Mars deposit tells of habitable conditions

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American scientists claim to have found evidence that suggests Mars had a warm and wet climate which could have supported life some 3.5 billion-years-ago.
A team led by planetary geologists at Brown University found mounds of a mineral deposited on a volcanic cone less than 3.5 billion-years-ago that speak of a warm and wet past and may preserve evidence of one of the most recent habitable microenvironments on the red planet.
Observations by Nasa’s Mars Reconnaissance Orbiter enabled the researchers to identify the mineral as hydrated silica which can be dissolved, transported and concentrated by hot water or steam — a dead ringer that water was present at some time.
The mineral and the mounds’ location on the flanks of a volcanic cone provide the best evidence yet found on Mars for an intact deposit from a hydrothermal environment — a steam fumarole or a hot spring, said the researchers.
Such environments might have provided habitats for some of earth’s earliest life forms, they hoped.
“The heat and water required to create this deposit probably made this a habitable zone,” said J R Skok, lead author of the study, published in journal Nature Geoscience.
“If life did exist there, this would be a promising spot where it would have been entombed — a microbial mortuary, so to speak.”
No studies have determined whether Mars has ever supported life, but this finding adds to accumulating evidence that at some times and in some places, Mars hosted favourable climate for microbial life.
The deposit is located in the sprawling, flat volcanic zone known as Syrtis Major and was believed to have been left during the early Hesperian period, when most of Mars was already turning chilly and arid.
“Mars is just drying out,” Skok said, “and this is one last hospitable spot in a cooling, drying Mars.”
Concentrations of hydrated silica have been identified on Mars previously, including a nearly pure patch found by Nasa’s Mars Exploration Rover Spirit in 2007. However, this is the first found in an intact setting that clearly signals the mineral’s origin.
“You have spectacular context for this deposit,” Skok said.
Observations by cameras on the Mars Reconnaissance Orbiter revealed patches of bright deposits near the summit of the cone, fanning down its flank, and on flatter ground in the vicinity.