A Neutron Activation Gamma Ray spectrometer for Planetary Surface Analysis

A pulsed DT neutron generator system, similar to that used in commercial well logging, offers the possibility of performing accurate elemental analyses to depths of tens of centimeters in a few seconds with the probe on the body's surface. Through time-phased measurements of the gamma-ray spectrum synchronized with the neutron pulses, concentrations of hydrogen, carbon and key mineral forming elements can be determined even with a low-resolution spectrometer. If a high resolution spectrometer is used, the number of elements measured and the sensitivity for measurement is increased. An implanted probe system, such as in a comet or ice cap penetrator, would offer the highest possible sensitivity. An inexpensive neutron probe system based on modifications of the Schlumberger well-logging system has been proposed for the Discovery/Venera/SAGE Mission to Venus and the Mars Polar Pathfinder. Preliminary experiments on a simulated Venusian surface indicate that high quality results can be obtained.