Mars once had an atmosphere that was thicker than Earth’s today

The atmosphere of Mars may have been thicker in the past than it is today, acting as a cover that protected it from frequent asteroids that ravaged other planets.

While the sun and most of the planets formed approximately 4 million years after the origin of the solar system, Mars was already almost finished. At present, the planets existed in a large ball of hot and dust gas which swirled around the young sun, called the solar nebula, which certain planets would have temporarily absorbed in their atmospheres. However, once the solar nebula fell, it was thought that the planets would have quickly lost this gas, reducing the densities of their atmospheres.

Now, Sarah Joiret at Collège de France in Paris and her colleagues think that Mars can have hung on her gas longer, forming a primordial atmosphere that has persisted.

Shortly after the nebula has fallen, astronomers think that the orbits of giant planets like Jupiter and Saturn changed, who had the training effect to disturb the orbits of the comets and asteroids, sending them to rush to the inner solar system where they bombed the rocky planets. We can find proof of this bombardment in the chemical signatures of rocks on earth and in our atmosphere, but the evidence of it is lower on Mars.

“All terrestrial planets were bombed by comets during this phase, and March cannot have avoided it, we should therefore see a trace of this cometary bombing on Mars,” Joiret told the Europlanet Congress in Helsinki, Finland, September 11.

JOIRET and his colleagues think that a thick atmosphere rich in hydrogen at that time may have diluted any comic material may have been absorbed by the planet. By estimating the quantity of comic material should have arrived at Mars using simulations of the early solar system and comparing it to the quantity of material which seems to be there, they calculated the mass of the primordial Martian atmosphere, and found that it would have been equivalent to a pressure of 2.9 bar, about three times the atmospheric pressure to the earth today.

However, this atmosphere would have been lost relatively quickly, in a period of about a million years, and would have largely disappeared when liquid water formed on the surface of March, said Raymond Pierrehumbert of the University of Oxford at the conference. He was not involved in work. Liquid water on Mars required distinct atmospheric conditions, including an abundance of carbon dioxide, which were probably not present in the thick primordial atmosphere.

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