title: Neutron activation analysis of a particle returned from asteroid Itokawa.
abstract: A single grain (~3 micrograms) returned by the Hayabusa spacecraft was analyzed by neutron activation analysis. This grain is mainly composed of olivine with minor amounts of plagioclase, troilite, and metal. Our results establish that the Itokawa sample has similar chemical characteristics (iron/scandium and nickel/cobalt ratios) to chondrites, confirming that this grain is extraterrestrial in origin and has primitive chemical compositions. Estimated iridium/nickel and iridium/cobalt ratios for metal in the Itokawa samples are about five times lower than CI carbonaceous chondrite values. A similar depletion of iridium was observed in chondrule metals of ordinary chondrites. These metals must have condensed from the nebular where refractory siderophile elements already condensed and were segregated.
authors.affiliation: Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan. ebihara-mitsuru@tmu.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Ebihara
authors.forename: S
authors.initials: S
authors.lastname: Sekimoto
authors.forename: N
authors.initials: N
authors.lastname: Shirai
authors.forename: Y
authors.initials: Y
authors.lastname: Hamajima
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Kumagai
authors.forename: Y
authors.initials: Y
authors.lastname: Oura
authors.forename: T R
authors.initials: TR
authors.lastname: Ireland
authors.forename: F
authors.initials: F
authors.lastname: Kitajima
authors.forename: K
authors.initials: K
authors.lastname: Nagao
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Naraoka
authors.forename: T
authors.initials: T
authors.lastname: Noguchi
authors.forename: R
authors.initials: R
authors.lastname: Okazaki
authors.forename: A
authors.initials: A
authors.lastname: Tsuchiyama
authors.forename: M
authors.initials: M
authors.lastname: Uesugi
authors.forename: H
authors.initials: H
authors.lastname: Yurimoto
authors.forename: M E
authors.initials: ME
authors.lastname: Zolensky
authors.forename: M
authors.initials: M
authors.lastname: Abe
authors.forename: A
authors.initials: A
authors.lastname: Fujimura
authors.forename: T
authors.initials: T
authors.lastname: Mukai
authors.forename: Y
authors.initials: Y
authors.lastname: Yada