Nitrogen on Mars
The Curiosity Mars rover finds an essential ingredient for life on Mars
Nitrogen makes up 80% of our atmosphere and about 2% of that of Mars. But the nitrogen gas in the atmosphere is not in a form that organisms can use to make amino acids, DNA and proteins. It must be made "bio-available" by cracking the strong bonds in nitrogen gas and recombining the atoms with oxygen or hydrogen.
According to Dr. Jennifer Stern, a planetary geochemist at the NASA Goddard Space Flight Center in Maryland, Curiosity has found nitrate - nitrogen and oxygen - in Martian soil and rocks, which would have been available for use by primitive life on Mars - if it existed.