According to new research, Mars was born wet with a dense atmosphere that allowed warm-to-hot oceans for millions of years. The first model of the evolution of the Martian atmosphere that links high temperatures associated with Mars's formation in a molten state through to the formation of the first oceans and atmosphere was developed by researchers.
The model shows that the upper atmosphere of Mars was dry and that the water in the atmosphere was concentrated in the lower atmosphere. The H 2 molecule did not condense and was lost to space. The model can be linked to the observations made by the Mars Science Laboratory rover.
In the time immediately after the planet formed, we believe we have modeled an overlooked chapter. The SETI Institute research scientist said that the primordial Martian atmosphere must have been very dense and made up of hydrogen.
It's significant that H 2 is a strong greenhouse gas in dense environments. The H 2 would have been lost to space and the warm-to-hot water oceans on the Martian surface would have been stable for millions of years. We think thatMars was born wet before the Earth formed.
The model is constrained by the deuterium-to-hydrogen ratio of different Martian samples. The meteorites from Mars were formed when the interior of the planet melted. The deuterium-to-hydrogen ratio is similar to that of the Earth's oceans and indicates that the two planets started with the same source.
The value of the D/H ratio on the Martian surface is three times that of Earth's oceans. By the time these ancient clays formed, the surface water on Mars had a high concentration of deuterium. The only way to get this level of deuterium concentration is to lose the lighter H to space.
The model shows that if the atmosphere was H 2 rich at the time of its formation, the surface waters would be enriched in deuterium by a factor of 2–3x. The water molecule is preferentially taken up by ordinary hydrogen and escapes from the top of the atmosphere.
Pahlevan said that the atmospheric evolutionary scenario we have described corresponds to early events on Mars.
H 2 rich atmospheres are important in the SETI Institute's search for life beyond Earth. Precousy molecule implicated in the origin of life form readily in H 2 rich atmospheres, but not so readily in H 2 poor atmospheres. The implication is that early Mars was a better place to start life than early Earth was.
More information: Kaveh Pahlevan et al, A primordial atmospheric origin of hydrospheric deuterium enrichment on Mars, Earth and Planetary Science Letters (2022). DOI: 10.1016/j.epsl.2022.117772 Journal information: Earth and Planetary Science Letters
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