title: Helium and neon abundances and compositions in cometary matter.
abstract: Materials trapped and preserved in comets date from the earliest history of the solar system. Particles captured by the Stardust spacecraft from comet 81P/Wild 2 are indisputable cometary matter available for laboratory study. Here we report measurements of noble gases in Stardust material. Neon isotope ratios are within the range observed in "phase Q," a ubiquitous, primitive organic carrier of noble gases in meteorites. Helium displays 3He/4He ratios twice those in phase Q and in Jupiter's atmosphere. Abundances per gram are surprisingly large, suggesting implantation by ion irradiation. The gases are probably carried in high-temperature igneous grains similar to particles found in other Stardust studies. Collectively, the evidence points to gas acquisition in a hot, high ion-flux nebular environment close to the young Sun.
authors.affiliation: Centre de Recherches Pétrographiques et Géochimiques, Nancy Université, BP 20, 54501 Vandoeuvre-lès-Nancy Cedex, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Marty
authors.forename: Russell L
authors.initials: RL
authors.lastname: Palma
authors.forename: Robert O
authors.initials: RO
authors.lastname: Pepin
authors.forename: Laurent
authors.initials: L
authors.lastname: Zimmermann
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Schlutter
authors.forename: Peter G
authors.initials: PG
authors.lastname: Burnard
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Westphal
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Snead
authors.forename: Sasa
authors.initials: S
authors.lastname: Bajt
authors.forename: Richard H
authors.initials: RH
authors.lastname: Becker
authors.forename: Jacob E
authors.initials: JE
authors.lastname: Simones