NASA's Curiosity Mars rover has made the first detection of usable nitrogen on the surface of the Red Planet.
Nitrogen is necessary for all known forms of life to exist because it is a "building block" of DNA and RNA, NASA's Jet Propulsion Laboratory (JPL) reported. The nitrogen was detected in the form of nitric oxide, which could be released from the breakdown of nitrates during heating. The findings add to past evidence that Mars once had the ability to harbor life, such as ancient riverbeds.
On Earth nitrogen is found in the form of nitrogen gas, which is composed of two atoms of nitrogen bound together so strongly that they cannot easily react with other molecules. In order to be a part of chemical reactions necessary for life, these atoms must be separated. The nitrogen atoms can be "fixed" in this way through the help of certain organisms as well as energetic events like lightning strikes; there is no evidence that the fixed nitrogen found on Mars is a result of living organisms, but could be linked to non-biological processes such as meteorite impacts.
"Finding a biochemically accessible form of nitrogen is more support for the ancient Martian environment at Gale Crater being habitable," said Jennifer Stern of NASA's Goddard Space Flight Center in Greenbelt, Maryland. Stern is lead author of a paper on this research published online in the Proceedings of the National Academy of Science on March 23.
The evidence of ancient nitrates was discovered in sand and dust at the "Rocknest" site and in samples of mudstone taken from the "John Klein" and "Cumberland" drill sites in Yellowknife Bay. Since the dust at Rocknest is believed to have been blown in from different regions, it is most likely across Mars' surface.
"Scientists have long thought that nitrates would be produced on Mars from the energy released in meteorite impacts, and the amounts we found agree well with estimates from this process," Stern said.
