Final reports of the Stardust Interstellar Preliminary Examination

Andrew J. Westphal , Hans A. Bechtel , Frank E. Brenker , Anna L. Butterworth , George Flynn , David R. Frank , Zack Gainsforth , Jon K. Hillier , Frank Postberg , Alexandre S. Simionovici , Veerle J. Sterken , Rhonda M. Stroud , Carlton Allen , David Anderson , Asna Ansari , Sasa Bajt , Ron K. Bastien , Nabil Bassim , Janet Borg , John Bridges , Donald E. Brownlee , Mark Burchell , Manfred Burghammer , Hitesh Changela , Peter Cloetens , Andrew M. Davis , Ryan Doll , Christine Floss , Eberhard Gruen , Philipp R. Heck , Peter Hoppe , Bruce Hudson , Joachim Huth , Brit Hvide , Anton Kearsley , Ashley J. King , Barry Lai , Jan Leitner , Laurence Lemelle (1) , Hugues Leroux , Ariel Leonard , Robert Lettieri , William Marchant , Larry R. Nittler , Ryan Ogliore , Wei Ja Ong , Mark C. Price , Scott A. Sandford , Juan-Angel Sans Tresseras , Sylvia Schmitz , Tom Schoonjans , Geert Silversmit , Vicente A. Sole , Ralf Srama , Frank Stadermann , Thomas Stephan , Julien Stodolna , Steven Sutton , Mario Trieloff , Peter Tsou , Akira Tsuchiyama , Tolek Tyliszczak , Bart Vekemans , Laszlo Vincze , Joshua von Korff , Naomi Wordsworth , Daniel Zevin , Michael E. Zolensky

1 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement

With the discovery of bona fide extraterrestrial materials in the Stardust Interstellar Dust Collector, NASA now has a fundamentally new returned sample collection, after the Apollo, Antarctic meteorite, Cosmic Dust, Genesis, Stardust Cometary, Hayabusa, and Exposed Space Hardware samples. Here, and in companion papers in this volume, we present the results from the Preliminary Examination of this collection, the Stardust Interstellar Preliminary Examination (ISPE). We found extraterrestrial materials in two tracks in aerogel whose trajectories and morphology are consistent with an origin in the interstellar dust stream, and in residues in four impacts in the aluminum foil collectors. While the preponderance of evidence, described in detail in companion papers in this volume, points toward an interstellar origin for some of these particles, alternative origins have not yet been eliminated, and definitive tests through isotopic analyses were not allowed under the terms of the ISPE. In this summary, we answer the central questions of the ISPE: How many tracks in the collector are consistent in their morphology and trajectory with interstellar particles? How many of these potential tracks are consistent with real interstellar particles, based on chemical analysis? Conversely, what fraction of candidates are consistent with either a secondary or interplanetary origin? What is the mass distribution of these particles, and what is their state? Are they particulate or diffuse? Is there any crystalline material? How many detectable impact craters ( 100 nm) are there in the foils, and what is their size distribution? How many of these craters have analyzable residue that is consistent with extraterrestrial material? And finally, can craters from secondaries be recognized through crater morphology (e.g., ellipticity)?

Domaines: Planète et Univers [physics]

Andrew J. Westphal, Hans A. Bechtel, Frank E. Brenker, Anna L. Butterworth, George Flynn, et al.. Final reports of the Stardust Interstellar Preliminary Examination. Meteoritics and Planetary Science, 2014, 49 (9, SI), pp.1720--1733. ⟨10.1111/maps.12221⟩. ⟨hal-02351048⟩