cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.fc5y5n
title: Emission modes in electrospray thrusters operating with high conductivity ionic liquids

description: Abstract: Electrospray thruster life and mission performance are strongly influenced by grid impingement, the extent of which can be correlated to emission modes that occur at steady-state extraction voltages, and thruster command transients. Most notably, we experimentally observed skewed cone-jet emission during steady-state electrospray thruster operation, which leads to the definition of an additional grid impingement mechanism that we have termed “tilted emission”. Long distance microscopy was used in conjunction with high speed videography to observe the emission site of an electrospray thruster operating with an ionic liquid propellant (EMI-Im). During steady-state thruster operation, no unsteady electrohydrodynamic emission modes were observed, though the conical meniscus exhibited steady off-axis tilt of up to 15◦. Cone tilt angle was independent over a wide range of flow rates but proved strongly dependent on extraction voltage. For the geometry and propellant used, the optimal extraction voltage was near 1.6 kV. A second experiment characterized transient emission behavior by observing startup and shutdown of the thruster via flow or voltage. Three of the four possible startup and shutdown procedures transition to quiescence within ∼475 µs, with no observed unsteady modes. However, during voltage-induced thruster startup, unsteady electrohydrodynamic modes were observed.
DOI: 10.48577/jpl.jqosay
title: The Mars 2020 Engineering Cameras and Microphone on the Perseverance Rover: A Next-Generation Imaging System for Mars Exploration

description: The Mars 2020 Perseverance rover is equipped with a next-generation engineering camera imaging system that represents an upgrade over previous Mars rover missions. These upgrades will improve the operational capabilities of the rover with an emphasis on drive planning, robotic arm operation, instrument operations, sample caching activities, and documentation of key events during entry, descent, and landing (EDL). There are a total of 16 cameras in the Perseverance engineering imaging system, including 9 cameras for surface operations and 7 cameras for EDL documentation. There are 3 types of cameras designed for surface operations: Navigation cameras (Navcams, quantity 2), Hazard Avoidance Cameras (Hazcams, quantity 6), and Cachecam (quantity 1). The Navcams will acquire color stereo images of the surface with a 96° x 73° field of view at 0.33 mrad/pixel. The Hazcams will acquire color stereo images of the surface with a 136° x 102° at 0.46 mrad/pixel. The Cachecam, a new camera type, will acquire images of Martian material inside the sample tubes during caching operations at a spatial scale of 12.5 microns/pixel. There are 5 types of EDL documentation cameras: The Parachute Uplook Cameras (PUCs, quantity 3), the Descent stage Downlook Camera (DDC, quantity 1), the Rover Uplook Camera (RUC, quantity 1), the Rover Descent Camera (RDC, quantity 1), and the Lander Vision System (LVS) Camera (LCAM, quantity 1). The PUCs are mounted on the parachute support structure and will acquire video of the parachute deployment event as part of a system to characterize parachute performance. The DDC is attached to the descent stage and pointed downward, it will characterize vehicle dynamics by capturing video of the rover as it descends from the skycrane. The rover-mounted RUC, attached to the rover and looking upward, will capture similar video of the skycrane from the vantage point of the rover and will also acquire video of the descent stage flyaway event. The RDC, attached to the rover and looking downward, will document plume dynamics by imaging the Martian surface before, during, and after rover touchdown. The LCAM, mounted to the bottom of the rover chassis and pointed downward, will acquire 90° x 90° FOV images during the parachute descent phase of EDL as input to an onboard map localization by the Lander Vision System (LVS). The rover also carries a microphone, mounted externally on the rover chassis, to capture acoustic signatures during and after EDL. The Perseverance rover launched from Earth on July 30th, 2020, and touchdown on Mars is scheduled for February 18th, 2021.
DOI: 10.48577/jpl.lss0i9
title: Wintertime particulate matter decrease buffered by unfavorable chemical processes despite emission reductions in China

description: Extreme and persistent haze events frequently occur during wintertime China. While recent emissions reductions reduced annual mean fine particulate matter (PM2.5) concentrations over eastern China, their effectiveness on wintertime PM2.5 trend remains uncertain. We use observations and model simulations to quantify seasonal differences in PM2.5 trends and investigate the underlying chemical mechanisms driving such differences. We find a much slower decrease in observed wintertime PM2.5 (–3.2% yr-1) since 2014, in contrast to a drastic summertime decrease (–10.3% yr-1). Simulations show two previously underappreciated mechanisms buffering wintertime PM2.5 decrease, indcluding an increase in oxidation capacity due to nitrogen oxides (NOx) reductions under wintertime volatile organic compound (VOC)-limited chemistry, and an enhanced conversion of nitric acid to nitrate by ammonia due to sulfur dioxide reductions. Our findings suggest that control policies targeting VOC and deep NOx reductions are needed to improve wintertime PM2.5 air quality over China.
DOI: 10.48577/jpl.lwrpih
title: Multilayer Heater Nano-Cryotron: A Superconducting Nanowire-Based Thermal Switch

description: We demonstrate a multilayer nanoscale cryogenic heater-based switch (M-hTron) that uses a nor-mal metal heater overlapping a thin lm superconductor separated by a thin insulating layer. TheM-hTron eliminates leakage current found in three terminal superconducting switches and appliesheat locally to the superconductor, reducing the energy required to switch the device. Modelingusing the energy balance equations and the acoustic mismatch model demonstrates reasonable agree-ment with experiment. The M-hTron is a promising device for digital superconducting electronicsrequiring high fan-out and oers the possibility of enhancing readout for superconducting nanowiresingle-photon detectors.
DOI: 10.48577/jpl.3l51o7
title: A Distant Fast Radio Burst Associated to its Host Galaxy with the Very Large Array

description: We present the discovery and subarcsecond localization of a new Fast Radio Burst with the Karl G. Jansky Very Large Array and realfast search system. The FRB was discovered on 2019 June 14 with a dispersion measure of 959 pc/cm3. This is the highest DM of any localized FRB and its measured burst fluence of 0.6 Jy ms is less than nearly all other FRBs. The source is not detected to repeat in 39 hours of VLA observing and 153 hours of CHIME/FRB observing. We describe a suite of statistical and data quality tests we used to verify the significance of the event and its localization precision. Follow-up optical/infrared photometry with Keck and Gemini associate the FRB to a pair of galaxies with r ∼ 23 mag. The false-alarm rate for radio transients of this significance that are associated with a host galaxy is roughly 3E−4 hr−1.
DOI: 10.48577/jpl.7tirr8
title: Improving Access to Geodetic Imaging Crustal Deformation Data Using GeoGateway

description: GeoGateway (http://geo-gateway.org) is a web-based interface for analysis and modeling of geodetic imaging data and to support response to related disasters. Geodetic imaging data product currently supported by GeoGateway include Global Navigation Satellite System (GNSS) daily position time series and derive velocities and displacements and airborne Interferometric Synthetic Aperture Radar (InSAR) from NASA’s UAVSAR platform. GeoGateway allows users to layer data products in a web map interface and extract information from various tools. Extracted products can be downloaded for further analysis. GeoGateway includes overlays of California fault traces, seismicity from user selected search parameters, and user supplied map files. GeoGateway also provides earthquake nowcasts and hazard maps as well as products created for related response to natural disasters. A user guide is present in the GeoGateway interface. The GeoGateway development team is also growing the user base through workshops, webinars, and video tutorials. GeoGateway is used in the classroom and for research by experts and non-experts including by students.
DOI: 10.48577/jpl.fpb8a8
title: Evaluation of precipitation vertical profiles estimated by GPM-era satellite-based passive microwave retrievals

description: Precipitation estimation based on passive microwave (MW) observations from low Earth-orbiting satellites is one of the essential variables for understanding the global climate. However, almost all validation studies for such precipitation estimation have focused only on the surface precipitation rate. This study investigates the vertical precipitation profiles estimated by two passive MW-based retrieval algorithms, i.e., the Emissivity Principal Components (EPC) algorithm and the Goddard Profiling Algorithm (GPROF). The passive MW-based condensed water content profiles estimated from the Global Precipitation Measurement Microwave Imager (GMI) are validated using the GMI + Dual-frequency Precipitation Radar combined algorithm as the reference product. It is shown that the EPC generally underestimates the magnitude of the condensed water content profiles, described by the mean condensed water content, by about 20 - 50% in the middle-to-high latitudes, while GPROF overestimates it by about 20 - 50% in the middle-to-high latitudes and more than 50% in the tropics. Part of the EPC magnitude biases is associated with the representation of the precipitation type (i.e., convective and stratiform) in the retrieval algorithm. This suggests that a separate technique for precipitation type identification would aid in mitigating these biases. In contrast to the magnitude of the profile, the profile shapes are relatively well represented by these two passive MW-based retrievals. The joint analysis between the estimation performances of the vertical profiles and surface precipitation rate shows that the physically reasonable connections between the surface precipitation rate and the associated vertical profiles are achieved to some extent by the passive MW-based algorithms.
DOI: 10.48577/jpl.il4nmw
title: Optimization of laser stabilization via self-injection locking to a whispering-gallery-mode microresonator

description: Self-injection locking is a dynamic phenomenon representing stabilization of the emission frequency of an oscillator with a passive cavity enabling frequency filtered coherent feedback to the oscillator cavity. For instance, self-injection locking of a semiconductor laser to a high-quality-factor (high-Q) whispering gallery mode (WGM) microresonator can result in multiple orders of magnitude reduction of the laser linewidth. The phenomenon was broadly studied in experiments, but its detailed theoretical model allowing improving the stabilization performance does not exist. In this paper we develop such a theory. We introduce five parameters identifying efficiency of the self-injection locking in an experiment, comprising back-scattering efficiency, phase delay between the laser and the high-Q cavities, frequency detuning between the laser and the high-Q cavities, the pump coupling efficiency, the optical path length between the laser and the microresonator. Our calculations show that the laser linewidth can be improved by two orders of magnitude compared with the case of not optimal self-injection locking. We present recommendations on the experimental realization of the optimal self-injection locking regime. The theoretical model provides deeper understanding of the self-injection locking and benefits multiple practical applications of self-injection locked oscillators.
DOI: 10.48577/jpl.orkgkt
title: Color Properties at the Mars InSight Landing Site

description: The color properties observed at the InSight landing site by the lander cameras are spectral mixtures of two source materials: gray-black rocky material with chromaticity values of (x = 0.32, y = 0.32) and yellowish-brown dust with chromaticity values of (x = 0.42, y = 0.36). These results are consistent with published values from other Mars landed missions. The InSight measurements also include the first published value of the whitepoint of Mars daylight (chromaticity of x=0.35,y=0.34), which is redder than earth daylight by 𝛿x= 0.04 and 𝛿y = 0.01. InSight measurements also show a subtle (𝛿x= 0.02 and 𝛿y = 0.01) difference in color between the near field terrain (within 20 meters of the lander) and the far field area beyond. This color difference is believed to be caused by dust being blown off by near field terrain by the lander rockets during the landing event. The visual difference between the two regions is caused primarily by the brightness variation. Chromaticity measurements of the Martian sky also match previous missions with additional variability caused by differences in dust loading and the dynamic nature of the Martian atmosphere.
DOI: 10.48577/jpl.v0w6o1
title: HAWC+ Far-Infrared Observations of the Magnetic Field Geometry in M51 and NGC 891.

description: SOFIA HAWC+ polarimetry at 154 m is reported for the face-on galaxy M51 and the edge-on galaxy NGC 891. For M51, the polarization vectors (1 􀀀 9%, rotated to show the inferred magnetic eld direction) generally follow the spiral pattern dened by the molecular gas distribution, the far- infrared (FIR) intensity contours, and other tracers of star formation. Accounting for observational errors and the uncertain contribution of a random component to the magnetic eld, the FIR vectors in the outer arms may be consistent with the spiral pattern, but in the center of M51 the vectors show a more open pattern than the tracers. The fractional polarization is much lower in the FIR- Corresponding author: Terry Jay Jones tjj@astro.umn.edu 2 Jones et al. bright central regions than in the outer regions, and we rule out loss of grain alignment and variations in magnetic eld strength as causes. When compared with existing synchrotron observations, which sample dierent regions with dierent weighting, we nd the net position angles are strongly correlated, the fractional polarizations are moderately correlated, but the polarized intensities are uncorrelated. We argue that the low fractional polarization in the central regions must be due to signicant numbers of highly turbulent segments across the beam and along lines of sight in the beam in the central 3 kpc of M51. For the region further out from the center, the fractional polarization is statistically the same in the relatively poorly sampled inter-arm regions and in the spiral arms themselves, indicating the random component to the eld geometry in our beam is similar between these regions. For NGC 891, the FIR polarization vectors within an intensity contour of 1500 MJy sr􀀀1 are oriented very close to the plane of the galaxy, unlike the near-infrared (NIR) and radio measurements of the magnetic eld geometry, which show a clear 15 oset from the plane at many locations. The FIR polarimetry is probably sampling the magnetic eld geometry in NGC 891 much deeper into the disk than is possible with NIR polarimetry and radio synchrotron measurements. In some locations in NGC 891 the FIR polarization is very low, suggesting we are preferentially viewing the magnetic eld mostly along the line of sight, down the length of embedded spiral arms. There is tentative evidence for a vertical eld in the polarized emission o the plane of the disk, possibly associated with vertical dust columns seen at optical wavelengths.
DOI: 10.48577/jpl.w58bfo
title: Cross-bispectra Constraints on Modi ed Gravity Theories from Nancy Grace Roman Space Telescope and Rubin Observatory Legacy Survey of Space and Time

description: One major goal of upcoming large-scale-structure surveys is to constrain dark energy and modified gravity theories. In particular, galaxy clustering and gravitational lensing convergence are probes sensitive to modifications of general relativity. While the standard analysis for these surveys typically includes power spectra or 2-point correlation functions, it is known that the bispectrum contains more information, and could offer improved constraints on parameters when combined with the power spectra. However, the use of bispectra has been limited so far to one single probe, e.g. the lensing convergence bispectrum or the galaxy bispectrum. In this paper, we extend the formalism to explore the power of cross-bispectra between different probes, and exploit their ability to break parameter degeneracies and improve constraints. We study this on a test case of lensing convergence and galaxy density auto- and cross-bispectra, for a particular sub-class of Horndeski theories parametrized by $c_M$ and $c_B$. Using the 2000 deg$^2$ notional survey of the Nancy Grace Roman Space Telescope with overlapping photometry from the Rubin Observatory Legacy Survey of Space and Time, we find that a joint power spectra and bispectra analysis with three redshift bins at $l_{\rm max} = 1000$ yields $\sigma_{c_M} = 1.0$ and $\sigma_{c_B} = 0.3$, both a factor of $\sim$1.2 better than the power spectra results; this would be further improved to $\sigma_{c_M} = 0.7$ and $\sigma_{c_B} = 0.2$ if $l_{\rm max} = 3000$ is taken. Furthermore, we find that using all possible cross-bispectra between the two probes in different tomographic bins improves upon auto-bispectra results by a factor of 1.3 in $\sigma_{c_M}$, 1.1 in $\sigma_{c_B}$ and 1.3 in $\sigma_{\Omega_m}$. We expect that similar benefits of using cross-bispectra between probes could apply to other science cases and surveys.
DOI: 10.48577/jpl.beflc0
title: Draft Genome Sequences of Bacillaceae strains isolated from International Space Station

description: The draft genome sequences of thirty bacterial isolates belonging to the family Bacillaceae were collected from the International Space Station, assembled and identified. Further analysis of these sequences will enable us to better study this organism for agricultural application, and planetary protection.
DOI: 10.48577/jpl.ltfazz
title: LEGO II: A 3 mm molecular line study covering 100 pc of one of the most actively star-forming portions

description: The current generation of (sub)mm-telescopes have allowed molecular line emission to become a major tool for studying the physical, kinematic, and chemical properties of extragalactic systems, yet exploiting these observations requires a detailed understanding of where emission lines originate within the MilkyWay. In this paper, we present 6000 ( 3 pc) resolution observations of many 3mm-band molecular lines across a large map of the W49 massive star-forming region ( 100 100 pc at 11 kpc), which were taken as part of the “LEGO” IRAM-30m large project. We find that the spatial extent or brightness of the molecular line transitions are not well correlated with their critical densities, highlighting abundance and optical depth must be considered when estimating line emission characteristics. We explore how the total emission and emission efficiency (i.e. line brightness per H2 column density) of the line emission vary as a function of molecular hydrogen column density and dust temperature. We find that there is not a single region of this parameter space responsible for the brightest and most efficiently emitting gas for all species. For example, we find that the HCN transition shows high emission efficiency at high column density (1022 cm􀀀2) and moderate temperatures (35 K), whilst e.g. N2H+ emits most efficiently towards lower temperatures (1022 cm􀀀2; &lt;20 K). We determine XCO¹1􀀀0º 0:31020 cm􀀀2 ¹Kkm s􀀀1º􀀀1, and HCN¹1􀀀0º 30M ¹Kkm s􀀀1 pc2º􀀀1, which both differ significantly from the commonly adopted values. In
DOI: 10.48577/jpl.pp3up2
title: A roadmap to IndOOS-2: Better observations of the rapidly-warming Indian Ocean

description: Almost one-third of humanity lives around the Indian Ocean, many in countriesdependent on fisheries and rain-fed agriculture that are vulnerable to climate variabilityand extremes. The Indian Ocean alone has absorbed a quarter of the global oceanic heatuptake over the last two decades and the fate of this heat and its impact on future changeis unknown. Climate models project accelerating sea level rise, more frequent extremes inmonsoon rainfall, and decreasing oceanic productivity. The Indian Ocean ObservingSystem (IndOOS), established in 2006, is a multi-national network of sustained oceanicmeasurements that underpin understanding and forecasting of weather and climate forthe Indian Ocean region and beyond. A three-year, international review of the IndOOSby more than 60 scientific experts highlights the need for an enhanced observing networkthat can better meet regional scientific and societal challenges and provide more reliableforecasts. Here we present core findings from this review, including the need for 1)chemical, biological, and ecosystem measurements alongside physical parameters; 2)expansion into the western tropics to improve understanding of the monsoon circulation;3) better resolved upper-ocean processes to improve understanding of air-sea couplingand yield better sub-seasonal to seasonal predictions; and 4) expansion into key coastalregions and the deep ocean to better constrain the basin-wide energy budget. These goalswill require new partnerships with and among Indian Ocean rim countries, creatingopportunities for them to enhance their monitoring and forecasting capacity as part ofIndOOS-2.
DOI: 10.48577/jpl.1x7eva
title: A Geologically Robust Procedure For Observing Rocky Exoplanets to Ensure that Detection of Atmospheric Oxygen is an Earth-Like Biosignature

description: In the next decades, the astrobiological community will debate whether the first observations of oxygen in an exoplanet’s atmosphere signifies life, so it is critical to establish procedures now for collection and interpretation of such data. We present a step-by-step observational strategy for using oxygen as a robust biosignature, to prioritize exoplanet targets and design future observations. It is premised on avoiding planets lacking subaerial weathering of continents, which would imply geochemical cycles drastically different from Earth’s, precluding use of oxygen as a biosignature. The strategy starts with the most readily obtained data: semi-major axis and stellar luminosity to ensure residence in the habitable zone; stellar XUV flux, to ensure an exoplanet can retain a secondary (outgassed) atmosphere. Next, high- precision mass and radius information should be combined with high-precision stellar abundance data, to constrain the exoplanet’s water content; those incompatible with &lt; 0.1wt% H2O can be deprioritized. Then, reflectance photometry or low-resolution transmission spectroscopy should confirm an optically thin atmosphere. Subsequent long-duration, high- resolution transmission spectroscopy should search for oxygen and ensure that water vapor and CO2 are present only at low (~102-104 ppm levels). Assuming oxygen is found, attribution to life requires the most difficult step, acquisition of a detailed, multispectral light curve of the exoplanet, to ensure both surface land and water. Exoplanets failing some of these steps might be habitable, even have observable biogenic oxygen, but should be deprioritized because oxygen could not be attributed unambiguously to life, and life therefore would not be detectable on such planets.