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40 Ar/ 39 Ar age of material returned from asteroid 25143 Itokawa
Author(s) -
Park Jisun,
Turrin Brent D.,
Herzog Gregory F.,
Lindsay Fara N.,
Delaney Jeremy S.,
Swisher Carl C.,
Uesugi Masayuki,
Karouji Yuzuru,
Yada Toru,
Abe Masanao,
Okada Tatsuaki,
Ishibashi Yukihiro
Publication year - 2015
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12564
Subject(s) - asteroid , chondrite , solar system , orbit (dynamics) , astrobiology , parent body , astrophysics , reset (finance) , rubble , formation and evolution of the solar system , physics , geology , astronomy , meteorite , engineering , aerospace engineering , geotechnical engineering , financial economics , economics
Abstract The Hayabusa mission to asteroid 25143, Itokawa, brought back 2000 small particles, which most closely resemble material found in LL 4‐6 chondrites. We report an 40 Ar/ 39 Ar age of 1.3 ± 0.3 Ga for a sample of Itokawa consisting of three grains with a total mass of ~2 μg. This age is lower than the >4.0 Ga ages measured for 75% of LL chondrites but close to one for Y‐790964 and its pairs. The flat 40 Ar/ 39 Ar release spectrum of the sample suggests complete degassing 1.3 Ga ago. Recent solar heating in Itokawa's current orbit does not appear likely to have reset that age. Solar or impact heating 1.3 Ga ago could have done so. If impact heating was responsible, then the 1.3 Ga age sets an upper bound on the time at which the Itokawa rubble pile was assembled and suggests that rubble pile creation was an ongoing process in the inner solar system for at least the first 3 billion years of solar system history.