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

Rafael Navarro-González (1) , Karina F. Navarro (1) , Patrice Coll (2) , Christopher P. Mckay (3) , Jennifer C. Stern (4) , Brad Sutter (5, 6) , P. Douglas Archer Jr (6, 5) , Arnaud Buch (7) , Michel Cabane (8) , Pamela G. Conrad (4) , Jennifer L. Eigenbrode (4) , Heather B. Franz (4) , Caroline Freissinet (8) , Daniel P. Glavin (4) , Joanna V. Hogancamp (5, 6) , Amy Mcadam (4) , Charles A. Malespin (4) , F. Javier Martin-Torres (9) , Douglas W. Ming (6) , Richard V. Morris (6) , Benny Prats (4) , François Raulin (2) , José Antonio Rodríguez-Manfredi (10) , Cyril Szopa (8) , María-Paz Zorzano-Mier (9) , Paul R. Mahaffy (4) , Sushil Atreya (11) , Melissa Grady Trainer (4) , Ashwin Vasavada (12)

1 Instituto de Ciencias Nucleares [Mexico]
2 LISA (UMR_7583) - Laboratoire Interuniversitaire des Systèmes Atmosphériques
3 ARC - NASA Ames Research Center
4 GSFC - NASA Goddard Space Flight Center
5 Jacobs Technology ESCG
6 JSC - NASA Johnson Space Center
7 LGPM - Laboratoire de Génie des Procédés et Matériaux - EA 4038
8 PLANETO - LATMOS
9 Department of Computer Science, Electrical and Space Engineering [Luleå]
10 CAB - Centro de Astrobiologia [Madrid]
11 AOSS - Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor]
12 JPL - Jet Propulsion Laboratory

Molecular hydrogen (H₂) from volcanic emissions is suggested to warm the Martian surface when carbon dioxide (CO₂) 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 (N₂) 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 CO₂‐N₂ atmospheres with or without H₂. Surprisingly nitric oxide (NO) was produced more efficiently in 20% H₂ 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 shockwave 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 (NO₂^–) and nitrate (NO₃^–) 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 H₂ in the atmosphere, and the rise of oxidizing conditions causing a shortage in the supply to putative microbial life.

Domaines: Astrophysique [astro-ph]; Physique Atmosphérique et Océanique [physics.ao-ph]

Rafael Navarro-González, Karina F. Navarro, Patrice Coll, Christopher P. Mckay, Jennifer C. Stern, et al.. Abiotic Input of Fixed Nitrogen by Bolide Impacts to Gale Crater During the Hesperian: Insights From the Mars Science Laboratory. Journal of Geophysical Research. Planets, 2019, 124 (1), pp.94-113. ⟨10.1029/2018je005852⟩. ⟨insu-01962074⟩