40Ar/39Ar age of material returned from asteroid 25143 Itokawa

• DOI: 10.1111/maps.12564
• Publication Date: 2015-11-08T18:55:07Z
• Authors: Jisun Park; Brent D. Turrin; Gregory F. Herzog; Fara N. Lindsay; Jeremy S. Delaney; Carl C. Swisher; Masayuki Uesugi; Yuzuru Karouji; Toru Yada; Masanao Abe; Tatsuaki Okada; Yukihiro Ishibashi
• Keywords: Orbit (dynamics); Parent body; Reset (finance); Rubble

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 Itokawa consisting three grains with total mass ~2 μg. This is lower than the >4.0 ages measured 75% chondrites but close one Y‐790964 and its pairs. flat release spectrum suggests complete degassing ago. Recent solar heating Itokawa's current orbit does not appear likely have reset that age. Solar or impact ago could done so. If was responsible, then sets upper bound on time at rubble pile assembled creation ongoing process inner system least first 3 billion years history.