Gamma Ray Spectrometer
Gamma Ray Spectrometer (GRS) is a gamma-ray spectrometer on the 2001 Mars Odyssey spacecraft, a space probe orbiting the planet Mars since 2001. Part of the United States' NASA's Mars Surveyor Program, it returns geological data about Mars' surface such as identifying elements and the location of water. It is managed by the Lunar and Planetary Laboratory at the University of Arizona in the United States. This instrument mapped the distribution of water in the surface..