This is the actual publication of the discovery, linked from ESA's page http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Mars_Express_detects_liquid

This is the actual publication of the discovery, linked from ESA's page http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Mars_Express_detects_liquid_water_hidden_under_planet_s_south_pole http://www.esa.int/Our_Activities/Space_Science/Mars_Express... Mars Express is an ESA satellite, with the Italian MARSIS radar instrument, two long antennas: https://en.wikipedia.org/wiki/MARSIS https://en.wikipedia.org/wiki/MARSIS