Cobalt is an advantageous target for probing the physics of nuclear spallation, because it is a naturally mono-isotopic element (Co-59), and its per-nucleon binding energy (BE/A = 8.768 MeV) is near the maximum value for all nuclei. We measured nuclear spallation cross sections for the Co-59(p,X) reaction at five kinetic energies ranging from 250 MeV to 2 GeV. Cross sections for the production of Co-58, Co-57, Mn-57, Co-56, Mn-56, Cr-56, Fe-55, Fe-53, Mn-54, Mn-52, Cr-51, Cr-49, V-48, Sc-47, Sc-46, Sc-44, and Sc-44(m) are reported. Where comparable data exist in the EXFOR reaction database, we find that our measured cross sections generally agree. In many cases, we provide data for reactions or energies not currently reported in EXFOR. Our cross sections also provide evidence for the presence of alpha-clusters within the Co-59 nucleus, a surprising result given the asymmetry in Z (27) and N (32) for this nucleus. Finally, we use our measurements to evaluate the accuracy of spallation cross section simulations from GEANT4-based radiation transport toolkit, performed with the INCLXX-, Bertini-, and Binary-ion-cascade (BIC) based physics lists. This benchmarking activity revealed that the simulations overestimated the cross sections by a factor of similar to 2-4 on average, and that the INCL-XX physics list provides the most reliable results. This evaluation informs the selection of the GEANT4 physics lists used for the analysis of data from NASA's Psyche mission, which will measure gamma rays and neutrons resulting from spallation reactions occurring on the surface of an asteroid whose surface is thought to be rich in iron-nickel metal.

We report new measurements of high-energy protons ejected by the sun during the May 2024 Ganon superstorm. Our observations were made by the Neutron Spectrometer (NS) on the Psyche spacecraft, which was located at a solar distance of approximately 2 AU and a Sun-Earth-Probe separation angle of 75 degrees. This unique vantage point can provide new insights into the nature of this exceptional space weather event. Our observations validated predictions from the WSA-ENLIL heliospheric model, which forecasted that the Psyche spacecraft would be magnetically-connected to the Coronal Mass Ejection (CME) on May 10th-11th, and that the Psyche spacecraft would pass through the periphery of the proton-rich region driven by the superstorm's CME on May 13th. This agreement both validates the large-scale CME propagation predicted by ENLIL and underscores the value of observations from a variety of geometries. The Psyche spacecraft will continue to make unique observations of solar particle events throughout its interplanetary cruise to asteroid 16 Psyche. We believe that these observations will be a valuable resource for refining particle-transport models and improving forecasts of solar energetic proton arrival times and intensities.

We present a technique for high-precision absolute measurements of gamma-ray production cross sections (n,xg) induced by 14 MeV neutrons. The technique is based on the Associated Particle Imaging (API) method, which tags individual neutrons emitted from a deuterium-tritium source with their associated alpha-particles, enabling coincidence-based suppression of lower-energy neutrons and room background signals, while also providing neutron flux measurements with uncertainties on the order of 1

JAXA’s Mars Moon eXploration (MMX) spacecraft carries a NASA-provided γ-ray and neutron spectrometer called MEGANE. MEGANE’s measurements will be used to characterize the elemental composition of Mars’ largest and innermost moon, Phobos, with the goal of providing data that directly tests existing hypotheses for the origin and evolution of the martian moons. We report results from the ground calibration of the MEGANE sensors. This information is required to accurately interpret the measurements collected by MEGANE during in-flight operations at Phobos.

NASA's Psyche spacecraft is currently enroute to the asteroid 16 Psyche, where it will perform an orbital investigation focused on determining the nature of the asteroid. A key part of this investigation is measurements of elemental composition to determine if the asteroid is rich in iron-nickel metal. To that end, the Psyche spacecraft payload includes a Gamma-Ray and Neutron Spectrometer (GRNS). GRNS is composed of two subsystems; a Gamma-Ray Spectrometer (GRS) with a high-purity germanium gamma-ray sensor surrounded by a borated plastic scintillator Anti-Coincidence Shield (ACS), and a Neutron Spectrometer (NS) with three 3He-filled gas proportional counters that are sensitive to different neutron energy regimes. We describe results from the pre-launch calibration campaign, along with early in-flight results from post-launch instrument commissioning. The information detailed here is focused on providing future users of GRNS data with the information needed to properly interpret the observations from the instrument.

The In Situ Nuclear Spectrometer with 3D Resolution (INSPECT3R) is a compact, 3D elemental imaging system for planetary exploration based on the Associated Particle Imaging (API) technique. This active neutron interrogation instrument achieves centimeter-scale spatial resolution (8 cm × 8 cm × 10 cm) over volumes of up to 50 cm × 50 cm × 40 cm—surpassing the capabilities of existing in-situ planetary nuclear spectrometers. INSPECT3R enables non-destructive, volumetric mapping of elemental composition, resolving layered structures and subsurface heterogeneities while suppressing all environmental background signals through coincidence detection. We present a series of experiments with lunar regolith simulants demonstrating INSPECT3R’s ability to identify and localize key elements and buried objects with high precision. This technology offers transformative potential for future planetary science and astrobiology missions and for In Situ Resource Utilization (ISRU) activities on the Moon and elsewhere, providing a new dimension of spatially resolved geochemical analysis critical to surface missions.

The Psyche spacecraft launched on October 13, 2023 to journey to the asteroid of the same name. Psyche is the largest M-class asteroid and possibly the remanent core of an early differentiated planetesimal that was disrupted by collisions. The Psyche mission will test that hypothesis as the 14th mission in NASA’s Discovery Program. An alternative hypothesis is that the asteroid is unmelted primordial material. We describe the proposal competition process leading to selection of the mission and its context with other small body missions. This paper will briefly introduce the three science instruments, gravity science investigation, and Deep Space Optical Communications technology demonstration, leading into a detailed explanation of the science mission architecture. The orbital science phase is divided into a series of circular mapping orbits at four distinct altitudes, each selected to address specific science objectives. The requirements and objectives for each orbit are accompanied by an assessment of the effectiveness of each phase. We discuss the structure of the Psyche team during the operations phase along with the roles and responsibilities of the science and flight operations teams. Key elements of mission operations that are unique to the Psyche mission are provided. The Science Data Center manages and archives the Psyche mission data. The contents of the archive data sets for each instrument are outlined as well as the interfaces between the Science Data Center, the instrument teams, and the Planetary Data System.

Psyche is a mission to explore what is believed to be the largest metal-rich asteroid in the solar system. This paper provides an overview of the spacecraft and its first six months of operations in space. It describes launch operations and initial testing, including tests of the spacecraft's unique electric propulsion and power systems, demonstration of its Deep Space Optical Communications payload, and validation of its all-electric three-axis momentum management strategy. The Psyche spacecraft has successfully completed its initial checkout, transitioned to cruise operations, and started its 2.2-billion-mile journey to its target in the main belt, asteroid (16) Psyche.

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 3He 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.

Questions about the formation of the primary anorthositic crust of the Moon remain unanswered. Spectroscopic surveys of the lunar crust have evidenced the presence of pure, crystalline plagioclase exposures (PCPEs) across the surface, which are assumed to be remnants of the Moon's ancient anorthositic crust. Results from our work show that the plagioclase composition within PCPEs in all geochemical terranes is relatively uniform and consistent with highly calcic anorthite found in immature and mature Apollo highlands regolith samples. Observed variations in our spectroscopic data sets are likely related to maturity, not plagioclase composition, supporting a single crust-forming event rather than serial magmatism. To constrain the plagioclase composition within the primary anorthositic crust, we use remote sensing data from two instruments on board different lunar orbiters, Moon Mineralogy Mapper (M ^3 ) and Diviner Lunar Radiometer (Diviner). When working with data sets acquired by different instruments, coregistration is key if one wants to extract values from those instruments at the same point on the lunar surface. Due to the suboptimal selenolocation of the M ^3 observations, misalignments exist between the M ^3 data and Diviner data sets. Here we present a methodology for extracting both data sets from a single locality while mitigating offsets, and provide results about the composition of the primary anorthositic crust. M ^3 was used to identify regions of interest within previously reported PCPEs at a selection of craters, and Diviner Christiansen feature data was utilized to constrain these locations’ plagioclase composition by comparing them against laboratory measurements of Apollo 16 highland soil samples.

This study introduces a data-driven approach using machine learning (ML) techniques to explore and predict albedo anomalies on the Moon's surface. The research leverages diverse planetary datasets, including high-spatial-resolution albedo maps and element maps (LPFe, LPK, LPTh, LPTi) derived from laser and gamma-ray measurements. The primary objective is to identify relationships between chemical elements and albedo, thereby expanding our understanding of planetary surfaces and offering predictive capabilities for areas with incomplete datasets. To bridge the gap in resolution between the albedo and element maps, we employ Gaussian blurring techniques, including an innovative adaptive Gaussian blur. Our methodology culminates in the deployment of an Extreme Gradient Boosting Regression Model, optimized to predict full albedo based on elemental composition. Furthermore, we present an interactive analytical tool to visualize prediction errors, delineating their spatial and chemical characteristics. The findings not only pave the way for a more comprehensive understanding of the Moon's surface but also provide a framework for similar studies on other celestial bodies.

The formation process of the two Martian moons, Phobos and Deimos, is still debated with two main competing hypotheses: the capture of an asteroid or a giant impact onto Mars. In order to reveal their origin, the Martian Moons eXploration (MMX) mission by Japan Aerospace Exploration Agency (JAXA) plans to measure Phobos’ elemental composition by a gamma-ray and neutron spectrometer called MEGANE. This study provides a model of Phobos’ bulk elemental composition, assuming the two formation hypotheses. Using the mixing model, we established a MEGANE data analysis flow to discriminate between the formation hypotheses by multivariate analysis. The mixing model expresses the composition of Phobos in 6 key lithophile elements that will be measured by MEGANE (Fe, Si, O, Ca, Mg, and Th) as a linear mixing of two mixing components: material from Mars and material from an asteroid as represented by primitive meteorite compositions. The inversion calculation includes consideration of MEGANE’s measurement errors (EP) and derives the mixing ratio for a given Phobos composition, based on which the formation hypotheses are judged. For at least 65% of the modeled compositions, MEGANE measurements will determine the origin uniquely (EP = 30%), and this increases from 74 to 87% as EP decreases from 20 to 10%. Although the discrimination performance depends on EP, the current operation plan for MEGANE predicts an instrument performance for EP of 20—30%, resulting in 70% discrimination between the original hypotheses. MEGANE observations can also enable the determination of the asteroid type of the captured body or the impactor. The addition of other measurements, such as MEGANE’s measurements of the volatile element K, as well as observations by other MMX remote sensing instruments, will also contribute to the MMX mission’s goal to constrain the origin of Phobos.

&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt;He gas proportional counters have an extensive history in planetary neutron spectroscopy and several upcoming missions including Psyche, VIPER, MMX and Dragonfly will include this technology. In space, Galactic Cosmic Ray (GCR) protons deposit energy in the &lt;sup&gt;3&lt;/sup&gt;He gas in these detectors via ionization. This energy deposition constitutes a background on top of the neutron capture pulse-height spectrum that is particularly prominent at low energies. As planetary nuclear spectroscopy experiments are often count-rate limited using the full pulse height spectrum, including the proton and triton wall effect regions, has significant value. This will be particularly true for the upcoming VIPER mission that will explore the permanently shaded regions at the Moon&amp;#8217;s south pole using the Neutron Spectrometer System (NSS).&amp;#160; The NSS does not include a neutron generator, so the count rates are low, and the rover will not spend long at any location.&amp;#160; However, using lower-energy parts of the spectrum requires understanding the GCR-originating background, which none of the previous missions were able to measure due to their low-energy cutoffs. GCR protons with mean energy around 400 MeV deposit similar amounts of energy to the 4 GeV mean-energy muons present at ground level as both represent minimum ionizing particles within the 3He sensors.&amp;#160; We therefore developed an experiment using a pair of plastic scintillators in coincidence with a &lt;sup&gt;3&lt;/sup&gt;He tube to measure energy deposition from muons while excluding room background gamma rays.&amp;#160; Here we will present results of this experiment to characterize the angular response to cosmic ray muons of a &lt;sup&gt;3&lt;/sup&gt;He flight spare detector from the VIPER NSS and explore the implications of these results for analysis of planetary neutron data sets.&lt;/p&gt;

NASA Ames Research Center and the Lockheed Martin Advanced Technologies Center have developed a rugged, low-resource neutron spectrometer instrument to characterize the near-surface hydrogen content of the lunar surface. This Neutron Spectrometer System (NSS) monitors local thermal and epithermal neutron rates to provide information about the depth-dependent distribution of hydrogen to depths of a few tens of cm. As of mid-2022, NSS is currently slated to fly on two NASA Commercial Lunar Payload Services (CLPS) missions; the Astrobotic Peregrine-1 lander to a near-side equatorial location, and the VIPER lunar rover to explore the polar terrain around Nobile crater. We report the results of a science calibration campaign that characterized the performance of the NSS sensors. These measurements were used to benchmark the accuracy of Geant4 radiation transport simulations that provide the energy- and angle-dependent neutron sensitivity of the NSS sensors. This information is a necessary input for converting NSS measurements of the thermal and epithermal neutron leakage flux to constraints on local hydrogen content in regions with otherwise known geochemical composition.

This work investigates a novel signature for measuring the Ni/Fe ratio on the asteroid (16) Psyche that is robust against interference from large Solar Particle Events. NASA's Psyche mission launched on October 13th, 2023, and is headed to investigate this M-type asteroid. A primary science requirement for the Psyche gamma-ray spectrometer is to measure the absolute surface abundance of Ni and Fe. In particular, the Ni/Fe ratio will help test the hypothesis that (16) Psyche is a metal-rich body, possibly a remnant core from a failed planetesimal. However, Solar Particle Events can activate iron in the spacecraft, as well as the body of Psyche itself, disrupting the measurement of the surface abundance of iron for six months or more. Such an event happened during NASA's MESSENGER mission in orbit around Mercury on June 4, 2011, precluding further mapping of iron for the remainder of the mission. A similar event at Psyche could adversely affect mission science goals and/or prolong operation. Given the expected high abundance of Fe at Psyche, this paper proposes an alternative signature that relies on gamma rays from 54Fe rather than 56Fe. Although 54Fe has a lower natural abundance than 56Fe (5.8% vs 91.7%, respectively), 54Fe is much less susceptible to interference from activation and would allow measurements of the surface abundance of iron to resume within days after a large Solar Particle Event. In addition, 58Ni is shown not to be susceptible to interference from activation, thus making the 58Ni/54Fe ratio a robust alternative signature in the presence of Solar Particle Events.

Mercury holds valuable clues to the distribution of elements at the birth of the solar system and how planets form and evolve in close proximity to their host stars. This Mercury Lander mission concept returns in situ measurements that address fundamental science questions raised by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission’s pioneering exploration of Mercury. Such measurements are needed to understand Mercury's unique mineralogy and geochemistry, characterize the proportionally massive core's structure, measure the planet's active and ancient magnetic fields at the surface, investigate the processes that alter the surface and produce the exosphere, and provide ground truth for remote data sets. The mission concept achieves one full Mercury year (∼88 Earth days) of surface operations with an 11-instrument, high-heritage payload delivered to a landing site within Mercury's widely distributed low-reflectance material, and it addresses science goals encompassing geochemistry, geophysics, the Mercury space environment, and geology. The spacecraft launches in 2035, and the four-stage flight system uses a solar electric propulsion cruise stage to reach Mercury in 2045. Landing is at dusk to meet thermal requirements, permitting ∼30 hr of sunlight for initial observations. The radioisotope-powered lander continues operations through the Mercury night. Direct-to-Earth communication is possible for the initial 3 weeks of landed operations, drops out for 6 weeks, and resumes for the final month. Thermal conditions exceed lander operating temperatures shortly after sunrise, ending operations. Approximately 11 GB of data are returned to Earth. The cost estimate demonstrates that a Mercury Lander mission is feasible and compelling as a New Frontiers–class mission.

The Psyche mission’s Oxidation-Reduction Working Group is focused on understanding, determining, and applying the redox state of (16) Psyche to understand the origin of a metal-rich world. The oxidation-reduction state of an asteroid, along with its temperature, parent body size, and composition, is a key parameter in determining the history of an asteroid. Determining the redox state from spacecraft data is most easily done by examining potential metal-oxide buffer pairs. The occurrence of Ni, Fe, C, Cr, P and Si, in that order, in the metal or sulfide phase of an asteroidal body indicates increasingly reduced conditions. Key observations by the Imager and Gamma-Ray and Neutron Spectrometer (GRNS) of Psyche can bracket the redox state using metal-oxide buffers. The presence of Fe,Ni metal can be confirmed by the ratios of Fe/O or Fe/Si and the concentration of Ni variability in metal across the asteroid can be determined by GRNS. The FeO concentration of silicates is complementary to the Ni concentration of metal and can be constrained using filters on the Imager. The presence of FeO in silicates from ground-based observations is one of the few measurements we already have of redox state, although available data permit a wide range of silicate compositions and mineralogies. The presence of C, P or Si concentrated in the metallic, Fe-rich portion of the asteroid, as measured by GRNS, or Ca-sulfide, determined by imaging, would indicate increasingly reducing conditions. Linkage to known types of meteorites, whether metal-rich chondrites, stony-irons or irons, expands the mineralogical, chemical and isotopic data not available from remote observations alone. Redox also controls both silicate and metal mineralogy, influencing differentiation, solidification, and subsolidus cooling, including the relative abundance of sulfur in the core and possible magnetic signatures. The redox state of Psyche, if a fully-differentiated metallic core, might constrain the location and timing of both the formation of Psyche and any oxidation it might have experienced.

Accurate nuclear data provide an essential foundation for advances in a wide range of fields, including nuclear energy, nuclear safety and security, safeguards, nuclear medicine, and planetary and space exploration. In these and other critical domains, outdated, imprecise, and incomplete nuclear data can hinder progress, limit precision, and compromise safety. Similar nuclear data needs are shared by many applications, thus prioritizing these needs is especially important and urgently needed. Many levels of analysis are required to prepare nuclear measurements for employment in end-user applications. Because research expertise is typically limited to one level, collaboration across organizations and international borders is essential. This perspective piece provides the latest advances in nuclear data for applications and describes an outlook for both near- and long-term progress in the field.

The asteroid (16) Psyche may be the metal-rich remnant of a differentiated planetesimal, or it may be a highly reduced, metal-rich asteroidal material that never differentiated. The NASA Psyche mission aims to determine Psyche’s provenance. Here we describe the possible solar system regions of origin for Psyche, prior to its likely implantation into the asteroid belt, the physical and chemical processes that can enrich metal in an asteroid, and possible meteoritic analogs. The spacecraft payload is designed to be able to discriminate among possible formation theories. The project will determine Psyche’s origin and formation by measuring any strong remanent magnetic fields, which would imply it was the core of a differentiated body; the scale of metal to silicate mixing will be determined by both the neutron spectrometers and the filtered images; the degree of disruption between metal and rock may be determined by the correlation of gravity with composition; some mineralogy (e.g., modeled silicate/metal ratio, and inferred existence of low-calcium pyroxene or olivine, for example) will be detected using filtered images; and the nickel content of Psyche’s metal phase will be measured using the GRNS.

Free neutrons decay via the weak interaction with a mean lifetime of around 15 minutes. Knowledge of this lifetime is important as it provides constraints on the unitarity of the CKM matrix and is a key parameter for studies of Big-Bang nucleosynthesis. However, current laboratory measurements differ by as much as 5σ. We are investigating a new technique to measure neutron lifetime: space-based neutron spectroscopy. We will complete a proof-of-principle demonstration using data from NASA's MESSENGER mission to Mercury.