Just 500,000 years ago water was sloshing all over Mars, despite the planet having lost its atmosphere four billion years ago, astroboffins have discovered.
In a paper titled "Earth-like aqueous debris-flow activity on Mars at high orbital obliquity in the last million years", and published today in Nature Communications, boffins have revealed their estimation of the last time the Red Planet saw any of the liquid stuff.
A team lead by Dutch physical geographer, Tjalling de Haas, focused on an ancient crater called Istok, and especially its pole-facing slope.
The ... crater hosts a bajada, a series of coalescing fans, with abundant debris-flow deposits, which are among the best preserved found on Mars to date.
Although morphometric analyses suggest that many gullies are formed by debris flows, evidence thereof is generally absent on gully-fan surfaces.
The unusually pristine debris-flow deposits in Istok crater therefore make it the best, and only, crater wherein detailed quantitative analyses using debris-flow volumes can be performed today.
Although they were unable to directly estimate the amount, and the frequency, of liquid water generated during recent periods in which the red planet tilted a little further towards the sun, thus melting some of the ice in the pole-facing wall of the Istok crater, they have managed to determine the "debris-flow size, frequency and associated water volumes in [the] Istok crater," and have shown "that debris flows occurred at Earth-like frequencies during high-obliquity periods in the last million years on Mars".
The results also implied that the accumulations of snow and ice within the crater's gullies were much more voluminous than had been estimated previously.
Melting "must have yielded centimetres of liquid water in catchments; and recent aqueous activity in some mid-latitude craters was much more frequent than previously anticipated".
It's generally accepted that Mars began to lose its water after the mysterious loss of its magnetosphere, when the solar wind began to strip away atoms from the outer layer of its atmosphere.
NASA's MAVEN spacecraft continues to orbit our red neighbour, having analysed the remnants of this astronomical undressing.
Liquid water is considered essential to the existence of life, both terrestrially and extra-terrestrially, and the search for signs of life on Mars continues with such intensity that the Earthling's orbiters now need a form of traffic policing to avoid colliding with each other.
The astroboffins estimate five periods during the last million years when the red planet tilted enough to present its frozen bottom (or top) to the sun. The muddy ice-water would have then flowed at the Istok crater.
The boffins acknowledge that their calculations are based on a number of assumptions. "However, this is inevitable for the current analysis that can only be based on remote sensing data." they write. ®