Sazuna/UAT_keywords huggingface dataset:
The Roles of Latent Heating and Dust in the Structure and Variability of the Northern Martian Polar Vortex. The winter polar vortices on Mars are annular in their potential vorticity (PV) structure, a phenomenon identified in observations, reanalysis, and some numerical simulations. Some recent modeling studies have proposed that condensation of atmospheric carbon dioxide at the winter pole is a contributing factor to maintaining the annulus through the release of latent heat. Dust and topographic forcing are also known to be causes of internal and interannual variability in the polar vortices. However, coupling between these factors remains uncertain, and previous studies of their impact on vortex structure and variability have been largely limited to a single Martian global climate model (MGCM). Here, by further developing a new MGCM, we decompose the relative roles of latent heat, topography, and dust as drivers for the variability and structure of the northern Martian polar vortex. Additionally, we analyze a reanalysis data set, finding that there are significant differences in vortex morphology and variability according to the spacecraft instrument used for the data assimilation. In both model and reanalysis, high atmospheric dust loading (such as that seen during a global dust storm) can disrupt the vortex, cause the destruction of PV in the low-to-mid-altitudes (&gt;0.1 hPa), and significantly reduce spatial and temporal vortex variability. Through our simulations, we find that the combination of dust and topography primarily drives the eddy activity throughout the Martian year, and that although latent heat release can produce an annular vortex, it has a relatively minor effect on vortex variability.

Keywords: Mars, Planetary atmospheres
The Road to an Archival Data Format-Data Structures. The current data formatting and labeling standards for the Planetary Data System (PDS) are known as the PDS4 Standards. They supersede the PDS3 Standards, but they represent a complete redesign of the requirements and implementation, rather than even a major incremental revision, from the previous standard. At the heart of the PDS4 Standards lies a fundamental, philosophical change from the PDS3 paradigm: the PDS4 Standards clearly and specifically constrain the way that the bytes comprising observational data may be stored in their data files-that is, the data structures-to a much greater degree than the PDS3 Standards ever did, even in their most mature realization. In PDS4, the PDS has defined data structures optimized for the long-term preservation of observational data. We explore the history of the PDS and its standards through the examination of a single, simple data structure (the 2D image), to understand the evolutionary pressures on the data and on the PDS that led to the development of the archival data structure requirements for observational data at the core of the PDS4 standards.

Keywords: Astroinformatics
Physical Characterization of Metal-rich Near-Earth Asteroids 6178 (1986 DA) and 2016 ED85. Metal-rich near-Earth asteroids (NEAs) represent a small fraction of the NEA population that is mostly dominated by S- and C-type asteroids. Because of this, their identification and study provide us with a unique opportunity to learn more about the formation and evolution of this particular type of bodies, as well as their relationship with meteorites found on Earth. We present near-infrared (NIR) spectroscopic data of NEAs 6178 (1986 DA) and 2016 ED85. We found that the spectral characteristics of these objects are consistent with those of metal-rich asteroids, showing red slopes, convex shapes, and a weak pyroxene absorption band at ~0.93 μm. The compositional analysis showed that they have a pyroxene chemistry of Fs40.6±3.3Wo8.9±1.1 and a mineral abundance of ~15% pyroxene and 85% metal. We determined that these objects were likely transported to the near-Earth space via the 5:2 mean motion resonance with Jupiter. Asteroid spectra were compared with the spectra of mesosiderites and bencubbinites. Differences in the NIR spectra and pyroxene chemistry suggest that bencubbinites are not good meteorite analogs. Mesosiderites were found to have a similar pyroxene chemistry and produced a good spectral match when metal was added to the silicate component. We estimated that the amounts of Fe, Ni, Co, and the platinum group metals present in 1986 DA could exceed the reserves worldwide.

Keywords: Meteorites, Iron meteorites, Asteroids, Spectroscopy
Inferring Vortex and Dust Devil Statistics from InSight. The InSight mission has operated on the surface of Mars for nearly two Earth years, returning detections of the first marsquakes. The lander also deployed a meteorological instrument package and cameras to monitor local surface activity. These instruments have detected boundary layer phenomena, including small-scale vortices. These vortices register as short-lived, negative pressure excursions and closely resemble those that could generate dust devils. Although our analysis shows that InSight encountered more than 900 vortices and collected more than 1000 images of the Martian surface, no active dust devils were imaged. In spite of the lack of dust devil detections, we can leverage the vortex detections and InSight's daily wind speed measurements to learn about the boundary layer processes that create dust devils. We discuss our analysis of InSight's meteorological data to assess the statistics of vortex and dust devil activity. We also infer encounter distances for the vortices and, therefrom, the maximum vortex wind speeds. Surveying the available imagery, we place upper limits on what fraction of vortices carry dust (i.e., how many are bona fide dust devils) and estimate threshold wind speeds for dust lifting. Comparing our results to detections of dust devil tracks seen in space-based observations of the InSight landing site, we can also infer thresholds and frequency of track formation by vortices. Comparing vortex encounters and parameters with advective wind speeds, we find evidence that high wind speeds at InSight may have suppressed the formation of dust devils, explaining the lack of imaged dust devils.

Keywords: Mars, Planetary atmospheres
A Multispecies Pseudoadiabat for Simulating Condensable-rich Exoplanet Atmospheres. Central stages in the evolution of rocky, potentially habitable planets may play out under atmospheric conditions with a large inventory of nondilute condensable components. Variations in condensate retention and accompanying changes in local lapse rate may substantially affect planetary climate and surface conditions, but there is currently no general theory to effectively describe such atmospheres. In this article, expanding on the work by Li et al., we generalize the single-component moist pseudoadiabat derivation in Pierrehumbert to allow for multiple condensing components of arbitrary diluteness and retained condensate fraction. The introduction of a freely tunable retained condensate fraction allows for a flexible, self-consistent treatment of atmospheres with nondilute condensable components. To test the pseudoadiabat's capabilities for simulating a diverse range of climates, we apply the formula to planetary atmospheres with compositions, surface pressures, and temperatures representing important stages with condensable-rich atmospheres in the evolution of terrestrial planets: a magma ocean planet in a runaway greenhouse state; a post-impact, late-veneer-analog planet with a complex atmospheric composition; and an Archean Earth-like planet near the outer edge of the classical circumstellar habitable zone. We find that variations in the retention of multiple nondilute condensable species can significantly affect the lapse rate and in turn outgoing radiation and the spectral signatures of planetary atmospheres. The presented formulation allows for a more comprehensive treatment of the climate evolution of rocky exoplanets and early Earth analogs.

Keywords: Atmospheric composition, Astrobiology, Planetary atmospheres, Exoplanet structure
Carbon Cycling and Habitability of Massive Earth-like Exoplanets. As the number of detected rocky extrasolar planets increases, the question of whether their surfaces could be habitable is becoming more pertinent. On Earth, the long-term carbonate-silicate cycle is able to regulate surface temperatures over timescales larger than one million years. Elevated temperatures enhance weathering, removing CO2 from the atmosphere, which is subducted into the mantle. At mid-ocean ridges, CO2 is supplied to the atmosphere from the interior. The carbon degassing flux is controlled by the melting depth beneath mid-ocean ridges and the spreading rate, influenced by the pressure- and temperature-dependent mantle viscosity. The influences of temperature and pressure on mantle degassing become increasingly important for more massive planets. Here, we couple a thermal evolution model of Earth-like planets of different masses with a model of the long-term carbon cycle and assess their surface temperature evolution. We find that the spreading rate at 4.5 Gyr increases with planetary mass up to 3 Earth masses, since the temperature dependence of viscosity dominates over its pressure dependency. For higher-mass planets, pressure dependence dominates and the plates slow down. In addition, the effective melting depth at 4.5 Gyr as a function of planetary mass has its maximum at 3 M⊕. Altogether, at 4.5 Gyr, the degassing rate and therefore surface temperature have their maximum at 3 M⊕. This work emphasizes that both age and mass should be considered when predicting the habitability of exoplanets. Despite these effects, the long-term carbon cycle remains an effective mechanism that regulates the surface temperature of massive Earth-like planets.

Keywords: Exoplanets, Super Earths, Mantle, Plate tectonics, Habitable planets
Past, Present, and Future of Mars Polar Science: Outcomes and Outlook from the 7th International Conference on Mars Polar Science and Exploration. Mars Polar Science is a subfield of Mars science that encompasses all studies of the cryosphere of Mars and its interaction with the Martian environment. Every 4 yr, the community of scientists dedicated to this subfield meets to discuss new findings and debate open issues in the International Conference on Mars Polar Science and Exploration (ICMPSE). This paper summarizes the proceedings of the seventh ICMPSE and the progress made since the sixth edition. We highlight the most important advances and present the most salient open questions in the field today, as discussed and agreed upon by the participants of the conference. We also feature agreed-upon suggestions for future methods, measurements, instruments, and missions that would be essential to answering the main open questions presented. This work is thus an overview of the current status of Mars Polar Science and is intended to serve as a road map for the direction of the field during the next 4 yr and beyond, helping to shape its contribution within the larger context of planetary science and exploration.

Keywords: Planetary polar regions, Mars, Polar caps, Planetary science, Planetary climates
The Timing of Alluvial Fan Formation on Mars. The history of rivers on Mars is an important constraint on Martian climate evolution. The timing of relatively young, alluvial fan-forming rivers is especially important, as Mars's Amazonian atmosphere is thought to have been too thin to consistently support surface liquid water. Previous regional studies suggested that alluvial fans formed primarily between the Early Hesperian and the Early Amazonian. In this study, we describe how a combination of a global impact crater database, a global geologic map, a global alluvial fan database, and statistical models can be used to estimate the timing of alluvial fan formation across Mars. Using our global approach and improved statistical modeling, we find that alluvial fan formation likely persisted into the last ~2.5 Gyr, well into the Amazonian period. However, the data we analyzed were insufficient to place constraints on the duration of alluvial fan formation. Going forward, more crater data will enable tighter constraints on the parameters estimated in our models and thus further inform our understanding of Mars's climate evolution.

Keywords: Mars, Planetary surfaces, Planetary climates
MOSAIC: A Satellite Constellation to Enable Groundbreaking Mars Climate System Science and Prepare for Human Exploration. The Martian climate system has been revealed to rival the complexity of Earth's. Over the last 20 yr, a fragmented and incomplete picture has emerged of its structure and variability; we remain largely ignorant of many of the physical processes driving matter and energy flow between and within Mars' diverse climate domains. Mars Orbiters for Surface, Atmosphere, and Ionosphere Connections (MOSAIC) is a constellation of ten platforms focused on understanding these climate connections, with orbits and instruments tailored to observe the Martian climate system from three complementary perspectives. First, low-circular near-polar Sun-synchronous orbits (a large mothership and three smallsats spaced in local time) enable vertical profiling of wind, aerosols, water, and temperature, as well as mapping of surface and subsurface ice. Second, elliptical orbits sampling all of Mars' plasma regions enable multipoint measurements necessary to understand mass/energy transport and ion-driven escape, also enabling, with the polar orbiters, dense radio occultation coverage. Last, longitudinally spaced areostationary orbits enable synoptic views of the lower atmosphere necessary to understand global and mesoscale dynamics, global views of the hydrogen and oxygen exospheres, and upstream measurements of space weather conditions. MOSAIC will characterize climate system variability diurnally and seasonally, on meso-, regional, and global scales, targeting the shallow subsurface all the way out to the solar wind, making many first-of-their-kind measurements. Importantly, these measurements will also prepare for human exploration and habitation of Mars by providing water resource prospecting, operational forecasting of dust and radiation hazards, and ionospheric communication/positioning disruptions.

Keywords: Space vehicle instruments, Space plasmas, Planetary ionospheres, Upper atmosphere, Mars, Space weather, Planetary atmospheres, Thermosphere, Mesosphere, Surface ices, Planetary climates, Planetary magnetospheres
OSSOS. XXIII. 2013 VZ<SUB>70</SUB> and the Temporary Coorbitals of the Giant Planets. We present the discovery of 2013 VZ70, the first known horseshoe coorbital companion of Saturn. Observed by the Outer Solar System Origins Survey for 4.5 yr, the orbit of 2013 VZ70 is determined to high precision, revealing that it currently is in "horseshoe" libration with the planet. This coorbital motion will last at least thousands of years but ends ~10 kyr from now; 2013 VZ70 is thus another example of the already-known "transient coorbital" populations of the giant planets, with this being the first known prograde example for Saturn (temporary retrograde coorbitals are known for Jupiter and Saturn). We present a theoretical steady-state model of the scattering population of trans-Neptunian origin in the giant planet region (2-34 au), including the temporary coorbital populations of the four giant planets. We expose this model to observational biases using survey simulations in order to compare the model to the real detections made by a set of well-characterized outer solar system surveys. While the observed number of coorbitals relative to the scattering population is higher than predicted, we show that the number of observed transient coorbitals of each giant planet relative to each other is consistent with a trans-Neptunian source.

Keywords: Small Solar System bodies, Centaur group, Kuiper belt, Asteroid dynamics, Planetary dynamics, Resonant Kuiper belt objects, Jupiter trojans, Orbital resonances, Trojan asteroids, Scattered disk objects, Trans-Neptunian objects, Neptune trojans
Analyzing Surface Ruggedness Inside and Outside of Ice Stability Zones at the Lunar Poles. We measured surface ruggedness within 12 polar craters on the Moon, six at each pole, using a variation of the Vector Ruggedness Measure (VRM*). We compare VRM* values derived within ice stability zones, where maximum surface temperatures are ≤112 K, to VRM* values from warmer surfaces where ice is not stable. Ruggedness values inside and outside of ice stability zones are statistically not from the same continuous distribution (α = 0.05). In nine of the 12 investigated craters, surfaces where ice is stable are smoother than neighboring warmer surfaces. These comparatively smooth surfaces are observed in both craters that host surface water-ice exposures and those that do not, suggesting that the presence of subsurface ice, rather than surface ice, may be responsible for the reduced surface ruggedness derived from a moving window of 3 × 3 cells applied to 120 m elevation models. Reduced ruggedness of ice stability zones is slightly greater in south polar craters and tends to correlate with enhanced hydrogen content as modeled from Lunar Prospector data. While ice stability zones may have a control on the distribution of softened topography at the lunar poles, the magnitude of this softening is small at the investigated baselines.

Keywords: Planetary surfaces, Surface variability, Planetary polar regions, Surface processes, The Moon, Lunar science, Surface ices
The Dark Side of Pluto. During its departure from Pluto, New Horizons used its LORRI camera to image a portion of Pluto's southern hemisphere that was in a decades-long seasonal winter darkness, but still very faintly illuminated by sunlight reflected by Charon. Recovery of this faint signal was technically challenging. The bright ring of sunlight forward-scattered by haze in the Plutonian atmosphere encircling the nightside hemisphere was severely overexposed, defeating the standard smeared-charge removal required for LORRI images. Reconstruction of the overexposed portions of the raw images, however, allowed adequate corrections to be accomplished. The small solar elongation of Pluto during the departure phase also generated a complex scattered-sunlight background in the images that was three orders of magnitude stronger than the estimated Charon-light flux (the Charon-light flux is similar to the flux of moonlight on Earth a few days before first quarter). A model background image was constructed for each Pluto image based on principal component analysis applied to an ensemble of scattered-sunlight images taken at identical Sun-spacecraft geometry to the Pluto images. The recovered Charon-light image revealed a high-albedo region in the southern hemisphere. We argue that this may be a regional deposit of N2 or CH4 ice. The Charon-light image also shows that the south polar region currently has markedly lower albedo than the north polar region of Pluto, which may reflect the sublimation of N2 ice or the deposition of haze particulates during the recent southern summer.

Keywords: Planetary surfaces, Pluto
Idunn Mons: Evidence for Ongoing Volcano-tectonic Activity and Atmospheric Implications on Venus. In 2010 the ESA Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument first observed 1 μm emissivity anomalies over the top and eastern flank of Idunn Mons (46° S; 146° W), a 200 km wide volcano located in Imdr Regio, a volcano-dominated large volcanic rise of Venus. The anomalies suggest the presence of chemically unweathered and fresh volcanic deposits, which provided the first hint that volcanism in this area may have been active during the past few million years. Subsequent studies have investigated the geologic and atmospheric evolution at Idunn Mons, but no study has comprehensively investigated the evolution and the implication for recent activity in Idunn Mons. Previous work, using both VIRTIS data and Magellan radar emissivity data, confirmed the occurrence of unaltered basaltic lava flows at Idunn Mons. Building on that previous work, experimental laboratory studies have revealed that chemical weathering on Venus may act much faster than previously expected, which suggests very young ages for these flows. This inference has been supported by investigations of the tectonic fracturing surrounding Idunn Mons. Finally, atmospheric data from VIRTIS also show regional anomalies in the speed of the winds in the lower atmosphere over Imdr Regio, which may be related to very recent or ongoing volcanism. In this paper, we take a comprehensive approach, using atmospheric to surface measurements, including recent laboratory experiments, to constrain the evolution of Idunn Mons. Our work suggests that Idunn Mons may be geologically both volcanically and tectonically active today.

Keywords: Venus, Solar system, Planetary atmospheres, Planetary science, Spectroscopy, Volcanoes
Was Venus Ever Habitable? Constraints from a Coupled Interior-Atmosphere-Redox Evolution Model. Venus's past climate evolution is uncertain. General circulation model simulations permit a habitable climate as late as ~0.7 Ga, and there is suggestive-albeit inconclusive-evidence for previous liquid water from surface geomorphology and mineralogy. However, it is unclear whether a habitable past can be reconciled with Venus's inferred atmospheric evolution. In particular, the lack of leftover atmospheric oxygen argues against recent water loss. Here, we apply a fully coupled model of Venus's atmospheric-interior-climate evolution from post-accretion magma ocean to present. The model self-consistently tracks C-, H-, and O-bearing volatiles and surface climate through the entirety of Venus's history. Atmospheric escape, mantle convection, melt production, outgassing, deep water cycling, and carbon cycling are explicitly coupled to climate and redox evolution. Plate tectonic and stagnant lid histories are considered. Using this coupled model, we conclude that both a habitable Venusian past and one where Venus never possessed liquid surface water can be reconciled with known constraints. Specifically, either scenario can reproduce bulk atmospheric composition, inferred surface heat flow, and observed 40Ar and 4He. Moreover, the model suggests that Venus could have been habitable with a ~100 m global ocean as late as 1 Ga, without violating any known constraints. In fact, if diffusion-limited water loss is throttled by a cool, CO2-dominated upper atmosphere, then a habitable past is tentatively favored by our model. This escape throttling makes it difficult to simultaneously recover negligible water vapor and ~90 bar CO2 in the modern atmosphere without temporarily sequestering carbon in the interior via silicate weathering to enhance H escape.

Keywords: Habitable planets, Planetary atmospheres, Venus, Solar system terrestrial planets, Planetary climates, Volcanoes, Atmospheric composition, Planetary interior, Tectonics