Washington, November 26 (ANI): Scientists have found a telltale "bathtub ring" of minerals inside an ancient Martian impact crater, which has led them to suggest that Mars may have once hosted a body of water roughly the size of Lake Michigan.
According to a report in National Geographic News, the find means that Columbus crater, in Mars's southern hemisphere, is the best place yet to study the chemistry of so-called fossil lakes on the red planet.
Hundreds of Martian craters have been identified as possible fossil lakes, based on the presence of now dry channels or sediments deposited at former deltas, according to lead study author James Wray of Cornell University.
But new pictures from NASA's Mars Reconnaissance Orbiter have revealed that Columbus crater has alternating layers of hydrated minerals-clays and sulfates known to form only in the presence of water.
"Some lakes in western Australia that are relatively acidic and pretty salty show similar minerals to what we see in Columbus crater," Wray said.
What's more, the crater is one of the few proposed fossil lakes thought to have been fed entirely by groundwater, Wray added.
"If the water had come from rain, we would expect to see channels. But we don't," Wray said.
Columbus crater dates back to Mars's Noachian epoch, a warm, wet period that lasted from about 4.6 to 3.5 billion years ago.
Using a near-infrared spectrometer, which reveals the types of minerals present based on the wavelengths of light they absorb and emit, Wray and colleagues have found clear layers of clay and sulfates in Columbus crater-just what would appear if a large lake had slowly evaporated.
Wray and colleagues think Columbus crater's lake might have formed when now inactive volcanoes in the nearby Tharsis Montes region were pouring out tons of lava.
"The weight of all that lava piling up warped the Martian surface," Wray said.
"This shifted the groundwater underneath, causing some of it to be pushed upward, filling the existing crater," he suggested.
The types of minerals found inside Columbus indicate that, at least in the lake's early days, the water might have been hospitable for life.
"For instance, the crater's layers are full of gypsum, which forms in relatively fresh water," Wray said.
"That probably means the lake was initially not as salty, so that's a good thing for life," considering that too much salt can be toxic to life as we know it," he added. (ANI)