NASA Science Briefing: Comet Siding Spring at Mars

Images from NASA’s Mars Reconnaissance Orbiter provide dramatic before-and-after shots of Mars showing the impact of a global dust storm that has obscured the surface.

NASA scientists have determined that a primitive ocean occupying almost half of Mars’ northern hemisphere once held more water than Earth’s Arctic Ocean and that the Red Planet has lost 87% of that water to space.

After a final attempt to restore contact with the Opportunity Mars rover, NASA managers declared the spacecraft lost, bringing a 15-year mission to an end.