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25143 Itokawa (//; Japanese: イトカワ,いとかわ,糸川 [itokaɰa]) is a stony sub-kilometer asteroid, classified as near-Earth object of the Apollo group and potentially hazardous asteroid, that measures approximately 350 meters in diameter. It was the first asteroid to be the target of a sample return mission, the Japanese space probe Hayabusa, and the smallest asteroid photographed and visited by a spacecraft.
|Discovery site||Lincoln Lab's ETS|
|Discovery date||26 September 1998|
|MPC designation||(25143) Itokawa|
(Japanese rocket scientist)
|Apollo · NEO · PHA |
|Orbital characteristics |
|Epoch 4 September 2017 (JD 2458000.5)|
|1.52 yr (557 days)|
|Earth MOID||0.0129 AU · 5 LD|
|Dimensions||535 × 294 × 209 m|
mean diameter in meters:
|Mass||(3.51±0.105)×1010 kg (3.58±0.18)×1010 kg|
|1.9 ±0.13 g/cm³|
±0.14 g/cm³ 1.95
±0.0002 h 12.1323
±0.01 h 12.09
|SMASS = S (IV) · Sqw  · S  · Q |
|18.61 · 18.95 (R) · 19.00 · 19.2 · 19.48 · ±0.0919.51 · 19.73|
Discovery and namingEdit
The asteroid was discovered in 1998 by the LINEAR project at the Lincoln Laboratory's Experimental Test Site in Socorro, New Mexico. It was given the provisional designation 1998 SF36. This minor planet was named after Hideo Itokawa (1912–1999), a Japanese rocket scientist. The official naming citation was published in the Minor Planet Center on 6 August 2003 (M.P.C. 49281).
The Hayabusa mission confirmed these findings and also suggested that Itokawa may be a contact binary formed by two or more smaller asteroids that have gravitated toward each other and stuck together. The Hayabusa images show a surprising lack of impact craters and a very rough surface studded with boulders, described by the mission team as a 'rubble pile'. Furthermore, the density of the asteroid is too low for it to be made from solid rock. This would mean that Itokawa is not a monolith but rather a 'rubble pile' formed from fragments that have cohered over time. Based on Yarkovsky–O'Keefe–Radzievskii–Paddack effect measurements, a small section of Itokawa is estimated to have a density of 2.9 g/cm³, whereas a larger section is estimated to have a density of 1.8 g/cm³.
In 2000, it was selected as the target of Japan's Hayabusa mission. The probe arrived in the vicinity of Itokawa on 12 September 2005 and initially "parked" in an asteroid–Sun line at 20 km (12 mi), and later 7 km (4.3 mi), from the asteroid (Itokawa's gravity was too weak to provide an orbit, so the spacecraft adjusted its orbit around the Sun until it matched the asteroid's). Hayabusa landed on 20 November for thirty minutes, but it failed to operate a device designed to collect soil samples. On 25 November, a second landing and sampling sequence was attempted. The sample capsule was returned to Earth and landed at Woomera, South Australia on 13 June 2010, around 13:51 UTC (23:21 local). On 16 November 2010, the Japan Aerospace Exploration Agency reported that dust collected during Hayabusa's voyage was indeed from the asteroid.
Names of major surface features were proposed by Hayabusa scientists and accepted by the Working Group for Planetary System Nomenclature of the International Astronomical Union. Also, the Hayabusa science team is using working names for smaller surface features. The following tables list the names of geological features on the asteroid. No naming conventions have been disclosed for surface features on Itokawa.
|Catalina||0.02||2009||Catalina Station (astronomical observatory) in Arizona, United States||WGPSN|
|Fuchinobe||0.04||2009||Fuchinobe in Sagamihara, Japan||WGPSN|
|Gando||n.a.||2009||Gando, Canary Islands; Spanish launch facility||WGPSN|
|Hammaguira||0.03||2009||Hammaguir, Algeria; abandoned French launch site and missile testing range in the Sahara desert||WGPSN|
|Kamisunagawa||0.01||2009||Kamisunagawa, town in Hokkaido Japan, where a microgravity test facility is located||WGPSN|
|Kamoi||0.01||2009||Japanese town of Kamoi in Yokohama, location of the NEC TOSHIBA Space Systems Ltd. factory||WGPSN|
|Komaba||0.03||2009||Komaba in Meguro, Japan, where the Institute of Space and Astronautical Science is located||WGPSN|
|Laurel||0.02||2009||U.S. city of Laurel in Maryland, where APL/JHU is located||WGPSN|
|Miyabaru||0.09||2009||Radar site of the Uchinoura Space Center in Japan||WGPSN|
|San Marco||n.a.||2009||San Marco platform, an old oil platform near Kenya that served as a launch pad for Italian spacecraft||WGPSN|
Regiones (geologically distinct areas) on Itokawa.
|Arcoona Regio||Arcoona, Australia|
|LINEAR Regio||Lincoln Near-Earth Asteroid Research|
|MUSES-C Regio||MUSES-C, name of the Hayabusa probe prior to launch.|
|Ohsumi Regio||Ōsumi Peninsula|
|Sagamihara Regio||Sagamihara, a town in Japan where Institute of Space and Astronautical Science is located.|
|Uchinoura Regio||Uchinoura, a town in Japan (now part of Kimotsuki), the location of Uchinoura Space Center, Hayabusa launch site.|
|Yoshinobu Regio||Launch site in the Tanegashima Space Center, Japan.|
Analysis of particles reported in August 2011Edit
The 26 August 2011 issue of Science devoted six articles to findings based on dust that Hayabusa had collected from Itokawa. Scientists' analysis suggested that Itokawa was probably made up from interior fragments of a larger asteroid that broke apart. Dust collected from the asteroid surface is thought to have been exposed there for about eight million years.
Scientists used varied techniques of chemistry and mineralogy to analyze the dust from Itokawa. Itokawa's composition was found to match the common type of meteorites known as "low-total-iron, low metal ordinary chondrites". Another team of scientists determined that the dark iron color on the surface of Itokawa was the result of abrasion by micrometeoroids and high-speed particles from the Sun which had converted the normally whitish iron oxide coloring.
2018 Hayabusa ResultsEdit
Jin et al. report water in low-calcium pyroxene grains. The water's isotope level corresponds with inner solar system and carbonaceous chondrite water isotope levels.
The water concentrations of the Itokawa grains would indicate an estimated BSI (Bulk Silicate Itokawa) water content in line with Earth's bulk water, and that Itokawa had been a "water-rich asteroid".
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- Schmadel, Lutz D. (2006). "(25143) Itokawa [1.32, 0.28, 1.6]". Dictionary of Minor Planet Names – (25143) Itokawa, Addendum to Fifth Edition: 2003–2005. Springer Berlin Heidelberg. p. 188. doi:10.1007/978-3-540-34361-5_2203. ISBN 978-3-540-34361-5.
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- Mueller, Michael; Delbo', M.; Hora, J. L.; Trilling, D. E.; Bhattacharya, B.; Bottke, W. F.; et al. (April 2011). "ExploreNEOs. III. Physical Characterization of 65 Potential Spacecraft Target Asteroids". The Astronomical Journal. 141 (4): 9. Bibcode:2011AJ....141..109M. doi:10.1088/0004-6256/141/4/109.
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- Sekiguchi, T.; Abe, M.; Boehnhardt, H.; Dermawan, B.; Hainaut, O. R.; Hasegawa, S. (January 2003). "Thermal observations of MUSES-C mission target (25143) 1998 SF36". Astronomy and Astrophysics. 397: 325–328. Bibcode:2003A&A...397..325S. doi:10.1051/0004-6361:20021437. Retrieved 15 August 2017.
- Shinsuke Abe, et al., Mass and Local Topography Measurements of Itokawa by Hayabusa, Science, Vol. 312. no. 5778, pp. 1344 – 1347, 2 June 2006
- Lambert, J. S.; Tholen, D. J. (December 2001). "Rotational Studies of MUSES-C Target Asteroid (25143) 1998 SF36". American Astronomical Society. 33: 1402. Bibcode:2001AAS...199.6303L. Retrieved 15 August 2017.
- Lowry, S. C.; Weissman, P. R.; Hicks, M. D. (November 2001). "CCD Observations of Asteroid 1998 SF36 (25143)". American Astronomical Society. 33: 1150. Bibcode:2001DPS....33.5909L. Retrieved 15 August 2017.
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- Dermawan, Budi; Nakamura, Tsuko; Fukushima, Hideo; Sato, Hideo; Yoshida, Fumi; Sato, Yusuke (August 2002). "CCD Photometry of the MUSES-C Mission Target: Asteroid (25143) 1998 SF36". Publications of the Astronomical Society of Japan. 54 (4): 635–640. Bibcode:2002PASJ...54..635D. doi:10.1093/pasj/54.4.635. Retrieved 15 August 2017.
- Kaasalainen, M.; Kwiatkowski, T.; Abe, M.; Piironen, J.; Nakamura, T.; Ohba, Y.; et al. (July 2003). "CCD photometry and model of MUSES-C target (25143) 1998 SF36". Astronomy and Astrophysics. 405 (3): L29–L32. Bibcode:2003A&A...405L..29K. doi:10.1051/0004-6361:20030819. Retrieved 15 August 2017.
- Durech, J.; Vokrouhlický, D.; Kaasalainen, M.; Weissman, P.; Lowry, S. C.; Beshore, E.; et al. (September 2008). "New photometric observations of asteroids (1862) Apollo and (25143) Itokawa – an analysis of YORP effect". Astronomy and Astrophysics. 488 (1): 345–350. Bibcode:2008A&A...488..345D. doi:10.1051/0004-6361:200809663. Retrieved 15 August 2017.
- Nishihara, S.; Abe, M.; Hasegawa, S.; Ishiguro, M.; Kitazato, K.; Miura, N.; et al. (March 2005). "Ground-based Lightcurve Observation of (25143) Itokawa, 2001–2004". 36th Annual Lunar and Planetary Science Conference. 36: 1833. Bibcode:2005LPI....36.1833N. Retrieved 15 August 2017.
- Ohba, Y.; Abe, M.; Hasegawa, S.; Ishiguro, M.; Kwiatkowski, T.; Colas, F.; et al. (June 2003). "Pole orientation and triaxial ellipsoid shape of (25143) 1998 SF36, a target asteroid of the MUSES-C* mission". Earth. 55: 341–347.(EP&SHomepage). Bibcode:2003EP&S...55..341O. Retrieved 15 August 2017.
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- S. M. Lederer, et al., Physical characteristics of Hayabusa target Asteroid 25143 Itokawa, Icarus, v. 173, p. 153–165 (2005)
- Thomas, Cristina A.; Emery, Joshua P.; Trilling, David E.; Delbó, Marco; Hora, Joseph L.; Mueller, Michael (January 2014). "Physical characterization of Warm Spitzer-observed near-Earth objects". Icarus. 228: 217–246. arXiv:1310.2000. Bibcode:2014Icar..228..217T. doi:10.1016/j.icarus.2013.10.004. Retrieved 15 August 2017.
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- "Hayabusa: Itokawa Beckons as Japan's Spacecraft Searches for Places to Touch Down". Archived from the original on 12 May 2008. Retrieved 11 August 2008.CS1 maint: BOT: original-url status unknown (link)
- "The Anatomy of an Asteroid". ESO. 5 February 2014. Retrieved 5 February 2014.
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- "Itowaka Geological Map". Archived from the original on 26 February 2009. Retrieved 11 August 2008.CS1 maint: BOT: original-url status unknown (link)
- "Local site names on Itowaka". Archived from the original on 26 February 2009. Retrieved 11 August 2008.CS1 maint: BOT: original-url status unknown (link)
- USGS: Itokawa nomenclature
- "The Anatomy of an Asteroid". ESO Press Release. Retrieved 6 February 2014.
- "Asteroid Dust Confirms Meteorite Origins". New York Times. 25 August 2011. Retrieved 26 August 2011.
- Nakamura, Tomoki; Noguchi, Takaaki; Tanaka, Masahiko; Zolensky, Michael E.; Kimura, Makoto; Tsuchiyama, Akira; Nakato, Aiko; Ogami, Toshihiro; Ishida, Hatsumi; Uesugi, Masayuki; Yada, Toru; Shirai, Kei; Fujimura, Akio; Okazaki, Ryuji; Sandford, Scott A.; Ishibashi, Yukihiro; Abe, Masanao; Okada, Tatsuaki; Ueno, Munetaka; Mukai, Toshifumi; Yoshikawa, Makoto; Kawaguchi, Junichiro (26 August 2011). "Itokawa Dust Particles: A Direct Link Between S-Type Asteroids and Ordinary Chondrites". Science. 333 (6046): 1113–6. Bibcode:2011Sci...333.1113N. doi:10.1126/science.1207758. PMID 21868667. Retrieved 26 August 2011.
- "Most Earth meteorites linked to single asteroid". Los Angeles Times. 26 August 2011. Retrieved 26 August 2011.
- Jin ZL, Bose M, Peeters Z (2018). "New Clues to Ancient Water on Itokawa". Lunar and Planetary Science Conference (2083): 1670. Bibcode:2018LPI....49.1670J.
- Daly, L; Lee, M; Hallis, L; Bland, P; Reddy, S; et al. (2018). "The origin of hydrogen in space weathered rims of Itokawa regolith particles". 2018 Hayabusa Symposium.
- Jin Z; Bose M (2018). "Establishing Itokawa's water contribution to Earth". 2018 Hayabusa Symposium.
- Durech, J.; Vokrouhlický, D.; Kaasalainen, M.; Weissman, P.; Lowry, S. C.; Beshore, E.; Higgins, D.; Krugly, Y. N.; et al. (September 2008). "New photometric observations of asteroids (1862) Apollo and (25143) Itokawa – an analysis of YORP effect" (PDF). Astronomy and Astrophysics. 488 (1): 345–350. Bibcode:2008A&A...488..345D. doi:10.1051/0004-6361:200809663.
- Normile, D (30 April 2010). "Spunky Hayabusa Heads Home With Possible Payload". Science. 328 (5978): 565. Bibcode:2010Sci...328..565N. doi:10.1126/science.328.5978.565. PMID 20430991.
|Wikimedia Commons has media related to 25143 Itokawa.|
- Hayabusa's Scientific and Engineering Achievements during Proximity Operations around Itokawa (JAXA press release)
- Gazetteer of Planetary Nomenclature
- MIT's LINEAR asteroid named for Japan's 'Dr. Rocket' (MIT press release)
- JAXA Hayabusa official page
- Earth impact probability of the Asteroid (25143) Itokawa to be sampled by the spacecraft Hayabusa (paper abstract)
- Astronomy Picture Of The Day: Approaching Asteroid Itokawa, A Robot's Shadow on Asteroid Itokawa, The Missing Craters of Asteroid Itokawa, Smooth Sections on Asteroid Itokawa
- Special issue: Hayabusa at Itokawa, Science, Vol. 312, no. 5778, 2 June 2006
- Lightcurve plot of 25143 Itokawa, Palmer Divide Observatory, B. D. Warner (2004)
- Initial Scientific Results of Hayabusa’s Investigation on Itokawa ~Summary of the Special Issue of "Science"Magazine~ (ISAS/JAXA press release)
- Hot Topic: Hayabusa—Dust from Itokawa, Science, Vol. 333, no. 6046, 26 August 2011
- Animated model of Itokawa rotating (in anaglyph form for use with red-blue glasses)
- Itokawa in enhanced color (From this presentation)
- 25143 Itokawa at the JPL Small-Body Database