Survival of seeds in hypervelocity impacts
Survival of seeds in hypervelocity impacts
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DOI：
10.1017/s1473550408004278
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发表时间：
2008-07-01
影响因子：
1.7
通讯作者：
Tepfer, David
中科院分区：
文献类型：
--
作者：
Jerling, Aaron;Burchell, Mark J.;Tepfer, David
胚种论（“种子无处不在”）假设生命自然地通过空间迁移。胚种论的实验室研究经常考察地球物种在太空转移过程中所发生的条件下的生存情况。大部分研究都集中在细菌上，但在这里我们考虑种子本身。我们模拟了它们从行星表面弹射出来所需的极端加速度，以及它们到达另一颗行星时的撞击。烟草、苜蓿和水芹的种子以1-3 km/s的速度被发射到水中，对应于大约0.24-2.4 GPa的冲击压力。没有种子保持完整，能够发芽，即使在最低的速度。尽管发生了碎片化，但即使在3 km s（-1）的速度下，一些碎片的大小也约为种子的25%。因此，虽然种子本身没有经受住极端的冲击，但它们质量的很大一部分在冲击后成功地提供了复杂的有机材料。这些结果进行了讨论，就古老的Panspermia和当代的影响，以弹射到太空中的生物体的潜力。
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 oil 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.