Search for Mars water goes underground New Scientist

A spindly radar antenna with the ambitious aim of revealing any water or ice buried below the Martian surface is set to be deployed Monday aboard the orbiting spacecraft Mars Express. MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) is the seventh and final instrument on the European Space Agency probe to be switched on since it arrived in December, and will take 10 days to set up. Its main antenna, composed of two 20-metre segments, will act as a 40-metre-long divining rod that will scout for water as deep as a few kilometres below ground.