cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.u9j763
title: Thermodynamic properties of the Yb-Sb system predicted from first-principles calculations

description: In the present work, thermodynamic properties of the Yb-Sb system have been studied by first-principles based quasiharmonic phonon approach, reporting the temperature-dependent isobaric heat capacity, entropy, formation enthalpy, isothermal bulk modulus, and thermal expansion. The effects by using different exchange-correlation functionals and the pseudopotentials on thermodynamic properties are examined. The results reveal that the combined Perdew-Burker-Ernzerhof functional revised for solids (PBEsol) together with the pseudopotential with all f-electrons frozen in the core is the best choice. This combination leads to an overall good description of the relative phase stabilities and thermodynamic properties, except for the rocksalt YbSb compound which is calculated to have an energy of ~25 kJ/mol-atom above the convex hull. The discrepancy is due probably to the change of the Yb valence states between the rocksalt YbSb structure and the other Yb-Sb compounds. Furthermore, the present calculations show that the Yb16Sb11 compound is stable. The analysis of stretching force constants demonstrates that the extremely strong Yb-Sb bonding is responsible for the stabilities of Yb11Sb10, Yb16Sb11, h-Yb5Sb3, and Yb4Sb3 at high temperatures.
DOI: 10.48577/jpl.g1izkc
title: Global contributions of mesoscale dynamics to meridional heat transport

description: Mesoscale ocean processes are prevalent in many parts of the global oceans, and may contribute substantially to the meridional movement of heat. Yet earlier global surveys of meridional heat transport (MHT) have not formally distinguished between mesoscale and large-scale contributions, or have defined eddy contributions based on temporal rather than spatial characteristics. This work uses spatial filtering methods to separate large-scale (gyre/planetary wave) contributions from mesoscale (eddy/recirculation) contributions to MHT by extending beyond a previous effort for the North Atlantic Ocean. Overall, mesoscale temperature fluxes produce a net poleward MHT at mid-latitudes and equatorward MHT in the tropics, thereby resulting in a net divergence of heat from the subtropics. Mesoscale temperature fluxes are often concentrated near the energetic currents at western boundaries, and the temperature difference between the boundary current and its recirculation determines the direction of the mesoscale temperature flux. The mesoscale contribution to MHT yields substantially different results from temporally-based "eddy" contributions to MHT, with the latter contributed substantially by gyre and planetary wave motions at low latitudes. Mesoscale temperature fluxes contribute the most to interannual and decadal variability of MHT in the Southern Ocean, the tropical Indo-Pacific, and the North Atlantic. Surface eddy kinetic energy (EKE) is not a good proxy for mesoscale temperature flux variability in regions with the highest time-mean EKE, though it does explain much of the temperature flux variability in regions of modest time-mean EKE. This approach to quantifying mesoscale fluxes can be used to improve parameterizations of mesoscale effects in coarse-resolution models, and assess regional impacts of mesoscale eddies and recirculations on tracer fluxes.
DOI: 10.48577/jpl.lb6frk
title: Radiometric cross comparison of eMAS, AirMSPI, and AVIRIS sensors over Railroad Valley

description: Remote sensing instruments, both aircraft and on-orbit platforms, undergo extensive laboratory calibrations to determine their geometric, spectral, and radiometric responses. Further validation of the latter is frequently made using in-flight Earth observations and sensor cross comparisons. The FIREX-AQ campaign provided such an opportunity when the ER-2 aircraft overflew Railroad Valley on 13 and 15 August 2019. This allowed the instruments to conduct a vicarious calibration, where surface observations are used to compute the at-sensor radiances. The laboratory and vicarious calibrations of the Enhanced MODIS Airborne Simulator (eMAS), the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI), and the “Classic” Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-C) sensors are presented here. Radiometric differences in their vicarious calibrations have been attributed to differences in the input solar spectral irradiance models, and surface reflectance datasets. Agreement is within the required 5 % uncertainty for the visible bands, but differences on the order of 10 % are shown for the SWIR bands, due to differences in these inputs.
DOI: 10.48577/jpl.qlgf8v
title: Voyager 3: A Concept Mission to Interstellar Medium

description: The Voyager 3 is a concept mission that sends a space telescope to the interstellar medium in a reasonable amount of time. Voyager 3 will take a direct image of an exoplanet using the solar gravitational lensing at the distance of 550 AU. The spacecraft will use its suite of scientific instruments to study the local solar system’s environment, interstellar medium and finalize its primary mission by imaging an exoplanet. Two architectures are proposed to meet this mission directive, using multiple gravitational assists and sizable electric propulsion burns to achievethe high escape speeds necessary to reach 550 AU. This paper expands on the science mission objectives, trajectory, and the preliminary design of the spacecraft.
DOI: 10.48577/jpl.nhtpxj
title: Improving FM Radar Dynamic Range using Target Phase Noise Cancellation

description: A method for improving the dynamic range of frequency-modulated continuous-wave (FMCW) radar systems is presented. Bright echo signals detected with FMCW radars can carry strong phase noise sidelobes, especially for radars at W-band and higher frequencies where extremely quiet local oscillators do not exist or are not practical. These sidelobes can hide targets that would otherwise be detectable by the radar. Owing to the mathematical symmetry of phase noise with respect to a dominant carrier tone, the phase noise on the negative-frequency side of a bright echo can be used in post-processing to coherently cancel the corresponding phase noise on the positive-frequency side, revealing the presence of any weak target on the positive-frequency side. We show experimentally how this procedure improves the dynamic range of an airborne 167 GHz cloud radar by up to 18 dB, albeit with a detection sensitivity penalty of about 3 dB.
DOI: 10.48577/jpl.wcccdl
title: A stochastic view of the 2020 Elazıg Mw6.8 earthquake (Turkey)

description: Until the Mw 6.8 Elazı˘g earthquake ruptured the central portion of the East Anatolian Fault (EAF, Turkey) on January 24, 2020, the region had only experienced moderate magnitude (Mw &lt; 6.2) earthquakes over the last century. Here, we use geodetic data to constrain a model of subsurface fault slip. We adopt an unregularized Bayesian sampling approach relying solely on physically justifiable prior information and account for uncertainties in both the assumed elastic structure and fault geometry. The rupture of the Elazı˘g earthquake was mostly unilateral, with two primary disconnected regions of slip. This rupture pattern may be controlled by structural complexity. Both the Elazı˘g and 2010 Mw 6.1 Kovancılar events ruptured portions of the central EAF that are believed to be coupled during interseismic periods, and the Palu segment is the last portion of the EAF showing a large fault slip deficit which has not yet ruptured in the last 145 years.
DOI: 10.48577/jpl.klazxn
title: Comparative Analysis of Model-based and Traditional Systems Engineering Approaches for Architecting a Robotic Space System through Automatic Information Transfer

description: This study seeks to compare the quantity of information that is automatically transferred through the associations generated using a model-based systems engineering (MBSE) approach versus a traditional systems engineering approach to measure the benefits of MBSE in architecting a robotic space system. An MBSE approach was applied to architecting an orbiting sample Capture and Orient Module (COM) system concept for a Capture, Containment, and Return System (CCRS) payload concept for Mars Sample Return (MSR). An architecting process was established, covering architecture of the system, subsystem, and assembly levels of the system. The process involved defining the structural, behavioral, data, and requirements perspectives for each system level, along with trade studies and peer reviews between each level. The architecting process was carried out to define the COM system architecture using both MBSE and non-MBSE approaches in parallel in order to provide a side-by-side comparison of the approaches. The approaches were analyzed using design structure matrices and evaluated based on the amount of information transferred between process tasks manually (e.g., elements physically typed into text boxes in a presentation slide) vs automatically (e.g., elements automatically filled out within a block in a model view due to explicitly defined element associations). A total of 4,819 information element transfers were traced in the DSMs and used to quantitatively compare the two approaches. The non-MBSE approach required manual transfer for all 4,819 information elements. The MBSE approach required manual transfer for 4,189 information elements and automatic transfer for 630 information elements, providing a minor increase in the automation of information transfer relative to the non-MBSE approach. Incorporating the use of additional MBSE artifacts into the trade study and peer review tasks, manual transfer could potentially be reduced to 931 information elements, and automatic transfer increased to 3,888 information elements. Automation of information transfer has the potential to improve communication of information and reduce errors that could later lead to costly process iterations, rework, and design changes. Demonstrating increased automatic information transfer can help communicate the benefits of MBSE in architecting robotic space systems and strengthen the case for adopting MBSE within the broader systems engineering community.
DOI: 10.48577/jpl.ojezq7
title: Sub-Orbital Flight Demonstration of a 183 / 540-600 GHz Hybrid CMOS-InP and CMOS-Schottky-MEMS Limb-Sounder

description: This paper presents an overview of a sub-orbital flight demonstration with a 183 GHz and 540-600 GHz limb-sounding instrument aboard a stratospheric ballooncraft. The 183 GHz band provides soundings of stratospheric H2O and is implemented with a hybrid CMOS-InP receiver architecture which provides excellent sensitivity while remaining compact (162g) and offering an extremely low DC power consumption (0.62W). The 540-600 GHz channel sounds stratospheric O3 and uses a combination of a CMOS local oscillator, GaAs Schottky mixer and micro-electro-mechanical-system (MEMS) RF switch for calibration, again offering competitive form factor (1.4 Kg) and low DC power consumption (6.6W) compared to prior instruments. The instrument was flown on the NASA Reck-Tang Limb-sounding Experiment (ReckTangLE) ballooncraft and performed atmospheric soundings across New Mexico and Northwestern Texas on Oct. 17 2019.
DOI: 10.48577/jpl.rrlmx3
title: Survey of Transverse Range Fire Scars in Ten Years of UAVSAR Polarimetry

description: Because cross-polarized radar returns are highly associated with volume scatter, radar polarimetry returns tend to show strong evidence of wildfire scars and recovery in forest and chaparral. We focus on the polarimetry images from UAVSAR (PolSAR) line SanAnd_08525, which covers a roughly 20 km wide swath over the Transverse Range including parts of the Santa Monica, San Gabriel and San Bernardino Mountains. We select images from four acquisition dates from October 2009 to September 2020, very roughly four years apart. These are compared to fire perimeters from the national GeoMAC and NIFC databases for years 2003-2020, which shows the areas affected by the major fires (west to east) Springs2013, Woolsey2018, Topanga2005, LaTuna2017, Station2009, BlueCut2016, Pilot2016, Slide2007, Butler2007 and many smaller fires. PolSAR images are shown to be helpful in identifying types and boundaries of fire, fifty-meter scale details of vegetation loss, and variability of vegetation recovery in post-fire years.
DOI: 10.48577/jpl.wbf9x6
title: Calibration of a 6-Axis Force-Torque Sensor for Robust Operation in the Mars 2020 Robot Arm

description: A main objective of the Mars 2020 rover mission (Perseverance) is to collect and preserve samples of rock and soil from the Martian surface. To accomplish this task, the Perseverance Rover carries a Sampling and Caching Subsystem outfitted with Coring Drill mounted on a 5 degree-of-freedom (DOF) robotic arm. Safe operation of the Robotic Arm and its tools relies on force feedback, provided by a custom Force-Torque Sensor (FTS) which is positioned to sense end-effector external loads. This work describes the methods and algorithms used in the calibration of the Robotic Arm FTS to achieve the required force-feedback accuracy over all expected Mars and Earth operating environments. Data collection strategies, standalone versus system-integrated sensor findings, and results of validation exercises in Earth-ambient and Mars-like environments are included.
DOI: 10.48577/jpl.wy7t4f
title: Challenges in Specifying and Predicting Space Weather

description: Physics-based Data Assimilation (DA) has been shown to be a powerful technique for specifying and predicting space weather. However, it is also known that different data assimilation models simulating the same geophysical event can display different space weather features even if the same data are assimilated. In this study, we used our Multimodel Ensemble Prediction System (MEPS) of DA models to elucidate the similarities and differences in the individual DA model reconstructions of the mid-low latitude ionosphere when the same data are assimilated. Ensemble model averages were also obtained. For this ensemble modeling study, we selected the quiet/storm period of 16–17 March 2013 (equinox, solar medium). Five data assimilation models and one physics-based model were used to produce an ensemble mean output for Total Electron Content (TEC), ionospheric peak density (NmF2), and ionospheric peak height (hmF2) for latitudes less than 60˚ and all longitudes. The data assimilated included ground-based Global Positioning Satellite TEC and topside plasma densities near 800 km altitude derived from the COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellites. Both a simple average and a weighted average of the models were used in the ensemble averaging in order to determine if there was an improvement of the ensemble averages over the individual models.
DOI: 10.48577/jpl.51pkc3
title: Clustering Analysis Methods for GNSS Observations: A Data-Driven Approach to Identifying California’s Major Faults

description: We present a data-driven approach to clustering or grouping Global Navigation Satellite System (GNSS) stations according to their observed velocities, displacements and/or other selected characteristics. Clustering GNSS stations not only has the potential for identifying useful scientific information (e.g., separating regions of post-seismic motion), but also is a necessary initial step in other GNSS analysis methods, such as those used to detect aseismic transient signals (Granat et. al., 2013). Using this approach, desired features of the data can be selected for clustering, including some subset of the three displacement or velocity components, uncertainty estimates, the station location, and any other relevant information present in the data set. Based on those selections, the clustering procedure autonomously groups the GNSS stations according to a selected clustering method; some methods require that the number of groups be specified in advance, while others estimate the number of groups from the data. We have implemented this approach as a Python application, allowing us to draw upon the full range of open source clustering methods available in Python’s scikit-learn package (Pedregosa et. al., 2011). The application returns the GNSS stations labeled by group in both tabular form and as a color coded KML file for overlay in Google Earth with other sources of information. Our implementation is designed to work with the GNSS displacement and velocity information available from GeoGateway (Heflin et. al., 2020; Donnellan et al, in press), a map-based science gateway supported by NASA, but is easily extendable to other data sources or output formats. Our analysis is focused on California and western Nevada. The results typically show partitions that follow faults or geologic boundaries, including for recent large earthquakes and post-seismic motion. The San Andreas fault system is the most prominent partition, reflecting Pacific-North American plate boundary motion. Deformation reflected as class boundaries is distributed north and south of the central California creeping section. For most models the southern San Andreas fault connects with the Eastern California Shear Zone (ECSZ) rather than continuing through the San Gorgonio Pass.
DOI: 10.48577/jpl.kofdlz
title: The mean seasonal cycle in relative sea level from satellite altimetry

description: Satellite altimetry is used to determine themean seasonal cycle in relative2 sea level, a quantity relevant to coastal flooding and related applications. The main3 harmonics (annual, semiannual, terannual) are estimated from 25 years of gridded4 altimetry, while several conventional altimeter ‘corrections’ (gravitational tide, pole5 tide, and inverted barometer) are restored. To transform from absolute to relative6 sea levels, a model of vertical land motion is developed from a high-resolution7 seasonal mass inversion estimated from satellite gravimetry. An adjustment for8 annual geocenter motion accounts for use of a center-of-mass reference frame9 in satellite orbit determination. A set of test tide gauges, from which seasonal harmonics have been estimated from hourly measurements, is used to assess how11 accurately each adjustment to the altimeter data helps converge the results to true12 relative sea levels.
DOI: 10.48577/jpl.yjnmr9
title: Brine Driven Destruction of Clay Minerals in Gale Crater, Mars

description: Mars’ sedimentary rock record preserves information on geological (and potentialastrobiological) processes that occurred on the planet billions of years ago. The Curiosity rover isexploring the lower reaches of Mt. Sharp, in Gale crater on Mars. A traverse from Vera Rubinridge to Glen Torridon has allowed Curiosity to examine a lateral transect of rock strata laid downin a Martian lake at ~3.5 Ga. We report spatial differences in the mineralogy of time equivalentsedimentary rocks &lt;400 m apart. These differences indicate localized infiltration of silica poorbrines, generated during deposition of overlying magnesium sulfate-bearing strata. We proposethat destabilization of silicate minerals driven by silica poor brines (rarely observed on Earth) waswidespread on ancient Mars, because sulfate deposits are globally distributed.
DOI: 10.48577/jpl.sut8nn
title: Buried Aseismic Slip and Off-Fault Deformation on the Southernmost San Andreas Fault triggered by the 2010 El Mayor Cucapah Earthquake revealed by UAVSAR

description: We use UAVSAR interferograms to characterize fault slip, triggered by the Mw 7.2 El Mayor-Cucapah earthquake on the southernmost San Andreas Fault in the Coachella Valley providing comprehensive maps of landscape change that complement in situ measurements. Creepmeters and geological mapping of fault offsets on Durmid Hill recorded 4 mm and 8 mm of average triggered slip respectively on the fault, in contrast to radar views that reveal significant off-fault dextral deformation averaging 20 mm. Unlike slip in previous triggered slip events on the southernmost San Andreas fault, dextral shear in 2010 is not confined to transpressional hills in the Coachella valley. Edge detection and gradient estimation applied to the 50-m-sampled interferogram data identify the location (to 20 m) and local strike (to &lt; 4°) of secondary surface ruptures. Transverse curve fitting applied to these local detections provides local estimates of the radar-projected dextral slip and a parameter indicating the transverse width of the slip, which we equate with the depth of subsurface shear. These estimates are partially validated by fault-transverse interferogram profiles generated using the web-based UAVSAR tool of GeoGateway, and appear consistent for radar-projected slip greater than about 5 mm. An unexpected finding is that creep and triggered slip on the San Andreas fault terminate in the shallow subsurface below a surface shear zone that resists the simple expression of aseismic fault slip. We introduce the notion of a surface locking depth above which fault slip is manifest as distributed shear, and evaluate its depth as 6-27 m.
DOI: 10.48577/jpl.xtloe0
title: Large-scale thermal unrest of volcanoes for years prior to eruption

description: Identifying the observables that warn of volcanic eruptions is a major challenge in natural hazard management. A potentially n important, but under-investigated, observable is the release of heat through volcano surfaces, which represents a major energy source at quiescent volcanismvolcanoes. However, it remains unclear whether surface heat emissions respond to pre-eruptive processes and vary before eruption. Here we show through a statistical analysis of satellite-based long-wavelength (10.780–11.280 μm) infrared data that the last magmatic and phreatic eruptions of five different volcanoes were preceded by subtle but significant long-term (~years), large-scale (10s tens of km2), increases of in their radiant heat flux (up to ~1 ℃ of in median radiant temperature). This pre-eruptive thermal unrest is found through a new statistical analysis of satellite-based long-wavelength (10.780–11.280 μm) infrared data, and is attributed to the enhancement of underground hydrothermal activity. Large-scale thermal unrest is detected even before eruptions that were impossible not to anticipated through from other geophysical/geochemicalvolcano monitoring methods, such as (e.g., the 2014 phreatic eruption of Ontake (, Japan) and; the 2015 magmatic eruption of Calbuco (, Chile). We attribute large-scale thermal unrest to the enhancement of underground hydrothermal activity, and suggest that ),such analysis of satellite-based infrared observations can improve thus opening new horizons to better constrainconstraints on the thermal budget of volcanoes, detections of pre-eruptive conditions, and and assessments of volcanic alert levels.