View source for Gamma Ray Spectrometer (2001 Mars Odyssey)

{{refimprove|date=April 2015}}
{{DISPLAYTITLE:Gamma Ray Spectrometer (''2001 Mars Odyssey'')}}
[[Image:Grs-draw.jpg|thumb|right|200px|A diagram of the scientific instruments present on 2001 Mars Odyssey; the Gamma Ray Spectrometer consists of the Gamma Sensor Head, the Neutron Spectrometer and HEND (High Energy Neutron Detector).]]
[[File:Grsradiation-med.jpg|thumb|right|200px|How GRS collects data from surface]]

The '''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 [[NASA]]'s [[Mars Surveyor 2001]] 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]] at the [[University of Arizona]] in the United States.  This instrument has mapped the distribution surface [[hydrogen]], thought to trace water in the surface layer of [[Martian soil]].<ref>{{cite web |url=http://grs.lpl.arizona.edu/latestresults.jsp |title=Gamma Ray Spectrometer : Latest Results |date=January 2008 |publisher=[[Lunar and Planetary Laboratory]], [[University of Arizona]] |accessdate=2018-01-08 |archive-date=2020-11-12 |archive-url=https://web.archive.org/web/20201112025551/https://grs.lpl.arizona.edu/latestresults.jsp |url-status=dead }}</ref>  

==GRS specifications==

The Gamma Ray Spectrometer weighs {{convert|30.5|kg|lbs}} and uses 32 watts of power. Along with its cooler, it measures {{convert|468|by|534|by|604|mm|in}}. The detector is a photodiode made of a {{convert|1.2|kg|lb|adj=on}} germanium crystal, reverse biased to about 3 kilovolts, mounted at the end of a {{convert|6|m|ft|adj=on}} boom to minimize interferences from the gamma radiation produced by the spacecraft itself. Its spatial resolution is about {{convert|300|km|mi}}.<ref>{{cite journal
 | title = The Mars Odyssey Gamma-Ray Spectrometer Instrument Suite
 | first1 = W. V. |last1 = Boynton |first2=W. C. |last2=Feldman |first3=I. G. |last3=Mitrofanov |first4=L. G. |last4=Evans |first5=R. C. |last5=Reedy |first6=S. W. |last6=Squyres |first7=R. |last7=Starr |first8=J. I. |last8=Trombka |first9=C. |last9=d'Uston |first10=J. R. |last10=Arnold |first11=P. A. J. |last11=Englert |first12=A. E. |last12=Metzger |first13=H. |last13=Wänke |first14=J. |last14=Brückner |first15=D. M. |last15=Drake |first16=C. |last16=Shinohara |first17=C. |last17=Fellows |first18=D. K. |last18=Hamara |first19=K. |last19=Harshman |first20=K. |last20=Kerry |first21=C. |last21=Turner |first22=M. |last22=Ward |first23=H. |last23=Barthe |first24=K. R. |last24=Fuller |first25=S. A. |last25=Storms |first26=G. W. |last26=Thornton |first27=J. L. |last27=Longmire |first28=M. L. |last28=Litvak |first29=A. K. |last29=Ton'chev
 | journal = Space Science Reviews 
 | volume = 110
 | issue = 1–2
 | doi = 10.1023/B:SPAC.0000021007.76126.15
 | date = 2004
 | pages = 37
 | bibcode=2004SSRv..110...37B
| s2cid = 121206223 }}</ref><ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2001-014A |title=2001 Mars Odyssey |work=NASA Space Science Data Coordinated Archive |publisher=NASA |accessdate=2018-01-08}}</ref>

The [[neutron spectrometer]] is {{convert|173|by|144|by|314|mm|in}}.

The high-energy neutron detector measures {{convert|303|by|248|by|242|mm|in}}. The instrument's central electronics box is {{convert|281|by|243|by|234|mm|in}}.

==References==
{{reflist}}

==External links==
* [http://grs.lpl.arizona.edu/ ''Mars Odyssey'' GRS instrument site] {{Webarchive|url=https://web.archive.org/web/20190505185150/http://grs.lpl.arizona.edu/ |date=2019-05-05 }} at the [[University of Arizona]]

{{Satellite and spacecraft instruments}}

[[Category:2001 Mars Odyssey]]
[[Category:Spectrometers]]
[[Category:Spacecraft instruments]]