Calibration of the NEAR gamma-ray spectrometer

The gamma-ray spectrometer onboard the Near Earth Asteroid Rendezvous space craft will measure gamma rays from the surface of 433 Eros in the 100-keV t o 10-MeV energy region. Detection of characteristic gamma-ray emissions fro m such elements as O, Si, Fe, Ca, Ti, Mg, Al, H, K, Th, and U will allow th e determination of abundances of these geologically important elements. Spa tial resolution will be large, but the emission detected will originate fro m a volume of material down to depths of 10-20 cm below the surface. These measurements will make it possible to relate Eros to known meteorite classe s and to relate these to geological processes on Eros. The calibration meas urements and analysis procedures that are described will be needed for the reduction and analysis of gamma-ray data collected during the mission. In a ddition to geochemical measurements, the gamma-ray detector is used to dete ct gamma-ray bursts and forms part of the interplanetary network of gamma-r ay detectors used to determine the source positions of gamma-ray bursts. (C ) Academic Press.