We present the catalog of InterPlanetary Network (IPN) localizations for 199 short-duration gamma-ray bursts (sGRBs) detected by the Konus-Wind (KW) experiment between 2011 January 1 and 2021 August 31, which extends the initial sample of IPN-localized KW sGRBs to 495 events. We present the most comprehensive IPN localization data on these events, including probability sky maps in Hierarchical Equal Area isoLatitude Pixelization format.

AND MEASUREMENT CAPABILITIES. David J. Lawrence1, Morgan Burks2, Michael Cully1, Linda T. ElkinsTanton3, John O. Goldsten1, Insoo Jun4, Timothy J. McCoy5, Patrick N. Peplowski1, Carol A. Polanskey4, Thomas H. Prettyman6, Brian C. Schratz1, Kalyani G. Sukhatme4, Zak K. Staniszewski4, Noah Z. Warner4, Zachary W. Yokley1, and the Psyche Mission Team. 1Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (David.J.Lawrence@jhuapl.edu); 2Lawrence Livermore National Laboratory, Livermore, CA 94550; 3Arizona State University, Tempe, AZ 85287; 4NASA Jet Propulsion Laboratory, Pasadena, CA, 91109, USA; 5Smithsonian Institution, Washington, DC, 20560; 6Planetary Science Institute, Tucson, AZ 85719.

1718, 2017; [2] T. H. Prettyman, Encyc. of Sol. Sys., 1161, 2014; [3] T. H. Prettyman et al., Sci. 355, 55, 2017; [4] D. J. Lawrence et al., 50 LPSC (this meeting), 2019; [5] W. C. Feldman et al., J. Geophys. Res. 109, E07S06, 2004; [6] P. N. Peplowski et al., Icarus, 253, 246, 2015; [7] J. O. Goldsten et al., Space Sci. Rev., 131, 339, 2007; [8] P. S, Hardersen et al., Icarus, 175, 141, 2005; [9] D. Takir et al., Astron. J., 153, 31, 2017; [10] S. Agostinelli et al., Nucl. Instrum. Methods Phys. Res. A, 506, 250, 2003. Fig. 3. (top) Neutron spectra for different Ni fractions in a 90% metal, 10% silicate reference Psyche. (bottom) Spectra for different H concentrations in 90% metal (8% Ni), 10% silicates. Fig. 4. The spectra for AC shield singles (green) and a GPC (purple). The background continuum is plotted with a lighter tint. These spectra have been scaled and shifted to place them on the same horizontal scale. Each spectra contains the same number of neutron captures. 1295.pdf 50th Lunar and Planetary Science Conference 2019 (LPI Contrib. No. 2132)

LOX is a lunar-orbiting astrophysics mission that will probe the cosmos at MeV energies. It is guided by open questions regarding thermonuclear, or Type-Ia, supernovae (SNeIa) and will characterize these inherently radioactive objects by enabling a systematic survey of SNeIa at gamma-ray energies for the first time. Astronomical investigations from lunar orbit afford new opportunities to advance our understanding of the cosmos. The foundation of LOX is an observational approach well suited to the all-sky monitoring demands of supernova investigations and time-domain astronomy. Its inherently wide field-of-view and continuous all-sky monitoring provides an innovative way of addressing decadal survey questions at MeV energies (0.1-10 MeV). The LOX approach achieves high sensitivity with a simple, high-heritage instrument design that eliminates the need for complex, position-sensitive detectors, kinematic event reconstruction, masks, or other insensitive detector mass, while also mitigating technology development, implementation complexity, and their associated costs. LOX can be realized within existing programs, like Explorer.

The Engineering Radiation Monitor measures dose, dose rate, and charging currents on the Van Allen Probes mission to study the dynamics of Earth's Van Allen radiation belts. Over 5 years, results from this monitor show a variation in dose rates with time, a correlation between the dosimeter and charging current data, and a comparison of cumulative dose to prelaunch modeling. Solar cell degradation monitor patches track the decrease in solar array output as displacement damage accumulates. The Solar Cell Monitor shows ~33% cumulative degradation in maximum power after 5.1 years of the mission. The desire to extend the mission to ~2,500 days from 800 days created increased requirements for the ionizing radiation hardness of spacecraft and science instrument electronics. We describe the investigations that insured compliance with these enhanced requirements.

Introduction: Gamma-ray spectrometers (GRS) are used on deep space missions to measure the elemental composition of planetary surfaces. Spectrometers based on high-purity germanium detectors offer the highest-resolution of any comparable technology. This resolution translates into superior sensitivity and higher science return. Germanium detectors have been successfully deployed in orbit around the Earth [1], the Moon [2], Mars [3], and Mercury [4]. However, germanium detectors only achieve this high resolution when cryogenically cooled to 100K or below. Cooling schemes have typically been bulky, massive, and/or consumed considerable power [2,3]. This has limited the widespread use of germanium in deep space. However, we have developed a germanium-based gamma-ray spectrometer for NASA’s MESSENGER mission to Mercury that utilized innovative infrared shielding and suspension technologies. This allowed for low-power, low-mass operation of the detector and the science results helped shape our understanding of the formation and evolution of Mercury [5]. As a result, gamma-ray spectrometers based on high-purity germanium detectors are emerging as a powerful tool for a range of planetary science applications. Our group will be providing germaniumbased spectrometers for two new missions: the first to the asteroid (16) Psyche; and the second to the moons of Mars onboard JAXA’s Martian Moons eXploration mission (MMX). In addition, NASA recently announced Phase A funding for the Drgaonfly mission that includes our technology on a dual-quadcopter that will explore Saturn’s moon Titan. Although all the detectors for each mission are based on similar technology, each planetary body offers unique and interesting challenges and the instruments must be adapted accordingly. This paper discusses the challenges and technical tradeoffs of each mission. Mercury MESSENGER: The MESSENGER mission to Mercury carried a 5x5 cm coaxial germanium detector [4]. It was notable for being the first mechanically-cooled germanium in deep space, as well as for overcoming the challenge of deploying a cryogenic detector at one of the hottest places in the Solar System. The instrument was designed to be lowmass and low-power. However, the most important design constraint was the need for infrared shielding that allowed for cryogenic cooling in the harsh thermal environment found at Mercury. Figure 1 shows the IR shields and some of the components that comprised this instrument.

InterPlanetary Network (IPN) data are presented for the gamma-ray bursts in the second Fermi Gamma-Ray Burst Monitor (GBM) catalog. Of the 462 bursts in that catalog between 2010 July 12 and 2012 July 11, 428, or 93%, were observed by at least 1 other instrument in the 9-spacecraft IPN. Of the 428, the localizations of 165 could be improved by triangulation. For these bursts, triangulation gives one or more annuli whose half-widths vary between about 2.′3° and 16°, depending on the peak flux, fluence, time history, arrival direction, and the distance between the spacecraft. We compare the IPN localizations with the GBM 1 σ , 2 σ , and 3 σ error contours and find good agreement between them. The IPN 3 σ error boxes have areas between about 8 square arcminutes and 380 square degrees, and are an average of 2500 times smaller than the corresponding GBM 3 σ localizations. We identify four bursts in the IPN/GBM sample whose origins were given as “uncertain,” but may in fact be cosmic. This leads to an estimate of over 99% completeness for the GBM catalog.

Introduction: On sol 1148, while traversing the “Home Plate” region of Gusev crater near the Columbia hills, the Mars Exploration Rover (MER) Spirit made perhaps its most important discovery when it inadvertently excavated a several-cm-deep trench with its inoperative front wheel. Subsequent geochemical analyses revealed the excavated material to be opaline silica [1], which, along with other contextual evidence from the Home Plate region, led to the conclusion that this site once hosted hydrothermal activity [1]. This accidental discovery, resulting from the unintentional excavation of the trench by Spirit’s inoperative wheel, is emblematic of a fundamental problem in Mars science – the existence of a near-ubiquitous layer of dust and soils across Mars’ surface that obscures older, native materials of scientific interest. This dust, which was emplaced by aeolian processes and is near homogenous in chemistry, frequently obscures underlying, ancient surface materials from remote sensing measurements [2]. Although dust-free regions exist and are frequently the subject of study [3], there is a need for remote sensing observations that can peer beneath the obscuring dust to characterize the composition of the native, underlying materials. Gamma ray spectroscopy is uniquely suited to the task of characterizing the elemental composition of materials beneath an optically thick (>100 μm) layer of dust and/or soil. There are two reasons for this: 1) gamma rays are produced at depths of order one meter beneath the surface, and 2) gamma rays have mean free paths of order tens of cm, with higher energy gamma rays having longer mean free paths. Gamma ray photon energies are characteristic of the elements from which they are emitted, and many elements have multiple gamma ray lines associated with different neutron collision and capture reactions (e.g. Si’s 1779 keV collision and 4934 keV capture lines). These different photon energies have differing mean free paths (12 and 23 cm, respectively), thus they sample different portions of the regolith. The observed ratio of same-element gamma rays will therefore vary in the presense of elemental stratgragphy at the tens of cm vertical scale. The results of prior Mars gamma ray spectroscopy investigations have been given as a bulk abundance of the top ~20 cm [4], under the assumption that no layering is present at the ~500 km sptial scale of gamma ray measurements. Here we report on an experiment designed to show that gamma ray measurements also allow cm-scale elemental stratigraphy to be measured. The results of this experiment provide the foundation for future re-analyses of Mars gamma ray datasets. Experiment: We performed a laboratory measurement that reproduced a planetary gamma ray measurement with as a high a fidelity – as compared to a GCR-induced measurement – as was practically possible. As the basis for our measurements, we adopt as a case study the scenario discovered by Spirit at Home Plate: a layer of nearly pure silica buried beneath a several-cm-thick layer of “typical” Mars soil. Since primary GCRs (protons) do not reach Earth’s surface, an artificial means of producing a neutron flux comparable to that produced via GCR spallation is necessary for our experiments. We generated a plane-

Introduction: Knowing the elemental composition of a planetary surface is key to understanding its formation and evolution. Planetary gamma-ray spectroscopy is a well-established technique for remotely measuring planetary elemental concentrations for the following elements: H, C, O, Na, Mg, Al, Si, S, Cl, K, Ca, Ti, Fe, Ni, Th, and U. It is unique among the available techniques in that it measures bulk concentrations to depths of tens of cm (in contrast to techniques sensitive only to the top tens of microns), and can quantify compositional layering within this range. Orbital gamma-ray measurements have resulted in significant discoveries from the Moon, Mars, Mercury, and asteroids [1–4]. A Gamma-Ray and Neutron Spectrometer (GRNS) is part of the recently selected Psyche mission, which will orbit the M-class asteroid 16 Psyche [5]. Surface-based, in situ gamma-ray spectroscopy has been relatively limited and not fully realized because the laboratory quality spectrometers needed to achieve full elemental sensitivitity require more resources (e.g., mass, power) than are available for landed missions. In addition, orbital missions increasingly require lower resource instruments, and new instruments need to incorporate lessons learned from prior flight instruments. Here we discuss a new instrument called GeMini Plus, which is a high-purity Ge (HPGe) Gamma-Ray Spectrometer (GRS) that can accomplish laboratory quality, high-precision gamma-ray measurements with the type of low resources needed for landed platforms as well as resource-constrained orbital missions. This abstract provides an overview of the GeMini Plus instrument, including improvements made to prior instruments, as well as future science applications for the use of GeMini-Plus technology. A complementary abstract provides additional information about GeMini Plus, including details of initial performance and expected future tests [6]. GeMini Plus Gamma-Ray Spectrometer: GeMini Plus is based on the MESSENGER GRS [7] and a miniature HPGe instrument known as GeMini (Fig. 1). GeMini was developed by Lawrence Livermore National Laboratory for national security applications [8]. GeMini Plus uses the same HPGe sensor as the MESSENGER GRS and so achieves the same sensitivety. Depending on mission scenario, GeMini Plus may or may not need a plastic scintillator anticoincidence shield (ACS) to reduce background from galactic cosmic rays. An ACS is generally not needed for surface-based measurements, whereas an ACS can significantly increase signal-to-background for many types of orbital measurements [9].

L.T. Elkins-Tanton, E. Asphaug, *James F Bell, D. Bercovici, B.G. Bills, R.P. Binzel, W.F. Bottke, G.M. Brown, J. Goldsten, R. Jaumann, I. Jun, D.J. Lawrence, P. Lord, S. Marchi, T. McCoy, D. Oh, R.S. Park, P.N. Peplowski, C.A. Polanskey, D. Potter, T.H. Prettyman, C.A. Raymond, C.T. Russell, S. Scott, H. Stone, K.G. Sukhatme, N.Z. Warner, B.P. Weiss, D.D. Wenkert, M. Wieczorek, D. Williams, M.T. Zuber

The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating Primordial Black Holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the distance to gamma-ray bursts using detections from widely separated, non-imaging spacecraft. This method can determine the actual distance to the burst if it is local. We applied this method to constrain distances to a sample of 36 short duration GRBs detected by the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 10^13-10^18 cm (7-10^5 AU) range, consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Assuming these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.

COMPOSITION OF A METAL-RICH BODY USING NUCLEAR SPECTROSCOPY. David J. Lawrence, Patrick N. Peplowski, John O. Goldsten, Morgan Burks, Andrew W. Beck, Linda T. Elkins-Tanton, Insoo Jun, Timothy J. McCoy, Carol A. Polanskey, Thomas H. Prettyman, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA (David.J.Lawrence@jhuapl.edu); Lawrence Livermore National Laboratory, Livermore, CA 94550; Arizona State University, Tempe, AZ 85287; NASA Jet Propulsion Laboratory, Pasadena, CA, 91109, USA; Smithsonian Institution, Washington, DC, 20560, USA; Planetary Science Institute, Tucson, AZ 85719, USA.

We report on the bright burst detected by four Interplanetary network (IPN) spacecraft on 2015 April 12. The IPN localization of the source is consistent with the position of the recently discovered soft gamma-repeater SGR 1935+2154. From the Konus-Wind (KW) observation, we derive temporal and spectral parameters of the emission, and the burst energetics. The rather long duration of the burst (similar to 1.7 s) and the large measured energy fluence (similar to 2.5 x 10(-5) erg cm(-2)) put it in the class of rare 'intermediate' soft gamma-repeater (SGR) flares, and this is the first one observed from SGR 1935+2154. A search for quasi-periodic oscillations in the KW light curve yields no statistically significant signal. Of four spectral models tested, optically thin thermal bremsstrahlung and a single blackbody (BB) function can be rejected on statistical grounds; two more complex models, a cutoff power law (CPL) and a sum of two BB functions (2BB), fit the burst spectra well and neither of them may be ruled out by the KW observation. The CPL and 2BB model parameters we report for this bright flare are typical of SGRs; they are also consistent with those obtained from observations of much weaker and shorter SGR 1935+2154 bursts with other instruments. From the distribution of 2BB spectral fit parameters we estimate the SGR 1935+2154 distance to be < 10.0 kpc, in agreement with that of the Galactic supernova remnant G57.2+0.8 at 9.1 kpc.