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

• Main Authors: Navarro-González, Rafael, Navarro, Karina F., Coll, Patrice, McKay, Christopher P., Stern, Jennifer C., Sutter, Brad, Douglas Archer Jr, P., Cabane, Michel, Conrad, Pamela G., Eigenbrode, Jennifer L., Franz, Heather B., Freissinet, Caroline, Glavin, Daniel P., Hogancamp, Joanna V., McAdam, Amy C., Malespin, Charles A., Martín-Torres, F. J., Ming, Douglas W., Morris, Richard V., Prats, Benny, Raulin, François, Rodriguez Manfredi, Jose Antonio, Szopa, Cyril, Zorzano, María Paz, Mahaffy, P.R., Atreya, Sushil, Trainer, Melissa G., Vasavada, Ashwin R.
• Other Authors: Universidad Nacional Autónoma de México, Consejo Nacional de Ciencia y Tecnología (México)
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2019
• Subjects: Papiit; Yellowknife; Yellowknife Bay
• Online Access: http://hdl.handle.net/10261/203453; https://doi.org/10.1029/2018JE005852; https://doi.org/10.13039/501100005739; https://doi.org/10.13039/501100003141

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, nitricoxide(NO)wasproducedmoreefficientlyin20%H2 inspiteofbeingareducingagentandnotlikelyto 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 (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 nitrogencontentsharplydecreasesinyoungersedimentsoftheMurrayformationsuggestingadeclineofH2 in the atmosphere and the rise of oxidizing conditions causing a shortage in the supply to putative microbial life. We acknowledge the NASA Mars Science Laboratory Program, Centre National d'Études Spatiales, the Universidad Nacional Autónoma de México (PAPIIT IN109416, IN111619, and PAPIME PE103216), and the Consejo Nacional de Ciencia y Tecnología de México (CONACyT 220626) for their support. We thank Fred Calef for constructing Figure 4 and appreciate the interest and support received from John P. Grotzinger and Joy A. Crisp throughout the Curiosity mission. The authors are grateful to the SAM and MSL teams ...