cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.cyrslm
title: Where are Mars’ Hypothesized Ocean Shorelines? Large Lateral and Topographic Offsets Between Different Versions of Paleoshoreline Maps.

description: Mars’ controversial hypothesized ocean shorelines have been found to deviate significantly from an expected equipotential surface. While multiple deformation models have been proposed to explain the wide range of elevations, here we show that the historical locations used in the literature and in these models vary widely. We find that the most commonly used version of the Arabia Level does not follow the originally described contact and can deviate laterally by ~500 km in Deuteronilus Mensae. A meta-analysis of different published maps shows that, globally, the minimum lateral offsets between the locations of the putative Arabia and Deuteronilus shorelines vary by an average of 141±142 km and 180±177 km, respectively. This leads to mean elevations of the Arabia Level that vary by up to 2.2 km between different mappings, and topographic ranges within each global mapping ranging from 2.7 to 7.7 km. The younger Deuteronilus Level has less topographic variation as it largely follows a formal contact (the Vastitas Borealis Formation) within the relatively flat northern plains. Given the high variance in position (spatial and topographic) of the maps, the use of such data and conclusions based on them are potentially problematic.
DOI: 10.48577/jpl.ybul0j
title: Precovery observations conrm the capture time of asteroid 2020 CD3 as Earth's minimoon

description: Asteroid 2020 CD3 was discovered on 2020 February 15 by the Catalina Sky Survey while it was temporarily captured in a geocentric orbit before escaping Earth'sHill sphere on 2020 March 7. We searched archival images and found precoveries of 2020 CD3 from the Dark Energy Camera and Catalina Sky survey. The Dark Energy Camera images yieldedthree observations on 2019 January 17, while the Catalina Sky Survey images yielded four observations on 2019 January 24 from the Mt. Lemmon telescope and four observations on 2018 May 9 from the Mt. Bigelow telescope.These precovery observations allowed us to refine the orbit of 2020CD3 and determine that it was captured in a geocentric orbit on 2017 September $15$ after a close approach to the Moon at a distance of $11,974 \pm 10$~km. We analyzed the trajectory of 2020~CD3 to look for potential Earth impactswithin the next 100 years and find a $\gtrsim1\%$ probability of an impact between 2061 and 2120 depending on non-gravitational force model assumptions. The small size of 2020~CD3, about 1 to 2 m, makes any potential impact harmless.
DOI: 10.48577/jpl.5jgolx
title: (6478) Gault: Physical characterization of an active main-belt asteroid

description: In December 2018, the main-belt asteroid (6478) Gault was reported to display activity. Gault is an asteroid belonging to the Phocaea dynamical family and was not previously known to be active, nor was any other member of the Phocaea family. In this work we present the results of photometric and spectroscopic observations that commenced soon after the discovery of activity. We obtained observations over two apparitions to monitor its activity, rotation period, composition, and possible non-gravitational orbital evolution. We find that Gault has a rotation period of 푃 = 2.4929 ± 0.0003 hours with a lightcurve amplitude of 0.06 magnitude. This short rotation period close to the spin barrier limit is consistent with Gault having a density no smaller than 휌 = 1.85 g/cm3 and its activity being triggered by the YORP spin-up mechanism. Analysis of the Gault phase curve over phase angles ranging from 0.4 ◦ to 23.6 ◦ provides an absolute magnitude of 퐻 = 14.81 ± 0.04, 퐺1 = 0.25 ± 0.07, and 퐺2 = 0.38 ± 0.04. Model fits to the phase curve find the surface regolith grain size constrained between 100-500 휇m. Using relations between the phase curve and albedo we determine that the geometrical albedo of Gault is 푝v = 0.26 ± 0.05 corresponding to an equivalent diameter of 퐷 = 2.8 +0.4 −0.2 km. Our spectroscopic observations are all consistent with an ordinary chondrite-like composition (S, or Q-type in the Bus-DeMeo taxonomic classification). A search through archival photographic plate surveys found previously unidentified detections of Gault dating back to 1957 and 1958. Only the latter had been digitized, which we measured to nearly double the observation arc of Gault. Finally, we did not find any signal of activity during the 2020 apparition or non-gravitational effects on its orbit.
DOI: 10.48577/jpl.oiympd
title: Eye on the Storm

description: The JPL Tropical Cyclone Information System integrates observations with model forecasts, allowing interrogation of a large number of variables, to help better understand the multiscale nonlinear interactions that lead to storm development and to evaluate models.
DOI: 10.48577/jpl.9dljdz
title: Carbon-Chain Chemistry vs. Complex-Organic-Molecule Chemistry in Envelopes around Three Low-Mass Young Stellar Objects in the Perseus Region

description: We have analyzed ALMA Cycle 5 data in Band 4 toward three low-mass young stellar objects (YSOs), 18 IRAS 03235+3004 (hereafter IRAS 03235), IRAS 03245+3002 (IRAS 03245), and IRAS 03271+3013 19 (IRAS 03271), in the Perseus region. The HC3N (J = 16􀀀15; Eup=k = 59:4 K) line has been detected 20 in all of the target sources, while four CH3OH lines (Eup=k = 15:4􀀀36:3 K) have been detected 21 only in IRAS 03245. Sizes of the HC3N distributions ( 2930􀀀3230 au) in IRAS 03235 and IRAS 22 03245 are similar to those of the carbon-chain species in the warm carbon chain chemistry (WCCC) 23 source L1527. The size of the CH3OH emission in IRAS 03245 is 1760 au, which is 24 slightly smaller than that of HC3N in this source.We compare the CH3OH/HC3N abundance 25 ratios observed in these sources with predictions of chemical models. We conrm that the observed 26 ratio in IRAS 03245 agrees with the modeled values at temperatures around 30{35 K, which supports 27 the HC3N formation by the WCCC mechanism. In this temperature range, CH3OH does not thermally 28 desorb from dust grains. Non-thermal desorption mechanisms or gas-phase formation of CH3OH seem 29 to work eciently around IRAS 03245. The fact that IRAS 03245 has the highest bolometric luminosity 30 among the target sources seems to support these mechanisms, in particular the non-thermal desorption 31 mechanisms.
DOI: 10.48577/jpl.l0hirg
title: The Relativistic Jet Orientation and Host Galaxy of the Peculiar Blazar PKS 1413+135

description: PKS 1413+135 is one of the most peculiar blazars known. Its strange properties led to the hypothesis almost four decades ago that it is gravitationally lensed by a mass concentration associated with an intervening galaxy. It exhibits symmetric achromatic variability, a rare form of variability that has been attributed to gravitational milli lensing. It has been classified as a BL Lac object, and is one of the rare objects in this class with a visible counterjet. BL Lac objects have jet axes aligned close to the line of sight. It has also been classified as a compact symmetric object, which have jet axes not aligned close to the line of sight. Intensive efforts to understand this blazar have hitherto failed to resolve even the questions of the orientation of the relativistic jet, and the host galaxy. Answering these two questions is important as they challenge our understanding of jets in active galactic nuclei and the classification schemes we use to describe them. We show that the jet axis is aligned close to the line of sight and PKS 1413+135 is almost certainly not located in the apparent host galaxy, but is a background object in the redshift range 0.247 &lt; z &lt; 0.5. The intervening spiral galaxy at z = 0.247 provides a natural host for the putative lens responsible for symmetric achromatic variability and is shown to be a Seyfert 2 galaxy. We also show that, as for the radio emission, a “multizone” model is needed to account for the high-energy emission.
DOI: 10.48577/jpl.v9yet5
title: Using Saildrones to Validate Arctic Sea-Surface Salinity from the SMAP satellite and from Ocean Models

description: Abstract: The Arctic Ocean is one of the most important and challenging regions to observe. It is the region experiencing the largest changes from climate warming, and at the same time it is one of the most difficult to sample because of sea ice and extreme cold temperatures. Two NASA-sponsored deployments of the Saildrone vehicle provided a unique opportunity for validating sea-surface salinity (SSS) derived from three separate products that use data from the Soil Moisture Active Passive (SMAP) satellite. To examine possible issues with resolving mesoscale-to-submesoscale variability, comparisons were also made with two versions of the Estimating the Circulation and Climate of the Ocean (ECCO) model. Results indicate that the three SMAP products resolve the runoff signal associated with the Yukon River, with high correlation between SMAP products and Saildrone SSS. Spectral slopes, overall, replicate the -2.0 slopes associated with mesoscale-submesoscale variability. Statistically significant spatial coherences exist for all products, with peaks close to 100 km. Based on these encouraging results, future research should focus on improving
DOI: 10.48577/jpl.kklqrr
title: Thermal Conductivity of the Martian Regolith at the InSight Landing site from HP3 Active Heating Experiments

description: The heat flow and physical properties package (HP3) of the InSight Mars mission is an instrument package designed to determine the martian planetary heat flow. To this end, the package was designed to emplace sensors into the martian regolith and measure the regolith thermal conductivity as well as the geothermal gradient in the 0-5 m depth range. After emplacing the probe to a tip depth of 0.37 m, a rst reliable measurement of the average regolith thermal conductivity in the 0.03 to 0.37 m depth range was performed. Using the HP3 mole as a modied line heat source, we determined a regolith thermal conductivity of 0.039 0.002 W m􀀀1 K􀀀1, consistent with the results of orbital and in-situ thermal inertia measurements. This low thermal conductivity implies that 85 to 95% of all particles are smaller than 125-160 m and suggests that any cement contributing to soil cohesion cannot significantly increase grain-to-grain contact areas by forming cementing necks, but could be distributed in the form of grain coatings instead. Regolith densities compatible with the measurements are 1211+149-113 kg m􀀀3, indicating regolith porosities of 61 %.
DOI: 10.48577/jpl.xnbuwr
title: Quantifying Contributions of External Drivers to the Global Ionospheric State

description: To advance our understanding of the global response of the ionospheric total electron content (TEC) to various external drivers, we apply entropy-based information theory to quantify contributions of solar, interplanetary, and lower atmospheric drivers to the global ionospheric state described by the Global Ionospheric Map (GIM). By computing normalized transfer entropy on 18 years of GIM TEC, F10.7, solar wind, and lower atmospheric data, we obtain the predictive information transfer from the present drivers to the global ionospheric state at various future time. We nd that the solar EUV irradiance dominates the information transfer within three days into the future, while the lower atmospheric migrating tidal sources dominate beyond three days into the future. The maximum information transfer from individual drivers reveals the maximum contributions from the drivers to the global ionospheric state: the lower atmospheric migrating tidal sources contribute most. The solar EUV irradiance and tropospheric deep convection are secondary drivers with comparable contributions at about half of the contribution from migrating tidal sources. The interplanetary driving contributes the leastto the global ionospheric state during both geomagnetic storm and quiet time, even though the contribution from the interplanetary magnetic eld can enhance four to six times during geomagnetic storm time than quiet time.
DOI: 10.48577/jpl.yiqqwr
title: Soil Thermophysical Properties near the InSight Lander Derived from 50 Sols of Radiometer Measurements

description: Measurements from the InSight lander radiometer acquired shortly after landing are used to characterize 41 the thermophysical properties of the martian soil in Homestead hollow. This dataset is unique as it stems 42 from a high measurement cadence fixed platform studying a simple well-characterized surface, and it 43 benefits from the environmental characterization provided by other instruments. We focus on observations 44 acquired before the arrival of a regional dust storm (near Sol 50), on the furthest observed patch of soil 45 (i.e., ~3.5 m away from the edge of the lander deck) where temperatures are least impacted by the 46 radiative/reflective presence of the lander and where the soil has been least disrupted during landing. 47 Diurnal temperature cycles are fit within error bars using a homogenous soil configuration with a thermal 48 inertia of 183 ± 25 J m-2 K-1 s-1/2 and an albedo of 0.16, corresponding to very fine to fine sand with the 49 vast majority of particles smaller than 140 μm. A pre-landing assessment leveraging orbital thermal 50 infrared data is consistent with these results, but our analysis of the full diurnal temperature cycle acquired 51 from the ground further indicates that near surface layers with different thermophysical properties must be 52 thin (i.e., typically within the top few mm) and deep layering with different thermophysical properties must 53 be at least below ~4 cm. The low thermal inertia value indicates limited soil cementation within the upper 54 one or two skin depths (i.e., ~4-8 cm and more), with cement volumes &lt;&lt;1%, which is challenging to 55 reconcile with visible images of overhangs in pits.
DOI: 10.48577/jpl.cwqqju
title: Automated Capillary Electrophoresis System Compatible with Mul-tiple Detectors for Potential In Situ Spaceflight Missions

description: The in situ search for chemical signatures of life on extraterrestrial worlds requires automated hardware capable of performing detailed compositional analysis during robotic missions of exploration. The use of electrophoretic separations in this search is particularly powerful, enabling analysis of a wide range of soluble organic compounds potentially indicative of life, as well as inorganic compounds that can serve as indicators of habitability. Yet to detect this broad range of compounds with a single electrophoresis instrument, a combination of different detection modes is required. For detection of any ionizable species, including organic compounds that do not participate in terrestrial biology (i.e “unknown unknowns”), mass spec-trometry (MS) is essential. Inorganic ions, or any dissolved charged species present, can be analyzed using capacitively cou-pled contactless conductivity detection (C4D). Additionally, for the trace analysis of compounds of key interest to astrobiol-ogy (particularly amino acids), laser-induced-fluorescence (LIF) detection holds unique promise, due to the fact that it has the highest demonstrated sensitivity of any form of detection. Here, we demonstrate a fully automated, portable capillary elec-trophoresis analyzer that is capable of all these modes of detection. The prototype system developed here addresses the three most significant challenges for doing electrophoretic separations: precise sample injection, HV isolation, and automation of all operational steps. These key challenges were successfully addressed with the use of custom-designed rotor-stator valves with optimized operational sequences incorporating gas purging steps, rinses, and HV application.
DOI: 10.48577/jpl.ra3odb
title: A Simple Gas Introduction System for Cryogenic Powder X-Ray Diffraction

description: Abstract We describe a simple system for the introduction of gases into standard X-ray diffraction capillaries while mounted in situ in the X-ray beam of laboratory X-ray diffraction instruments. This system retains many of the advantages of the standard Norby cell, but does not require custom machining and has less stringent space restrictions. We have used the system to study the crystallization and interaction of volatile organics at cryogenic temperatures, but gas-solid interactions could also be studied at elevated temperatures using this approach.
DOI: 10.48577/jpl.ykfogh
title: Ephemeris and hazard assessment for near-Earth asteroid (101955) Bennu based on OSIRIS-REx data

description: Small bodies such as the near-Earth asteroid Bennu drift in their orbit due to thermalradiation forces (the Yarkovsky eect). Ground-based observations have indicateda nonzero probability of Bennu impacting Earth, depending on how its orbit evolves.Thus, among the goals of the OSIRIS-REx (Origins, Spectral Interpretation, ResourceIdentication, and Security-Regolith Explorer) mission to Bennu were to precisely measurethe Yarkovsky eect and rene the impact hazard assessment for this body. Herewe address these objectives. Using OSIRIS-REx spacecraft tracking data, we derivemeter-level constraints on the distance between Earth and Bennu from January 2019to October 2020. While these data greatly improve the knowledge of the trajectoryof Bennu, they also require an unprecedented delity for the modeling of an asteroid'strajectory. In particular, special care is needed to take into account the contribution of343 small-body perturbers and the uncertainty in their masses. Radiation eects suchas the Poynting-Robertson drag, so far only considered for interplanetary dust dynamics,now become a consideration for modeling the trajectory of a 500-m asteroid such asBennu. By employing a thermophysical model based on OSIRIS-REx's characterizationof Bennu, we estimate a semimajor axis drift of 􀀀284:60:2 m/yr (signal-to-noise ratio1400) at epoch 2011 January 1 caused by the Yarkovsky eect. The largest source ofmodeling error is solar wind drag, which may lower the magnitude of the semimajor axisdrift from the Yarkovsky eect by up to 0.16 m/yr. The Yarkovsky-related semimajoraxis drift varies by roughly 1 m/yr as the orbit of Bennu evolves due to planetaryperturbations from 1900 to 2135. The Yarkovsky model proves to be extremely accurateby predicting a bulk density estimate within 0.1% of that estimated through gravity scienceanalysis. Compared to the information available before the OSIRIS-REx mission,the knowledge of the circumstances of the scattering Earth encounter that will occur in2135 improves by a factor of 20, thus allowing us to rule out many previously possibleimpact trajectories. However, there remain some impact trajectories compatible withthe data. Prior to the spacecraft encounter, the overall impact probability through 2200was 3:710􀀀4 (1 in 2700). As a result of our analysis, the cumulative impact probabilitythrough 2300 becomes 5:710􀀀4 (1 in 1750) and the most signicant individual impactsolution is for September 2182, with an impact probability of 3:7 10􀀀4 (1 in 2700).Both Bennu and (29075) 1950 DA have a Palermo scale value of 􀀀1:42 and share thedistinction as the most hazardous object in the asteroid catalog.
DOI: 10.48577/jpl.in8ew8
title: High-temperature absorption line shape parameters for CO2 in the 6800-7000 cm-1 region from dual frequency comb measurements up to 1000 K

description: We present the first systematic study of self-broadened CO2 line shape parameters in the 00031←00001 and 01131←01101 bands at high temperature. We report temperature-dependent broadening coefficients and pressure shifts for more than 40 transitions in the 00031←00001 band, and 70 transitions in the 01131←01101 hot band. The majority of these parameters have never been measured at high temperature. The new parameters are determined from spectra measured with a broadband, high resolution dual frequency comb absorption spectrometer in a high-temperature gas cell up to 981 K. We fit the measured spectra using a multispectrum fitting approach to derive line shape parameters with both a Voigt and speed-dependent Voigt profile. We compare the measured parameters to calculated line shape parameters, including those used in the HITRAN2020 database. For the bands included in this study, these comparisons identify several deviations between the measured and calculated line shape parameters that ultimately limit the accuracy of absorption models when using the calculated parameters. Additionally, we fit the measured line shape parameters using empirical expressions for the broadening coefficient and pressure shift, which we validate for high-temperature transitions up to |m|≈90. We use these models to construct a set of database files that can be used to supplement the HITRAN database for self-broadened CO2 in the 6800 – 7000 cm-1 region. These new parameters significantly improve the accuracy of absorption models for high-temperature CO2 in this frequency range, and also provide useful data to test and improve methods used to calculate CO2 line shape parameters.
DOI: 10.48577/jpl.zj78rg
title: Leaf surface water, not plant water stress, drives diurnal variation in tropical forest canopy water content

description: • Variation in canopy water content (CWC) that can be detected from microwave remote sensing of vegetation optical depth (VOD) has been proposed as an important measure of vegetation water stress. However, the contribution of leaf surface water (LWs), arising from dew formation and rainfall interception, to CWC is largely unknown, particularly in tropical forests and other high-humidity ecosystems.• We compared the AMSR-E VOD and CWC predicted by a plant hydro-dynamics model at four tropical sites in Brazil spanning a rainfall gradient. We assessed how LWs influenced the relationship between VOD and CWC. • The analysis indicates that while CWC is strongly correlated with VOD (R2=0.62 across all sites), LWs accounts for 61-76% of the diurnal variation in CWC despite being less than 10% of CWC. Ignoring LWs weakens the near-linear relationship between CWC and VOD and reduces the consistency in diurnal variation. The contribution of LWs to CWC variation, however, decreases at longer, seasonal to interannual, time scales.• Our results demonstrate that diurnal patterns of dew formation and rainfall interception can be an important driver of diurnal variation in CWC and VOD over tropical ecosystems and therefore should be accounted for when inferring plant diurnal water stress from VOD measurements.
DOI: 10.48577/jpl.4ka5qd
title: The Far-Infrared Spectroscopic Surveyor (FIRSS)

description: We are standing at the crossroads of pow- erful new facilities emerging in the next decade on the ground and in space like ELT, SKA, JWST, and Athena. Turning the narrative of the star formation potential of galaxies into a quantitative theory will provide an- swers to many outstanding questions in astrophysics, from the formation of planets to the evolution of galax- ies and the origin of heavy elements. To achieve this goal, there is an urgent need for a dedicated space- borne, far-infrared spectroscopic facility capable of de- livering, for the rst time, large scale, high spectral reso- lution (velocity resolved) multiwavelength studies of the chemistry and dynamics of the ISM of our own Milky Way and nearby galaxies. The Far Infrared Spectro- scopic Surveyor (FIRSS) fullls these requirements and by exploiting the legacy of recent photometric surveys it seizes the opportunity to shed light on the fundamental building processes of our Universe.