Detection of Nitric Oxide by the Sample Analysis at Mars (SAM) Instrument Implications for the Presence of Nitrates

One of the main goals of the Mars Science Laboratory is to determine whether the plan et ever had environmental conditions able to support m i- crobial life. Nitrogen is a fundamental element fo r life, and is present in structural ( e.g. , proteins), catalytic ( e.g., enzymes and ribozymes), energy transfer ( e.g., ATP) and information storage (RNA and DNA) bio- molecules. Planetary models suggest that molecular nitrogen was abundant in the early Martian atmosphe re, but was rapidly lost to space by photochemistry, sp ut- tering [1, 2], impact erosion [3], and oxidized and de- posited to the surface as nitrate [4]. Nitrates are a fun- damental source for nitrogen to terrestrial microor gan- isms. Therefore, the detection of nitrates in soils and rocks is important to assess the habitability of a Mar- tian environment. SAM is capable of detecting nitr ates by their thermal decomposition into nitric oxide, N O [5]. Here we analyze the release of NO from soils and rocks examined by the SAM instrument at Gale crater , and discuss its origin.