Sazuna/UAT_keywords huggingface dataset:
Rover-mounted Hydrated Mineral Detector for Mars Exploration: A Preliminary Report. The rover-mounted hydrated mineral detector (HMD) is based on a dielectric spectrometer (tuned frequency range of 0.8-4 MHz) that will detect bulk subsurface hydrated minerals in local scale. The HMD is a compact, low-mass (1.5 kg), and low-power instrument (5 W) suitable for Mars application. Compared with orbiter-based instruments with low horizontal resolution (5-10 km), the HMD will offer high resolution (2 m) that can identify optimal sampling sites for the presence of hydrated minerals. From field testing with reduced radio frequency (RF) power (P rf = 10 mW), the HMD demonstrated detection of shallow buried gypsum samples. When developed with full RF power, the HMD could potentially detect hydrates down to depths of 2 m (P rf = 1 W) or 4 m (P rf = 36 W) in Martian soil. Unlike conventional dielectric spectrometers, which require small amounts of the sample (5-10 g) to be placed inside sample cells, the HMD will detect hydrated minerals by scanning over the Mars surface mounted on a rover platform (&lt;1 m above ground) without any sample preparation. This capability will allow future rovers to rapidly assess the scientific potential of field sites. Compared with optical techniques that are limited to surface exposed mineralogical features that could be obscured by dust and weathering products, the HMD will detect bulk subsurface hydrated minerals along the rover traverse irrespective of surface obscuration. The HMD (TRL 4) is a proof-of-concept instrument that can be developed and matured for future Mars rover missions.

Keywords: Space vehicle instruments
Estimation of Crust and Lithospheric Properties for Mercury from High-resolution Gravity and Topography. We have analyzed the entire set of radiometric tracking data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. This analysis employed a method where standard Doppler tracking data were transformed into line-of-sight accelerations. These accelerations have greater sensitivity to small-scale features than standard Doppler. We estimated a gravity model expressed in spherical harmonics to degree and order 180 and showed that this model is improved, as it has increased correlations with topography in areas where tracking data were collected when the spacecraft altitude was low. The new model was used in an analysis of the localized admittance between gravity and topography to determine properties of Mercury's lithosphere. Four areas with high correlations between gravity and topography were selected. These areas represent different terrain types: the high-Mg region, the Strindberg crater plus some lobate scarps, heavily cratered terrain, and smooth plains. We employed a Markov Chain Monte Carlo method to estimate crustal density, load density, crustal thickness, elastic thickness, load depth, and a load parameter that describes the ratio between surface and depth loading. We find densities around 2600 kg m-3 for three of the areas, with the density for the fourth area, the northern rise, being higher. The elastic thickness is generally low, between 11 and 30 km.

Keywords: Metropolis-Hastings, Gravitational fields, Lithosphere, Mercury (planet), Markov chain Monte Carlo, Planetary interior, Planetary structure
Variability in Titan's Mesospheric HCN and Temperature Structure as Observed by ALMA. The temperature structure of Titan's upper atmosphere exhibits large variability resulting from numerous spatially and temporally irregular external energy sources, seasonal changes, and the influence of molecular species produced via photochemistry. In particular, Titan's relatively abundant HCN is thought to provide substantial cooling to the upper atmosphere through rotational emission, balancing UV/EUV heating, and thermal conduction. Here we present the analysis of ALMA observations of Titan from 2012, 2014, 2015, and 2017, corresponding to planetocentric solar longitudes of ~34°-89°, including vertical HCN and temperature profiles retrieved from the lower mesosphere through the thermosphere (~350-1200 km; 3 × 10-2-2 × 10-8 mbar). Throughout the atmosphere, temperature profiles differ by 10 to 30 K between observations approximately 1 Earth yr apart, particularly from 600 to 900 km. We find evidence for a large imbalance in Titan's upper atmospheric energy budget between 2014 and 2015, where the mesospheric thermal structure changes significantly and marks the transition between a mesopause located at ~600 km (2 × 10-4 mbar) and ~800 km (3 × 10-6 mbar). The retrieved HCN abundances vary dramatically during the 2012-2017 time period as well, showing close to 2 orders of magnitude difference in abundance at 1000 km. However, the change in HCN abundance does not appear to fully account for the variation in mesospheric temperatures over the L  S  ~ 34°-89° period. These measurements provide additional insight into the variability of Titan's mesospheric composition and thermal structure following its 2009 vernal equinox and motivate continued investigation of the origins of such rapid changes in Titan's atmosphere throughout its seasonal cycle.

Keywords: Titan, Planetary atmospheres, Astrochemistry, Natural satellite atmospheres, Remote sensing, Radiative transfer, Planetary science, Submillimeter astronomy, Solar system astronomy
Pre- and Post-entry, Descent and Landing Assessment of the Martian Atmosphere for the Mars 2020 Rover. This review provides an analysis of activities undertaken by the Mars 2020 Council of Atmospheres (CoA) in support of the entry, descent, and landing (EDL) of the Mars 2020 rover Perseverance in Jezero crater, Mars. The activities of the CoA were designed to evaluate the safety of early-stage landing site candidates and, later, to constrain the range of plausible conditions expected at Jezero crater during the early northern spring season of EDL, following the successful blueprint of similar councils for prior landed Mars missions. The multiyear effort of the CoA involved using a combination of numerical modeling of the local Martian atmosphere with limited-domain mesoscale models and atmospheric reanalysis using data assimilation techniques, along with atmospheric observations from multiple orbiting assets, to generate an atmospheric "forecast" for the day of landing. Here we present an overview of these activities, focusing in greater detail on those elements that depart from prior CoA activities as performed for Mars Phoenix, Mars Science Laboratory, and the InSight lander. Following the successful landing of Perseverance on 2021 February 18, reconstruction and reassessment activities were performed and are presented here, comparing prelanding predictions with actual, as-flown conditions.

Keywords: Mars, Planetary atmospheres, Planetary science, Planetary climates, Atmospheric science
NASA's Double Asteroid Redirection Test (DART): Mutual Orbital Period Change Due to Reshaping in the Near-Earth Binary Asteroid System (65803) Didymos. The Double Asteroid Redirection Test (DART) is the first planetary defense mission to demonstrate the kinetic deflection technique. The DART spacecraft will collide with the asteroid Dimorphos, the smaller component of the binary asteroid system (65803) Didymos. The DART impact will excavate surface/subsurface materials of Dimorphos, leading to the formation of a crater and/or some magnitude of reshaping (i.e., shape change without significant mass loss). The ejecta may eventually hit Didymos's surface. If the kinetic energy delivered to the surface is high enough, reshaping may also occur in Didymos, given its near-critical spin rate. Reshaping on either body will modify the mutual gravitational field, leading to a reshaping-induced orbital period change, in addition to the impact-induced orbital period change. If left unaccounted for, this could lead to an erroneous interpretation of the effect of the kinetic deflection technique. Here we report the results of full two-body problem simulations that explore how reshaping influences the mutual dynamics. In general, we find that the orbital period becomes shorter linearly with increasing reshaping magnitude. If Didymos's shortest axis shrinks by ~0.7 m, or Dimorphos's intermediate axis shrinks by ~2 m, the orbital period change would be comparable to the Earth-based observation accuracy, ~7.3 s. Constraining the reshaping magnitude will decouple the reshaping- and impact-induced orbital period changes; Didymos's reshaping may be constrained by observing its spin period change, while Dimorphos's reshaping will likely be difficult to constrain but will be investigated by the ESA's Hera mission that will visit Didymos in late 2026.

Keywords: Near-Earth objects, Two-body problem, Asteroid dynamics, Gravitational interaction, Asteroid satellites, Asteroid rotation, Planetary science, Planetary structure
Tidal Heating at Europa Using the Multifrequency Analysis of Tidal Heating Toolkit. We evaluate the thermal response of Europa's ice shell to the gravity perturbation of Jupiter using a comprehensive toolkit (dubbed Multifrequency Analysis of Tidal Heating, MATH) that evaluates tidal heating and heat flow in planetary bodies. The tidal heating source is radially resolved and can capture the temperature-dependent pattern of heat production with depth. We use MATH to examine the steady-state thermal profiles through a conductive Europan ice shell, considering the tidal effects of long-term eccentricity variations, obliquity, libration, and nonsynchronous rotation (NSR). In each case, we vary the shell thickness, calculate the combination of tidal heating generated within the shell and heat flux into the shell base that would maintain that thickness, and track the resulting surface heat flux. We find that Europa's ice shell should be, on average, no more than 12-17 km thick, due to long-term eccentricity variations, and could be even thinner if the basal heat flux is nonnegligible. These results are more consistent with inferences from Europa's surface geology than previous tidal heating studies that used simplified interior models, a globally averaged tidal heating rate, and/or constant eccentricity. We also find that, for a given stable shell thickness, the surface heat flow remains fairly consistent even as other parameters are varied, perhaps providing an additional method for constraining ice shell thicknesses on ocean-bearing moons. Although Europa's tidal heat budget and shell thickness seem relatively insensitive to constant obliquity, libration, and NSR, moons in closer-in orbits may be more sensitive to these other effects and should be further explored.

Keywords: Tides, Europa
The Volatile Carbon-to-oxygen Ratio as a Tracer for the Formation Locations of Interstellar Comets. Based on the occurrence rates implied by the discoveries of 1I/'Oumuamua and 2I/Borisov, the forthcoming Rubin Observatory Legacy Survey of Space and Time (LSST) should detect ≥one interstellar object every year. We advocate for future measurements of the production rates of H2O, CO2, and CO in these objects to estimate their carbon-to-oxygen ratios, which trace formation locations within their original protoplanetary disks. We review similar measurements for solar system comets, which indicate formation interior to the CO snow line. By quantifying the relative processing in the interstellar medium and solar system, we estimate that production rates will not be representative of primordial compositions for the majority of interstellar comets. Preferential desorption of CO and CO2 relative to H2O in the interstellar medium implies that measured C/O ratios represent lower limits on the primordial ratios. Specifically, production rate ratios of Q(CO)/Q(H2O) &lt; 0.2 and Q(CO)/Q(H2O) &gt; 1 likely indicate formation interior and exterior to the CO snow line, respectively. The high C/O ratio of 2I/Borisov implies that it formed exterior to the CO snow line. We provide an overview of the currently operational facilities capable of obtaining these measurements that will constrain the fraction of ejected comets that formed exterior to the CO snow line. This fraction will provide key insights into the efficiency of and mechanisms for cometary ejection in exoplanetary systems.

Keywords: Interstellar objects
Formation of Vitreous Salt Hydrates Under Conditions Relevant to Europa. Technologies are being developed to enable a robotic spacecraft to directly access Europa's ocean by penetrating its kilometers-thick ice crust. Until such time comes, however, our ability to characterize it will be limited to observations of its expression on the surface. Further, the ability to place meaningful constraints on the composition of the source brines will depend on our understanding of the chemistry associated with their freezing and emplacement. Among the body of research focused on improving this understanding, recent laboratory studies have shown that Mg-bearing salts, previously proposed as constituents of Europa's surface, have a propensity to form vitreous hydrates when flash frozen from their parent brines. The possibility that such vitreous species could form on Europa is important as their presence will be a confounding factor in their detection and identification of the underlying salt hydrates. Further, since glass formation can protect biological molecules and even microorganisms from damage caused by crystallization, they may prove to be important targets of astrobiological interest. This work explores the conditions under which vitreous salt hydrates form in order to better assess their potential for forming on Europa. Specifically, solutions of Mg- and Na-bearing salts were frozen over a range of freezing rates and interrogated with Raman spectroscopy to determine whether vitreous or crystalline species (including hydration state) formed. These results show that vitreous salt hydrates can form at freezing rates as low as ~10 K minute-1, thus expanding their potential for occurrence on Europa beyond extreme flash-freezing scenarios such as plume deposition.

Keywords: High resolution spectroscopy, Surface processes, Experimental techniques, Astrochemistry, Europa, Planetary science
VALENTInE: A Concept for a New Frontiers-Class Long-duration In Situ Balloon-based Aerobot Mission to Venus. Described here is a concept for a variable-altitude aerobot mission to Venus developed as part of the 2020 NASA Planetary Science Summer School in collaboration with NASA Jet Propulsion Laboratory. The Venus Air and Land Expedition: a Novel Trailblazer for in situ Exploration (VALENTInE) is a long-duration New Frontiers-class mission to Venus in alignment with the goals recommended by the 2013 Planetary Science Decadal Survey. VALENTInE would have five science objectives: (1) determine the driving force of atmospheric superrotation, (2) determine the source of D/H and noble gas inventory, (3) determine the properties that govern how light is reflected within the lower cloud later, (4) determine whether the tesserae are felsic, and (5) determine whether there is evidence of a recent dynamo preserved in the rock record. The proposed mission concept has a total duration of 15 Earth days and would float at an altitude of 55 km, along with five dips to a lower altitude of 45 km to study Venus's lower atmosphere. The instrument payload allows for measurements of the atmosphere, surface, and interior of Venus and includes six instruments: an atmospheric weather suite, a mass spectrometer, a multispectral imager, a near-infrared spectrometer, light detection and ranging, and a magnetometer. Principle challenges included a limitation caused by battery lifetime and low technology readiness levels for aerobots that can survive the harsh conditions of Venus's atmosphere. This preliminary mission was designed to fit within an assumed New Frontiers 5 (based on inflated New Frontiers 4) cost cap.

Keywords: High altitude balloons, Planetary atmospheres, Venus, Planetary probes
The Nature of Low-albedo Small Bodies from 3 μm Spectroscopy: One Group that Formed within the Ammonia Snow Line and One that Formed beyond It. We present evidence, via a large survey of 191 new spectra along with previously published spectra, of a divide in the 3 μm spectral properties of the low-albedo asteroid population. One group ("sharp types," or STs, with band centers &lt;3 μm) has a spectral shape consistent with carbonaceous chondrite meteorites, while the other group ("not sharp types," or NSTs, with bands centered &gt;3 μm) is not represented in the meteorite literature but is as abundant as the STs among large objects. Both groups are present in most low-albedo asteroid taxonomic classes, and, except in limited cases, taxonomic classifications based on 0.5-2.5 μm data alone cannot predict whether an asteroid is an ST or NST. Statistical tests show that the STs and NSTs differ in average band depth, semimajor axis, and perihelion at confidence levels ≥98% while not showing significant differences in albedo. We also show that many NSTs have a 3 μm absorption band shape like comet 67P and likely represent an important small-body composition throughout the solar system. A simple explanation for the origin of these groups is formation on opposite sides of the ammonia snow line, with the NST group accreting H2O and NH3 and the ST group only accreting H2O, with subsequent thermal and chemical evolution resulting in the minerals seen today. Such an explanation is consistent with recent dynamical modeling of planetesimal formation and delivery and suggests that much more outer solar system material was delivered to the main asteroid belt than would be thought based on the number of D-class asteroids found today.

Keywords: Small Solar System bodies, Main belt asteroids, Hilda group, Spectroscopy, Asteroid surfaces
Experimental Constraints on Deliquescence of Calcium Perchlorate Mixed with a Mars Regolith Analog. Hygroscopic salts within the Martian regolith may actively participate in the near-surface water cycle by exchanging water vapor via solid-state salt hydration and deliquescence. To elucidate this process, experimental work has constrained the phase diagram of Mars-relevant salts and the stability of the resultant brines. However, salt interactions with a Mars-like regolith, which itself can exchange water vapor with the atmosphere via adsorption, has not yet been well explored. Here, to better understand water exchange with a salty Mars-like regolith and, particularly, the potential to form brines, we have conducted a series of experiments using JSC Mars-1 regolith simulant mixed with calcium perchlorate in a Mars simulation chamber at a temperature &lt;5°C and a relative humidity &lt;20%. During the experiments, we measured the sample mass, as well as the temperature and relative humidity of the sample and the chamber. We found that the water uptake of a salty Mars-like regolith is about twice as fast as that of a salt-free regolith. Furthermore, we found evidence to suggest that deliquescence occurred; however, not all the salt within the sample may have entered solution. The amount of water in solution was small and did not lead to regolith darkening. Our results suggest that, under the tested experimental conditions, salt deliquescence and regolith adsorption can occur simultaneously.

Keywords: Surface processes, Mars, Astrobiology, Water vapor
CI Asteroid Regolith as an In Situ Plant Growth Medium for Space Crop Production. Human expansion into the solar system is currently at the forefront of space research. For our astronauts to survive, they will need to be fed a healthy and nutritious diet on a consistent basis. Right now, our current method of feeding astronauts consists of resupplied prepackaged food from Earth, which is unsustainable for long-term missions. Using planetary resources via in situ resource utilization to grow crops is the next step toward sustainability in space. Asteroids are an abundant space resource and should not be overlooked when considering crewed missions. In particular, the primordial CI carbonaceous asteroids are of interest because the regolith is suggested to contain soluble elemental nutrients, such as phosphorous and potassium, that crops can use for growth and development. We present a study on the ability of CI carbonaceous asteroid regolith simulant to sustain plant growth of lettuce (Latuca sativa), radishes (Raphanus sativus), and peppers (Capsicum annuum). We tested growing the selected crops in increasing mixtures of simulant and peat moss. The results showed that each species reacted differently to each treatment and that the radishes were more affected by the treatments. Subsequent analysis showed that the simulant contains small amounts of plant-usable nutrients, despite its high pH, low cation exchange capacity, and classification as a silt-based soil. Our results indicate that the simulant is prone to compaction and crusting, leading to drought stress on the crops. Further investigations are needed to determine mitigation strategies to make CI asteroid regolith a more conducive soil.

Keywords: Interdisciplinary astronomy, Space research, Astrobiology
International Asteroid Warning Network Timing Campaign: 2019 XS. As part of the International Asteroid Warning Network's observational exercises, we conducted a campaign to observe near-Earth asteroid 2019 XS around its close approach to Earth on 2021 November 9. The goal of the campaign was to characterize errors in the observation times reported to the Minor Planet Center, which become an increasingly important consideration as astrometric accuracy improves and more fast-moving asteroids are observed. As part of the exercise, a total of 957 astrometric observations of 2019 XS during the encounter were reported and subsequently were analyzed to obtain the corresponding residuals. While the timing errors are typically smaller than 1 s, the reported times appear to be negatively biased, i.e., they are generally earlier than they should be. We also compared the observer-provided position uncertainty with the cross-track residuals, which are independent of timing errors. A large fraction of the estimated uncertainties appear to be optimistic, especially when &lt;0.″2. We compiled individual reports for each observer to help identify and remove the root cause of any possible timing error and improve the uncertainty quantification process. We suggest possible sources of timing errors and describe a simple procedure to derive reliable, conservative position uncertainties.

Keywords: Near-Earth objects, Astrometry, Optical telescopes, Asteroids