The Red Planet by the Viking Orbiters in the 1970s. Image credit: NASA
Radar data collected by ESA’s Mars Express point to a pond of liquid water buried under layers of ice and dust in the south polar region of Mars.
Evidence for the Red Planet’s watery past is prevalent across its surface in the form of vast dried-out river valley networks and gigantic outflow channels clearly imaged by orbiting spacecraft. Orbiters, together with landers and rovers exploring the Martian surface, also discovered minerals that can only form in the presence of liquid water.
But the climate has changed significantly over the course of the planet’s 4.6-billion-year history and liquid water cannot exist on the surface today, so scientists are looking underground. Early results from the 15-year-old Mars Express spacecraft already found that water ice exists at the planet’s poles and is also buried in layers interspersed with dust.
The presence of liquid water at the base of the polar ice caps has long been suspected; after all, from studies on Earth, it is well known that the melting point of water decreases under the pressure of an overlying glacier. Moreover, the presence of salts on Mars could further reduce ...