The scarps directly expose bright glimpses into vast underground ice previously detected with spectrometers on NASA's Mars Odyssey (MRO) orbiter, with ground - penetrating radar instruments on MRO and on the European Space Agency's Mars Express orbiter, and with observations of fresh impact craters that uncover subsurface ice. (sciencedaily.com)
Using the Shallow Radar instrument aboard NASA's Mars Reconnaissance Orbiter, Holt was able to peek beneath the ice's surface for clues; in particular, the radar could pick out differences in electrical reflectivity between overlying layers, showing how the ice built up over time. (discovermagazine.com)
The volume of water ice in the region were based on measurements from the ground - penetrating radar instrument on Mars Reconnaissance Orbiter, called SHARAD. (en.wikipedia.org)