Back in June, NASA announced that it may have discovered the building blocks for life on Mars via a study published in the Journal of Geophysical Research. However, this discovery might be more accurately described as a confirmation.
In 1976, stationary landers called the Vikings collected soil samples on Mars, part of an effort to locate organic matter. The Vikings never found any. This surprised scientists because meteorites, which commonly pelt Mars, should have left some organic matter on the surface. The image above shows a view of Mars captured by Viking 2 in '76.
Both the June study and New Scientist suggest the Viking landers may have discovered organic matter, but because their primary instrument — a gas chromatograph-mass spectrometer — used heat to detect molecules, it may have destroyed any organic material it collected. The heat likely ignited salt-like materials on Mars called perchlorate, a substance confirmed to be on Mars in 2008 by the Phoenix lander.
Confirmation of this accidental burning came about as a result of the June study. The Curiosity rover detected traces of chlorobenzene, a compound only produced when carbon molecules burn with flammable salt.
This isn't the first time it's been suggested that the Viking landers should've/could've/did discover evidence of ancient life on Mars. Researchers involved with the Viking project wrote as much in a 2016 paper.
So while the June study may have been a major milestone, it's possible a Viking lander made the discovery long ago. Still, it's good news for the search for life on Mars. The landers and the rover tested different locations on Mars, meaning organic matter exists in different spots on the planet. That could mean Mars has always had proof that it once was able to support life — and we're just getting the memo a little late.
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