Mars pictures reveal frozen sea
A huge, frozen sea lies just below the surface of Mars, a team of European scientists has announced. Their assessment is based on pictures of the planet's near-equatorial Elysium region that show plated and rutted features across an area 800 by 900km. The team think a catastrophic event flooded the landscape five million years ago and then froze out.
See also: 'Pack ice' suggests frozen sea on Mars (New Scientist)