Wet, almost, all over

Water on Mars was surprisingly widespread, long-lasting and perhaps life-friendly

Water on Mars was once widespread and long-lasting, providing environments with the potential to support life, a new study finds.

FLOW AND TRAP It turns out that certain types of clay minerals are widespread on Mars, suggesting that water was also widespread — and at life-friendly temperatures — on the planet early in the solar system’s history, according to a new study. Pictured is Jezero Crater. The new work suggests it was a lake as large as Lake Tahoe. Ancient rivers carried clay-like minerals (shown in green) into the lake, forming the delta. Rocks (shown in purple) then trapped the clays. The team found evidence of many such deltas. NASA, JPL, JHUAPL, MSSS, Brown University

Previously, scientists had strong evidence that liquid water chemically altered the Red Planet’s crust at certain times and locations. Those locations hold the mineral traces of water and preserve in the rock the planet’s past organic chemistry, says Scott Murchie, co-author of the new paper published in the July 17 Nature.

Those locations are also “really important” because the rocks there could hold possible evidence of past life, says Murchie, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.

Using the Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM, and other instruments aboard NASA’s Mars Reconnaissance Orbiter, the team looked for specific types of phyllosilicates, or clay-like minerals, that can form only in the presence of water. The team suggests the water was present early in the solar system’s history, between 4.6 billion and 3.8 billion years ago, based on where in the planet’s rocky layers the minerals occur.

Scientists previously identified a few types of these minerals at about 100 sites, but the sensitivity of CRISM picked up a large variety of the phyllosilicates at thousands of locations across Mars’ southern highlands.

“Finding all these different water-based minerals at all these locations really blows the doors off Mars research,” says University of Paris’ Joseph Michalski, a Mars researcher who was not involved in the study. But, he adds, it all will take years of scientific study and debate to understand what these sites mean for the history of Mars, and whether these sites hosted life.

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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