Showing papers by "Ames Research Center published in 2021"
Google1, University of Michigan2, University of Massachusetts Amherst3, University of California, Santa Barbara4, University of California, Riverside5, Volkswagen6, University of California, Berkeley7, Ames Research Center8, Leiden University9, University of Erlangen-Nuremberg10, Harvard University11
TL;DR: The application of the Google Sycamore superconducting qubit quantum processor to combinatorial optimization problems with the quantum approximate optimization algorithm (QAOA) is demonstrated and an approximation ratio is obtained that is independent of problem size and for the first time, that performance increases with circuit depth.
Abstract: Faster algorithms for combinatorial optimization could prove transformative for diverse areas such as logistics, finance and machine learning. Accordingly, the possibility of quantum enhanced optimization has driven much interest in quantum technologies. Here we demonstrate the application of the Google Sycamore superconducting qubit quantum processor to combinatorial optimization problems with the quantum approximate optimization algorithm (QAOA). Like past QAOA experiments, we study performance for problems defined on the planar connectivity graph native to our hardware; however, we also apply the QAOA to the Sherrington–Kirkpatrick model and MaxCut, non-native problems that require extensive compilation to implement. For hardware-native problems, which are classically efficient to solve on average, we obtain an approximation ratio that is independent of problem size and observe that performance increases with circuit depth. For problems requiring compilation, performance decreases with problem size. Circuits involving several thousand gates still present an advantage over random guessing but not over some efficient classical algorithms. Our results suggest that it will be challenging to scale near-term implementations of the QAOA for problems on non-native graphs. As these graphs are closer to real-world instances, we suggest more emphasis should be placed on such problems when using the QAOA to benchmark quantum processors. It is hoped that quantum computers may be faster than classical ones at solving optimization problems. Here the authors implement a quantum optimization algorithm over 23 qubits but find more limited performance when an optimization problem structure does not match the underlying hardware.
411 citations
22 Mar 2021
TL;DR: This paper presents several new evaluation metrics tailored for prognostics that were recently introduced and were shown to effectively evaluate various algorithms as compared to other conventional metrics.
Abstract: Prognostic performance evaluation has gained significant attention in the past few years. Currently, prognostics concepts lack standard definitions and suffer from ambiguous and inconsistent interpretations. This lack of standards is in part due to the varied end-user requirements for different applications, time scales, available information, domain dynamics, etc. to name a few. The research community has used a variety of metrics largely based on convenience and their respective requirements. Very little attention has been focused on establishing a standardized approach to compare different efforts. This paper presents several new evaluation metrics tailored for prognostics that were recently introduced and were shown to effectively evaluate various algorithms as compared to other conventional metrics. Specifically, this paper presents a detailed discussion on how these metrics should be interpreted and used. These metrics have the capability of incorporating probabilistic uncertainty estimates from prognostic algorithms. In addition to quantitative assessment they also offer a comprehensive visual perspective that can be used in designing the prognostic system. Several methods are suggested to customize these metrics for different applications. Guidelines are provided to help choose one method over another based on distribution characteristics. Various issues faced by prognostics and its performance evaluation are discussed followed by a formal notational framework to help standardize subsequent developments.
364 citations
University of Chicago1, University of Delaware2, ETH Zurich3, Ames Research Center4, Oregon State University5, University of Southern California6, Stanford University7, University of Helsinki8, Cleveland Clinic Lerner College of Medicine9, Cleveland Clinic Lerner Research Institute10, Swedish Defence Research Agency11, Smithsonian Tropical Research Institute12, University of New South Wales13, Montana State University14, University of Wisconsin-Madison15, Carleton College16, University of Copenhagen17, IFREMER18, Marine Biological Laboratory19, Université Paris-Saclay20, University of Washington21
TL;DR: The workflows designed to enable researchers to interpret data can constrain the biological questions that can be asked as discussed by the authors, but the workflows can also be difficult to adapt to real-world applications.
Abstract: Big data abound in microbiology, but the workflows designed to enable researchers to interpret data can constrain the biological questions that can be asked. Five years after anvi’o was first published, this community-led multi-omics platform is maturing into an open software ecosystem that reduces constraints in ‘omics data analyses.
220 citations
Massachusetts Institute of Technology1, University of Wisconsin-Madison2, University of Texas at Austin3, Dartmouth College4, Smithsonian Institution5, California Institute of Technology6, University of New Mexico7, University of Bern8, Lehigh University9, Open University10, Columbia University11, University of Florida12, University of California, Santa Cruz13, University of Maryland, College Park14, University of Cambridge15, Space Telescope Science Institute16, Goddard Space Flight Center17, University of Maryland, Baltimore County18, Ames Research Center19, Search for extraterrestrial intelligence20, Princeton University21, University of Chicago22, University of Colorado Boulder23, Technical University of Denmark24, Arizona State University25, Cornell University26, University of California, Riverside27, Aarhus University28, Max Planck Society29, Spanish National Research Council30, Western Connecticut State University31, INAF32, Vanderbilt University33, Fisk University34, University of Geneva35
TL;DR: In this article, the authors presented 2241 exoplanet candidates identified with data from the Transiting Exoplanet Survey Satellite (TESS) during its 2-year Prime Mission.
Abstract: We present 2241 exoplanet candidates identified with data from the Transiting Exoplanet Survey Satellite (TESS) during its 2 yr Prime Mission. We list these candidates in the TESS Objects of Interest (TOI) Catalog, which includes both new planet candidates found by TESS and previously known planets recovered by TESS observations. We describe the process used to identify TOIs, investigate the characteristics of the new planet candidates, and discuss some notable TESS planet discoveries. The TOI catalog includes an unprecedented number of small planet candidates around nearby bright stars, which are well suited for detailed follow-up observations. The TESS data products for the Prime Mission (sectors 1-26), including the TOI catalog, light curves, full-frame images, and target pixel files, are publicly available at the Mikulski Archive for Space Telescopes.
140 citations
University of New South Wales1, Boise State University2, United States Geological Survey3, Ames Research Center4, Northern Arizona University5, Bermuda Institute of Ocean Sciences6, Goddard Space Flight Center7, University of South Florida8, California Institute of Technology9, University of Maryland, Baltimore County10, University of California, Santa Cruz11, Arizona State University12, United States Naval Research Laboratory13, Kent State University14, Joint Institute for Nuclear Research15, University of Nebraska–Lincoln16, University of California, Santa Barbara17, University of Zurich18, Brookhaven National Laboratory19, City University of New York20, University of California, Davis21, University of Massachusetts Amherst22, Universiti Sains Malaysia23, Universities Space Research Association24
TL;DR: The 2017-2027 National Academies' Decadal Survey, Thriving on Our Changing Planet, recommended Surface Biology and Geology (SBG) as a "designated targeted observable" (DO) as discussed by the authors.
135 citations
University of Oklahoma1, University of Washington2, University of Miami3, Ames Research Center4, Universities Space Research Association5, Goddard Space Flight Center6, North-West University7, University of Exeter8, University of Paris9, Centre national de la recherche scientifique10, University of Oxford11, Goddard Institute for Space Studies12, University of Iowa13, University of California, Los Angeles14, University of Hawaii15, California Institute of Technology16, Cooperative Institute for Mesoscale Meteorological Studies17, University of North Dakota18, École Polytechnique Fédérale de Lausanne19, Georgia Institute of Technology20, Foundation for Research & Technology – Hellas21, Mount Allison University22, Langley Research Center23, University of Auckland24, University of Colorado Boulder25, Brookhaven National Laboratory26, Marshall Space Flight Center27, Tel Aviv University28, University of California, Santa Cruz29, NASA Headquarters30
TL;DR: The ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) project is a five-year NASA EVS-2 (Earth Venture Suborbital-2) investigation with three Intensive Observation Periods designed to study key atmospheric processes that determine the climate impacts of these aerosols.
Abstract: . Southern Africa produces almost a third of the Earth’s biomass burning (BB) aerosol particles, yet the fate of these particles and their influence on regional and global climate is poorly understood. ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) is a five-year NASA EVS-2 (Earth Venture Suborbital-2) investigation with three Intensive Observation Periods designed to study key atmospheric processes that determine the climate impacts of these aerosols. During the Southern Hemisphere winter and spring (June-October), aerosol particles reaching 3–5 km in altitude are transported westward over the South-East Atlantic, where they interact with one of the largest subtropical stratocumulus subtropical stratocumulus (Sc) cloud decks in the world. The representation of these interactions in climate models remains highly uncertain in part due to a scarcity of observational constraints on aerosol and cloud properties, and due to the parameterized treatment of physical processes. Three ORACLES deployments by the NASA P-3 aircraft in September 2016, August 2017 and October 2018 (totaling ~350 science flight hours), augmented by the deployment of the NASA ER-2 aircraft for remote sensing in September 2016 (totaling ~100 science flight hours), were intended to help fill this observational gap. ORACLES focuses on three fundamental science questions centered on the climate effects of African BB aerosols: (a) direct aerosol radiative effects; (b) effects of aerosol absorption on atmospheric circulation and clouds; (c) aerosol-cloud microphysical interactions. This paper summarizes the ORACLES science objectives, describes the project implementation, provides an overview of the flights and measurements in each deployment, and highlights the integrative modeling efforts from cloud to global scales to address science objectives. Significant new findings on the vertical structure of BB aerosol physical and chemical properties, chemical aging, cloud condensation nuclei, rain and precipitation statistics, and aerosol indirect effects are emphasized, but their detailed descriptions are the subject of separate publications. The main purpose of this paper is to familiarize the broader scientific community with the ORACLES project and the data set it produced.
122 citations
TL;DR: In this article, the authors describe the quantum information propagation process in quantum systems, which can spread initially localized quantum information into the exponentially many degrees of freedom of the entire system, known as quantum quantum information dissemination.
Abstract: Interactions in quantum systems can spread initially localized quantum information into the exponentially many degrees of freedom of the entire system. Understanding this process, known as quantum ...
74 citations
TL;DR: This paper presented a new generation of substellar atmosphere and evolution models, appropriate for application to studies of L, T, and Y-type brown dwarfs and self-luminous extrasolar planets.
Abstract: We present a new generation of substellar atmosphere and evolution models, appropriate for application to studies of L, T, and Y-type brown dwarfs and self-luminous extrasolar planets. The atmosphere models describe the expected temperature-pressure profiles and emergent spectra of atmospheres in radiative-convective equilibrium with effective temperatures and gravities within the ranges $200\le T_{\rm eff}\le2400\,\rm K$ and $2.5\le \log g \le 5.5$. These ranges encompass masses from about 0.5 to 85 Jupiter masses for a set of metallicities ($[{\rm M/H}] = -0.5$ to $+0.5$), C/O ratios (from 0.5 to 1.5 times that of solar), and ages. The evolution tables describe the cooling of these substellar objects through time. These models expand the diversity of model atmospheres currently available, notably to cooler effective temperatures and greater ranges in C/O. Notable improvements from past such models include updated opacities and atmospheric chemistry. Here we describe our modeling approach and present our initial tranche of models for cloudless, chemical equilibrium atmospheres. We compare the modeled spectra, photometry, and evolution to various datasets.
66 citations
Arizona State University1, California Institute of Technology2, University of Copenhagen3, Cornell University4, The Planetary Society5, University of Winnipeg6, University College London7, Ames Research Center8, University of Hawaii9, United States Geological Survey10, Purdue University11, Free University of Berlin12, Johns Hopkins University13, Space Science Institute14, Joanneum Research15, Imperial College London16, VRVis17, German Aerospace Center18, Western Washington University19
TL;DR: Mastcam-Z as discussed by the authors is a multispectral, stereoscopic imaging investigation on the Mars 2020 mission's Perseverance rover, which consists of a pair of focusable, 4:1 zoomable cameras that provide broadband red/green/blue and narrowband 400-1000-nm color imaging with fields of view from 25.6°× 19.2° (26mm focal length at 283μrad/pixel) to 62°
Abstract: Mastcam-Z is a multispectral, stereoscopic imaging investigation on the Mars 2020 mission's Perseverance rover. Mastcam-Z consists of a pair of focusable, 4:1 zoomable cameras that provide broadband red/green/blue and narrowband 400-1000 nm color imaging with fields of view from 25.6° × 19.2° (26 mm focal length at 283 μrad/pixel) to 6.2° × 4.6° (110 mm focal length at 67.4 μrad/pixel). The cameras can resolve (≥ 5 pixels) ∼0.7 mm features at 2 m and ∼3.3 cm features at 100 m distance. Mastcam-Z shares significant heritage with the Mastcam instruments on the Mars Science Laboratory Curiosity rover. Each Mastcam-Z camera consists of zoom, focus, and filter wheel mechanisms and a 1648 × 1214 pixel charge-coupled device detector and electronics. The two Mastcam-Z cameras are mounted with a 24.4 cm stereo baseline and 2.3° total toe-in on a camera plate ∼2 m above the surface on the rover's Remote Sensing Mast, which provides azimuth and elevation actuation. A separate digital electronics assembly inside the rover provides power, data processing and storage, and the interface to the rover computer. Primary and secondary Mastcam-Z calibration targets mounted on the rover top deck enable tactical reflectance calibration. Mastcam-Z multispectral, stereo, and panoramic images will be used to provide detailed morphology, topography, and geologic context along the rover's traverse; constrain mineralogic, photometric, and physical properties of surface materials; monitor and characterize atmospheric and astronomical phenomena; and document the rover's sample extraction and caching locations. Mastcam-Z images will also provide key engineering information to support sample selection and other rover driving and tool/instrument operations decisions.
58 citations
13 Jan 2021
TL;DR: In this article, the authors developed a new realistic dataset of run-to-failure trajectories for a fleet of aircraft engines under real flight conditions, which can be used for fault diagnostics.
Abstract: A key enabler of intelligent maintenance systems is the ability to predict the remaining useful lifetime (RUL) of its components, i.e., prognostics. The development of data-driven prognostics models requires datasets with run-to-failure trajectories. However, large representative run-to-failure datasets are often unavailable in real applications because failures are rare in many safety-critical systems. To foster the development of prognostics methods, we develop a new realistic dataset of run-to-failure trajectories for a fleet of aircraft engines under real flight conditions. The dataset was generated with the Commercial Modular Aero-Propulsion System Simulation (CMAPSS) model developed at NASA. The damage propagation modelling used in this dataset builds on the modelling strategy from previous work and incorporates two new levels of fidelity. First, it considers real flight conditions as recorded on board of a commercial jet. Second, it extends the degradation modelling by relating the degradation process to its operation history. This dataset also provides the health, respectively, fault class. Therefore, besides its applicability to prognostics problems, the dataset can be used for fault diagnostics.
54 citations
Johns Hopkins University Applied Physics Laboratory1, Goddard Space Flight Center2, Jet Propulsion Laboratory3, Ithaca College4, Ames Research Center5, Planetary Science Institute6, Southwest Research Institute7, Smithsonian Institution8, NASA Headquarters9, University of Oxford10, Honeybee Robotics11, ETH Zurich12
TL;DR: The Dragonfly mission as discussed by the authors was the first NASA mission to explicitly incorporate the search for signs of life into its mission goals since the Viking landers in 1976, along with Perseverance.
Abstract: NASA's Dragonfly mission will send a rotorcraft lander to the surface of Titan in the mid-2030s. Dragonflyʼs science themes include investigation of Titan's prebiotic chemistry, habitability, and potential chemical biosignatures from both water-based "life as we know it" (as might occur in the interior mantle ocean, potential cryovolcanic flows, and/or impact melt deposits) and potential "life, but not as we know it" that might use liquid hydrocarbons as a solvent (within Titan's lakes, seas, and/or aquifers). Consideration of both of these solvents simultaneously led to our initial landing site in Titan's equatorial dunes and interdunes to sample organic sediments and water ice, respectively. Ultimately, Dragonflyʼs traverse target is the 80 km diameter Selk Crater, at 7°N, where we seek previously liquid water that has mixed with surface organics. Our science goals include determining how far prebiotic chemistry has progressed on Titan and what molecules and elements might be available for such chemistry. We will also determine the role of Titan's tropical deserts in the global methane cycle. We will investigate the processes and processing rates that modify Titan's surface geology and constrain how and where organics and liquid water can mix on and within Titan. Importantly, we will search for chemical biosignatures indicative of past or extant biological processes. As such, Dragonfly, along with Perseverance, is the first NASA mission to explicitly incorporate the search for signs of life into its mission goals since the Viking landers in 1976.
University of California, Berkeley1, Swarthmore College2, Smithsonian Institution3, Massachusetts Institute of Technology4, Princeton University5, Ames Research Center6, Goddard Space Flight Center7, University of Maryland, Baltimore County8, Cadi Ayyad University9, University of Liège10, Université de Montréal11, George Mason University12, American Association of Variable Star Observers13, University of Southern Queensland14, University of Louisville15, Space Telescope Science Institute16, University of La Laguna17, Spanish National Research Council18, University of Arizona19, Search for extraterrestrial intelligence20, University of Colorado Boulder21
TL;DR: TICERATOPS is currently the only TESS vetting and validation tool that models transits from nearby contaminant stars in addition to the target star and should be encouraged to prioritize follow-up observations that confirm bona fide planets and identify false positives originating from nearby stars.
Abstract: We thank the NASA TESS Guest Investigator Program for supporting this work through grant 80NSSC18K1583 (awarded to C.D.D.). S.G. and C.D.D. also appreciate and acknowledge support from the Hellman Fellows Fund, the Alfred P. Sloan Foundation, the David and Lucile Packard Foundation, and the NASA Exoplanets Research Program (XRP) through grant
80NSSC20K0250. This work makes use of observations from the LCOGT network. This material is based on work supported by the National Science Foundation Graduate Research Fellowship Program under grant No. DGE-1650115. The research leading
to these results has received funding from the ARC grant for Concerted Research Actions, financed by the WalloniaBrussels Federation. TRAPPIST is funded by the Belgian Fund for Scientific Research (Fond National de la Recherche Scientifique, FNRS) under the grant FRFC 2.5.594.09.F, with the participation of the Swiss National Science Foundation (SNF). M.G. and E.J. are F.R.S.-FNRS Senior Research Associates. The MEarth Team gratefully acknowledges the David and Lucile Packard Fellowship for Science and Engineering (awarded to D.C.), continued support by the NSF mostly recently under grant AST-1616624, and support by NASA under grant 80NSSC18K0476 (XRP Program). This work is made possible by a grant from the John Templeton
Foundation. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the John Templeton Foundation. J.N.W. thanks the HeisingSimons Foundation for support. Funding for the TESS mission is provided by NASA’s Science Mission directorate. This research has made use of the Exoplanet Follow-up Observation Program website, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This paper includes data collected by the TESS mission, which are publicly available from the Mikulski Archive for Space Telescopes (MAST). We acknowledge the use of public TESS Alert data from pipelines at the TESS Science Office and TESS Science Processing Operations Center. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products.
TL;DR: In this paper, the authors present a model that incorporates randomized injection of reducing greenhouse gases and oxidation due to hydrogen escape to investigate the conditions responsible for these diverse observations, and find that Mars could have transitioned repeatedly from reducing (hydrogen-rich) to oxidizing (oxygen-rich), atmospheric conditions in its early history.
Abstract: Reconciling the geology of Mars with models of atmospheric evolution remains a major challenge. Martian geology is characterized by past evidence for episodic surface liquid water, and geochemistry indicating a slow and intermittent transition from wetter to drier and more oxidizing surface conditions. Here we present a model that incorporates randomized injection of reducing greenhouse gases and oxidation due to hydrogen escape to investigate the conditions responsible for these diverse observations. We find that Mars could have transitioned repeatedly from reducing (hydrogen-rich) to oxidizing (oxygen-rich) atmospheric conditions in its early history. Our model predicts a generally cold early Mars, with mean annual temperatures below 240 K. If peak reducing-gas release rates and background carbon dioxide levels are high enough, it nonetheless exhibits episodic warm intervals sufficient to degrade crater walls, form valley networks and create other fluvial/lacustrine features. Our model also predicts transient build-up of atmospheric oxygen, which can help explain the occurrence of oxidized mineral species such as manganese oxides at Gale Crater. We suggest that the apparent Noachian–Hesperian transition from phyllosilicate deposition to sulfate deposition around 3.5 billion years ago can be explained as a combined outcome of increasing planetary oxidation, decreasing groundwater availability and a waning bolide impactor flux, which dramatically slowed the remobilization and thermochemical destruction of surface sulfates. Ultimately, rapid and repeated variations in Mars’s early climate and surface chemistry would have presented both challenges and opportunities for any emergent microbial life. Mars’s early climate and surface chemistry varied between a generally cold, oxidizing environment and warmer, more reducing conditions, according to a model of atmospheric evolution driven by stochastic, random injection of greenhouse gases.
University of Sydney1, Macquarie University2, University of Western Australia3, Australian National University4, Ghent University5, University of New South Wales6, University of Toledo7, University of Hamburg8, University of North Carolina at Chapel Hill9, University of Oxford10, University of Queensland11, University of La Laguna12, University College London13, Spanish National Research Council14, Leiden University15, Ames Research Center16, Princeton University17, Swinburne University of Technology18, University of Melbourne19
TL;DR: In this paper, the SAMI Galaxy Survey was extended to include the full sample of 3068 unique galaxies observed, including 888 unique galaxies for the first time, and two primary spectral cubes covering the blue (370-570 nm) and red (630-740 nm) optical wavelength ranges at spectral resolving power of R = 1808 and 4304, respectively.
Abstract: We have entered a new era where integral-field spectroscopic surveys of galaxies are sufficiently large to adequately sample large-scale structure over a cosmologically significant volume. This was the primary design goal of the SAMI Galaxy Survey. Here, in Data Release 3, we release data for the full sample of 3068 unique galaxies observed. This includes the SAMI cluster sample of 888 unique galaxies for the first time. For each galaxy, there are two primary spectral cubes covering the blue (370-570 nm) and red (630-740 nm) optical wavelength ranges at spectral resolving power of R = 1808 and 4304, respectively. For each primary cube, we also provide three spatially binned spectral cubes and a set of standardized aperture spectra. For each galaxy, we include complete 2D maps from parametrized fitting to the emission-line and absorption-line spectral data. These maps provide information on the gas ionization and kinematics, stellar kinematics and populations, and more. All data are available online through Australian Astronomical Optics Data Central.
Belgian Institute for Space Aeronomy1, California Institute of Technology2, Karlsruhe Institute of Technology3, Netherlands Institute for Space Research4, University of Bremen5, European Space Agency6, University of Wollongong7, Max Planck Society8, German Aerospace Center9, Ludwig Maximilian University of Munich10, International Agency for Research on Cancer11, National Autonomous University of Mexico12, National Center for Atmospheric Research13, Finnish Meteorological Institute14, Ames Research Center15, University of Paris16, University of Liège17, Saint Petersburg State University18, Chalmers University of Technology19, University of La Réunion20, National Institute for Environmental Studies21, Nagoya University22, National Institute of Water and Atmospheric Research23, University of Toronto24, The Cyprus Institute25, Japan Aerospace Exploration Agency26, Chinese Academy of Sciences27, Remote Sensing Center28
TL;DR: In this article, the Sentinel-5 Precursor (S5P) data were validated using global Total Carbon Column Observing Network (TCCON) and Infrared Working Group of the Network for the Detection of Atmospheric Composition Change (NDACC-IRWG) network data, accounting for a prior alignment and smoothing uncertainties in the validation.
Abstract: . The Sentinel-5 Precursor (S5P) mission with the TROPOspheric Monitoring Instrument (TROPOMI) on board has been measuring solar radiation backscattered by the Earth's atmosphere and surface since its launch on 13 October 2017. In this paper, we present for the first time the S5P operational methane ( CH4 ) and carbon monoxide (CO) products' validation results covering a period of about 3 years using global Total Carbon Column Observing Network (TCCON) and Infrared Working Group of the Network for the Detection of Atmospheric Composition Change (NDACC-IRWG) network data, accounting for a priori alignment and smoothing uncertainties in the validation, and testing the sensitivity of validation results towards the application of advanced co-location criteria. We found that the S5P standard and bias-corrected CH4 data over land surface for the recommended quality filtering fulfil the mission requirements. The systematic difference of the bias-corrected total column-averaged dry air mole fraction of methane ( XCH4 ) data with respect to TCCON data is - 0.26 ± 0.56 % in comparison to - 0.68 ± 0.74 % for the standard XCH4 data, with a correlation of 0.6 for most stations. The bias shows a seasonal dependence. We found that the S5P CO data over all surfaces for the recommended quality filtering generally fulfil the missions requirements, with a few exceptions, which are mostly due to co-location mismatches and limited availability of data. The systematic difference between the S5P total column-averaged dry air mole fraction of carbon monoxide (XCO) and the TCCON data is on average 9.22±3.45 % (standard TCCON XCO) and 2.45±3.38 % (unscaled TCCON XCO). We found that the systematic difference between the S5P CO column and NDACC CO column (excluding two outlier stations) is on average 6.5±3.54 %. We found a correlation of above 0.9 for most TCCON and NDACC stations. The study shows the high quality of S5P CH4 and CO data by validating the products against reference global TCCON and NDACC stations covering a wide range of latitudinal bands, atmospheric conditions and surface conditions.
Ames Research Center1, California State University, Monterey Bay2, Desert Research Institute3, Environmental Defense Fund4, Google5, University of Idaho6, United States Department of Agriculture7, University of California, Los Angeles8, University of Nebraska–Lincoln9, United States Geological Survey10, Universidade Federal do Rio Grande do Sul11, Stanford University12, California Institute of Technology13, University of Wisconsin-Madison14, University of Montana15, University of Maryland, College Park16, University of California, Berkeley17
Instituto Geográfico Nacional1, University of La Laguna2, Spanish National Research Council3, National Autonomous University of Mexico4, University of Southampton5, University of Alaska Anchorage6, Durham University7, Max Planck Society8, Academy of Sciences of the Czech Republic9, University of Oxford10, Leiden University11, Foundation for Research & Technology – Hellas12, Tohoku University13, National Institutes of Natural Sciences, Japan14, Graduate University for Advanced Studies15, Space Telescope Science Institute16, Ames Research Center17, Stanford University18, University of Texas at San Antonio19, Peking University20, Diego Portales University21, Ghent University22, University of Belgrade23, Hokkaido University24, Ehime University25, Kagoshima University26
TL;DR: The results of the Galaxy Activity, Torus, and Outflow Survey (GATOS) as discussed by the authors were used to study the properties of the dusty molecular tori and their connection to the host galaxy in nearby Seyfert galaxies.
Abstract: We present the first results of the Galaxy Activity, Torus, and Outflow Survey (GATOS), a project aimed at understanding the properties of the dusty molecular tori and their connection to the host galaxy in nearby Seyfert galaxies. Our project expands the range of active galactic nuclei (AGN) luminosities and Eddington ratios covered by previous surveys of Seyferts conducted by the Atacama Large Millimeter Array (ALMA), allowing us to study the gas feeding and feedback cycle in a combined sample of 19 Seyferts. We used ALMA to obtain new images of the emission of molecular gas and dust using the CO(3–2) and HCO+ (4–3) lines as well as their underlying continuum emission at 870 μm with high spatial resolutions (0.1″ ∼ 7 − 13 pc) in the circumnuclear disks (CND) of ten nearby (D M ⊙ , respectively. We also detected the emission of the 4–3 line of HCO+ in four GATOS targets. The order of magnitude differences found in the CO/HCO+ ratios within our combined sample point to a very different density radial stratification inside the dusty molecular tori of these Seyferts. We find a positive correlation between the line-of-sight gas column densities responsible for the absorption of X-rays and the molecular gas column densities derived from CO toward the AGN in our sources. Furthermore, the median values of both column densities are similar. This suggests that the neutral gas line-of-sight column densities of the dusty molecular tori imaged by ALMA significantly contribute to the obscuration of X-rays. The radial distributions of molecular gas in the CND of our combined sample show signs of nuclear-scale molecular gas deficits. We also detect molecular outflows in the sources that show the most extreme nuclear-scale gas deficits in our sample. These observations find for the first time supporting evidence that the imprint of AGN feedback is more extreme in higher luminosity and/or higher Eddington ratio Seyfert galaxies.
TL;DR: In this paper, the authors compute the water activity within the clouds of Venus and other Solar System planets from observations of temperature and water-vapour abundance and find water-activity values of sulfuric acid droplets, which constitute the bulk of Venus's clouds, of ≤ 0.004, two orders of magnitude below the 0.585 limit for known extremophiles.
Abstract: The recent suggestion of phosphine in Venus’s atmosphere has regenerated interest in the idea of life in clouds. However, such analyses usually neglect the role of water activity, which is a measure of the relative availability of water, in habitability. Here we compute the water activity within the clouds of Venus and other Solar System planets from observations of temperature and water-vapour abundance. We find water-activity values of sulfuric acid droplets, which constitute the bulk of Venus’s clouds, of ≤0.004, two orders of magnitude below the 0.585 limit for known extremophiles. Considering other planets, ice formation on Mars imposes a water activity of ≤0.537, slightly below the habitable range, whereas conditions are biologically permissive (>0.585) at Jupiter’s clouds (although other factors such as their composition may play a role in limiting their habitability). By way of comparison, Earth’s troposphere conditions are, in general, biologically permissive, whereas the atmosphere becomes too dry for active life above the middle stratosphere. The approach used in the current study can also be applied to extrasolar planets. Calculations of water activity reveal that this parameter can be a substantial barrier to habitability for clouds of Solar System planets. In particular, water activity within droplets of Venus’s clouds is more than 100-fold below the threshold for biotic activity of known extremophiles.
TL;DR: In this paper, the authors summarized two decades (2000-2019) of climatology and trends in aerosol loading and optical properties using a high spatial resolution data obtained from NASA's MODIS MAIAC and MISR aerosol products supplemented by moderate resolution aerosol data from OMI sensor over South Asia (SA).
University of Southern Queensland1, University of Oxford2, George Mason University3, University of California, Riverside4, University of Wisconsin-Madison5, University of Birmingham6, Aarhus University7, Smithsonian Institution8, University of Toronto9, Adolfo Ibáñez University10, Millennium Institute11, Space Telescope Science Institute12, University of New South Wales13, University of Louisville14, Kutztown University of Pennsylvania15, Vanderbilt University16, Fisk University17, University of Sydney18, University of Texas at Austin19, Wilmington University20, Massachusetts Institute of Technology21, University of Kansas22, Yale University23, Ames Research Center24, University of North Carolina at Chapel Hill25, Indiana University26, Nanjing University27, Max Planck Society28, Pontifical Catholic University of Chile29, Princeton University30, Open University31, Lehigh University32, Goddard Space Flight Center33, Florida Gulf Coast University34, University of Porto35, INAF36, University of La Laguna37, Spanish National Research Council38, Federal University of Rio Grande do Norte39, Paris Diderot University40, Université Paris-Saclay41, Pennsylvania State University42, Heidelberg University43, University of Vienna44, Iowa State University45, Erciyes University46, University of Paris47, New York University Abu Dhabi48
TL;DR: In this paper, the authors reported the discovery of a warm sub-Saturn, TOI-257b (HD 19916b), based on data from NASA's Transiting Exoplanet Survey Satellite (TESS).
Abstract: We report the discovery of a warm sub-Saturn, TOI-257b (HD 19916b), based on data from NASA’s Transiting Exoplanet Survey Satellite (TESS). The transit signal was detected by TESS and confirmed to be of planetary origin based on radial velocity observations. An analysis of the TESS photometry, the Minerva-Australis, FEROS, and HARPS radial velocities, and the asteroseismic data of the stellar oscillations reveals that TOI-257b has a mass of MP = 0.138 ± 0.023 $\rm {M_J}$ (43.9 ± 7.3 $\, M_{\rm \oplus}$), a radius of RP = 0.639 ± 0.013 $\rm {R_J}$ (7.16 ± 0.15 $\, \mathrm{ R}_{\rm \oplus}$), bulk density of $0.65^{+0.12}_{-0.11}$ (cgs), and period $18.38818^{+0.00085}_{-0.00084}$ $\rm {days}$. TOI-257b orbits a bright (V = 7.612 mag) somewhat evolved late F-type star with M* = 1.390 ± 0.046 $\rm {M_{sun}}$, R* = 1.888 ± 0.033 $\rm {R_{sun}}$, Teff = 6075 ± 90 $\rm {K}$, and vsin i = 11.3 ± 0.5 km s−1. Additionally, we find hints for a second non-transiting sub-Saturn mass planet on a ∼71 day orbit using the radial velocity data. This system joins the ranks of a small number of exoplanet host stars (∼100) that have been characterized with asteroseismology. Warm sub-Saturns are rare in the known sample of exoplanets, and thus the discovery of TOI-257b is important in the context of future work studying the formation and migration history of similar planetary systems.
TL;DR: The outreach efforts by GeneLab to utilize the spaceflight data in the repository to generate novel discoveries and develop new hypotheses are reviewed, including spearheading data analysis working groups, and a high school student training program.
Abstract: The mission of NASA's GeneLab database (https://genelab.nasa.gov/) is to collect, curate, and provide access to the genomic, transcriptomic, proteomic and metabolomic (so-called 'omics') data from biospecimens flown in space or exposed to simulated space stressors, maximizing their utilization. This large collection of data enables the exploration of molecular network responses to space environments using a systems biology approach. We review here the various components of the GeneLab platform, including the new data repository web interface, and the GeneLab Online Data Entry (GEODE) web portal, which will support the expansion of the database in the future to include companion non-omics assay data. We discuss our design for GEODE, particularly how it promotes investigators providing more accurate metadata, reducing the curation effort required of GeneLab staff. We also introduce here a new GeneLab Application Programming Interface (API) specifically designed to support tools for the visualization of processed omics data. We review the outreach efforts by GeneLab to utilize the spaceflight data in the repository to generate novel discoveries and develop new hypotheses, including spearheading data analysis working groups, and a high school student training program. All these efforts are aimed ultimately at supporting precision risk management for human space exploration.
TL;DR: In this paper, the authors used OMI satellite atmospheric data for ozone, clouds, and aerosols to estimate the inactivation action spectrum of SARS CoV-2 and showed that exposure to ultraviolet irradiance in the UVC range inactivates many viruses and bacteria in times less than 30 min.
Abstract: UVB in sunlight, 290–315 nm, can inactivate SARS CoV and SARS CoV-2 viruses on surfaces and in the air. Laboratory exposure to ultraviolet irradiance in the UVC range inactivates many viruses and bacteria in times less than 30 min. Estimated UVB inactivation doses from sunlight in J/m2 are obtained from UVC measurements and radiative transfer calculations, weighted by a virus inactivation action spectrum, using OMI satellite atmospheric data for ozone, clouds, and aerosols. For SARS CoV, using an assumed UVC dose near the mid-range of measured values, D90 = 40 J/m2, 90% inactivation times T90 are estimated for exposure to midday 10:00–14:00 direct plus diffuse sunlight and for nearby locations in the shade (diffuse UVB only). For the assumed D90 = 40 J/m2 model applicable to SARS CoV viruses, calculated estimates show that near noon 11:00–13:00 clear-sky direct sunlight gives values of T90 < 90 min for mid-latitude sites between March and September and less than 60 min for many equatorial sites for 12 months of the year. Recent direct measurements of UVB sunlight inactivation of the SARS CoV-2 virus that causes COVID-19 show shorter T90 inactivation times less than 10 min depending on latitude, season, and hour. The equivalent UVC 254 nm D90 dose for SARS CoV-2 is estimated as 3.2 ± 0.7 J/m2 for viruses on a steel mesh surface and 6.5 ± 1.4 J/m2 for viruses in a growth medium. For SARS CoV-2 clear-sky T90 on a surface ranges from 4 min in the equatorial zone to less than 30 min in a geographic area forming a near circle with solar zenith angle < 60O centered on the subsolar point for local solar times from 09:00 to 15:00 h.
TL;DR: GeeSEBAL as discussed by the authors is a new tool for automatic estimation of evapotranspiration (ET), based on the Surface Energy Balance Algorithm for Land and simplified version of the CIMEC (Calibration using Inverse Modeling at Extreme Conditions) process for the endmembers selection, developed within the Google Earth Engine (GEE) environment.
Abstract: Accurate estimation of evapotranspiration ( ET ) is essential for several applications in water resources management. ET models using remote sensing data have flourished in recent years allowing spatial and temporal assessments at unprecedented resolutions. This study presents geeSEBAL, a new tool for automated estimation of ET , based on the Surface Energy Balance Algorithm for Land (SEBAL) and a simplified version of the CIMEC (Calibration using Inverse Modeling at Extreme Conditions) process for the endmembers selection, developed within the Google Earth Engine (GEE) environment. The tool framework is introduced, and case studies across multiple biomes in Brazil are presented by comparing daily ET estimates with eddy covariance (EC) data from 10 flux towers. Based on 224 Landsat images using ERA5 Land as meteorological inputs, daily ET estimates of geeSEBAL yielded an average root mean squared difference (RMSD) of 0.67 mm day−1 when compared to EC data corrected for the energy balance closure. Additional analyses indicate a low geeSEBAL sensitivity to meteorological inputs, yielding an average RMSD of 0.71 mm day−1 when driven by in situ meteorological measurements. On the other hand, we found a higher sensitivity of the automated CIMEC algorithm to the selection of endmembers for internal calibration. For instance, by adjusting the endmembers percentiles to tropical biomes we found an error that was 36% lower compared to the standard CIMEC percentiles. Finally, we assessed the long-term effects (1984–2020) of land cover changes on surface energy fluxes and water use in agriculture for key areas in Brazil, from deforested areas in the Amazon to irrigated crops in the Pampas and Cerrado biomes. A comparison with a land surface temperature-based (SSEBop) and a vegetation-based (MOD16) model was also performed to assess relative advantages and disadvantages. This analysis showed that geeSEBAL has a significant potential for long-term assessment of ET in data-scarce areas, due to its lower sensitivity to meteorological inputs. geeSEBAL codes are written in Python and JavaScript and are freely available on GitHub ( https://github.com/et-brasil/geesebal ). geeSEBAL also includes a graphical user interface ( https://etbrasil.org/geesebal ), allowing important advances in water resources management at regional scales.
TL;DR: In this paper, the authors present and analyze XCO2 distributions over the Los Angeles megacity (LA) derived from OCO-3 SAM and target mode observations, and show good agreement with nearby ground-based TCCON measurements of CO2.
Johns Hopkins University Applied Physics Laboratory1, University of Maryland, College Park2, Goddard Space Flight Center3, Ames Research Center4, Cornell University5, Jet Propulsion Laboratory6, Southwest Research Institute7, Tufts University8, Free University of Berlin9, University of California, Berkeley10, Woods Hole Oceanographic Institution11, German Aerospace Center12, INAF13
TL;DR: Orbilander, a mission concept that would first orbit and then land on Enceladus, represented the best balance as discussed by the authors, including a more detailed science operations plan during both orbital and landing phases, landing site characterization and selection analyses, and landing procedures.
Abstract: Enceladus’s long-lived plume of ice grains and water vapor makes accessing oceanic material readily achievable from orbit (around Saturn or Enceladus) and from the moon’s surface. In preparation for the National Academies of Sciences, Engineering and Medicine 2023–2032 Planetary Science and Astrobiology Decadal Survey, we investigated four architectures capable of collecting and analyzing plume material from orbit and/or on the surface to address the most pressing questions at Enceladus: Is the subsurface ocean inhabited? Why, or why not? Trades specific to these four architectures were studied to allow an evaluation of the science return with respect to investment. The team found that Orbilander, a mission concept that would first orbit and then land on Enceladus, represented the best balance. Orbilander was thus studied at a higher fidelity, including a more detailed science operations plan during both orbital and landed phases, landing site characterization and selection analyses, and landing procedures. The Orbilander mission concept demonstrates that scientifically compelling but resource-conscious Flagship-class missions can be executed in the next decade to search for life at Enceladus.
TL;DR: An open-source workflow to refine the SkySat-C camera models and improve absolute image geolocation using external reference DEMs, without manual ground control point (GCP) selection is developed.
Abstract: The Planet SkySat-C SmallSat constellation can acquire very high resolution (0.7 m to 0.9 m) triplet stereo and video imagery with short revisit times, providing an exciting opportunity for global, on-demand 3D mapping of dynamic surface features. However, a lack of suitable processing software, limited geolocation accuracy, and scene-to-scene offsets currently limit the potential for accurate SkySat digital elevation model (DEM) production. We developed an open-source workflow to refine the SkySat-C camera models and improve absolute image geolocation using external reference DEMs, without manual ground control point (GCP) selection. The refined camera models are used to generate accurate and self-consistent DEMs with 2-m posting and orthoimages at native resolution. We present sample DEM products for a triplet stereo collection over Mt. Rainier, USA and two video collections over Mt. St. Helen’s, USA. The output DEMs display 1 to 2 m relative and 2 to 3 m absolute vertical accuracy when compared to DEMs generated with stereo image pairs acquired by the DigitalGlobe/Maxar WorldView satellites and airborne LiDAR. Differencing the two SkySat-C video DEMs over Mt. St. Helen’s shows elevation change of ~ 5 to 15 m due to melting of seasonal snow and glacier flow. Our workflow can be scaled for batch processing of SkySat stereo imagery, and extended to other frame camera systems with limited initial geolocation accuracy.
Ames Research Center1, California Institute of Technology2, Natural History Museum3, Planetary Science Institute4, University of Arizona5, University of Tennessee6, University of Copenhagen7, Goddard Space Flight Center8, Carnegie Institution for Science9, Jacobs Engineering Group10, Universities Space Research Association11, University of Guelph12, Los Alamos National Laboratory13, University of California, Berkeley14, United States Geological Survey15, Brown University16
TL;DR: The Curiosity rover is exploring the lower reaches of Mount Sharp, in Gale crater on Mars as discussed by the authors, and a traverse from Vera Rubin ridge to Glen Torridon has allowed Curiosity to examine a lateral transect of rock strata laid down in a martian lake ~3.5 billion years ago.
Abstract: Mars’ sedimentary rock record preserves information on geological (and potential astrobiological) processes that occurred on the planet billions of years ago. The Curiosity rover is exploring the lower reaches of Mount Sharp, in Gale crater on Mars. A traverse from Vera Rubin ridge to Glen Torridon has allowed Curiosity to examine a lateral transect of rock strata laid down in a martian lake ~3.5 billion years ago. We report spatial differences in the mineralogy of time-equivalent sedimentary rocks
TL;DR: In this article, a 3D Monte-Carlo radiative transfer code, HIRES-MCRT, was employed to self-consistently model high-resolution transmission spectra with iron lines at different phases during the transit.
Abstract: Ultra-hot Jupiters are tidally locked gas giants with dayside temperatures high enough to dissociate hydrogen and other molecules. Their atmospheres are vastly non-uniform in terms of chemistry, temperature and dynamics, and this makes their high-resolution transmission spectra and cross-correlation signal difficult to interpret. In this work, we use the SPARC/MITgcm global circulation model to simulate the atmosphere of the ultra-hot Jupiter WASP-76b under different conditions, such as atmospheric drag and the absence of TiO and VO. We then employ a 3D Monte-Carlo radiative transfer code, HIRES-MCRT, to self-consistently model high-resolution transmission spectra with iron (Fe I) lines at different phases during the transit. To untangle the structure of the resulting cross-correlation map, we decompose the limb of the planet into four sectors, and we analyse each of their contributions separately. Our experiments demonstrate that the cross-correlation signal of an ultra-hot Jupiter is primarily driven by its temperature structure, rotation and dynamics, while being less sensitive to the precise distribution of iron across the atmosphere. We also show that the previously published iron signal of WASP-76b can be reproduced by a model featuring iron condensation on the leading limb. Alternatively, the signal may be explained by a substantial temperature asymmetry between the trailing and leading limb, where iron condensation is not strictly required to match the data. Finally, we compute the $K_{p}-V_{sys}$ maps of the simulated WASP-76b atmospheres, and we show that rotation and dynamics can lead to multiple peaks that are displaced from zero in the planetary rest frame.
National Center for Atmospheric Research1, Dalhousie University2, University of Toronto3, Université libre de Bruxelles4, University of Paris5, Jet Propulsion Laboratory6, University of California, Los Angeles7, Goddard Space Flight Center8, University of Maryland, College Park9, National Oceanic and Atmospheric Administration10, Ames Research Center11
TL;DR: In this paper, the authors used the long-term records of CO from the Measurements of Pollution in the Troposphere (MOPITT) and AOD from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument.
University of Graz1, Ilia State University2, Abastumani Astrophysical Observatory3, University of Göttingen4, IAC5, Bilkent University6, Max Planck Society7, High Altitude Observatory8, New York University Abu Dhabi9, Tel Aviv University10, INAF11, Goddard Space Flight Center12, The Catholic University of America13, Cornell University14, Ames Research Center15
TL;DR: A review of theoretical and observational aspects of Rossby waves on different spatial and temporal scales in various astrophysical settings is provided in this article, where the physical role played by Rossby-type waves and associated instabilities is discussed in the context of solar and stellar magnetic activity, angular momentum transport in astrophysical discs, planet formation, and other astrophysical processes.
Abstract: Rossby waves are a pervasive feature of the large-scale motions of the Earth’s atmosphere and oceans. These waves (also known as planetary waves and r-modes) also play an important role in the large-scale dynamics of different astrophysical objects such as the solar atmosphere and interior, astrophysical discs, rapidly rotating stars, planetary and exoplanetary atmospheres. This paper provides a review of theoretical and observational aspects of Rossby waves on different spatial and temporal scales in various astrophysical settings. The physical role played by Rossby-type waves and associated instabilities is discussed in the context of solar and stellar magnetic activity, angular momentum transport in astrophysical discs, planet formation, and other astrophysical processes. Possible directions of future research in theoretical and observational aspects of astrophysical Rossby waves are outlined.