2015 లో, ఘనీభవించిన నీటి భూగర్భ హిమానీనదాలను ______ పై కనుగొన్నారు

In 2015, radar studies by NASA's Mars Reconnaissance Orbiter showed huge glaciers of water ice buried under rocky debris at Mars's mid-latitudes, enough to cover the planet in about a metre of ice.