DOE OSTI · 3365013
The Psyche Gamma-Ray and Neutron Spectrometer
Abstract
A Gamma-Ray and Neutron Spectrometer (GRNS) instrument has been developed as part of the science payload for NASA’s Discovery Program Psyche mission to the M-class asteroid (16) Psyche. The GRNS instrument is designed to measure the elemental composition of Psyche with the goal to understand the origin of this mysterious, potentially metal-rich planetary body. The GRNS will measure the near-surface abundances for the elements Ni, Fe, Si, K, S, Al, and Ca, as well as the spatial distribution of Psyche’s metal-to-silicate fraction (or metal fraction). These measurements address three of the five Psyche mission science objectives: determine if Psyche is a core; determine whether small metal bodies incorporate light elements into the metal phase; and determine whether Psyche was formed under reducing conditions. The Gamma-Ray Spectrometer (GRS) uses a cryocooled, high-purity Ge (HPGe) sensor to detect cosmic-ray generated gamma rays in the 60 to 9000-keV energy range. The HPGe sensor is surrounded by a borated plastic anticoincidence shield that provides three functions: active background rejection from charged particle interactions in the HPGe sensor; fast neutron measurements; and direct measurements of the incident galactic cosmic ray flux. The Neutron Spectrometer (NS) uses three 3 He gas proportional sensors, each with different material wraps to measure thermal (<0.4 eV), low-energy epithermal (0.4 eV to 1 keV), and high-energy epithermal (up to 100 keV) neutrons. This paper provides an overview of the Psyche GRNS, including: its science and measurement objectives; the design of the instrument hardware, software, and operation; pre-launch performance measurements and its initial performance in space; and an overview of its data products and expected operation for different Psyche mission phases.
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Lawrence, David J. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)] (ORCID:0000000276966667), Goldsten, John O. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Peplowski, Patrick N. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Burks, Morgan T. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)], Cheng, Shuo [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Cully, Michael J. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Effron, Jordan M. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)], Elkins-Tanton, Linda T. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL); University of California, Berkeley, CA (United States)], Espiritu, Raymond C. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Fix, Samuel G. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Graziano, Milena B. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Hoffer, Erin M. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Jun, Insoo [California Institute of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Laboratory (JPL)], Kim, Geon-Bo [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)], Hines, Nathan R. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)], LeBlanc, Mark T. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Livingstone, Evan M. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL); Northrop Grumman, Linthicum Heights, MD (United States)], Marcotte, Kathryn M. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], McCoy, Timothy J. [Smithsonian Institute, Washington, DC (United States). National Museum of Natural History (NMNH)], Polanskey, Carol A. [California Institute of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Laboratory (JPL)], Sreekantamurthy, Meena [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)], Yokley, Zachary W. [Johns Hopkins University, Laurel, MD (United States). Applied Physics Laboratory (APL)]. 2025-09-01. The Psyche Gamma-Ray and Neutron Spectrometer. https://doi.org/10.1007/s11214-025-01201-6
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