Radon leaks could reveal water on Mars New Scientist

Sniffing for puffs of radioactive radon gas could be the easiest way to find water lurking metres beneath the Martian soil. We already know there should be plenty of water on Mars. Probes have found water vapour in the Martian atmosphere and ice on the surface at the poles. And NASA’s Mars Odyssey spacecraft recently detected traces of hydrogen, almost certainly bound up in ice near the surface.