- Lunar meteorite
A Lunar meteorite is a
meteoritethat is known to have originated on the Moon.
1982, John Schutt, leading an expedition in Antarcticafor the ANSMETprogram, found a meteorite that he recognized to be unusual. Shortly thereafter, the meteorite now called Allan Hills 81005was sent to Washington, DC, where Smithsonian Institution geochemistBrian Mason recognized that the sample was unlike any other known meteorite and resembled some rocks brought back from the Moonby the Apollo program[Marvin U. B. (1983) The discovery and initial characterization of Allan Hills 81005: The first lunar meteorite, "Geophys. Res. Lett." 10, 775–778] . Several year later, Japanese scientists recognized that they had also collected a lunar meteorite, Yamato 791197, during the 1979field season in Antarctica. About 112 (as of February, 2008) other lunar meteoriteshave subsequently been discovered, perhaps representing 50 separate meteorite falls (i.e., many of the stones are "paired" fragments of the same meteoroid). The total mass is more than 46 kg. All lunar meteorites have been found in deserts; most have been found in Antarctica, northern Africa, and the Sultanate of Oman. None have yet been found in North America, South America, or Europe.
Lunar origin is established by comparing the mineralogy, the chemical composition, and the isotopic composition between meteorites and samples from the Moon collected by Apollo missions.
Transfer to Earth
Most lunar meteorites are launched from the Moon by impacts making lunar craters of a few kilometers in diameter or less. [cite journal| last =James N. Head, H. Jay Melosh, and Boris A. Ivanov | title=High-speed ejecta from small craters | journal=Science | volume=298 |pages=1752–1756 | doi=10.1126/science.1077483 | year=2002 | pmid=12424385] No source crater of lunar meteorites has been positively identified, although there is speculation that the highly anomalous lunar meteorite
Sayh al Uhaymir 169derives from the Lalande impact crater on the Lunar nearside [Gnos E., Hofmann B. A., Al-Kathiri A., Lorenzetti S., Eugster O., Whitehouse M. J., Villa I., Jull A. J. T., Eikenberg J., Spettel B., Krähenbühl U., Franchi I. A., and Greenwood G. C. (2004) Pinpointing the source of a lunar meteorite: Implications for the evolution of the Moon, "Science" 305, 657–659] [cite web | url = http://www.psrd.hawaii.edu/Oct04/SaU169.html | title = New Lunar Meteorite Provides its Lunar Address and Some Clues about Early Bombardment of the Moon | publisher = Planetary Science Research Discoveries | last = G. Jeffrey Taylor | date = October 31, 2004] .
Cosmic ray exposure history established with noble gas measurements have shown that all lunar meteorites were ejected from the Moon in the past 20 million years. Most left the Moon in the past 100,000 years. After leaving the Moon, most lunar meteoroids go into orbit around Earth and eventually succumb to Earth's gravity. Some meteoroids ejected from the Moon get launched into orbits around the sun. These meteoroids remain in space longer but eventually intersect the Earth's orbit and land.
All six of the Apollo missions on which samples were collected landed in the central nearside of the Moon, an area that has subsequently been shown to be geochemically anomalous by the
Lunar Prospectormission. In contrast, the numerous lunar meteorites are random samples of the Moon and consequently provide a more representative sampling of the lunar surface than the Apollo samples. Half the lunar meteorites, for example, likely sample material from the farside of the Moon.
At the time the first meteorite from the Moon was discovered in 1982, there was speculation that some other unusual meteorites that had been found previously originated from Mars. The positive identification of lunar meteorites on Earth supported the hypothesis that meteoroid impacts on Mars could eject rocks from that planet. There are also speculations about the possibility of finding "Earth meteorites" on the surface of the Moon [cite journal | last = John Armstrong, Llyd Wells, and Guillermo Gonzalez | title = Rummaging through Earth’s Attic for Remains of Ancient Life | journal=Icarus |volume = 160 | pages = 183–196 | date=2002 | doi = 10.1006/icar.2002.6957] . This would be very interesting because in this case stones from earth older than 3.9 billion years, which are destroyed on earth by various geological processes, may have survived on the Moon. Thus some scientists propose new missions to the Moon to search for ancient rocks from
Today, about one in every thousand newly discovered meteorites is a lunar meteorite, whereas the vast majority of meteorites are from the asteroid belt. In the early 19th century most scientists believed that all meteorites were from the Moon. Although today supported only by a minority of researchers, there are also theories that
Tektites are from the Moon, and should therefore also be regarded as lunar meteorites. However, most scientists regard such theories as outdated.
Lunar meteorites collected in Africa and Oman are, for all practical purposes, the only source of moon rocks available for private ownership. This is because all rocks collected during the
Apollomoon-landing program are property of the United States Government, or other nations to which the U.S. conveyed them as gifts. Similarly, all lunar meteorites collected by the U.S. and Japanese Antarctic programs are, by treaty, held by those governments for research and education purposes only. Although there is no U.S. law specifically against the ownership of Apollo moonrocks, none has ever been (or is likely to ever be) given or sold by the U.S. government to private citizens. Even in the cases of plaques containing genuine Apollo moonrocks given in 2004 to astronauts and Walter Cronkite, NASA retained ownership of the rocks themselves [ [http://www.msnbc.msn.com/id/5431472 MS-NBC story, "Astronauts, Cronkite to get moon rock plaques"] ] . Most of the moonrocks collected by the Luna 16probe are also unavailable for private ownership, although three tiny samples were sold at auction for $442,500 in 1993 [ [http://query.nytimes.com/gst/fullpage.html?res=9C0DEFD91139F931A35751C1A963958260&sec=&spon=&pagewanted=all NY Times story, "F.B.I. Revisits Earthly Theft of Moon Rock] ] .
ReferencesCited referencesScientific reference
* cite journal
last =Bill Cooke
year = 2006
month = August
title = The Great Interplanetary Rock Swap
journal = Astronomy
volume = 34
issue = 8
pages = 64–67
Geology of the Moon
List of lunar meteorites
* [http://meteorites.wustl.edu/lunar/moon_meteorites.htm Lunar Meteorites, Washington Univ. St.Louis]
* [http://meteorites.wustl.edu/lunar/moon_meteorites_list_alumina.htm List of Lunar Meteorites]
* [http://www.lpl.arizona.edu/SIC/moon/lunar_meteorites/ Lunar Meteorites, Univ. of Arizona]
* [http://www.psrd.hawaii.edu/Archive/Contents.html Lunar meteorite articles in Planetary Science Research Discoveries]
Wikimedia Foundation. 2010.
Look at other dictionaries:
Météorite lunaire — Allan Hills 81005 Une météorite lunaire est une météorite de type achondrite connue pour être originaire de la lune. En d autres termes, une météorite lunaire est une roche trouvée sur Terre éjectée de la Lune à la suite d un impact avec un objet … Wikipédia en Français
Meteorite fall statistics — are frequently used by planetary scientists to approximate the true flux of meteorites on the Earth. Meteorite falls are those meteorites that are collected after being witnessed to fall, whereas meteorite finds are discovered at a later time.… … Wikipedia
Meteorite classification — The ultimate goal of meteorite classification is to group all meteorite specimens that share a common origin on a single, identifiable parent body. This could be a planet, asteroid, Moon, or other current Solar System object, or one that existed… … Wikipedia
Météorite martienne — EETA79001 Une météorite martienne est une météorite retrouvée sur la Terre dont l origine est la planète Mars. Ces météorites peuvent résulter notamment par la chute sur la Terre d un résidu d impact cosmique entre Mars et un autre corps céleste … Wikipédia en Français
Météorite de Chassenon — Astroblème de Rochechouart Chassenon Astroblème de Rochechouart Chassenon Image de synthèse du cratère quelques années après l’impact. Localisation Astre … Wikipédia en Français
Météorite de Rochechouart — Astroblème de Rochechouart Chassenon Astroblème de Rochechouart Chassenon Image de synthèse du cratère quelques années après l’impact. Localisation Astre … Wikipédia en Français
Meteorite — This article is about debris from space that survives impact with the ground. For other uses of Meteor and Meteors , see Meteor (disambiguation). For popular applications, see Falling star. For the fictional superhero in the Marvel Comics… … Wikipedia
meteorite — meteoritic /mee tee euh rit ik/, meteoritical, meteorital /mee tee euh ruyt l/, adj. /mee tee euh ruyt /, n. 1. a mass of stone or metal that has reached the earth from outer space; a fallen meteoroid. 2. a meteoroid. [1815 25; METEOR + ITE1] * * … Universalium
meteorite crater — crater (def. 2). * * * Depression that results from the impact of a meteorite with a solid object in space. Impact craters have been discovered on Earth, the Moon, Mars, other planets and satellites, and asteroids; they probably occur on… … Universalium
Lunar soil — Moondust redirects here. For the Commodore 64 video game, see Moondust (video game). For the Psychoactive drug, see Phencyclidine. Bootprint on lunar soil … Wikipedia