The Curiosity Rover has found evidence of an ancient stream that flowed "vigorously" on Mars where the Rover is now exploring, NASA said on Thursday. NPR reports that this is "definitive proof" that water once existed on Mars. Stream bed gravels were observed among the rocks on the surface of Mars, according to a statement from NASA. "From the size of gravels it carried, we can interpret the water was moving about 3 feet per second, with a depth somewhere between ankle and hip deep," said Curiosity science co-investigator William Dietrich of the University of California, Berkeley. The rock outcrop was named "Hottah" after Hottah Lake in Canada's Northwest Territories, per The Scientific American. Reacting to the news, American astrophysicist Neil deGrasse Tyson wrote in an email to The Huffington Post: Read more: http://www.huffingtonpost.com/2012/09/27/mars-water-stream-curiosity-nasa_n_1920402.html
http://www.sciencenews.org/view/generic/id/344133/title/Mars_clays_may_have_volcanic_source Ancient clay deposits on Mars may not indicate that the Red Planet was originally a warm, wet place, as scientists have thought. Instead of needing liquid water to form, many of Mars’ 4-billion-year-old clays could have originated from cooling lava, researchers report online September 9 in Nature Geoscience. Clays are widely scattered across Mars’ oldest terrain, dating to the Noachian period 4.1 billion to 3.7 billion years ago. When the Mars Express and Mars Reconnaissance Orbiter discovered these minerals from orbit several years ago, geologists assumed the clays were a result of large bodies of water weathering and altering Mars’ basalt surface. But last year, some researchers suggested that underground hydrothermal activity provided the water that is necessary to form the clays (SN: 12/3/11, p. 5). Now there’s another suggestion: Crystallizing lava may have contained tiny pockets where water could react with other chemicals to make small amounts of iron- and magnesium-rich clay. No additional water flowing on the surface or belowground would be needed. So early Mars could have been a largely cold, dry world.
