Abiotic Input of Fixed Nitrogen by Bolide Impacts to Gale Crater During the Hesperian: Insights From the Mars Science Laboratory

Rafael Navarro-González, Karina F. Navarro, Patrice Coll, Christopher P. McKay, Jennifer C. Stern, Brad Sutter, P. Douglas Archer, Arnaud Buch, Michel Cabane, Pamela G. Conrad, Jennifer L. Eigenbrode, Heather B. Franz, Caroline Freissinet, Daniel P. Glavin, Joanna V. Hogancamp, Amy C. McAdam, Charles A. Malespin, F. Javier Martín-Torres, Douglas W. Ming, Richard V. MorrisBenny Prats, François Raulin, José Antonio Rodríguez-Manfredi, Cyril Szopa, María Paz Zorzano-Mier, Paul R. Mahaffy, Sushil Atreya, Melissa G. Trainer, Ashwin R. Vasavada

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

Molecular hydrogen (H 2 ) from volcanic emissions is suggested to warm the Martian surface when carbon dioxide (CO 2 ) levels dropped from the Noachian (4100 to 3700 Myr) to the Hesperian (3700 to 3000 Myr). Its presence is expected to shift the conversion of molecular nitrogen (N 2 ) into different forms of fixed nitrogen (N). Here we present experimental data and theoretical calculations that investigate the efficiency of nitrogen fixation by bolide impacts in CO 2 -N 2 atmospheres with or without H 2 . Surprisingly, nitric oxide (NO) was produced more efficiently in 20% H 2 in spite of being a reducing agent and not likely to increase the rate of nitrogen oxidation. Nevertheless, its presence led to a faster cooling of the shock wave raising the freeze-out temperature of NO resulting in an enhanced yield. We estimate that the nitrogen fixation rate by bolide impacts varied from 7 × 10 −4 to 2 × 10 −3  g N·Myr −1 ·cm −2 and could imply fluvial concentration to explain the nitrogen (1.4 ± 0.7 g N·Myr −1 ·cm −2 ) detected as nitrite (NO 2 ) and nitrate (NO 3 ) by Curiosity at Yellowknife Bay. One possible explanation is that the nitrogen detected in the lacustrine sediments at Gale was deposited entirely on the crater's surface and was subsequently dissolved and transported by superficial and ground waters to the lake during favorable wet climatic conditions. The nitrogen content sharply decreases in younger sediments of the Murray formation suggesting a decline of H 2 in the atmosphere and the rise of oxidizing conditions causing a shortage in the supply to putative microbial life.

Original languageEnglish
Pages (from-to)94-113
Number of pages20
JournalJournal of Geophysical Research: Planets
Volume124
Issue number1
DOIs
Publication statusPublished - Jan 2019
Externally publishedYes

Keywords

  • Curiosity
  • Gale crater
  • Mars
  • bolide impacts
  • nitrates
  • nitrogen fixation

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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