Flash heating on the early earth

James Lyons, Ashwin R. Vasavada

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

It has been suggested that very large impact events (~ 500 km diameter impactors) sterilized the surface of the young Earth by producing enough rock vapor to boil the oceans. Here, we consider surface heating due to smaller impactors, and demonstrate that surface temperatures conducive to organic synthesis resulted. In particular, we focus on the synthesis of thermal peptides. Previously, laboratory experiments have demonstrated that dry heating a mixture of amino acids containing excess Asp, Glu, or Lys to temperatures ~ 170 °C for ~ 2 hours yields polypeptides. It has been argued that such temperature conditions would not have been available on the early Earth. Here we demonstrate, by analogy with the K/T impact, that the requisite temperatures are achieved on sand surfaces during the atmospheric reentry of fine ejecta particles produced by impacts of bolides ~10-20 km in diameter, assuming ~ 1 - 100 PAL CO2. Impactors of this size struck the Earth with a frequency of ~ 1 per 104 - 105 y at 4.2 Ga. Smaller bolides produced negligible global surface heating, whereas bolides > 30 km in diameter yielded solid surface temperatures > 1000 K, high enough to pyrolyze amino acids and other organic compounds. Thus, peptide formation would have occurred globally for a relatively narrow range of bolide sizes.

Original languageEnglish (US)
Pages (from-to)123-138
Number of pages16
JournalOrigins of Life and Evolution of the Biosphere
Volume29
Issue number2
DOIs
StatePublished - Mar 1 1999
Externally publishedYes

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bolides
early Earth
impactors
flash
heating
heat
peptide
surface temperature
peptides
amino acids
amino acid
bolide
temperature
reentry
synthesis
polypeptides
ejecta
organic compounds
vapors
solid surfaces

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Space and Planetary Science

Cite this

Flash heating on the early earth. / Lyons, James; Vasavada, Ashwin R.

In: Origins of Life and Evolution of the Biosphere, Vol. 29, No. 2, 01.03.1999, p. 123-138.

Research output: Contribution to journalArticle

Lyons, James ; Vasavada, Ashwin R. / Flash heating on the early earth. In: Origins of Life and Evolution of the Biosphere. 1999 ; Vol. 29, No. 2. pp. 123-138.
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