Discovered through satellite radar readings, the lake lies beneath the ice caps at the south pole of Mars, and has profound implications for future missions and the search for extraterrestrial life.
According to its discoverers, the lake lies below 1.5 km (0.9 mi) of solid ice, and stretches 20 km (12.4 mi) wide. Although temperatures at that spot plummet to about -68° C (-90° F), the water remains in a liquid form thanks to the heavy presence of sodium, magnesium and calcium salts. This, along with the immense pressure of the ice from above, lowers the freezing point.
The discovery was made by astronomers using the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) onboard the Mars Express orbiter. This instrument beams radar pulses down to the planet's surface and measures how the waves reflect back to the spacecraft, which can tell scientists what kind of materials lie down there, even below the surface.