NASA's Curiosity Rover has detected the first traces of nitrogen on Mars, a discovery that adds to the mounting evidence that the red planet could have, at one time, supported life. The rover team using the Sample Analysis at Mars (SAM) instrument suite aboard the rover made the discovery of nitrogen on the surface during the heating of sediments. The nitrogen was detected in the form of nitric oxide, and could be released from the breakdown of nitrates during the heating process.
"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," NASA said in a statement.
Nitrogen is essential for all life as we know it because it is used in the building blocks of larger molecules such as DNA and RNA, which encode the genetic instructions for life, and proteins which are used to build biological structures such as hair. Researchers believe the nitrates they have discovered are ancient, and likely came from non-biological processes such as lightning or maybe even a meteorite impact.
"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.
The team found evidence for nitrates in scooped samples of windblown sand and dust at the "Rocknest" site, and in samples drilled from mudstone at the "John Klein" and "Cumberland" drill sites in Yellowknife Bay.
Since the Rocknest sample is a combination of dust blown in from other regions, the nitrates are likely widespread across the service, Stern said. The results show that the nitrates make up about 1,000 parts per million in the soil of the drill sites.
The various nitrogen compounds were identified using two instruments, a mass spectrometer and a gas chromatograph. Along with these compounds, the instruments also deteced nitric oxide or a nitrogen bound to an oxygen atom in samples from all three sites.
Certain compounds can release nitrogen as the sample breaks down when heated. However, the amount of nitric oxide found was more than twice what could be produced in even the most extreme and unrealistic scenario.
The team now believes that nitrates really are present on Mars, and the abundance estimates may be higher than originally thought causing scientists to adjust the estimates of nitrogen present on the red planet.
