Ancient mars may have been warm, wet, and possibly inhabited

An artist rendering of what Mars might look like over time if efforts were made to give it an artificial magnetic field to then enrich its atmosphere and made it more hospitable to human explorers and scientists. (NASA)

doi.org/10.1038/s43247-025-02856-3
Credibility: 989
#Mars

New research reveals that billions of years ago, parts of Mars had a warm, wet climate for extended periods, with intense rainfall and conditions that could have favored the emergence of life

This discovery challenges the long-held idea that the planet was, from the beginning, cold and covered in ice.

Scientists analyzed clay minerals found on Mars, especially inside the ancient lake in Jezero Crater, where NASA’s Perseverance rover landed in 2021. These minerals, known as kaolinite, are rich in aluminum and poor in iron and magnesium.

This composition indicates that they were formed not by hot, temporary water (like that from volcanoes or meteorite impacts), but by persistent rainfall and moderate temperatures over thousands or even millions of years.

During the Noachian epoch (between 4.1 and 3.7 billion years ago), Mars underwent a period of numerous asteroid impacts, which created large basins such as Hellas and Argyre.

Despite this violence, there is clear evidence of rivers, lakes, deltas, and valleys carved by water.

Researchers compared Martian clays with similar formations on Earth from periods when the climate was warm and humid, such as during greenhouse periods.

Although the Sun was about 30% weaker at that time, a thick atmosphere rich in greenhouse gases could have kept the planet warm enough to allow for abundant liquid water.

Data from Perseverance suggest that, at least in some regions, Mars experienced prolonged humid periods, possibly the most habitable in its entire history.

These favorable conditions coincide with the recent discovery of possible biological signals in the same location.

Samples collected by the rover are being stored for a future mission to bring them back to Earth-although that mission has been canceled by NASA, which could delay the analyses for many years.

Just imagine: billions of years before the first humans existed, what is now a cold and windy desert may have been a tropical environment, with flowing rivers and, who knows, primitive life forms.

This new perspective makes Mars even more fascinating and reinforces the importance of continuing to explore the red planet to better understand its past and our own.

Published in 04/02/2026 18h28

Portuguese version

Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.

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