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GeMini-Plus: A high-resolution gamma-ray spectrometer for planetary composition measurements

Author: 
Lena Heffern
Topic: 
Geochemistry/Petrology
Delivered As: 
Poster
Abstract Text: 

Gamma-ray spectroscopy is a well-known technique used in measuring planetary elemental composition, a key to understanding planet formation and evolution. Orbital gamma-ray measurements have already been done on Mercury, the Moon, asteroids, and Mars. However, due to the need for a low-resource (power, mass) instrument, few surface measurements have been made using gamma-ray spectroscopy, especially at high resolution. Under NASA’s Maturation of Instruments for Solar System Exploration (MatISSE) program, the development of a new high-purity germanium (HPGe) gamma-ray spectrometer (GRS), called the GeMini-Plus, is currently underway and will allow for high-resolution, laboratory quality measurements to be made in both orbital and landed missions. GeMini-Plus is a high-heritage design based on both the successful MESSENGER GRS, as well as the terrestrial GeMini spectrometer currently being commercialized by Ortec. GeMini-Plus uses a modular base design that can be customized depending on the mission requirements; the design also allows for the use of anticoincidence neutron shielding to be integrated if needed. GeMini-Plus is capable of measuring a range of major (e.g. O, Mg, Al, Si, Ca, Ti, Fe), minor (e.g. H, Na, S, Ti) and trace (K, Th, U) elements, many of which are only discernable due to GeMini’s superior energy resolution (~3keV energy resolution at 662keV) as compared to scintillator-based GRS systems (~50+ keV energy resolution at 662keV). We present the instrument design and capabilities of the GeMini-Plus, including its use characterizing the surface compositions and resources available on the Moon, near-Earth asteroids, and the Martian moons Phobos and Deimos.

Co-Authors: 
Alexander Sehlke "...
SSERVI Identifier: 
NESF2016-062

About SSERVI
Recognizing that science and human exploration are mutually enabling, NASA created the Solar System Exploration Research Virtual Institute (SSERVI) to address basic and applied scientific questions fundamental to understanding the Moon, Near Earth Asteroids, the Martian moons Phobos and Deimos, and the near space environments of these target bodies. As a virtual institute, SSERVI funds investigators at a broad range of domestic institutions, bringing them together along with international partners via virtual technology to enable new scientific efforts."