A new study has revealed that asteroid impacts on ancient Mars could have produced ingredients for life if Mars' atmosphere was rich in hydrogen. Researchers on the Curiosity Mars Sampling Instrument (SAM) said a hydrogen-rich atmosphere would explain how the planet was habitable. The ingredients are nitrites (NO2) and nitrates (NO3).
Both nitrates are important for establishing and maintaining life.
The rover discovered both ingredients in soil and rock samples in the Gale crater, site of ancient lakes on Mars.
The researchers recreated the early Martian atmosphere to understand how fixed nitrogen could be deposited in the crater.
They discovered that the red planet may have been warmer in the past.
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Dr. Rafael Navarro-González said, "The big surprise was that nitrate yield increased when hydrogen was included in laser shock experiments simulating asteroid impacts.
"It was counterintuitive because hydrogen created a low oxygen environment while nitrate formation required oxygen.
"However, the presence of hydrogen led to a faster cooling of the shock-heated gas, trapping nitric oxide, the precursor of nitrate, at higher temperatures where its yield was higher."
Climate models show that hydrogen in the atmosphere is needed to raise the temperature in order to have a liquid on the surface of the planet.
Christopher McKay explained that the presence of nitrate had a "major astrobiological significance".
"Due to the low nitrogen gas content in the atmosphere, nitrate is the only form of biologically useful nitrogen on Mars.
"Its presence in the soil is therefore of major astrobiological importance.
"This document helps us understand the possible sources of this nitrate."