@article{0153de933976496e9ed5cf23c1bb02d6,
title = "Abiotic Input of Fixed Nitrogen by Bolide Impacts to Gale Crater During the Hesperian: Insights From the Mars Science Laboratory",
abstract = "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 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 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. ",
keywords = "Mars, Nitrogen fixation, nitrates, Bolide impacts, Gale crater, Hesperian, Curisoity",
author = "Rafael Navarro-Gonz{\'a}lez and Navarro, {Karina F.} and Patrice Coll and McKay, {Christopher P.} and Stern, {Jennifer C.} and Brad Sutter and Archer, {P. Douglas} and Arnaud Buch and Michel Cabane and Conrad, {Pamela G.} and Eigenbrode, {Jennifer L.} and Franz, {Heather B.} and Caroline Freissinet and Glavin, {Daniel P.} and Hogancamp, {Joanna V.} and McAdam, {Amy C.} and Malespin, {Charles A.} and Mart{\'i}n-Torres, {F. Javier} and Ming, {Douglas W.} and Morris, {Richard V.} and Benny Prats and Fran{\c c}ois Raulin and Rodr{\'i}guez-Manfredi, {Jos{\'e} Antonio} and Cyril Szopa and Mar{\'i}a-Paz Zorzano-Mier and Mahaffy, {Paul R.} and Sushil Atreya and Trainer, {Melissa G.} and Vasavada, {Ashwin R.}",
note = "We acknowledge the NASA Mars Science Laboratory Program, Centre National d'{\'E}tudes Spatiales, the Universidad Nacional Aut{\'o}noma de M{\'e}xico (PAPIIT IN109416, IN111619, and PAPIME PE103216), and the Consejo Nacional de Ciencia y Tecnolog{\'i}a de M{\'e}xico (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 for successful operation of the SAM instrument and the Curiosity rover. The data used in this paper are listed in the supporting information, figures, and references. SAM Data contained in this paper are publicly available through the NASA Planetary Data System at http://pds‐geosciences.wustl.edu/missions/msl/sam.htm. We would like to express gratitude to Pierre‐Yves Meslin from the Research Institute in Astrophysics and Planetology at Toulouse, France, and five anonymous reviewers whose comments/suggestions on earlier drafts helped improve and clarify this manuscript. The authors declare no conflicts of interests.",
year = "2019",
month = jan,
doi = "10.1029/2018JE005852",
language = "English",
volume = "124",
pages = "94--113",
journal = "Journal of Geophysical Research - Planets",
issn = "2169-9097",
publisher = "John Wiley & Sons",
number = "1",
}