A team of Italian researchers have poked at the polar ice caps on Mars with a radar and uncovered a lake that stretches about 20km across and 1.5km deep. Previous discoveries have only been around temporary trickles of water and so to have found a massive reservoir of liquid hidden underground has been hailed a stunningly amazing result. The researchers say the lake was likely able to stay liquid because of salts from Martian rocks dissolving into the water, coupled with the incredible pressure of the ice above. The all-Italian team led by the National Institute of Astrophysics made the discovery using MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding), a radar installed on board the European Mars Express probe and developed under the control of the Italian Space Agency. “We discovered water on Mars,” said lead researcher Roberto Orosei at the National Institute of Astrophysics in Bologna, Italy. He added that any other explanation for the bright reflections the scientists saw in the radar data was “untenable”. The findings were published overnight in the journal Science and have excited the scientific community. “There is no reason to conclude that the presence of subsurface water on Mars is limited to a single location,” the researchers wrote.