The Mars Odyssey (MO) spacecraft has made its first significant discovery: it has detected large deposits of hydrogen – possibly water – near the Red Planet’s poles. Reporting MO’s preliminary observations, scientists said the first pass by the probe’s neutron spectrometer had revealed evidence of the element in soil at high latitudes. “It is big,” Bill Feldman, of Los Alamos National Laboratory, said of the strength of the signal picked up by Odyssey. The results indicate large amounts of hydrogen on the surface, a likely sign of water-ice. The observations “are precisely what you would expect for a very hydrogen-rich environment”, Feldman said.