Testing the survival of microfossils in artificial martian sedimentary meteorites during entry into Earth's atmosphere

the STONE 6 experiment

Frederic Foucher, Frances Westall, Franz Brandstaetter, Rene Demets, John Parnell, Charles S. Cockell, Howell G. M. Edwards, Jean-Michel Beny, Andre Brack

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

If life ever appeared on Mars, could we find traces of primitive life embedded in sedimentary meteorites? To answer this question, a 3.5-byr-old volcanic sediment containing microfossils was embedded in the heat shield of a space capsule in order to test survival of the rock and the microfossils during entry into the Earth's atmosphere (the STONE 6 experiment). The silicified volcanic sediment from the Kitty's Gap Chert (Pilbara, Australia) is considered to be an excellent analogue for Noachian-age volcanic sediments. The microfossils in the chert are also analogues for potential martian life. An additional goal was to investigate the survival of living microorganisms (Chroococcidiopsis) protected by a 2-cm thick layer of rock in order to test whether living endolithic organisms could survive atmospheric entry when protected by a rocky coating.

Mineralogical alteration of the sediment due to shock heating was manifested by the formation of a fusion crust, cracks in the chert due to prograde and retrograde changes of alpha quartz to beta quartz, increase in the size of the fluid inclusions, and dewatering of the hydromuscovite-replaced volcanic protoliths. The carbonaceous microfossils embedded in the chert matrix survived in the rock away from the fusion crust but there was an increase in the maturity index of the kerogen towards the crust. We conclude that this kind of sediment can survive atmospheric entry and, if it contains microfossils, they could also survive. The living microorganisms were, however, completely carbonised by flame leakage to the back of the sample and therefore non-viable. However, using an analytical model to estimate the temperature reached within the sample thickness, we conclude that, even without flame leakage, the living organisms probably need to be protected by at least 5 cm of rock in order to be shielded from the intense heat of entry. (C) 2009 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)616-630
Number of pages15
JournalIcarus
Volume207
Issue number2
DOIs
Publication statusPublished - Jun 2010

Keywords

  • meteorites
  • thermal histories
  • astrobiology
  • mineralogy
  • Mars
  • Greenstone-belt
  • West Greenland
  • life
  • diversity
  • search
  • rocks
  • deposits
  • impact
  • temperature

Cite this

Testing the survival of microfossils in artificial martian sedimentary meteorites during entry into Earth's atmosphere : the STONE 6 experiment. / Foucher, Frederic; Westall, Frances; Brandstaetter, Franz; Demets, Rene; Parnell, John; Cockell, Charles S.; Edwards, Howell G. M.; Beny, Jean-Michel; Brack, Andre.

In: Icarus, Vol. 207, No. 2, 06.2010, p. 616-630.

Research output: Contribution to journalArticle

Foucher, F, Westall, F, Brandstaetter, F, Demets, R, Parnell, J, Cockell, CS, Edwards, HGM, Beny, J-M & Brack, A 2010, 'Testing the survival of microfossils in artificial martian sedimentary meteorites during entry into Earth's atmosphere: the STONE 6 experiment', Icarus, vol. 207, no. 2, pp. 616-630. https://doi.org/10.1016/j.icarus.2009.12.014
Foucher, Frederic ; Westall, Frances ; Brandstaetter, Franz ; Demets, Rene ; Parnell, John ; Cockell, Charles S. ; Edwards, Howell G. M. ; Beny, Jean-Michel ; Brack, Andre. / Testing the survival of microfossils in artificial martian sedimentary meteorites during entry into Earth's atmosphere : the STONE 6 experiment. In: Icarus. 2010 ; Vol. 207, No. 2. pp. 616-630.
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AB - If life ever appeared on Mars, could we find traces of primitive life embedded in sedimentary meteorites? To answer this question, a 3.5-byr-old volcanic sediment containing microfossils was embedded in the heat shield of a space capsule in order to test survival of the rock and the microfossils during entry into the Earth's atmosphere (the STONE 6 experiment). The silicified volcanic sediment from the Kitty's Gap Chert (Pilbara, Australia) is considered to be an excellent analogue for Noachian-age volcanic sediments. The microfossils in the chert are also analogues for potential martian life. An additional goal was to investigate the survival of living microorganisms (Chroococcidiopsis) protected by a 2-cm thick layer of rock in order to test whether living endolithic organisms could survive atmospheric entry when protected by a rocky coating.Mineralogical alteration of the sediment due to shock heating was manifested by the formation of a fusion crust, cracks in the chert due to prograde and retrograde changes of alpha quartz to beta quartz, increase in the size of the fluid inclusions, and dewatering of the hydromuscovite-replaced volcanic protoliths. The carbonaceous microfossils embedded in the chert matrix survived in the rock away from the fusion crust but there was an increase in the maturity index of the kerogen towards the crust. We conclude that this kind of sediment can survive atmospheric entry and, if it contains microfossils, they could also survive. The living microorganisms were, however, completely carbonised by flame leakage to the back of the sample and therefore non-viable. However, using an analytical model to estimate the temperature reached within the sample thickness, we conclude that, even without flame leakage, the living organisms probably need to be protected by at least 5 cm of rock in order to be shielded from the intense heat of entry. (C) 2009 Elsevier Inc. All rights reserved.

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KW - mineralogy

KW - Mars

KW - Greenstone-belt

KW - West Greenland

KW - life

KW - diversity

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KW - rocks

KW - deposits

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