25143 Itokawa

25143 Itokawa

Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0
name=25143 Itokawa


discoverer=LINEAR
discovered=September 26 1998
alt_names=mp|1998 SF|36
mp_category=Apollo asteroid,
Mars-crosser asteroid
epoch=August 18 2005 (JD 2453600.5)
semimajor=198.044 Gm (1.324 AU)
perihelion=142.568 Gm (0.953 AU)
aphelion=253.520 Gm (1.695 AU)
eccentricity=0.280
period=556.355 d (1.52 a)
inclination=1.622°
asc_node=69.095°
arg_peri=162.760°
mean_anomaly=294.502°
avg_speed=25.37 km/s
dimensions= 535 × 294 × 209 m Akira Fujiwara, et al., [http://www.sciencemag.org/cgi/content/abstract/312/5778/1330 The Rubble-Pile Asteroid Itokawa as Observed by Hayabusa] , Science, Vol. 312. no. 5778, pp. 1330 - 1334, June 2, 2006]
mass= (3.51±0.105)e|10 kg ditto] , (3.58±0.18)e|10 kg Shunsuke Abe, et al., [http://www.sciencemag.org/cgi/content/abstract/312/5778/1344 Mass and Local Topography Measurements of Itokawa by Hayabusa] , Science, Vol. 312. no. 5778, pp. 1344 - 1347, June 2, 2006]
density=1.9 ±0.13 g/cm³ ditto] , 1.95 ± 0.14 g/cm³ ditto]
surface_grav=~0.0001 m/s²
escape_velocity=~0.0002 km/s
rotation= 0.5055 d (12.132 h) M. Kaasalainen, et al., [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003A%26A...405L..29K&db_key=AST&data_type=HTML&format= CCD photometry and model of MUSES-C target (25143) 1998 SF36] , Astronomy and Astrophysics, v.405, p.L29-L32 (2003)]
spectral_type=S
abs_magnitude=19.2
albedo=0.53
single_temperature=~206 K

25143 Itokawa (pronEng|ˌiːtoʊˈkɑːwə, Japanese イトカワ, from 糸川) is an Apollo and Mars-crosser asteroid. It was the focus of detailed study by the Japanese space probe "Hayabusa" and may become the first asteroid sample-return target.

History

The asteroid was discovered in 1998 by the LINEAR project, and given the provisional designation mp|1998 SF|36. In 2000, it was selected as the target of Japan's Hayabusa mission. Soon thereafter, it was officially named after Hideo Itokawa, a Japanese rocket scientist.

Description

Itokawa is an S-type asteroid. Radar imaging by Goldstone revealed an elongated irregular shape.cite news
url=http://echo.jpl.nasa.gov/~ostro/itokawa.html
title=Radar Observations of Asteroid 25143 Itokawa (1998 SF36)
publisher=
author=
date=
accessdate=2008-08-11
quote=
[http://www.webcitation.org/query?url=http%3A%2F%2Fecho.jpl.nasa.gov%2F%7Eostro%2Fitokawa.html&date=2008-08-11 mirror] ]

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, but a very rough surface studded with boulders. These particular boulders were referred by the mission team as being in a 'rubble'.cite news
url=http://www.planetary.org/news/2005/0916_Hayabusa_Itokawa_Beckons_as_Japans.html
title=Hayabusa: Itokawa Beckons as Japan's Spacecraft Searches for Places to Touch Down
publisher=
author=
date=
accessdate=2008-08-11
quote=
[http://www.webcitation.org/query?url=http%3A%2F%2Fwww.planetary.org%2Fnews%2F2005%2F0916_Hayabusa_Itokawa_Beckons_as_Japans.html&date=2008-08-11 mirror] ] This would mean that Itokawa is not a monolith but rather a ‘rubble pile’ formed from fragments that have cohered over time.

"Hayabusa" mission

The Japanese probe "Hayabusa" arrived in the vicinity of Itokawa on September 12 2005 and initially "parked" in an asteroid-sun line at 20 km, and later 7 km, from the asteroid. "Hayabusa" landed November 20 for thirty minutes, but failed to operate a device designed to collect soil samples. On November 25, a second landing and the sampling sequence was attempted. Hayabusa has since left the asteroid, and the sample capsule is planned to land at Woomera, South Australia in 2010; however, it is unclear if any samples were collected.

Named surface features

Names of major features were proposed by "Hayabusa" scientists and accepted by the Working Group for Planetary System Nomenclature of the International Astronomical Union.See the list of geological features on 25143 Itokawa.

Also, the "Hayabusa" science team is using working names for smaller surface features. [cite news
url=http://www.isas.jaxa.jp/e/snews/2006/image/0602/b/08.jpg
title=Itowaka Geological Map
publisher=
author=
date=
accessdate=2008-08-11
quote=
[http://www.webcitation.org/query?url=http%3A%2F%2Fwww.isas.jaxa.jp%2Fe%2Fsnews%2F2006%2Fimage%2F0602%2Fb%2F08.jpg&date=2008-08-11 mirror]
] [cite news
url=http://www.isas.jaxa.jp/e/snews/2006/image/0602/b/09.jpg
title=Local site names on Itowaka
publisher=
author=
date=
accessdate=2008-08-11
quote=
[http://www.webcitation.org/query?url=http%3A%2F%2Fwww.isas.jaxa.jp%2Fe%2Fsnews%2F2006%2Fimage%2F0602%2Fb%2F09.jpg&date=2008-08-11 mirror]
]

References

External links

* [http://www.isas.jaxa.jp/j/snews/2005/1101_hayabusa.shtml Close-up images of Itokawa, a rubble pile asteroid]
* [http://nettv.gov-online.go.jp/prg/prg1018.html Hayabusa mission Video] March 2007
* [http://planetarynames.wr.usgs.gov/ Gazetteer of Planetary Nomenclature]
* [http://web.mit.edu/newsoffice/2003/asteroids2.html MIT's LINEAR asteroid named for Japan's 'Dr. Rocket'] (MIT press release)
* [http://www.hayabusa.isas.jaxa.jp/e/index.html Latest news and images from "Hayabusa"] (JAXA Hayabusa official page)
* [http://www.isas.jaxa.jp/e/snews/2005/1102.shtml Hayabusa's Scientific and Engineering Achievements during Proximity Operations around Itokawa ] (JAXA press release)
* [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005Icar..179..291M Earth impact probability of the Asteroid (25143) Itokawa to be sampled by the spacecraft Hayabusa] (paper abstract)
* Astronomy Picture Of The Day: [http://antwrp.gsfc.nasa.gov/apod/ap050919.html Approaching Asteroid Itokawa] , [http://antwrp.gsfc.nasa.gov/apod/ap051116.html A Robot's Shadow on Asteroid Itokawa] , [http://antwrp.gsfc.nasa.gov/apod/ap051121.html The Missing Craters of Asteroid Itokawa] , [http://antwrp.gsfc.nasa.gov/apod/ap051228.html Smooth Sections on Asteroid Itokawa]
* [http://www.sciencemag.org/content/vol312/issue5778/index.dtl Special issue: Hayabusa at Itokawa] , Science, Vol. 312, no. 5778, June 2 2006
* [http://www.isas.jaxa.jp/e/snews/2006/0602.shtml Initial Scientific Results of Hayabusa’s Investigation on Itokawa ~Summary of the Special Issue of “Science”Magazine~] (ISAS/JAXA press release)
* [http://hayabusa.sci.isas.jaxa.jp/data/shape/movies/itokawa_g070104.mov Animated model of Itokawa rotating (in anaglyph form for use with red-blue glasses)]



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