When Earth first formed, Mars was a watery world capable of supporting life

A new study published in the journal Earth and Planetary Science Letters shows that Mars was capable of supporting life at a time when Earth was just forming.

The question of whether Mars was habitable in the distant past is one of the greatest mysteries for astrobiologists. In fact, we’re so sure of it that we’ve already sent more than a dozen scientific missions to the surface of the red planet in an attempt to find out. Decades ago, scientists weren’t so sure and believed that Mars had always been barren and dry and not a planet suitable for life. However, today, based on a lot of scientific evidence, we know that this is not the case. And now a new study shows that not only was Mars habitable in the past, but it could even have developed life at a time when our planet was just forming.

The study, published in the journal Earth and Planetary Science Letters, indicates that Mars was born wet, retaining a dense atmosphere conducive to warm or hot oceans for millions of years. This conclusion was based on the first model of the evolution of Mars’ atmosphere that accounts for the high temperatures associated with the formation of Mars when it was in a molten state, before the first oceans and atmosphere formed.

According to this model, Mars’ upper atmosphere was “dry” because water vapor condensed as clouds at lower levels of the atmosphere, as it still does on Earth today. In contrast, the hydrogen molecule (H2) did not condense and was transported to the upper atmosphere of Mars where it was lost. As a result of this finding, the model can be used to link directly to measurements made by the Curiosity rover, which measures water vapor condensation and retention on early Mars.

The new model shows one of the earliest chapters in the history of Mars in the immediate post-formation stage. Kaveh Pahlevan, a researcher at the SETI Institute, believes that Mars’ original atmosphere must have been dense (more than 1,000 times denser than today’s atmosphere) and mostly composed of molecular hydrogen (H2). The importance of this discovery is that H2 is known as a potent greenhouse gas in dense environments.

The dense atmosphere of Mars would have created a strong greenhouse effect, allowing warm or hot water oceans to persist on the surface for millions of years before the H2 disappeared into space. The study suggested that Mars was humid before the Earth formed.

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