NASA researchers found evidence that a massive ocean once covered nearly half of the northern hemisphere of Mars. The ancient ocean held 20 million cubic kilometers of water, it covered roughly one-fifth of the red planet's surface 4.5 billion years ago and was a mile deep in places.
Previously it was believed that Mars had standing water for 1.5 billion years, longer than it took for life to emerge on Earth, but now the research suggests Mars must have been wet for a period even longer. Over the last billion years however the huge ocean evaporated into space as the Martian atmosphere thinned. The planet lost much of its insulation too, which caused the remainder of the ocean to recede and freeze. Today about 13 percent of the ocean remains in the form of Martian polar caps. Full details at The Guardian.
The search for life on Mars will ramp up in 2018 when the European Space Agency sends its Exomars rover to the red planet. The rover will look for chemical signatures of life, perhaps emanating from microbes living deep beneath the Martian soil. Last year, Nasa’s Curiosity rover detected methane in the Martian atmosphere. The finding sparked intense speculation that the gas might be coming from living organisms. It might, but there is no evidence to suggest it is. Methane is regularly produced on planets through geological processes without any need for life.
Charles Cockell, professor of astrobiology at Edinburgh University, said: “The longer water persists on a planetary body in one location, particularly if there is geological turnover, the more likely it is that it would provide a habitable environment for a suitable duration for life to either originate or proliferate. An ocean would meet this need.” That life was possible does not make it inevitable though. “Of course, it could have been uninhabited,” he added.