Scientific research in meteoritics includes thecollection, identification, andclassification of meteorites and the analysis of samples taken from them in alaboratory. Typical analyses include investigation of theminerals that make up the meteorite, their relative locations, orientations, and chemical compositions; analysis ofisotope ratios; andradiometric dating. These techniques are used to determine the age, formation process, and subsequent history of the material forming the meteorite. This provides information on thehistory of the Solar System, how it formed and evolved, and the process ofplanet formation.
Before the documentation ofL'Aigle it was generally believed that meteorites were a type of superstition and those who claimed to see them fall from space were lying.
In 1960John Reynolds discovered that some meteorites have an excess of129Xe, a result of the presence of129I in the solar nebula.[5]
The presence or absence of certain minerals is indicative of physical and chemical processes. Impacts on the parent body are recorded by impact-breccias and high-pressure mineral phases (e.g.coesite,akimotoite,majorite,ringwoodite,stishovite,wadsleyite).[6][7][8]Water bearing minerals, and samples of liquid water (e.g.,Zag,Monahans) are an indicator for hydrothermal activity on the parent body (e.g.clay minerals).[9]
Radiometric methods can be used to date different stages of the history of a meteorite. Condensation from thesolar nebula is recorded bycalcium–aluminium-rich inclusions andchondrules. These can be dated by using radionuclides that were present in the solar nebula (e.g.26Al/26Mg,53Mn/53Cr,U/Pb,129I/129Xe). After the condensed material accretes toplanetesimals of sufficient size melting and differentiation take place. These processes can be dated with the U/Pb,87Rb/87Sr,[10]147Sm/143Nd and176Lu/176Hf methods.[11] Metallic core formation and cooling can be dated by applying the187Re/187Os method toiron meteorites.[12][13] Large scale impact events or even the destruction of the parent body can be dated using the39Ar/40Ar method and the244Pu fission track method.[14] After breakup of the parent body meteoroids are exposed to cosmic radiation. The length of this exposure can be dated using the3H/3He method,22Na/21Ne,81Kr/83Kr.[15][16] After impact on earth (or any other planet with sufficient cosmic ray shielding) cosmogenic radionuclides decay and can be used to date the time since the meteorite fell. Methods to date this terrestrial exposure are36Cl,14C,81Kr.[17]
^Ameteorite is a solid rock which has landed on Earth after originating in space. It should not be confused with ameteor (a shooting star, caused by an incoming object burning up in the Earth's atmosphere) or ameteoroid (a small body orbiting within the Solar System).
When the Journal of the Meteoritical Society and the Institute of Meteoritics of the University of New Mexico first appeared in 1953, it quoted the then accepted definition of meteoritics asthe science of meteorites and meteors, but it went on to explain that meteorites at the time included what are now called meteoroids:Meteoritics may be defined independently of meteorites and meteors, however, as that branch of astronomy that is concerned with the study of the solid matter that comes to the Earth from space; of the solid bodies of subplanetary mass that lie beyond the Earth; and of the phenomena that are associated with such matter or such bodies.[1]
^Hutchison, R.; Alexander, C.M.O.; barber, D.J. (30 June 1987). "The Semarkona meteorite: First recorded occurrence of smectite in an ordinary chondrite, and its implications".Geochimica et Cosmochimica Acta.51 (7):1875–1882.Bibcode:1987GeCoA..51.1875H.doi:10.1016/0016-7037(87)90178-5.
^Birck, J.L.; Allègre, C. J. (28 February 1978). "Chronology and chemical history of the parent body of basaltic achondrites studied by the87Rb-87Sr method".Earth and Planetary Science Letters.39 (1):37–51.Bibcode:1978E&PSL..39...37B.doi:10.1016/0012-821X(78)90139-5.
^Bouvier, Audrey; Vervoort, Jeffrey D.; Patchett, P. Jonathan (31 July 2008). "The Lu–Hf and Sm–Nd isotopic composition of CHUR: Constraints from unequilibrated chondrites and implications for the bulk composition of terrestrial planets".Earth and Planetary Science Letters.273 (1–2):48–57.Bibcode:2008E&PSL.273...48B.doi:10.1016/j.epsl.2008.06.010.
^Bogard, D.D; Garrison, D.H; Jordan, auJ.L; Mittlefehldt, D (31 August 1990). "39Ar-40Ar dating of mesosiderites: Evidence for major parent body disruption < 4 Ga ago".Geochimica et Cosmochimica Acta.54 (9):2549–2564.Bibcode:1990GeCoA..54.2549B.doi:10.1016/0016-7037(90)90241-C.
^Eugster, O (31 May 1988). "Cosmic-ray production rates for3He,21Ne,38Ar,83Kr, and126Xe in chondrites based on81Kr-Kr exposure ages".Geochimica et Cosmochimica Acta.52 (6):1649–1662.Bibcode:1988GeCoA..52.1649E.doi:10.1016/0016-7037(88)90233-5.
^Nishiizumi, K.; Regnier, S.; Marti, K. (1 October 1980). "Cosmic ray exposure ages of chondrites, pre-irradiation and constancy of cosmic ray flux in the past".Earth and Planetary Science Letters.50 (1):156–170.Bibcode:1980E&PSL..50..156N.doi:10.1016/0012-821X(80)90126-0.
G. J. H. McCall, ed. (2006).The history of meteoritics and key meteorite collections : fireballs, falls and finds. London:Geological Society.ISBN978-1862391949.
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