Sentences with phrase «once had liquid water on its surface»
Studies of hydrogen molecules in the Venusian atmosphere by NASA's Pioneer - Venus probe indicate that the planet once had liquid water on its surface, perhaps even expansive oceans.
http://discovermagazine.com/ Not exact matches
NASA's twin Mars Exploration Rovers have discovered evidence that liquid water once flowed, at least fitfully, on the Red Planet's surface (ScienceNOW, 13 December 2006).
The surface of the red planet is bone dry, but several studies have shown liquid water may once have flowed on Mars and could still exist in pockets below the surface.
Venus may have once been habitable; current research puts liquid water on the surface about 2 billion years ago.
Clues on the Martian surface, including features resembling dry riverbeds and minerals that only form in the presence of water, suggest Mars once had a denser atmosphere that supported the presence of liquid water on the surface.
Other factors also suggest Mars once had a much thicker atmosphere, such as evidence of persistent presence of liquid water on the planet's surface long ago even though the atmosphere is too scant for liquid water to persist on the surface now.