Gravitational Evidence for an Undifferenctiated Callisto
Galileo's first encounter with Callisto took place on 4 November 1996, and the gravity signal was detected in the radio Doppler data recorded during the encounter.
Gravitation↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Optical design of the Extreme Coronagraph for Living Planetary Systems instrument for the LUVOIR mission study
The large UV/optical/IR surveyor (LUVOIR) is a concept for a highly capable, multiwavelength space observatory with ambitious science goals. Finding and characterizing a wide range of exoplanets, including those that might be habitable, is a major goal of the study. The ambitious science goals drive the challenges of optical design. This paper will present how the optical design meets the unique challenges for coronagraphs on large telescopes to achieve high contrast for a wide wavelength range from 200 to 2000 nm. Some of these unique challenges include the position and size of occulter masks, deformable mirror placement and separation, tight tolerances on the optical system and each element, and finally, packaging all instruments in a limited space. Three types of modules are designed after the coronagraph to explore the exoplanets and analyze the spectrum of detected exoplanet signals: two imaging cameras, two integral field spectrographs, and one high-resolution spectrometer. All of them work together to provide information to meet scientific challenges in searching for habitable planets. The optical designs, unique challenges, and the solutions for all coronagraph and spectral modules are presented. Their specifications derived from science goals are also presented.
Qian Gong↗
Gravitational-Wave Physics and Astronomy in the 2020s and 2030s
The 100 years since the publication of Albert Einstein’s theory of General Relativity saw significant development of the understanding of the theory, the identification of potential astrophysical sources of sufficiently strong gravitational waves, and development of key technologies for gravitational-wave detectors. In 2015, the first gravitational wave signals were detected by the two US Advanced LIGO instruments. In 2017, Advanced LIGO and the European Advanced Virgo detectors pinpointed a binary neutron star coalescence that was also seen across the electromagnetic spectrum. The field of gravitational wave astronomy is just starting, and this Roadmap of future developments surveys the potential for growth in bandwidth and sensitivity of future gravitational-wave detectors and discusses the science results anticipated to come from upcoming instruments.
Compact astrophysical objects↗
CubeSat Array for Detection of RF Emissions from Exoplanets using Inter-Satellite Optical Communicators
We are presenting a CubeSat mission concept wherein a large number of small spacecraft furnished with Ultra-Long Wavelength (ULW) observation antennas is to be implemented to synthesize a large aperture for detecting ULW emissions from selected exoplanets. The CubeSat Array for the Detection of RF Emissions from Exoplanets (CADRE) concept involves the placement of a swarm arrangement of CubeSats into small amplitude Lissajous orbits around the Earth-Moon L2 point. In addition to the ULW receivers, each CADRE CubeSat will be furnished with a novel omnidirectional optical communicator which should allow data sharing at gigabit per second data rates. In this paper we discuss the science goals, potential architecture and key technical challenges of an eventual CADRE implementation. We present the estimated interferometer specifications needed to detect Exoplanet RF emissions, CubeSat orbits and formations as well as CubeSat design considerations. Special focus is placed on the design of the mission-enabling inter-CubeSat optical cross link which allows for fast sharing of the detected RF signals for subsequent correlation.
Bentum, Mark↗
TOI-257b (HD 19916b): a warm sub-saturn orbiting an evolved F-type star
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 M(P) = 0.138 ± 0.023 M(J) (43.9 ± 7.3 Mꚛ), a radius of R(P) = 0.639 ± 0.013 R(J) (7.16 ± 0.15 Rꚛ), bulk density of 0.65 (+0.12,−0.11) (cgs), and period 18.38818 (+0.00085,−0.00084) days. TOI-257b orbits a bright (V = 7.612 mag) somewhat evolved late F-type star with M⁎ = 1.390 ± 0.046 M(sun), R⁎ = 1.888 ± 0.033 R(sun), T(eff) = 6075 ± 90 K, and 𝜈sin 𝑖 = 11.3 ± 0.5 km/s. 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.
asteroseismology↗
TOI-257b (HD 19916b): a warm sub-saturn orbiting an evolved F-type star
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 M P = 0.138 ± 0.023 M J (43.9 ± 7.3 M ⊕ ), a radius of R P = 0.639 ± 0.013 R J (7.16 ± 0.15 R ⊕ ), bulk density of 0.65+0.12 −0.11 (cgs), and period 18.38818+0.00085 −0.00084 days. TOI-257b orbits a bright (V = 7.612 mag) somewhat evolved late F-type star with M ∗ = 1.390 ± 0.046 M sun , R ∗ = 1.888 ± 0.033 R sun , T eff = 6075 ± 90 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.
Brett C. Addison↗
Constraints from LIGO O3 Data on Gravitational-wave Emission Due to R-modes in the Glitching Pulsar PSR J0537-6910
We present a search for continuous gravitational-wave emission due to r-modes in the pulsar PSR J0537–6910 using data from the LIGO–Virgo Collaboration observing run O3. PSR J0537–6910 is a young energetic X-ray pulsar and is the most frequent glitcher known. The inter-glitch braking index of the pulsar suggests that gravitational-wave emission due to r-mode oscillations may play an important role in the spin evolution of this pulsar. Theoretical models confirm this possibility and predict emission at a level that can be probed by groundbased detectors. In order to explore this scenario, we search for r-mode emission in the epochs between glitches by using a contemporaneous timing ephemeris obtained from NICER data. We do not detect any signals in the theoretically expected band of 86–97 Hz, and report upper limits on the amplitude of the gravitational waves. Our results improve on previous amplitude upper limits from r-modes in J0537-6910 by a factor of up to 3 and place stringent constraints on theoretical models for r-mode-driven spin-down in PSR J0537–6910, especially for higher frequencies at which our results reach below the spin-down limit defined by energy conservation.
J. B. Camp↗
Secure Mass Measurements From Transit Timing: 10 Kepler Exoplanets Between 3 and 8M⊕ with Diverse Densities and Incident Fluxes
We infer dynamical masses in eight multiplanet systems using transit times measured from Keplerʼs complete dataset, including short-cadence data where available. Of the 18 dynamical masses that we infer, 10 pass multiple tests for robustness. These are in systems Kepler-26 (KOI-250), Kepler-29 (KOI-738), Kepler-60 (KOI-2086), Kepler-105 (KOI-115), and Kepler-307 (KOI-1576). Kepler -105 c has a radius of 1.3R⊕ and a density consistent with an Earth-like composition. Strong transit timing variation (TTV) signals were detected from additional planets, but their inferred masses were sensitive to outliers or consistent solutions could not be found with independently measured transit times, including planets orbiting Kepler-49 (KOI-248), Kepler-57 (KOI-1270), Kepler-105 (KOI-115), and Kepler-177 (KOI-523). Nonetheless, strong upper limits on the mass of Kepler-177 cimply an extremely low density of 0.1 g cm−3. In most cases, individual orbital eccentricities were poorly constrained owing to degeneracies in TTV inversion. For five planet pairs in our sample, strong secular interactions imply a moderate to high likelihood of apsidal alignment over a wide range of possible eccentricities. We also find solutions for the three planets known to orbit Kepler-60 in a Laplace-like resonance chain. However, nonlibrating solutions also match the transit timing data. For six systems, we calculate more precise stellar parameters than previously known, enabling useful constraints on planetary densities where we have secure mass measurements. Placing these exoplanets on the mass–radius diagram, we find that a wide range of densities is observed among sub-Neptune-mass planets and that the range in observed densities is anticorrelated with incident flux.
Stars individual↗
Remote sensing-based vegetation and soil moisture constraints reduce irrigation estimation uncertainty
Understanding the human water footprint and its impact on the hydrological cycle is essential to inform water management under climate change. Despite efforts in estimating irrigation water withdrawals in earth system models, uncertainties and discrepancies exist within and across modeling systems conditioned by model structure, irrigation parameterization, and the choice of input datasets. Achieving model reliability could be much more challenging for data-sparse regions, given limited access to ground truth for parameterization and validation. Here, we demonstrate the potential of utilizing remotely sensed vegetation and soil moisture observations in constraining irrigation estimation in the Noah-MP land surface model. Results indicate that the two constraints together can effectively reduce model sensitivity to the choice of irrigation parameterization by 7%–43%. It also improves the characterization of the spatial patterns of irrigation and its impact on evapotranspiration and surface soil moisture by correcting for vegetation conditions and irrigation timing. This study highlights the importance of utilizing remotely sensed soil moisture and vegetation measurements in detecting irrigation signals and correcting for vegetation growth. Integrating the two remote sensing datasets into the model provides an effective and less feature engineered approach to constraining the uncertainty of irrigation modeling. Such strategies can be potentially transferred to other modeling systems and applied to regions across the globe.
Wanshu Nie↗
Validation of IMERG Oceanic Precipitation over Kwajalein
The integrated Multi-satellitE Retrievals for GPM (IMERG) Version V05B and V06B precipitation products from the Global Precipitation Measurement (GPM) mission are validated against ground-based observations from the Kwajalein Polarimetric S-band Weather Radar (KPOL) deployed at Kwajalein Atoll in the central Pacific Ocean. Such a validation is particularly important as comprehensive surface measurements over the oceans are practically infeasible, which hampers the identification of possible errors, and improvement of future versions of IMERG and other satellitebased retrieval algorithms. The V05B and V06B IMERG products are validated at their native 0.1°, 30 min resolution from 2014 to 2018 based on both volumetric and categorical metrics. This validation study indicates that precipitation rates from both IMERG V05B and V06B are underestimated with respect to radar surface estimates, but the underestimation is much reduced from V05B IMERG V06B outperforms V05B with reduced systematic bias and improved precipitation detectability. The IMERG performance is further traced back to its individual sensors and morphing-based algorithms. The overall underestimation in V05B is mainly driven by the negative relative biases from morphing-based algorithms which are largely corrected in V06B. Imagers perform generally better than sounders because of the usage of low-frequency channels in imagers which can better detect emission signals by the hydrometeors. Among imagers, the GPM Microwave Imager (GMI) and Advanced Microwave Scanning Radiometer Version 2 (AMSR2) are the best, followed by Special Sensor Microwave Imager/Sounder (SSMIS). Among sounders, the Microwave Humidity Sounder (MHS) is the best, followed by Advanced Technology Microwave Sounder (ATMS) and the Sounder for Atmospheric Profiling of Humidity in the Intertropics by Radiometry (SAPHIR) for V06B. Among all categories, morph-only and IR+morph only perform better than SAPHIR. SAPHIR shows the worst performance among all categories, likely due to its limited channel selection. It is envisaged that these results will improve our understanding of IMERG performance over oceans and aid in the improvement of future versions of IMERG.
KPOL↗
Secure Mass Measurements From Transit Timing: 10 Kepler Exoplanets Between 3 and 8 M⊕ With Diverse Densities and Incident Fluxes
We infer dynamical masses in eight multiplanet systems using transit times measured from Keplerʼs complete data set, including short-cadence data where available. Of the 18 dynamical masses that we infer, 10 pass multiple tests for robustness. These are in systems Kepler-26 (KOI-250), Kepler-29 (KOI-738), Kepler-60 (KOI-2086), Kepler-105 (KOI-115), and Kepler-307 (KOI-1576). Kepler-105 c has a radius of 1.3 R(sub ⨁) and a density consistent with an Earth-like composition. Strong transit timing variation (TTV) signals were detected from additional planets, but their inferred masses were sensitive to outliers or consistent solutions could not be found with independently measured transit times, including planets orbiting Kepler-49 (KOI-248), Kepler-57 (KOI-1270), Kepler-105 (KOI-115), and Kepler-177 (KOI-523). Nonetheless, strong upper limits on the mass of Kepler-177 c imply an extremely low density of ∽0.1 g cm(exp −3). In most cases, individual orbital eccentricities were poorly constrained owing to degeneracies in TTV inversion. For five planet pairs in our sample, strong secular interactions imply a moderate to high likelihood of apsidal alignment over a wide range of possible eccentricities. We also find solutions for the three planets known to orbit Kepler-60 in a Laplace-like resonance chain. However, nonlibrating solutions also match the transit timing data. For six systems, we calculate more precise stellar parameters than previously known, enabling useful constraints on planetary densities where we have secure mass measurements. Placing these exoplanets on the mass–radius diagram, we find that a wide range of densities is observed among sub-Neptune-mass planets and that the range in observed densities is anticorrelated with incident flux.
Individual stars↗
Role of PIEZO1 in T Cell Activation Under Simulated Microgravity
True and simulated microgravity conditions have been well documented to cause the inhibition of T cell activation by mitogens. Although several studies aimed at exploring the mechanisms for such a phenomenon have been published, how this is occurring remains unresolved. PIEZO1 is a known mechanosensing gene and has been shown to be critically involved in human T cell activation. In our analysis of transcriptomics changes in peripheral mononuclear cells (PBMC) collected from the ISS crewmembers in space, the expression of PIEZO1 was downregulated. To investigate the role of the PIEZO1 gene in T cell activation in microgravity, we used rotating wall vessels (RWV), which simulate microgravity on the ground and are known to inhibit T cell activation. In this pilot study, PBMC cultured in RWV and in the static 1g condition were stimulated with Human T-Activator CD3/CD28 beads. The cells were also treated with and without Yoda1, a chemical agonist that activates PIEZO1 independent of mechanical cues or any other cellular component. After culturing for 24 hours, the cells were stained for activation markers and the PIEZO1 antibody, then were analyzed by flow cytometry. Our results indicate reduced T cell activation with mitogen under simulated microgravity, but no changes of the PIEZO1 signals were detected. In addition, the reduced activation was not restored in cells cultured with Yoda1. Taken together, our results suggest that PIEZO1 may play a minimal role in the inhibition of T cell activation in space.
Honglu Wu↗
Role of PIEZO1 in T Cell Activation Under Simulated Microgravity
True and simulated microgravity conditions have been well documented to cause the inhibition of T cell activation by mitogens. Although several studies aimed at exploring the mechanisms for such a phenomenon have been published, how this is occurring remains unresolved. PIEZO1 is a known mechanosensing gene and has been shown to be critically involved in human T cell activation. In our analysis of transcriptomics changes in peripheral mononuclear cells (PBMC) collected from the ISS crewmembers in space, the expression of PIEZO1 was downregulated. To investigate the role of the PIEZO1 gene in T cell activation in microgravity, we used rotating wall vessels (RWV), which simulate microgravity on the ground and are known to inhibit T cell activation. In this pilot study, PBMC cultured in RWV and in the static 1g condition were stimulated with Human T-Activator CD3/CD28 beads. The cells were also treated with and without Yoda1, a chemical agonist that activates PIEZO1 independent of mechanical cues or any other cellular component. After culturing for 24 hours, the cells were stained for activation markers and the PIEZO1 antibody, then were analyzed by flow cytometry. Our results indicate reduced T cell activation with mitogen under simulated microgravity, but no changes of the PIEZO1 signals were detected. In addition, the reduced activation was not restored in cells cultured with Yoda1. Taken together, our results suggest that PIEZO1 may play a minimal role in the inhibition of T cell activation in space.
Honglu Wu↗
Role of PIEZO1 in T Cell Activation Under Simulated Microgravity
True and simulated microgravity conditions have been well documented to cause the inhibition of T cell activation by mitogens. Although several studies aimed at exploring the mechanisms for such a phenomenon have been published, how this is occurring remains unresolved. PIEZO1 is a known mechanosensing gene and has been shown to be critically involved in human T cell activation. In our analysis of transcriptomics changes in peripheral mononuclear cells (PBMC) collected from the ISS crewmembers in space, the expression of PIEZO1 was downregulated. To investigate the role of the PIEZO1 gene in T cell activation in microgravity, we used rotating wall vessels (RWV), which simulate microgravity on the ground and are known to inhibit T cell activation. In this pilot study, PBMC cultured in RWV and in the static 1g condition were stimulated with Human T-Activator CD3/CD28 beads. The cells were also treated with and without Yoda1, a chemical agonist that activates PIEZO1 independent of mechanical cues or any other cellular component. After culturing for 24 hours, the cells were stained for activation markers and the PIEZO1 antibody, then were analyzed by flow cytometry. Our results indicate reduced T cell activation with mitogen under simulated microgravity, but no changes of the PIEZO1 signals were detected. In addition, the reduced activation was not restored in cells cultured with Yoda1. Taken together, our results suggest that PIEZO1 may play a minimal role in the inhibition of T cell activation in space.
Honglu Wu↗
Quantum random number generators
Random number generators include a thermal optical source and detector configured to produce random numbers based on quantum-optical intensity fluctuations. An optical flux is detected, and signals proportional to optical intensity and a delayed optical intensity are combined. The combined signals can be electrical signals or optical signals, and the optical source is selected so as to have low coherence over a predetermined range of delay times. Balanced optical detectors can be used to reduce common mode noise, and in some examples, the optical flux is directed to only one of a pair of balanced detectors.
97 MATHEMATICS AND COMPUTING↗
System and method for monitoring atomic absorption during a surface modification process
A processing system monitors and/or controls a surface modification process occurring on a substrate within a processing chamber. An optical processing module having a light emission submodule to output a generated light signal and an optical detection submodule to detect a resultant light signal, is connected via fiber optic cables to light illuminating and light receiving components located within the chamber. A processor determines an amount of atomic absorption by an atomic element encountered by a probing beam passing between the illuminating and receiving components, based on the intensity of the generated light signal, the intensity of the received light signal and optionally the spontaneous emission of the atomic element in the absence of illumination by a probing beam. Based on the determined amount, the system derives a plurality of parameters of the modified substrate, their spatial and temporal uniformity, and information about process conditions in the processing chamber.
Atanasoff, George↗
Seismoacoustic Monitoring of Pyroprocessing Equipment
With the projected increase in world nuclear capacity comes the hurdle of spent nuclear fuel. Pyroprocessing is one method to process irradiated fuel by using high temperatures and electrochemical steps to separate radioactive components. High temperatures, high radiation levels, and equipment confined to a heavily shielded hot cell are a few of the challenges introduced regarding safeguards for pyroprocessing. The first stage of the process utilizes an element chopper to cut irradiated fuel into smaller pieces, offering the potential to identify equipment operation through seismoacoustic monitoring. Eleven seismic and infrasound sensors were deployed at various locations and distances near a pyroprocessing hot cell to evaluate signals emitted from the chopper. Signals were processed using short-time Fourier transforms and manually scanned to locate chopping events. Operator logs were then collected for a ground truth comparison. Results indicate that both infrasound and seismic signals offer the ability to accurately measure this stage of pyroprocessing, though seismic signals are more prominent. Sensor locations are also evaluated to determine where the signal is detectable. This type of monitoring offers a method to aid in safeguards and proliferation detection by validating a pyroprocessing facility’s schedule and identifying activity that does not align with records.
11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Galaxy Clusters Selected via the Sunyaev-Zel'dovich Effect in 5 year data from the SPT-3G Main Survey
We report a new galaxy cluster catalog, selected using the thermal Sunyaev-Zel'dovich (SZ) effect, from 5 years of observations of the SPT-3G Main field. Drawn from arcminute-resolution data with white noise levels of 3.2, 2.5, and 8.9 $μ$K-arcmin at 95, 150, and 220 GHz, respectively, the sample consists of 8,892 cluster candidates detected above significance $ξ=4$, with an expected purity of $>82\%$ (4,480 at $ξ\ge5$ with purity $>99\%$). Using optical and infrared data we have confirmed 7,190 candidates as clusters. The sample spans a mass range $7.9 \times 10^{13}M_\odot/h_{70}< M_\textrm{500c} < 1.6 \times 10^{15}M_\odot/h_{70}$ with a median mass of $1.65 \times 10^{14}M_\odot/h_{70}$, and a redshift range of $0.0371$ and 271 at $z>1.5$. Compared to previous SZ cluster samples from South Pole Telescope and Atacama Cosmology Telescope data, the SPT-3G sample is highly consistent in mass and redshift but is significantly deeper, with per-cluster detection signal-to-noise 2-4 times higher and a cluster density of 4.5 confirmed clusters/deg$^2$. We cross match with eRASS1 cluster and point source catalogs, finding 1,279 and 1,319 matches, respectively. The SPT and eROSITA cluster mass estimates are in relatively good agreement. We perform a series of validation checks using both internal data splits and comparisons to external samples. These tests show increasing correlated (dusty) emission with redshift, with a $\sim17\times$ larger 220 GHz temperature increment for clusters at $z\sim1.5$ than $z\sim0.25$, but only weak evidence for correlated synchrotron emission. Finally, a number of clusters are flagged as candidate strong gravitational lenses.
Bleem, L. E. [Argonne (main); Chicago U., KICP; Ch↗