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Survival of seeds in hypervelocity impacts

Published online by Cambridge University Press:  04 December 2008

Aaron Jerling
Affiliation:
School of Physical Sciences, Ingram Building, University of Kent, Canterbury, Kent CT2 7NH, UK
Mark J. Burchell
Affiliation:
School of Physical Sciences, Ingram Building, University of Kent, Canterbury, Kent CT2 7NH, UK
David Tepfer
Affiliation:
Biologie de al Rhizosphére, Institut National de la Recherche Agronomique, F-78026 Versailles, Francee-mail: [email protected]

Abstract

Panspermia (‘seeds everywhere’) postulates that life naturally migrates through space. Laboratory studies of Panspermia often examine the survival of Earth's species under the conditions thought to occur during transfer through space. Much of this research has centred on bacteria, but here we consider seeds themselves. We simulated the extreme accelerations necessary for their hypothetical ejection from a planetary surface and the impacts associated with their arrival on another planet. Seeds of tobacco, alfalfa and cress were fired into water at speeds in the range 1–3 km s−1, corresponding to impact shock pressures of circa 0.24–2.4 GPa. No seeds remained intact and able to germinate, even at the lowest speeds. Although fragmentation occurred, even at 3 km s−1 the size of some of the fragments was about 25% that of the seeds. Thus, whilst the seeds themselves did not survive extreme shocks, a substantial fraction of their mass did and might successfully deliver complex organic materials after impact. These results are discussed with respect to ancient Panspermia and the potential of contemporary impacts to eject living organisms into space.

Type
Research Article
Copyright
Copyright © 2008 Cambridge University Press

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