The Gamma Ray Spectrometer (GRS) is a

gamma-ray spectrometer A gamma-ray spectrometer (GRS) is an instrument for measuring the distribution (or spectrum—see figure) of the intensity of gamma radiation versus the energy of each photon. The study and analysis of gamma-ray spectra for scientific and techni ...

on the ''

2001 Mars Odyssey ''2001 Mars Odyssey'' is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectro ...

'' spacecraft, a space probe orbiting the planet

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmosp ...

since 2001. Part of NASA's

Mars Surveyor 2001 The Mars Surveyor 2001 project was a multi-part Mars exploration mission intended as a follow-up to Mars Surveyor '98. After the two probes of the 1998 project, Mars Climate Orbiter and Mars Polar Lander, were both lost, NASA's "better, faster ...

program, it returns geological data about Mars's surface such as identifying elements and the location of water. It is maintained by the

Lunar and Planetary Laboratory The Lunar and Planetary Laboratory (LPL) is a research center for planetary science located in Tucson, Arizona. It is also a graduate school, constituting the Department of Planetary Sciences at the University of Arizona. LPL is one of the wo ...

at the

University of Arizona The University of Arizona (Arizona, U of A, UArizona, or UA) is a public land-grant research university in Tucson, Arizona. Founded in 1885 by the 13th Arizona Territorial Legislature, it was the first university in the Arizona Territory. Th ...

in the United States. This instrument has mapped the distribution surface

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxi ...

, thought to trace water in the surface layer of

Martian soil Martian soil is the fine regolith (a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock) found on the surface of Mars. Its properties can differ significantly from those of terrestrial soil, including its to ...

GRS specifications

The Gamma Ray Spectrometer weighs and uses 32 watts of power. Along with its cooler, it measures . The detector is a photodiode made of a germanium crystal, reverse biased to about 3 kilovolts, mounted at the end of a boom to minimize interferences from the gamma radiation produced by the spacecraft itself. Its spatial resolution is about . The neutron spectrometer is . The high-energy neutron detector measures . The instrument's central electronics box is .

References

External links

''Mars Odyssey'' GRS instrument site
at the

{{Satellite and spacecraft instruments 2001 Mars Odyssey Spectrometers Spacecraft instruments