MESSENGER Gamma Ray Spectrometer Instrument

PDS Geosciences Node: PDS Source Information

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The MESSENGER Gamma Ray Spectrometer (GRS) instrument measures gamma rays emitted from Mercury’s surface in the energy range 0.1 to 10 MeV. This allows identification of elements, such as O, Si, S, Fe, H, K, Th, and U, and their abundances.

MESSENGER GRS Products have been converted to the PDS4 standard. They are grouped into PDS4 collections based on processing level.

PDS4 Collection	Description	PDS4 Bundle
Raw Data	The MESSENGER GRS raw product collection consists of uncalibrated observations from the GRS instrument. There are ten standard product types associated with the GRS sensor. Six product types contain spectra from either the high-purity germanium or scintillator detector. The remaining raw product types pertain to the operation of the GRS instrument, including a time-tagged list of commands executed. A single raw product typically contains data collected over one Earth day.	urn:nasa:pds:mess_grs_raw
Calibrated Data	The MESSENGER GRS calibrated product collection consists of GRS data that have been calibrated for instrument and geometrical effects. There are eight product types in this collection that include spectra in addition to engineering and shield count rate data. Spectral products contain spacecraft navigation and attitude data derived from SPICE files, as well as selected relevant engineering data. A single product typically contains data collected over one Earth day.	urn:nasa:pds:mess_grs_derived
Derived Data	The MESSENGER GRS derived product collection has a series of maps derived from the GRS instrument for the northern hemisphere of Mercury. These were created from calibrated gamma ray spectra, represent spatially resolved measurements, and have been highly processed to remove variability originating from detector altitude and viewing geometry. The measurements were also corrected for dead time.	urn:nasa:pds:mess_grs_derived

MESSENGER GRS Advanced Products that use the PDS4 standard:

Type	Description	Collection ID
MEAP4	Mercury GRS Thermal Neutron Map (MEAP-4) - MESSENGER Thermal Neutron Map Collection by Noam Izenberg, PDART 2014. See MESSENGER Advanced Product Specification (PDF).	urn:nasa:pds:izenberg_pdart14_meap:data_tnmap

More information about the GRS can be found in:

Goldsten, J. O., et al., 2007, The MESSENGER Gamma-Ray and Neutron Spectrometer, Space Science Reviews, 131, p. 339-391, doi: 10.1007/s11214-007-9262-7.