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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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At least 19 records

The Detection of Mesoscale Convective Systems by the GPM Ku-Band Spaceborne Radar

The Global Precipitation Measurement (GPM) core observatory satellite launched in 2014 features more extended latitudinal coverage (65 degree S-65 degree N) than its predecessor Tropical Rainfall Measuring Mission (TRMM, 35 degree S-35 degree N). The Ku-band radar onboard of the GPM is known to be capable of characterizing the 3D structure of deep convection globally. In this study, GPM’s capability for detecting mesoscale convective systems (MCSs) is evaluated. Extreme convective echoes seen by GPM are compared against an MCS database based on tracking convective entities over the contiguous US. The tracking is based on geostationary satellite and ground-based Next Generation Radar (NEXRAD) network data obtained during the 2014-2016 warm seasons. Results show that more than 70% of the GPM-detected Deep-Wide Convective Core (DWC) and Wide Convective Core (WCC) objects are part of NEXRAD identified MCSs, indicating that GPM-classified DWCs and WCCs correlate well with typical MCSs containing large convective features. By applying this method to the rest of the world, a global view of MCS distribution is obtained. This work reveals GPM’s potential in MCS detection at the global scale, particularly over remote regions without dense observation network.

3D reflectivity structure↗

ASTROSAT CZT IMAGER OBSERVATIONS OF GRB 151006A: TIMING, SPECTROSCOPY, AND POLARIZATION STUDY

AstroSat is a multi-wavelength satellite launched on 2015 September 28. The CZT Imager of AstroSat on its very first day of operation detected a long duration gamma-ray burst (GRB), namely GRB 151006A. Using the off-axis imaging and spectral response of the instrument, we demonstrate that the CZT Imager can localize this GRB correctly to about a few degrees, and it can provide, in conjunction with Swift , spectral parameters similar to those obtained from Fermi /GBM. Hence, the CZT Imager would be a useful addition to the currently operating GRB instruments ( Swift and Fermi ). Specifically, we argue that the CZT Imager will be most useful for the short hard GRBs by providing localization for those detected by Fermi and spectral information for those detected only by Swift . We also provide preliminary results on a new exciting capability of this instrument: the CZT Imager is able to identify Compton scattered events thereby providing polarization information for bright GRBs. GRB 151006A, in spite of being relatively faint, shows hints of a polarization signal at 100–300 keV (though at a low significance level). We point out that the CZT Imager should provide significant time resolved polarization measurements for GRBs that have fluence three times higher than that of GRB 151006A. We estimate that the number of such bright GRBs detectable by the CZT Imager is five to six per year. The CZT Imager can also act as a good hard X-ray monitoring device for possible electromagnetic counterparts of gravitational wave events.

79 ASTRONOMY AND ASTROPHYSICS↗

New Space Companies Meet a “Normal” Solar Maximum

The monthly mean sunspot number has been larger in June–July 2023 than the double peak of solar cycle 24 (146 in February 2014 and 139 in November 2011) and brings us back to the sunspot level of solar cycle 23. However, the number of rocket launches, satellites in orbit and private space companies has increased dramatically in the past 20 years. Additionally, there is a growing interest for space exploration beyond Earth's orbit, to the Moon and beyond, which comes with higher risk of being affected by space weather. Here, we discuss some of these trends and the role of the journal to improve awareness of space weather impacts.

79 ASTRONOMY AND ASTROPHYSICS↗

Trapped Positrons and Electrons in the Inner Radiation Belt According to Data of the PAMELA Experiment

Measurements of secondary-electron and secondary-positron fluxes below the geomagnetic cutoff in near-Earth space were performed by means of the PAMELA magnetic spectrometer installed on board the Resurs-DK1 satellite launched on June 15, 2006, in an elliptical orbit of inclination 70° and altitude 350 to 600 km. This spectrometer permits measuring the fluxes of electrons and positrons over a wide energy range, as well as determining their spatial distributions to a precision of about 2°. A calculation of particle trajectories in the geomagnetic field makes it possible to separate electrons and positrons originating from cosmic-ray interactions in the Earth’s magnetosphere. The spatial distributions of quasitrapped, trapped, and short-lived albedo positrons and electrons of energy above 70 MeV in the radiation belt were analyzed. The ratio of the electron-to-positron fluxes and the energy spectra of the electrons and positrons in question are indicative of different productionmechanisms for stably trapped and quasitrapped secondary particles.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Green Ocean Amazon 2014/15 – Scaling Amazon Carbon Water Couplings Field Campaign Report

Forests soak up 25% of the carbon dioxide (CO2) emitted by anthropogenic fossil energy use (10 Gt C y-1), moderating its atmospheric accumulation. How this terrestrial CO2 uptake will evolve with climate change in the 21st Century is largely unknown. Rainforests are the most active ecosystems, with the Amazon basin storing 120 Gt C as biomass and exchanging 18 Gt C y-1 of CO2 via photosynthesis and respiration and fixing carbon at 2-3 kg C m-2 y-1. Furthermore, the intense hydrologic and carbon cycles are tightly coupled in the Amazon where about half of the water is recycled by evapotranspiration and the other half imported from the ocean by Northeasterly trade winds. Climate models predict a drying in the Amazon with reduced carbon uptake while observationally guided assessments indicate sustained uptake. We set out to resolve this huge discrepancy in the size and sign of the future Amazon carbon cycle by performing the first simultaneous regional-scale high-frequency measurements of atmospheric CO2, H2O, HOD, CH4, N2O, and CO at the T3 site in Manacupuru, Brazil, as part of DOE's GoAmazon 2014/15 project. Our data will be used to inform and develop DOE's Community Land Model (CLM) on the tropical carbon-water couplings at the appropriate grid scale (10-50 km). Our measurements will also validate the CO2 data from Japan's Greenhouse gases Observing Satellite (GOSAT) and NASA's Orbiting Carbon Observatory (OCO)-2 satellite (launched in July, 2014). Our data addresses these science questions: 1. How does ecosystem heterogeneity and climate variability influence the rainforest carbon cycle? 2. How well do current tropical ecosystem models simulate the observed regional carbon cycle? 3. Does nitrogen deposition (from the Manaus, Brazil, plume) enhance rainforest carbon uptake?

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗

GoAmazon – Scaling Amazon Carbon Water Couplings

Forests soak up 25% of the carbon dioxide (CO 2 ) emitted by anthropogenic fossil energy use (10 Gt C y -1 ) moderating its atmospheric accumulation. How this terrestrial CO 2 uptake will evolve with climate change in the 21st century is largely unknown. Rainforests are the most active ecosystems with the Amazon basin storing 120 Gt C as biomass and exchanging 18 Gt C y -1 of CO 2 via photosynthesis and respiration and fixing carbon at 2-3 kg C m -2 y -1 . Furthermore, the intense hydrologic and carbon cycles are tightly coupled in the Amazon where about half of the water is recycled by evapotranspiration and the other half imported from the ocean by Northeasterly trade winds. Climate models predict a drying in the Amazon with reduced carbon uptake while observationally guided assessments indicate sustained uptake. We will resolve this huge discrepancy in the size and sign of the future Amazon carbon cycle by performing the first simultaneous regional scale high frequency measurements of atmospheric CO 2 , H 2 O, HOD, CH 4 , N 2 O and CO at the T3 site in Manacupuru, Brazil as part of DOE's GoAmazon project. Our data will be used to inform and develop DOE's CLM on the tropical carbon-water couplings at the appropriate grid scale (10-50km). Our measurements will also validate the CO 2 data from Japan's GOSAT and NASA's imminent OCO-2 satellite (launch date July 2014).

54 ENVIRONMENTAL SCIENCES↗

Resurrecting Hitomi for Decaying Dark Matter and Forecasting Leading Sensitivity for XRISM

The Hitomi x-ray satellite mission carried unique high-resolution spectrometers that were set to revolutionize the search for sterile neutrino dark matter (DM) by looking for narrow x-ray lines arising from DM decays. Unfortunately, the satellite was lost shortly after launch, and to date the only analysis using Hitomi for DM decay used data taken towards the Perseus cluster. Here, in this work we present a significantly more sensitive search from an analysis of archival Hitomi data towards blank sky locations, searching for DM decaying in our own Milky Way. The recently launched XRISM satellite has nearly identical soft-x-ray spectral capabilities to Hitomi; we project the full-mission sensitivity of XRISM for analyses of their future blank-sky data, and we find that XRISM will have the leading sensitivity to decaying DM for masses between roughly 1 to 18 keV, with important implications for sterile neutrino and heavy axionlike particle DM scenarios.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

South Asia in the Space Age: Security Implications of Private-Sector Military Innovation on the Subcontinent

On 15 February 2017, India achieved the impressive feat of launching 104 commercial satellites into space from a single delivery vehicle. This launch was being closely watched by international firms, as India was asking for significantly less than the price of their American or European counterparts. Prime Minister Modi remarked that the launch cost less than the Hollywood move “Gravity.” C. Uday Bhaskar, Director of the Society for Policy Studies in New Delhi, commented that “by charging significantly less to launch satellites into space, India could carve out a niche in the $3 billion to $4 billion market for detailed information about climate, topography and defense.”

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

Satellite-Based Assessment of Rocket Launch and Coastal Change Impacts on Cape Canaveral Barrier Island, Florida, USA

The Cape Canaveral Barrier Island, home to the National Aeronautics and Space Administration (NASA)’s Kennedy Space Center and the United States (U.S.) Space Force’s Cape Canaveral Space Force Station, is situated in a unique ecological transition zone that supports diverse wildlife. This study evaluates the recent changes in vegetation cover (2016–2023) and dune elevation (2007–2017) within the Cape Canaveral Barrier Island using high-resolution optical satellite and light detection and ranging (LiDAR) data. The study period was chosen to depict the time period of a recent increase in rocket launches. The study objectives include assessing changes in vegetation communities, identifying detectable impacts of liquid propellant launches on nearby vegetation, and evaluating dune elevation and tide level shifts near launchpads. The results indicate vegetation cover changes, including mangrove expansion in wetland areas and the conversion of coastal strands to denser scrubs and hardwood forests, which were likely influenced by mild winters and fire management. While detectable impacts of rocket launches on nearby vegetation were observed, they were less severe than those caused by solid rocket motors. Compounding challenges, such as rising tide levels, beach erosion, and wetland loss, potentially threaten the resilience of launch operations and the surrounding habitats. The volume and scale of launches continue to increase, and a balance between space exploration and ecological conservation is required in this biodiverse region. This study focuses on the assessment of barrier islands’ shorelines.

54 ENVIRONMENTAL SCIENCES↗

Initial in-orbit operation of the soft X-ray spectrometer Resolve onboard the X-ray imaging and spectroscopy mission satellite

The X-Ray Imaging and Spectroscopy Mission satellite was launched on September 6, 2023 (UT). Its Resolve instrument is a high-resolution X-ray spectrometer enabled by a microcalorimeter array thermally anchored to a 50-mK heat sink. Many sensitive, critical sub-systems comprise Resolve, including a multistage cryogenic cooling system, thin-film aperture filters, low-noise electronics, on-board signal processing, and several sources of X-rays for calibration. We summarize the initial on-orbit power-on and checkout of Resolve that commenced immediately after launch. Soon after launch, the cryocoolers were activated, and their operation was successfully established. On October 9, 2023, the first cycle of the adiabatic demagnetization refrigerator was carried out, bringing the sensors to their steady-state operational temperatures. Following this, the energy resolution at 5.9 keV was successfully measured. The energy scale of the system is highly sensitive to the thermal environment surrounding both the sensors and their analog electronics. Gain correction was performed using reference X-ray lines from onboard calibration sources. To optimize cooler frequency settings, noise spectra were collected across a range of frequencies, and the most suitable frequency pair was selected based on the in-orbit environment. During the final phase of the checkout, an attempt was made to open the gate valve, which is designed to protect the Dewar’s interior from external pressure during ground operations and launch. Unfortunately, this attempt was unsuccessful. As a result, the checkout process was temporarily paused, and a stable operational strategy was subsequently developed to enable Resolve to function effectively with the gate valve remaining closed.

X-ray micro-calorimeter↗

ARM Radiosondes for Joint Polar Satellite System (JPSS) Validation Field Campaign Report

The Joint Polar Satellite System (JPSS) Radiosonde Field Campaign has been a coordinated multi-year effort involving the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) user facility, the University of Wisconsin at Madison (UW-M), and the JPSS project to validate the National Oceanic and Atmospheric Administration (NOAA) JPSS operational satellite sounding products. In this arrangement, funding for radiosondes has been provided by the JPSS project to ARM. These radiosondes have been launched coincident with JPSS satellite overpasses at ARM field sites, with UW-M personnel coordinating the radiosonde launch schedules. This work has been a fundamental, integral, and costeffective part of both the Suomi National Polar-Orbiting Partnership (SNPP) and NOAA20 satellite validation efforts and has provided critical accuracy assessments of the temperature and water vapor soundings. It is anticipated that these effort will continue throughout the lifetime of NOAA20. JPSS validation efforts began in July 2012, with radiosonde launches targeting overpasses of the recently launched SNPP satellite from the ARM sites at the North Slope Alaska (NSA), Southern Great Plains (SGP), and Tropical West Pacific (TWP) at Manus Island, Papua New Guinea. Launches at TWP ceased in May 2014, with the closure of the site, and launches began at the Eastern North Atlantic (ENA) site in February 2015. Radiosonde launches targeting SNPP continued through January 2018 and a total of 204/443/482/190 SNPP overpasses were targeted at the ENA/NSA/SGP/TWP sites respectively. More information about the SNPP radiosonde launches is provided in Table 1.

Satellite meteorology, radiosondes, North Slope of↗

Long-term nitrogen dioxide exposure assessment using back-extrapolation of satellite-based land-use regression models for Australia

Highlights: • We assessed how well a year-2006 satellite-based LUR model captures historical NO{sub 2}. • We used three methods to estimate annual mean NO{sub 2} during 1990–2005. • We measured their performance using standard LUR validation techniques. • Back-extrapolated 2006 levels captured up to 76% of spatial variability (90–05). Assessing historical exposure to air pollution in epidemiological studies is often problematic because of limited spatial and temporal measurement coverage. Several methods for modelling historical exposures have been described, including land-use regression (LUR). Satellite-based LUR is a recent technique that seeks to improve predictive ability and spatial coverage of traditional LUR models by using satellite observations of pollutants as inputs to LUR. Few studies have explored its validity for assessing historical exposures, reflecting the absence of historical observations from popular satellite platforms like Aura (launched mid-2004). We investigated whether contemporary satellite-based LUR models for Australia, developed longitudinally for 2006–2011, could capture nitrogen dioxide (NO{sub 2}) concentrations during 1990–2005 at 89 sites around the country. We assessed three methods to back-extrapolate year-2006 NO{sub 2} predictions: (1) ‘do nothing’ (i.e., use the year-2006 estimates directly, for prior years); (2) change the independent variable ‘year’ in our LUR models to match the years of interest (i.e., assume a linear trend prior to year-2006, following national average patterns in 2006–2011), and; (3) adjust year-2006 predictions using selected historical measurements. We evaluated prediction error and bias, and the correlation and absolute agreement of measurements and predictions using R{sup 2} and mean-square error R{sup 2} (MSE-R{sup 2}), respectively. We found that changing the year variable led to best performance; predictions captured between 41% (1991; MSE-R{sup 2} = 31%) and 80% (2003; MSE-R{sup 2} = 78%) of spatial variability in NO{sub 2} in a given year, and 76% (MSE-R{sup 2} = 72%) averaged over 1990–2005. We conclude that simple methods for back-extrapolating prior to year-2006 yield valid historical NO{sub 2} estimates for Australia during 1990–2005. These results suggest that for the time scales considered here, satellite-based LUR has a potential role to play in long-term exposure assessment, even in the absence of historical predictor data.

54 ENVIRONMENTAL SCIENCES↗

Detecting high-emitting methane sources in oil/gas fields using satellite observations

Methane emissions from oil/gas fields originate from a large number of relatively small and densely clustered point sources. A small fraction of high-mode emitters can make a large contribution to the total methane emission. Here we conduct observation system simulation experiments (OSSEs) to examine the potential of recently launched or planned satellites to detect and locate these high-mode emitters through measurements of atmospheric methane columns. We simulate atmospheric methane over a generic oil/gas field (20–500 production sites of different size categories in a 50 × 50 km 2 domain) for a 1-week period using the WRF-STILT meteorological model with 1.3 × 1.3 km 2 horizontal resolution. The simulations consider many random realizations for the occurrence and distribution of high-mode emitters in the field by sampling bimodal probability density functions (PDFs) of emissions from individual sites.

54 ENVIRONMENTAL SCIENCES↗

Design and performance of Soft Gamma-ray Detector onboard the Hitomi (ASTRO-H) satellite

Hitomi (ASTRO-H) was the sixth Japanese x-ray satellite that carried instruments with exquisite energy resolution of <7 eV and broad energy coverage of 0.3 to 600 keV. The Soft Gamma-ray Detector (SGD) was the Hitomi instrument that observed the highest energy band (60 to 600 keV). The SGD design achieves a low background level by combining active shields and Compton cameras where Compton kinematics is utilized to reject backgrounds coming from outside of the field of view. A compact and highly efficient Compton camera is realized using a combination of silicon and cadmium telluride semiconductor sensors with a good energy resolution. Compton kinematics also carries information for gamma-ray polarization, making the SGD an excellent polarimeter. Following several years of development, the satellite was successfully launched on February 17, 2016. After proper functionality of the SGD components were verified, the nominal observation mode was initiated on March 24, 2016. The SGD observed the Crab Nebula for approximately two hours before the spacecraft ceased to function on March 26, 2016. We present concepts of the SGD design followed by detailed description of the instrument and its performance measured on ground and in orbit.

79 ASTRONOMY AND ASTROPHYSICS↗

Updated design of the CMB polarization experiment satellite LiteBIRD

Recent developments of transition-edge sensors (TESs), based on extensive experience in ground-based experiments, have been making the sensor techniques mature enough for their application on future satellite CMB polarization experiments. LiteBIRD is in the most advanced phase among such future satellites, targeting its launch in Japanese Fiscal Year 2027 (2027FY) with JAXA's H3 rocket. It will accommodate more than 4000 TESs in focal planes of reflective low-frequency and refractive medium-and-high-frequency telescopes in order to detect a signature imprinted on the cosmic microwave background (CMB) by the primordial gravitational waves predicted in cosmic inflation. The total wide frequency coverage between 34GHz and 448GHz enables us to extract such weak spiral polarization patterns through the precise subtraction of our Galaxy's foreground emission by using spectral differences among CMB and foreground signals. Telescopes are cooled down to 5Kelvin for suppressing thermal noise and contain polarization modulators with transmissive half-wave plates at individual apertures for separating sky polarization signals from artificial polarization and for mitigating from instrumental 1/f noise. Passive cooling by using V-grooves supports active cooling with mechanical coolers as well as adiabatic demagnetization refrigerators. Sky observations from the second Sun-Earth Lagrangian point, L2, are planned for three years. An international collaboration between Japan, USA, Canada, and Europe is sharing various roles. In May 2019, the Institute of Space and Astronautical Science (ISAS), JAXA selected LiteBIRD as the strategic large mission No. 2.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Optimization of X-ray event screening using ground and in-orbit data for the Resolve instrument onboard the XRISM satellite

The X-Ray Imaging and Spectroscopy Mission (XRISM) satellite was successfully launched and put into a low-Earth orbit on September 6, 2023 (UT). The Resolve instrument onboard XRISM hosts an X-ray microcalorimeter detector, which was designed to achieve a high-resolution ( ≤ 7 eV FWHM at 6 keV), high-throughput, and non-dispersive spectroscopy over a wide energy range. It also excels in a low background with a requirement of < 2 × 10 -3 s -1 keV -1 (0.3 to 12.0 keV), which is equivalent to only one background event per spectral bin per 100-ks exposure. Event screening to discriminate X-ray events from background is a key to meeting the requirement. We present the result of the Resolve event screening using data sets recorded on the ground and in orbit based on the heritage of the preceding X-ray microcalorimeter missions, in particular, the Soft X-ray Spectrometer onboard ASTRO-H. We optimize and evaluate 19 screening items of three types based on (1) the event pulse shape, (2) relative arrival times among multiple events, and (3) good time intervals. We show that the initial screening, which is applied for science data products in the performance verification phase, reduces the background rate to 1.8 × 10 -3 s -1 keV -1 meeting the requirement. We further evaluate the additional screening utilizing the correlation among some pulse shape properties of X-ray events and show that it further reduces the background rate, particularly in the < 2 keV band. Over 0.3 to 12 keV, the background rate becomes 1.0 × 10 -3 s -1 keV -1 .

47 OTHER INSTRUMENTATION↗

archi : pipeline for light curve extraction of CHEOPS background stars

ABSTRACT High precision time-series photometry from space is being used for a number of scientific cases. In this context, the recently launched CHaracterizing ExOPlanet Satellite (CHEOPS) (ESA) mission promises to bring 20 ppm precision over an exposure time of 6 h, when targeting nearby bright stars, having in mind the detailed characterization of exoplanetary systems through transit measurements. However, the official CHEOPS (ESA) mission pipeline only provides photometry for the main target (the central star in the field). In order to explore the potential of CHEOPS photometry for all stars in the field, in this paper, we present archi, an additional open-source pipeline module1 to analyse the background stars present in the image. As archi uses the official data reduction pipeline data as input, it is not meant to be used as an independent tool to process raw CHEOPS data but, instead, to be used as an add-on to the official pipeline. We test archi using CHEOPS simulated images, and show that photometry of background stars in CHEOPS images is only slightly degraded (by a factor of 2–3) with respect to the main target. This opens a potential for the use of CHEOPS to produce photometric time-series of several close-by targets at once, as well as to use different stars in the image to calibrate systematic errors. We also show one clear scientific application where the study of the companion light curve can be important for the understanding of the contamination on the main target.

Silva, André M.↗