New clues about early atmosphere on Mars suggest wet planet capable of supporting life

New clues about early atmosphere on Mars suggest wet planet capable of supporting life

3D render of a blue wet planet. credit: Anode on Planet Volume/Unsplash

new research published Earth and Planetary Science Papers Turns out that Mars was born wet, with a dense atmosphere that allowed warmer-than-warm oceans for millions of years. To reach this conclusion, the researchers developed the first model of the evolution of the Martian atmosphere that first links the high temperatures associated with the formation of Mars to a molten state through the formation of oceans and atmospheres.

This model shows that—as on modern Earth—Steam The atmosphere of Mars was concentrated in the lower atmosphere and the upper atmosphere of Mars was “dry” because water vapor would condense to form clouds at lower levels in the atmosphere. Molecular Hydrogen (H)2), in contrast, did not condense and was carried into the upper atmosphere of Mars, where it was lost to space. This finding – that water vapor condensed and remained intact on early Mars, while molecular hydrogen did not condense and escape – allows the model to be directly linked to measurements made by spacecraft, in particular, the Mars Science Laboratory rover. Curiosity.

“We believe that we have modeled an overlooked chapter in the early history of Mars in the time immediately after the planet’s formation. For the data to be interpreted, the early Martian atmosphere must have been very dense (like the modern atmosphere). in ~1000x more dense) and composed primarily of molecular hydrogen (H.)2),” said Keve Pehelwan, research scientist at SETI Institute.

“This finding is important because H2 Known as a strong greenhouse gas in a dense atmosphere. This dense atmosphere would have generated a strong greenhouse effect, allowing oceans of much warmer-than-warm water to remain stable on the Martian surface for millions of years, until H.2 Slowly lost in space. For this reason, we infer that – in the time before Earth was formed – Mars was born wet.”

The data constraining the model are the deuterium-to-hydrogen (D/H) ratios (deuterium is the heavy isotope of hydrogen) of various Martian samples, including the Martian meteorites and those analyzed by Curiosity. Meteorites from Mars are mostly igneous rocks – they form when the interior of Mars melts, and magma rises toward the surface. The water dissolved in these interior (mantle-derived) igneous samples has a deuterium-to-hydrogen ratio similar to Earth’s oceans, indicating that the two planets began with similar D/H ratios and that their water came from the same source. had come. in the early solar system.

In contrast, Curiosity measured the D/H ratio of an ancient 3-billion-year-old soil on the Martian surface and found it to be ~3x that of Earth’s oceans. Apparently, by the time these ancient soils formed, the surface water reservoir on Mars—the hydrosphere—had largely concentrated deuterium relative to hydrogen. The only process known to produce this level of deuterium concentration (or “enrichment”) is the preferential loss of lighter H isotopes into space.

The model further shows that if the Martian atmosphere is H. was2-enriched at the time of its formation (and ~1000x more dense as it is today), then surface water would naturally be enriched in deuterium by a factor of 2-3x relative to the interior, reproducing observations. Prefers splitting in a water molecule relative to deuterium molecular hydrogen (h)2), which preferentially takes up ordinary hydrogen and leaves the atmosphere.

“This is the first published model that naturally reproduces these data, giving us some confidence that the atmospheric evolutionary scenario we described corresponds to early events on Mars,” Pahlavan said. “

In addition to curiosity about the early atmosphere on the planets, H2Rich environments are important in the SETI Institute’s search for life beyond Earth. Experiments going back to the middle of the 20th century show that prebiotic molecules implicated in the origin of life are readily formed in such H.2-enriched environment but H. I’m not that easy2-Poor (or more “oxidizing”) atmosphere. The implication is that early Mars was a hotter version of modern Titan and at least as promising, if not more promising, a site for the origin of life as early Earth.

Help NASA Scientists Find Clouds on Mars

more information:
Kaveh Pahlevan et al, An early atmospheric origin of hydrospheric deuterium enrichment on Mars, Earth and Planetary Science Papers (2022). DOI: 10.1016/j.epsl.2022.117772

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SETI Institute

Citation: New clues about early atmosphere on Mars suggest a wetter planet capable of supporting life (2022, Sept. 21) on Sept. 22, 2022 Retrieved from early-atmosphere-mars-planet. .html

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