What scientists used to think was an impact crater on the surface of Mars now appears to be the site of an ancient supervolcano.
The volcano could have been so violently explosive that it spewed enough ash and other materials into the Martian atmosphere to change the Red Planet's temperature for years, according to a report by Joseph R. Michalski, a senior scientist at the Planetary Science Institute in Tucson, Ariz.
Michalski based his findings on images and topographic data from several orbiting Mars spacecrafts, including NASA's Mars Odyssey, the Mars Reconnaissance Orbiter and the European Space Agency's Mars Express orbiter.
The scientist began to doubt the basin he was studying was an impact crater when he noticed it lacked the usual raised rim of an impact crater. He also could not find nearby evidence of the rock that would be thrown out of the crater after an object crashes.
"On Mars, young volcanoes have a very distinctive appearance that allows us to identify them," Michalski said in a statement. "The long-standing question has been what ancient volcanoes on Mars look like. Perhaps they look like this one."
The crater, which was recently named Eden Patera, is a vast circular basin, according to the institute.
Michalski described the basin as a volcanic caldera, a depression formed by a volcano, although it can look much like a crater created by a meteor impact.
The researcher also believes the volcano was created when a large amount of magma, which contained dissolved gas similar to the carbonation in soda, rose through Mars' thin crust and burst through the surface.
Scientists compared the event to a shaken bottle of soda that blows its contents when the cap is removed. After the eruption ends. the depression that is left often collapses further.
According to the institute, scientists think similar ancient volcanoes erupted in Yellowstone National Park in the U.S. and in Lake Taupo in New Zealand.
"This highly explosive type of eruption is a game-changer, spewing many times more ash and other material than typical, younger Martian volcanoes," said Jacob E. Bleacher, a volcanic specialist at the NASA Goddard Space Flight Center and co-author on a report about the discovery. "During these types of eruptions on Earth, the debris may spread so far through the atmosphere and remain so long that it alters the global temperature for years."
Bleacher and Michalski reported that there may have been other supervolcanoes in the area around the one they've identified.
Bleacher noted, "If just a handful of volcanoes like these were once active, they could have had a major impact on the evolution of Mars."
Scientists have been putting a lot of focus on Mars in the last several years.
NASA has two robotic rovers , Curiosity and Opportunity, currently working on Mars. Curiosity, the most recent rover, has been tasked with discovering whether Mars is now, or ever has been, able to support life, even in microbial form.
Methane is produced by living beings, including microbes. If there is no methane, there may not be life as we know it on Mars. NASA scientists will continue to search for even trace amounts of methane, as well as for microbes that don't emit methane.
This article, Scientists say Mars crater may be 'game-changing' supervolcano, was originally published at Computerworld.com.
Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed. Her email address is email@example.com.
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