BackForwardInstrument:  GRS 

Instrument details
Acronym GRS
Full name Gamma-Ray Spectrometer
Purpose Spectrometry of solar gamma-rays
Short description Assemblage of three units: 1) seven integral-line calibrated NaI(Tl) detectors for nuclear lines between 0.3 and 0.9 MeV; energy resolution 7 % at 0.662 MeV; 2) a thick CsI(Na) crystal, along with the NaI(Tl) spectrometers, for gamma-rays in the range 10-140 MeV and neutrons with energies above 20 MeV; and 3) an auxiliary system of two NaI detectors for hard X-ray fluxes in the range 10-140 keV. Time resolutions are typically about 2 s and 16 s, but can be as fine as 64 ms for the 300-350 keV energy band
Background New development
Scanning Technique Sun pointing from a low-inclination LEO
Resolution N/A (full disk)
Coverage / Cycle Full solar disk at 10 s intervals
Mass Power Data Rate


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 1980 to 1989
Last update: 2017-05-19
Detailed characteristics
Satellites this instrument is flying on

Note: a red tag indicates satellites no longer operational, a green tag indicates operational satellites, a blue tag indicates future satellites

Instrument classification
  • Solar and space environment monitors
  • Solar activity monitor
WIGOS Subcomponents
  • Subcomponent 3
  • UV spectral imagery (e.g. GEO, HEO, MEO, LEO)
  • Gamma-ray spectrometer [from GEO, HEO, MEO, LEO]
  • X-ray spectrometer [from GEO, HEO, MEO, LEO]
Mission objectives
Primary mission objectives
  • Solar gamma-ray flux spectrum
Evaluation of Measurements

The following list indicates which measurements can typically be retrieved from this category of instrument. To see a full Gap Analysis by Variable, click on the respective variable.

Note: table can be sorted by clicking on the column headers
Note: * Primary mission objective.
VariableRelevance for measuring this variableOperational limitationsExplanation
Solar gamma-ray flux spectrum*3 - highNo specific limitation.Wide dynamic range