Evidence suggests ancient Mars ocean

PARIS, Feb. 6 (UPI) -- The European Space Agency says its Mars Express orbiter has discovered strong evidence for a large ocean once covering part of the Red Planet.

Using radar, it has detected sediments suggestive of an ocean floor within the boundaries of previously identified ancient shorelines on Mars, an ESA release said Monday.

"We interpret these as sedimentary deposits, maybe ice-rich," Jeremie Mouginot, of the Institut de Planetologie et d'Astrophysique de Grenoble said. "It is a strong new indication that there was once an ocean here."

Scientists have theorized oceans could have formed at two points in the planet's history: 4 billion years ago, when warmer conditions prevailed, or 3 billion years ago when subsurface ice melted following a large impact.

This later ocean would have been temporary, researchers said, since in a million years or less the water would have either frozen back in place and gone underground or turned into vapor and lifted gradually into the atmosphere.

"I don't think it could have stayed as an ocean long enough for life to form," Mouginot said.

However, researchers said, the new data provides some of the best evidence yet for large bodies of liquid water on Mars in the planet's past.