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 Gamma spectroscopy#Scintillation detectors, figure) of the intensity of gamma radiation versus the energy of each photon. The study and analysis of ...

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. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

since 2001. Part of

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

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 wor ...

at the

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

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

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

, thought to trace water in the surface layer of

Martian soil Martian regolith is the fine blanket of unconsolidated, loose, heterogeneous superficial deposits covering the surface of Mars. The term ''Martian soil'' typically refers to the finer fraction of regolith. So far, no samples have been returned 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 Neutron spectroscopy is a spectroscopic method of measuring atomic and magnetic motions by measuring the kinetic energy of emitted neutrons. The measured neutrons may be emitted directly (for example, by nuclear reactions), or they may scatter off ...

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