Red Planet Radar: Probing the Martian Underground for Water

European researchers hope to pin down exactly where Mars is hiding its water by looking through the planet rather than on its surface. A ground penetrating radar system aboard Mars Express, a European Space Agency (ESA) probe set to launch in early June, will use radio waves to map out any water reservoirs as deep as 3 miles (5 kilometers) below the surface. “We are looking for serious amounts of water, for mountains of the stuff,” said Iwan Williams, a professor with Queen Mary University of London and co-investigator of the radar experiment. “Everybody believes that it’s there.”