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They ask, did they come from outside Mars or were they formed on Mars?
Scientists exploring Mars and analysing Martian meteorite samples have found organic compounds essential for life: nitrogen-bearing organics in a 4-billion-year-old Martian meteorite. With a new high-spatial resolution in-situ N-chemical speciation technique, they found organic materials — either synthesized locally or delivered during the Noachian — preserved intact in carbonate minerals over a long geological period. Their presence requires abiotic or biotic N-fixation and ammonia storage, suggesting early Mars had a less oxidizing environment than today.
Tokyo Institute of Technology, “4-billion-year-old nitrogen-containing organic molecules discovered in Martian meteorites” at ScienceDaily
Paper. (open access)
Timothy Standish of the Geoscience Research Institute offers some thoughts:
This is interesting, but not quite as novel and exciting as the press release would lead you to believe. It reminded me of this paper:
Mancinelli RL, Banin A. 2003. Where is the nitrogen on Mars?(paywall)]
In which the nitrogen missing from the Martian atmosphere is speculated to be in the regolith. It’s not really a surprise to find nitrogen-containing compounds there, even organic compounds. What would be surprising, would be if they were abundant, large, complex, favored a specific chirality and formed the complete set of nitrogen containing molecules used in life on Earth… well, maybe not, maybe then it would be good evidence that the molecules didn’t necessarily come from Mars after all (which may still be the case, although the authors seem to have tried hard to eliminate this possibility).
Having said that, it also points out a problem with chemical evolution, without a functioning nitrogen cycle, atmospheric nitrogen will be fixed via thermal shock and possibly some other processes. If the nitrogen cycle isn’t established within a certain time, nitrogen will be removed from the atmosphere and the surface will become rich in nitrate (bad) or, in a reducing atmosphere, ammonia (really bad). The bottom line is that there are speculations that probably get around this, but it is one more needle that has to be threaded for chemical evolution to produce the first life, or a problem for the first life to quickly take care of.