Mars was born wet with a thick atmosphere

Using a newly developed model to understand the evolution of the Martian atmosphere, a new study suggests that Mars Born wet with a dense atmosphere that allows warm to warm oceans for millions of years. The model links the evolution of the Martian atmosphere with Mars formation In a molten state until the formation of the first oceans and atmosphere.

The model shows that the water vapor in Mars atmosphere They were concentrated in the lower atmosphere, similar to what they are today on Earth, while the higher atmosphere of Mars was “dry” because it would condense into clouds at lower levels in the atmosphere. Conversely, molecular hydrogen (H2) 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 held on early Mars while molecular hydrogen neither condensed nor escaped—allows the model to relate directly to measurements made by the spacecraft, specifically the Curiosity spacecraft at the Mars Science Laboratory.

Kaveh Pahlivan, SETI Institute research scientist, said, “We think we modeled a class that was overlooked in Closest date to Mars At the time immediately after the formation of the planet. To explain the data, the atmosphere of primitive Mars must have been very dense (about 1,000 times as dense as the modern atmosphere) and composed primarily of molecular hydrogen (H2). “

“This discovery is important because H2 is known to be a potent greenhouse gas in dense environments. This dense atmosphere would have produced a strong greenhouse effect, allowing warm to hot water oceans much earlier to stabilize Mars surface For millions of years, H2 was gradually lost in space. For this reason, we conclude that – sometime before the Earth itself formed – Mars was born wet.”

The deuterium-to-hydrogen (D/H) ratio of various Martian rocks, including Martian meteorites and those studied by Curiosity, serves as a primary source of data limitations in the model. Deuterium is a heavy isotope of hydrogen. Most meteorites from Mars are igneous rocks. They were created when the interior of Mars melted and magma rose to the surface.

The ratio of deuterium to hydrogen in the dissolved water in these inland igneous rocks (derived from the mantle) is similar to that found in oceans on earthindicating that the two planets initially had identical D/H ratios and that their water originated from the same source in the early Solar System.

The model also shows that if the Martian atmosphere was rich in H at the time of its formation (and about 1,000 times more than it is today), then surface waters would naturally be enriched with deuterium by a factor of 2–3x relative to the interior, reproducing observations. Deuterium prefers splitting into a water molecule relative to molecular hydrogen (H2), which preferentially takes up ordinary hydrogen and escapes from the upper atmosphere.

Philvan He saidAnd the “This is the first published model that naturally reproduces this data, giving us some confidence that the atmospheric evolution scenario we describe is consistent with early events on Mars.”

Journal reference:

  1. Kaveh Pahlevan et al. A primitive atmospheric origin of deuterium enrichment in the Martian hydrosphere, Earth and Planetary Science Letters (2022). DOI: 10.1016 / j.epsl.2022.117772