Detecting Subsurface Water

Neutrons escaping from the planet's surface can be a sign of the presence of water and ice, and researchers are using a tool called the Detector of Albedo Neutrons, or DAN, on the Mars Science Laboratory rover to search for them.

Cosmic rays bombarding the planet from space knock neutrons in soils and rocks out of their atomic orbits, and hydrogen atoms present in liquid or frozen water slow the movement of these neutrons. DAN detects the slowed neutron, which may signal the presence of water or ice.

Read the related story: "The Mars science gear on Curiosity"