Washington- NASA's Curiosity rover has found nitrogen on the surface of Mars, a significant discovery that adds to evidence the Red Planet could once have sustained life, the space agency said. By drilling into Martian rocks, Curiosity found evidence of nitrates, compounds containing nitrogen that can be used by living organisms.

The Curiosity team has already found evidence that other ingredients needed for life, such as liquid water and organic matter, once existed at the site known as Gale Crater.

"Finding a biochemically accessible form of nitrogen is more support for the ancient Martian environment at Gale Crater being habitable," Jennifer Stern of NASA's Goddard Space Flight Center in Greenbelt, Maryland said in a statement Tuesday.

Nitrogen is essential for all known forms of life, because it's a building block of DNA and RNA.

However, "there is no evidence to suggest that the fixed nitrogen molecules found by the team were created by life," NASA cautioned.

"The surface of Mars is inhospitable for known forms of life." The research team suggested that instead, the nitrates are ancient and likely came from meteorite impacts, lightning and other non-biological processes.

On Earth and Mars, nitrogen is found in the form of nitrogen dioxide gas -- two atoms locked together so tightly that they do not react easily with other molecules.

The nitrogen atoms must 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," NASA said.

"However, smaller amounts of nitrogen are also fixed by energetic events like lightning strikes."

Courtesy: Yahoo