Why Mars may have supported life for a long time, a long time ago

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Jun 18, 2017, 6:16 PM EDT (Updated)

Life on Mars seems to elude us with or without the question being repeated by David Bowie in a powder-blue jacket and eyeshadow to match, but even though this barren planet is hardly the freakiest show, we may have found a portal into the Red Planet’s past that could possibly mean something was there for much longer than we thought.

When not desperately trying to detect some signs of microbial life on the sunburnt surface that have been relentlessly battered and stripped by solar winds, scientists turn to astrogeology for any evidence of something that might at least have once been creeping in what are now the dusty wastelands of the Red Planet. Curiosity’s latest discovery means that something could have been swimming in the Gale Crater.

Curiosity initially found what is believed to have been an ancient system of Martian lakes and streams meandering through the crater. High-silica “haloes,” which overlay long dry lake sediment also rich in silica, were unearthed around the fractures by Gale’s floor. This could only mean that the silica glimmering in these haloes, which appeared in the younger rocks of the crater, was carried there by water seeping through the fractures. It upholds an earlier Curiosity study that suggests Gale may have had all the right conditions to support microbial life for not just hundreds or even thousands, but hundreds of millions of years.

Pale, silica-rich "haloes" border bedrock fractures on Mars' Gale Crater.

"What this finding tells us is that, even when the lake eventually evaporated, substantial amounts of groundwater were present for much longer than we previously thought, thus further expanding the window for when life might have existed on Mars," said scientist Jens Frydenvang of Los Alamos National Laboratory in New Mexico and the University of Copenhagen in Denmark. Might is the operative word here.

The haloes first came to light for Curiosity as it crawled through the foothills of Mount Sharp, which it has been exploring since 2014 to help those back on Earth better understand how Mars evolved from a possibly habitable world to a desolate desert after it lost its magnetic field and radiation from the sun-ravaged its atmosphere some 3.7 billion years ago. The craft zeroed in on the unexpected silica deposits with its multiple cameras, X-ray spectrometer and Chemistry and Camera (ChemCam) Instrument, which shoots lasers to vaporize rock and other materials for analysis.  

Is there life on Mars? Was there life on Mars? Bowie’s question still echoes in the planet’s almost nonexistent atmosphere.