hirabayashi, M.; Hirata, N.; Hirata, N.; Noguchi, R.; Shimaki, Y.; et al. (April 2019). "Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu—A spinning top–shaped rubble pile". Science. 364 (6437): 268–272. Bibcode:2019Sci...364..268W. doi:10.1126/science.aav8032. PMID 30890588. S2CID 84183033.
  4. ^ a b Clark, Stephen (6 September 2018). "Hayabusa 2 team sets dates for asteroid landings – Spaceflight Now". spaceflightnow.com. Retrieved 7 September 2018.
  5. ^ a b Abe, M.; Kawakami, K.; Hasegawa, S.; Kuroda, D.; Yoshikawa, M.; Kasuga, T.; et al. (March 2008). Ground-based Observational Campaign for Asteroid 162173 1999 JU3 (PDF). 37th COSPAR Scientific Assembly. Lunar and Planetary Science. No. 1391. p. 1594. Bibcode:2008LPI....39.1594A. Retrieved 30 October 2018.
  6. ^ Yu, Liang-Liang; Ji, Jiang-Hui; Wang, Su (July 2014). "Investigation of Thermal Inertia and Surface Properties for Near-earth Asteroid (162173) 1999 JU3". Chinese Astronomy and Astrophysics. 38 (3): 317–329. arXiv:1805.05244. Bibcode:2014ChA&A..38..317Y. doi:10.1016/j.chinastron.2014.07.008. S2CID 119186039.
  7. ^ a b c d Müller, T. G.; Durech, J.; Ishiguro, M.; Mueller, M.; Krühler, T.; Yang, H.; et al. (March 2017). "Hayabusa-2 mission target asteroid 162173 Ryugu (1999 JU3): Searching for the object's spin-axis orientation". Astronomy and Astrophysics. 599: 25. arXiv:1611.05625. Bibcode:2017A&A...599A.103M. doi:10.1051/0004-6361/201629134. S2CID 73519172.
  8. ^ a b Hasegawa, S.; Müller, T. G.; Kawakami, K.; Kasuga, T.; Wada, T.; Ita, Y.; et al. (December 2008). "Albedo, Size, and Surface Characteristics of Hayabusa-2 Sample-Return Target 162173 1999 JU3 from AKARI and Subaru Observations". Publications of the Astronomical Society of Japan. 60 (SP2): S399––S405. Bibcode:2008PASJ...60S.399H. doi:10.1093/pasj/60.sp2.S399.
  9. ^ Campins, H.; Emery, J. P.; Kelley, M.; Fernández, Y.; Licandro, J.; Delbó, M.; et al. (August 2009). "Spitzer observations of spacecraft target 162173 (1999 JU3)". Astronomy and Astrophysics. 503 (2): L17–L20. arXiv:0908.0796. Bibcode:2009A&A...503L..17C. doi:10.1051/0004-6361/200912374. S2CID 16329091.
  10. ^ a b Kim, Myung-Jin; Choi, Young-Jun; Moon, Hong-Kyu; Ishiguro, Masateru; Mottola, Stefano; Kaplan, Murat; et al. (February 2013). "Optical observations of NEA 162173 (1999 JU3) during the 2011–2012 apparition". Astronomy and Astrophysics. 550: 4. arXiv:1302.4542. Bibcode:2013A&A...550L..11K. doi:10.1051/0004-6361/201220673. S2CID 54684944.
  11. ^ a b c Sugita, S.; Honda, R.; Morota, T.; Kameda, S.; Sawada, H.; Tatsumi, E.; Honda, C.; Yokota, Y.; Yamada, M.; Kouyama, T.; Sakatani, N. (July 2019). "Ryugu's Parent-Body Processes Estimated from Hayabusa2 Multi-Band Optical Observations". 82nd Annual Meeting of The Meteoritical Society, held 7-12 July, 2019 in Sapporo, Japan. LPI Contribution. Vol. 2157. p. 6366. Bibcode:2019LPICo2157.6366S. ISSN 0161-5297.{{cite book}}: CS1 maint: date and year (link)
  12. ^ Chang, Kenneth; Stirone, Shannon (19 March 2019). "The Asteroid Was Shooting Rocks Into Space. 'Were We Safe in Orbit?'". The New York Times. Retrieved 21 March 2019. NASA's Osiris-Rex and Japan's Hayabusa2 spacecraft reached the space rocks they are surveying last year, and scientists from both teams announced early findings on Tuesday.
  13. ^ a b Stephen Clark (13 November 2019). "Japanese sample return craft departs asteroid, heads for Earth"./
  14. ^ a b c Chang, Kenneth (5 December 2020). "Japan's Journey to an Asteroid Ends With a Hunt in Australia's Outback – The Hayabusa2 mission cements Japan's role in exploring the solar system, but finding its asteroid cargo presents one last challenge". The New York Times. Retrieved 5 December 2020.
  15. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 30 October 2018.
  16. ^ "Name Selection of Asteroid 1999 JU3 Target of the Asteroid Explorer "Hayabusa2"" (Press release). JAXA. 5 October 2015. Retrieved 30 October 2018.
  17. ^ a b c Sugita, S.; Honda, R.; Morota, T.; Kameda, S.; Honda, C.; Yokota, Y.; Yamada, M.; Kouyama, T.; Sakatani, N.; Suzuki, H.; Yoshioka, K. (March 2019). "The Evolution of Ryugu's Parent Body Constrained by Hayabusa2 Imaging Observations". LPI (2132): 2622. Bibcode:2019LPI....50.2622S.
  18. ^ a b Michikami, Tatsuhiro; Honda, Chikatoshi; Miyamoto, Hideaki; Hirabayashi, Masatoshi; Hagermann, Axel; Irie, Terunori; Nomura, Keita; Ernst, Carolyn M.; Kawamura, Masaki; Sugimoto, Kiichi; Tatsumi, Eri (October 2019). "Boulder size and shape distributions on asteroid Ryugu". Icar. 331: 179–191. Bibcode:2019Icar..331..179M. doi:10.1016/j.icarus.2019.05.019. hdl:1893/29777. ISSN 0019-1035.
  19. ^ a b Hercik, David; Auster, Hans-Ulrich; Constantinescu, Dragos; Blum, Jürgen; Fornaçon, Karl-Heinz; Fujimoto, Masaki; Gebauer, Kathrin; Grundmann, Jan-Thimo; Güttler, Carsten; Hillenmaier, Olaf; Ho, Tra-Mi (2020). "Magnetic Properties of Asteroid (162173) Ryugu". Journal of Geophysical Research: Planets. 125 (1): e2019JE006035. Bibcode:2020JGRE..12506035H. doi:10.1029/2019JE006035. hdl:1721.1/136097.2. ISSN 2169-9100.
  20. ^ a b Hirabayashi, Masatoshi; Tatsumi, Eri; Miyamoto, Hideaki; Komatsu, Goro; Sugita, Seiji; Watanabe, Sei-ichiro; Scheeres, Daniel J.; Barnouin, Olivier S.; Michel, Patrick; Honda, Chikatoshi; Michikami, Tatsuhiro (March 2019). "The Western Bulge of 162173 Ryugu Formed as a Result of a Rotationally Driven Deformation Process". Astrophysical Journal Letters. 874 (1): L10. arXiv:1904.03480. Bibcode:2019ApJ...874L..10H. doi:10.3847/2041-8213/ab0e8b. ISSN 0004-637X. S2CID 102350610.
  21. ^ Miura, H.; Nakamura, E.; Kunihiro, T. (2022). "The Asteroid 162173 Ryugu: a Cometary Origin". The Astrophysical Journal Letters. 925 (2): 15. Bibcode:2022ApJ...925L..15M. doi:10.3847/2041-8213/ac4bd5.
  22. ^ S. Sugita; et al. (19 March 2019). "The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes". Science. 364 (6437): eaaw0422. Bibcode:2019Sci...364..252S. doi:10.1126/science.aaw0422. hdl:1893/29363. PMC 7370239. PMID 30890587.
  23. ^ "From a distance of about 700km, Ryugu's rotation was observed". JAXA. 16 June 2016. Retrieved 30 October 2018.
  24. ^ Plait, Phil (20 June 2018). "Asteroid Ryugu Starts to Come Into Focus". SyFy Wire. Retrieved 30 October 2018.
  25. ^ Bartels, Meghan (10 July 2018). "Queen's Brian May Will Rock You with This Stereo Image of Asteroid Ryugu". Space.com. Retrieved 24 December 2018.
  26. ^ Hayabusa-2: Asteroid mission exploring a 'rubble pile'. Paul Rincon, BBC News. 19 March 2019.
  27. ^ Operation status for the asteroid explorer, Hayabusa2, in the vicinity of Ryugu (PDF), JAXA, 5 September 2018, retrieved 30 October 2018
  28. ^ Arakawa, M.; Saiki, T.; Wada, K.; Ogawa, K.; Kadono, T.; Shirai, K.; Sawada, H.; Ishibashi, K.; Honda, R.; Sakatani, N.; Iijima, Y. (19 March 2020). "An artificial impact on the asteroid 162173 Ryugu formed a crater in the gravity-dominated regime". Science. 368 (6486): 67–71. Bibcode:2020Sci...368...67A. doi:10.1126/science.aaz1701. ISSN 0036-8075. PMID 32193363. S2CID 214591738.
  29. ^ "DLR – MASCOT confirms what scientists have long suspected". DLRARTICLE DLR Portal. Retrieved 7 March 2020.
  30. ^ Grott, M.; Knollenberg, J.; Hamm, M.; Ogawa, K.; Jaumann, R.; Otto, K. A.; Delbo, M.; Michel, P.; Biele, J.; Neumann, W.; Knapmeyer, M. (15 July 2019). "Low thermal conductivity boulder with high porosity identified on C-type asteroid (162173) Ryugu". Nature Astronomy. 3 (11): 971–976. Bibcode:2019NatAs...3..971G. doi:10.1038/s41550-019-0832-x. hdl:1893/29871. ISSN 2397-3366. S2CID 197402876.
  31. ^ Jaumann, R.; Schmitz, N.; Ho, T.-M.; Schröder, S. E.; Otto, K. A.; Stephan, K.; Elgner, S.; Krohn, K.; Preusker, F.; Scholten, F.; Biele, J. (23 August 2019). "Images from the surface of asteroid Ryugu show rocks similar to carbonaceous chondrite meteorites" (PDF). Science. 365 (6455): 817–820. Bibcode:2019Sci...365..817J. doi:10.1126/science.aaw8627. ISSN 0036-8075. PMID 31439797. S2CID 201616571.
  32. ^ "The near-Earth asteroid Ryugu – a fragile cosmic rubble pile". DLRARTICLE DLR Portal. Retrieved 7 March 2020.
  33. ^ "Hayabusa-2 Reveals Surface of Near-Earth Asteroid Ryugu in Stunning Detail". Sci News. 11 May 2020. Retrieved 12 May 2020.
  34. ^ Hirata, Naoyuki; Morota, Tomokatsu; Cho, Yuichiro; Kanamaru, Masanori; Watanabe, Sei-ichiro; Sugita, Seiji; Hirata, Naru; Yamamoto, Yukio; Noguchi, Rina; Shimaki, Yuri; Tatsumi, Eri (March 2020). "The spatial distribution of impact craters on Ryugu". Icar. 338: 113527. arXiv:2205.05818. Bibcode:2020Icar..33813527H. doi:10.1016/j.icarus.2019.113527. ISSN 0019-1035. S2CID 209903294.
  35. ^ "Apr. 24, 2019. What's new". JAXA Hayabusa2 project (in Japanese). Retrieved 9 March 2020.
  36. ^ "Asteroid explorer, Hayabusa2, reporter briefing" (PDF). JAXA Hayabusa2 Project. 25 June 2019. Retrieved 9 March 2020.
  37. ^ "JAXA | Asteroid Explorer Hayabusa2 Initial Analysis Chemical Analysis Team reveals aqueous alteration and primitive composition of asteroid Ryugu". JAXA | Japan Aerospace Exploration Agency. Retrieved 28 September 2022.
  38. ^ a b c d e "JAXA | Asteroid Explorer Hayabusa2 Initial Analysis Stone Team reveals the formation and evolution of carbonaceous asteroid Ryugu". JAXA | Japan Aerospace Exploration Agency. Retrieved 28 September 2022.
  39. ^ a b "JAXA | Asteroid Ryugu is a drifter from the outer Solar System: Results from the Hayabusa2 Phase-2 Curation Kochi Team published in Nature Astronomy". JAXA | Japan Aerospace Exploration Agency. Retrieved 28 September 2022.
  40. ^ Hopp, Timo; et al. (2022). "Ryugu's nucleosynthetic heritage from the outskirts of the Solar System Science Advances (2022): eadd8141". Science Advances. 8 (46): 3. doi:10.1126/sciadv.add8141. hdl:20.500.11850/583897. PMID 36264823. S2CID 253045585.
  41. ^ Yada, T.; Fujimura; Abe M.; Nakamura T.; Noguchi T; Okazaki R.; Nagao K.; Ishibashi Y.; Shirai K.; Zolensky M. E.; Sandford S.; Okada, T.; Uesugi M.; Karouji Y.; Ogawa M.; Yakame S.; Ueno M.; Mukai T.; Yoshikawa M.; Kawaguchi J. (2014). "Hayabusa-returned sample curation in the Planetary Material Sample Curation Facility of JAXA". Met. & Planet. Sci. 49 (2): 135. Bibcode:2014M&PS...49..135Y. doi:10.1111/maps.12027. S2CID 56357760.
  42. ^ Abe, M.; Yada, T.; Okada, T.; Sakamoto, K.; Yoshitake, M.; Nakano Y.; Matsumoto, T.; Kawasaki, N.; Kumagai, K.; Matsui S.; Nishimura, M.; Yurimoto, H. (2017). Readiness of Receiving and Curation facility for Hayabusa2 Asteroid Sample Return Mission (PDF). Hayabusa 2017.
  43. ^ Nittler, L. R. (2022). Can SIMS measurements constrain the D/H ratio of water on Ryugu?. 2022 Hayabusa Symposium. p. S21-02.
  44. ^ Piani, L.; Marrocchi; Nagashima; Kawasaki; Sakamoto; Bajo; Yurimoto (2022). H isotopic composition of water in Ryugu samples returned by the Hayabusa2 mission. 85th MetSoc. p. 6058.
  45. ^ Nittler, L. R.; Barosch, J.; Wang, J.; Alexander, C. M. O'D. (2023). Water in Asteroid Ryugu is Deuterium-Rich Compared to Earth and CI Chondrites. 54th LPSC.
  46. ^ Yesiltas, M.; Glotch, T. D.; Kebukawa, Y.; Northrup, P.; Sava, B. (2023). Nano-Scale Infrared and Raman Spectroscopy of Ryugu Particles. 86th Meteoritical Society Meeting. p. 6161.
  47. ^ Yokoyama, T.; Nagashima K.; Nakai I.; Young E. D.; and 145 coauthors (2023). "Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites" (PDF). Science. 379 (6634). Bibcode:2023Sci...379.7850Y. doi:10.1126/science.abn7850. PMID 35679354. S2CID 249544031.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  48. ^ a b Verchovsky, A. B.; Abernethy, F. A. J.; Anand, M.; Franchi, I. A.; Grady, M. M.; Greenwood, R. C.; Suttle, M.; Ito, M.; Tomioka, N.; Uesugi, M.; Yamaguchi, A.; Kimura, M.; Imae, N.; Shirai, N.; Ohigashi, T.; Liu, M-C.; Yada, T.; Abe, M.; Usui, T. (2023). Ryugu's volatiles investigated using stepped combustion and EGA methods. 54th LPSC. p. 2471.
  49. ^ Taaki; Noguchi T.; Matsumoto, Y; Tsuda (19 December 2022). "A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu". Nature. 7: 170. Bibcode:2023NatAs...7..170N. doi:10.1038/s41550-022-01841-6. hdl:2433/279328. PMID 36845884. S2CID 254908999.
  50. ^ Tachibana, S. (12 July 2023). Hayabusa2 and Sample Science – JAXA. NASA Small Bodies Assessment Group July 2023 Meeting.
  51. ^ Hamann, C.; Bonato E.; Maturilli A.; Mahlow K.; Patzschke M.; Alemanno G.; Schwinger S.; Van den Neucker A.; Baqué M.; Greshake A.; Hecht L.; Helbert J. (11 August 2023). CRISPY On The OUTSIDE, RAW On The INSIDE: IMPACT-INDUCED MELTING And FRAGMENTATION Of C-Type ASTEROID Regolith DocumentedIn A Ryugu Sample. 86th Meteoritical Society Meeting. p. 6296.
  52. ^ Zolensky, M.; Dolocan, A.; Bodnar, R.; Gearba, I.; Martinez, J.; Han, J.; Nakamura, T.; Tsuchiyama, A.; Matsuno, J.; Sun, M.; Matsumoto, M.; Fujioka, Y.; Enokido, Y.; Uesugi, K.; Takeuchi, A.; Yasutake, M.; Miyake, A.; Okumura, S.; Mitsukawa, I.; Takigawa, A.; Mikouchi, T.; Enju, S.; Morita, T.; Kikuiri, M.; Amano, K.; Yurimoto, H.; Noguchi, T.; Okazaki, R.; Yabuta, H.; Naraoka, H.; Sakamoto, K.; Tachibana, S.; Watanabe, S.; Tsuda, Y (2022). Direct Measurement of the Composition of Aqueous Fluids from the Parent Body of Asteroid 162173 Ryugu. 53rd Lun. Plan. Sci. Conf. p. 1451.
  53. ^ Nakamura, T; Matsumoto, M.; Amano, K.; and 70+ coauthors (2022). Early History of Ryugu's Parent Asteroid: Evidence from Return Sample. 53rd LPSC. p. 1753.{{cite conference}}: CS1 maint: numeric names: authors list (link)
  54. ^ "Team identifies parent body materials in Ryugu asteroid". www.llnl.gov. Retrieved 28 September 2022.
  55. ^ Okazaki, R.; Miura, Y. N.; Takano, Y.; Sawada, H.; Sakamoto, K.; Yada, T.; Yamada, K.; Kawagucci, S.; Matsui, Y, and 115 others (20 October 2022). "First asteroid gas sample delivered by the Hayabusa2 mission: a treasure box from Ryugu". Science Advances. 8 (46): eabo7239. Bibcode:2022SciA....8O7239O. doi:10.1126/sciadv.abo7239. hdl:20.500.11850/583894. PMID 36264781. S2CID 253045236.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  56. ^ Okazaki, R.; Marty, B.; Busemann, H.; Hashizumi, K.; Gilmour, J. D.; Meshik, A.; Yada, T.; Kitajima, F.; Broadley, M. W. and 114 others (2023). "Noble gases and nitrogen in samples of asteroid Ryugu record its volatile sources and recent surface evolution". Science. 379 (6634). Bibcode:2023Sci...379.0431O. doi:10.1126/science.abo0431. S2CID 253045328.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  57. ^ Busemann, H.; Krietsch D.; Mertens C. A. K.; Maden C. (11 August 2023). Recently Recovered Pristine Extraterrestrial Materials As Carriers of Primordially Trapped Noble Gases. 86th Meteoritical Society Meeting. p. 6211.
  58. ^ Verchovsky, A. B.; Abernethy, F. A. J.; Anand, M.; Franchi, I. A.; Grady, M. M.; Greenwood, R. C.; Barber, S. J.; Suttle, M.; Ito, M.; Tomioka, N.; Uesugi, M.; Yamaguchi, A.; Kimura, M.; Imae, N.; Shirai, N.; Ohigashi, T.; Liu, M-C.; Yada, T.; Abe, M.; Usui, T. (2023). Extremely High Xe Concentration in The Hayabusa2 C0209 Sample. 54th LPSC. p. 6323.
  59. ^ 'Rubber-ducky' asteroid 200 million miles away holds building blocks of life Ben Turner, LiveScience. June 9th, 2022
  60. ^ Ashley Strickland (22 March 2023). "RNA compound and vitamin B3 found in samples from near-Earth asteroid". CNN. Retrieved 22 March 2023.
  61. ^ Oba, Yasuhiro; Koga, Toshiki; Takano, Yoshinori; Ogawa, Nanako O.; Ohkouchi, Naohiko; Sasaki, Kazunori; Sato, Hajime; Glavin, Daniel P.; Dworkin, Jason P.; Naraoka, Hiroshi; Tachibana, Shogo; Yurimoto, Hisayoshi; Nakamura, Tomoki; Noguchi, Takaaki; Okazaki, Ryuji (21 March 2023). "Uracil in the carbonaceous asteroid (162173) Ryugu". Nature Communications. 14 (1): 1292. Bibcode:2023NatCo..14.1292O. doi:10.1038/s41467-023-36904-3. ISSN 2041-1723. PMC 10030641. PMID 36944653. S2CID 257641373.
  62. ^ Barosch, Jens; Nittler, Larry R.; Wang, Jianhua; Alexander, Conel M. O'D.; De Gregorio, Bradley T.; Engrand, Cécile; Kebukawa, Yoko; Nagashima, Kazuhide; Stroud, Rhonda M.; Yabuta, Hikaru; Abe, Yoshinari; Aléon, Jérôme; Amari, Sachiko; Amelin, Yuri; Bajo, Ken-ichi (1 August 2022). "Presolar Stardust in Asteroid Ryugu". The Astrophysical Journal. 935 (1): L3. arXiv:2208.07976. Bibcode:2022ApJ...935L...3B. doi:10.3847/2041-8213/ac83bd. ISSN 0004-637X. S2CID 251538946.
  63. ^ "Researchers have used beams of muons to analyze the elemental composition of Asteroid Ryugu samples". Kavli IPMU-カブリ数物連携宇宙研究機構. 23 September 2022. Retrieved 28 September 2022.
  64. ^ Jason Davis Hayabusa2 team sets date for sample collection, considers two touchdown sites Planetary.org January 16, 2019
  65. ^ a b c "Jan. 21, 2019. What's new".
  66. ^ "Jan. 21, 2019. What's new". JAXA Hayabusa2 project (in Japanese). Retrieved 7 September 2019. The brave young man who defeated a giant
  67. ^ "July 8, 2019. What's new". JAXA Hayabusa2 project (in Japanese). Retrieved 7 September 2019.
  68. ^ "Current status of the asteroid explorer, Hayabusa2, leading up to arrival at asteroid Ryugu in 2018" (PDF). JAXA. 14 June 2016. Retrieved 30 October 2018.
  69. ^ Wall, Mike (21 September 2018). "Japanese Probe Deploys Tiny Hopping Robots Toward Big Asteroid Ryugu". space.com. Retrieved 30 October 2018.
  70. ^ Yoshimitsu, Tetsuo; Kubota, Takashi; Tsuda, Yuichi; Yoshikawa, Makoto (23 September 2015). "MINERVA-II1: Successful image capture, landing on Ryugu and hop!". JAXA Hayabusa2 Project. JAXA. Retrieved 30 October 2018.
  71. ^ "Touchdown! Japan space probe lands new robot on asteroid". phys.org. 3 October 2018. Retrieved 30 October 2018.
  72. ^ Touchdown: Japan probe Hayabusa2 lands on distant asteroid. Kyoko Hasegawa, PhysOrg. February 22, 2019.
  73. ^ "Hayabusa2 successfully collects 1st-ever subsurface samples: JAXA". Kyodo News. 11 July 2019. Retrieved 15 July 2019.
  74. ^ Yada T, Abe M, Okada T, et al. (2022). "Preliminary analysis of the Hayabusa2 samples returned from C-type asteroid Ryugu". Nature Astronomy. 6 (2): 214–220. doi:10.1038/s41550-021-01550-6. S2CID 245366019.
  75. ^ Rincon, Paul (6 December 2020). "Hayabusa-2: Capsule with asteroid samples in 'perfect' shape". BBC News. Retrieved 6 December 2020.
  76. ^ "Hayabusa2 Project". Astromaterials Science Research Group, Extraterrestrial Sample Curation Center, JAXA. Archived from the original on 25 September 2018. Retrieved 10 December 2020.
  77. ^ a b c d e f 安部 正真; 橘 省吾; 小林 桂; 伊藤 元雄; 渡邊 誠一郎 (2020). 火の鳥「はやぶさ」未来編 その20 ～小惑星リュウグウからの リターンサンプル分析の全体像～. 日本惑星科学会誌遊星人 (in Japanese). 29 (1): 28–37. doi:10.14909/yuseijin.29.1_28.
  78. ^ JAXA Astromaterials Science Research Group. はやぶさ2試料の初期記載・分析 (PDF) (in Japanese). JAXA. Retrieved 10 December 2020.
  79. ^ JAXA Hayabusa2 Project (16 November 2020). "Asteroid explorer, Hayabusa2, reporter briefing" (PDF). JAXA. Retrieved 10 December 2020.{{cite web}}: CS1 maint: numeric names: authors list (link)
  80. ^ Ōtsuka, Minoru (19 June 2021). はやぶさ2の帰還サンプル、JAXA外部機関8チームでの分析が開始へ (in Japanese). TECH+. Retrieved 20 June 2021.
  81. ^ 小惑星探査機「はやぶさ２」記者説明会 (PDF) (in Japanese). JAXA. 17 June 2021. Retrieved 20 June 2021.

General references

[edit]
[edit]
Wikimedia Commons has media related to 162173 Ryugu.
Retrieved from "https://en.wikipedia.org/w/index.php?title=162173_Ryugu&oldid=1239517002"