A team using the Sample Analysis at Mars (SAM) instrument suite aboard NASA’s Curiosity rover has made the first detection of nitrogen on the surface of Mars from release during heating of Martian sediments.
The nitrogen was detected in the form of nitric oxide, and could be released from the breakdown of nitrates during heating. Nitrates are a class of molecules that contain nitrogen in a form that can be used by living organisms. The discovery adds to the evidence that ancient Mars was habitable for life.
Nitrogen is essential for all known forms of life, since it is used in the building blocks of larger molecules like DNA and RNA, which encode the genetic instructions for life, and proteins, which are used to build structures like hair and nails, and to speed up or regulate chemical reactions.
However, on Earth and Mars, atmospheric nitrogen is locked up as nitrogen gas (N2) – two atoms of nitrogen bound together so strongly that they do not react easily with other molecules. The nitrogen atoms have to be separated or “fixed” so they can participate in the chemical reactions needed for life. On Earth, certain organisms are capable of fixing atmospheric nitrogen and this process is critical for metabolic activity. However, smaller amounts of nitrogen are also fixed by energetic events like lightning strikes.