Did Mars ever support life? This question has intrigued us for centuries! We have had spacecraft on Mars for quite a while poking and analyzing soil and rocks and taking photos. Now NASA has new data which help answer these questions.
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.
Did Mars ever support life? This question has intrigued us for centuries! We have had spacecraft on Mars for quite a while poking and analyzing soil and rocks and taking photos. Now NASA has new data which help answer these questions.
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.
Nitrate (NO3) - a nitrogen atom bound to three oxygen atoms - is a source of fixed nitrogen. A nitrate molecule can join with various other atoms and molecules; this class of molecules is known as nitrates.
There is no evidence to suggest that the fixed nitrogen molecules found by the team were created by life. The surface of Mars is inhospitable for known forms of life. Instead, the team thinks the nitrates are ancient, and likely came from non-biological processes like meteorite impacts and lightning in Mars' distant past.
Features resembling dry riverbeds and the discovery of minerals that form only in the presence of liquid water suggest that Mars was more hospitable in the remote past. The Curiosity team has found evidence that other ingredients needed for life, such as liquid water and organic matter, were present on Mars at the Curiosity site in Gale Crater billions of years ago.
"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 March 23.
Photo self-portrait of NASA's Mars rover Curiosity combines dozens of exposures taken by the rover's Mars Hand Lens Imager (MAHLI) during the 177th Martian day, or sol, of Curiosity's work on Mars (Feb. 3, 2013), plus three exposures taken during Sol 270 (May 10, 2013) to update the appearance of part of the ground beside the rover. Credit: NASA.
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