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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Exploring the Interstellar Medium with SOFIA

SOFIA, the Stratospheric Observatory for Infrared Astronomy, is being developed to operate at wavelengths from 0.3 microns to 1.6 mm over a 20 year lifetime. Its 2.5 m effective diameter telescope will be diffraction limited (approximately 8.5 arc seconds FWHM at 100 microns) at wavelengths beyond about 5 microns. Its B747SP aircraft platform will allow coverage of the entire sky and enable observation of ephemeral events. Nine first-generation focal plane instruments are being built, and more will be added later. These attributes assure SOFIA a vital role in future studies of the interstellar medium (ISM), in addition to topics such as the solar system. SOFIA observers will explore the gamut of ISM topics: star formation; the Galactic Center; debris disks; recycling of materials through the stellar life cycle; the origin and evolution of biogenic materials; shock, photodissociation, and photoexcitation physics; gas and grain chemistry. Imaging, spectroscopy, and eventually polarimetry covering much of the infrared spectrum will all be part of SOFIA's arsenal in the attack on these and other important problems. The talk will describe the observatory, its status, its science instruments and anticipated program. SOFIA is a joint program of NASA in the U.S. and DLR in Germany. Broad participation by the international science community in SOFIA observations will be encouraged via annual proposal opportunities and user-friendly tools. Roughly 80% of the observing time will be granted by the U.S. and 20% by Germany. For further information, see http://sofia.arc.nasa.gov.

Erickson, Edwin F.↗
NASA NTRS2003

Mechanical Amplifier for a Piezoelectric Transducer

A mechanical amplifier has been devised to multiply the stroke of a piezoelectric transducer (PZT) intended for use at liquid helium temperatures. Interferometry holds the key to high angular resolution imaging and astrometry in space. Future space missions that will detect planets around other solar systems and perform detailed studies of the evolution of stars and galaxies will use new interferometers that observe at mid- and far-infrared wavelengths. Phase-measurement interferometry is key to many aspects of astronomical interferometry, and PZTs are ideal modulators for most methods of phase measurement, but primarily at visible wavelengths. At far infrared wavelengths of 150 to 300 m, background noise is a severe problem and all optics must be cooled to about 4 K. Under these conditions, piezos are ill-suited as modulators, because their throw is reduced by as much as a factor of 2, and even a wavelength or two of modulation is beyond their capability. The largest commercially available piezo stacks are about 5 in. (12.7 cm) long and have a throw of about 180 m at room temperature and only 90 m at 4 K. It would seem difficult or impossible to use PZTs for phase measurements in the far infrared were it not for the new mechanical amplifier that was designed and built.

Moore, James↗
NASA NTRS1979

NASA's search for the solar connection. I

NASA's solar research, which leans toward the study of the sun as a star, is surveyed. The Orbiting Solar Observatory (OSO) program is covered, which yielded data such as spectras of 140-400 A wavelength of the entire solar disk. Attention is also given to the results obtained by Skylab, such as data showing that whenever a large coronal hole exists near the sun's equator, a stream of high-speed solar wind will be observed at the earth. Finally areas of future research, such as a concerted study of flare phenomenon, are discussed.

Chapman, R. W.↗
DOE OSTI2024

Prospects for measuring the time variation of astrophysical neutrino sources at dark matter detectors

We study the prospects for measuring the time variation of solar and atmospheric neutrino fluxes at future large-scale xenon and argon dark matter detectors. For solar neutrinos, a yearly time variation arises from the eccentricity of Earth’s orbit and, for charged current interactions, from a smaller energy-dependent day-night variation due to flavor regeneration as neutrinos travel through Earth. For a 100-ton xenon detector running for ten years with a xenon-136 fraction of ≲ 0.1 % , in the electron recoil channel a time-variation amplitude of about 0.8% is detectable with a power of 90% and the level of significance of 10%. This is sufficient to detect time variation due to eccentricity, which has amplitude of ∼ 3 % . In the nuclear recoil channel, the detectable amplitude is about 10% under current detector resolution and efficiency conditions, and this generally reduces to about 1% for improved detector resolution and efficiency, the latter of which is sufficient to detect time variation due to eccentricity. Our analysis assumes both known and unknown periods. We provide scalings to determine the sensitivity to an arbitrary time-varying amplitude as a function of detector parameters. Identifying the time variation of the neutrino fluxes will be important for distinguishing neutrinos from dark matter signals and other detector-related backgrounds and extracting properties of neutrinos that can be uniquely studied in dark matter experiments. Published by the American Physical Society 2024

Zhuang, Yi (ORCID:0000000277138724)↗
DOE OSTI2026

Enhancing Building Resilience: Maintaining Energy Efficiency and Thermal Comfort During Power Outages in Cold Climates

The increasing frequency and intensity of extreme weather events, such as heatwaves and cold snaps, present significant challenges to building energy performance and occupant comfort. Highly correlated with climate events are widespread long duration power interruptions that may affect thousands of buildings and millions of customers. This study evaluates the impact of building energy performance and occupant thermal comfort in medium-sized office buildings in a cold climate region. Using energy models representing pre-1980 and 2019 vintages, simulations were conducted to assess energy performance under typical weather conditions and occupant thermal comfort during power interrupted extreme cold snap and heatwave climate events under both current 2020s and future 2050s weather conditions. The results show a projected 33% increase in cooling energy demand and a 19% reduction in heating energy by 2050. Findings reveal that older buildings are more susceptible to cold discomfort during cold snaps, while modern airtight buildings are more vulnerable to overheating during heatwaves. Various passive energy efficiency measures, such as improved infiltration control, thermal windows, solar-controlled windows, and cool envelopes, were evaluated for their ability to mitigate thermal discomforts. Solar controlled windows and weatherstripping contribute to reducing cold thermal discomfort by 21% during a power-interrupted cold snap. Solar-controlled windows were found to reduce hot thermal discomfort by 34% during a future power-interrupted heatwave. The study highlights the importance of targeted retrofitting strategies to enhance thermal resilience, especially during power outages, to ensure occupant safety and comfort during extreme climate events.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

Method for Spatiotemporal Solar Power Profile Estimation for a Proposed U.S.–Caribbean–South America Super Grid under Hurricanes

Solar photovoltaic (PV) generation technology stands out as a scalable and cost-effective solution to enable the transition toward decarbonization. However, PV solar output, beyond the daily solar irradiance variability and unavailability during nights, is very sensitive to weather events like hurricanes. Hurricanes nucleate massive amounts of clouds around their centers, shading hundreds of kilometers in their path, reducing PV power output. This research proposes a spatiotemporal method, implemented in MATLAB R2023b coding, to estimate the shading effect of hurricanes over a wide distribution of PV solar plants connected to a high-voltage power infrastructure called the U.S.–Caribbean–South America super grid. The complete interconnection of the U.S., the Caribbean, and South America results in the lowest power valley levels, i.e., an overall percentual reduction in PV power output caused by hurricane shading. The simulations assess the impact of hurricanes in 10 synthetic trajectories spanning from Texas to Florida. The Caribbean would also experience lower power valleys with expanded interconnectivity schemes. The U.S.–Caribbean–South America super grid reduces Caribbean variability from 37.8% to 8.9% in the case study. The proposed spatiotemporal method for PV power profile estimation is a valuable tool for future solar power generation expansion, transmission planning, and system design considering the impact of hurricanes.

14 SOLAR ENERGY↗
NASA NTRS1978

The solar power satellite concept - A space program perspective

The Space Shuttle will reduce the cost of transportation to space from thousands of dollars per pound to hundreds of dollars per pound. Studies of future systems indicate that these costs may be further reduced to tens of dollars per pound by using large space freighters, which would be required to build solar power satellites. It is pointed out that the Space Shuttle will provide a versatile tool in the 1980's to support the exploration of the solar power satellite concept as well as other space programs of the future. Three apparently different applications, related to materials processing in space, advanced satellite communications, and solar power satellites, have a number of common requirements. These include the need for large solar power arrays in space and/or the need to construct large systems in space. Consequently, a space program which includes development of the techniques for large power supplies and structural systems provides the basis for selecting and implementing any or all of these promising applications.

Kraft, C. C., Jr.↗
NASA NTRS1987

Advanced solar receiver conceptual design study

High temperature solar dynamic Brayton and Stirling receivers are investigated as candidate electrical power generating systems for future LEO missions. These receivers are smaller and more efficient than conventional receivers, and they offer less structural complexity and fewer thermal stress problems. Use of the advanced Direct Absorption Storage Receiver allows many of the problems associated with working with high-volumetric-change phase-change materials to be avoided. A specific mass reduction of about 1/3 with respect to the baseline receiver has been realized.

Kesseli, J. B.↗
NASA NTRS1985

Glancing incidence X-ray optics for solar X-ray astronomy

Glancing incidence X-ray optics have been developed into a highly valuable tool for high-resolution investigations of the sun in the X-ray/XUV regime. A brief overview of the development of X-ray optics technology is presented. Techniques currently under study for increasing the plate scale and improving the off-axis performance of future X-ray telescopes for solar X-ray astronomy are briefly discussed.

Hoover, Richard B.↗
NASA NTRS2011

Exoplanets, Exo-Solar Life, and Human Significance

With the recent detection of over 500 extrasolar planets, the existence of "other worlds", perhaps even other Earths, is no longer in the realm of science fiction. The study of exoplanets rapidly moved from an activity on the fringe of astronomy to one of the highest priorities of the world's astronomical programs. Actual images of extrasolar planets were revealed over the past two years for the first time. NASA's Hubble Space Telescope is already characterizing the atmospheres of Jupiter-like planets, in other systems. And the recent launch of the NASA Kepler space telescope is enabling the first statistical assessment of how common solar systems like our own really are. As we begin to characterize these "other worlds" and assess their habitability, the question of the significance and uniqueness of life on Earth will impact our society as never before. I will provide a comprehensive overview of the techniques and status of exoplanet detection, followed by reflections as to the societal impact of finding out that Earths are common, or rare. Will finding other potentially habitable planets create another "Copernican Revolution"? Will perceptions of the significance of life on Earth change when we find other Earth-like planets? I will discuss the plans of the scientific community for future telescopes that will be abe to survey our solar neighborhood for Earth-like planets, study their atmospheres, and search for biological signs of life.

Wiseman, Jennifer↗
NASA NTRS1976

Instrumentation for solar and cosmic X-ray spectroscopy

Five flight instruments for high resolution X-ray spectroscopy are described. They include one- and two-dimensionally collimated solar rocket X-ray spectrometers, a 1-23 A X-ray polychromator for the Solar Maximum Mission, a collimated crystal spectrometer for cosmic X-ray studies, and a grating spectrometer/spectrograph with paraboloidal telescope for 10 to 50 A solar X-ray research. The discussion includes factors motivating design and use, examples of results for those already flown, and potential for future studies.

Acton, L. W.↗
NASA NTRS2008

Development of Improved Aerogels for Spacecraft Hypervelocity Capture

The highly successful NASA Discovery mission Stardust became the first mission to return samples to Earth from a known comet in January 2006 [1]. The samples were captured during a flyby of comet 81P/Wild2 using aerogel, a very low density, silica (SiO2)-based solid with a highly porous structure [2]. Currently, scientists around the world are studying the cometary particles returned by Stardust and reporting fascinating discoveries about the history of comets and the evolution of our solar system. Given the widely acknowledged success of the Stardust mission, additional comet sample return missions are attractive and competitive concepts for future NASA Discovery-class missions; in particular, additional comet sample return missions will allow the first laboratory studies to investigate the naturally occurring diversity among comets, a crucial scientific question for understanding not just the formation of comets but also the very nature of the early solar system. Though Stardust was highly successful, there are important lessons learned from the mission on which advances in aerogel technology can be based

Lisse, C. M.↗
DOE OSTI2023

Impact of Wildfires on Solar Generation, Reserves and Energy Prices

Wildfire seasons in the Western U.S. become more prolonged and intense in recent years bringing significant variability and uncertainty of solar generation. It greatly challenges the bulk power system and electricity market operation managed by California Independent System Operator (CAISO) as California leads both the wildfire records and the solar power integration. This study presents a screening-level analysis of the impact of wildfires on solar generation, operating reserve and energy prices applying historical real-world wildfire and market operation data. To the best of the authors knowledge, it is a first-of-its-kind study and will lay the foundation for market impact quantification and wildfire mitigation strategies design based on projected wildfire activities in future years.

electricity price↗
NASA NTRS1978

Status of knowledge of the extraterrestrial solar 'constant' and spectral distribution

Current knowledge of the total solar flux (the solar constant) and its spectral distribution at the top of the earth's atmosphere is reviewed. The development of pyrheliometers and radiation scales is traced, noting that active cavity pyrheliometers have been developed to reduce measurement uncertainty to within 0.1/%. The weighted mean solar constant from ground-based, aircraft, balloon, spacecraft and sounding rocket observations has been calculated to be 1369 W/sq m. Future observations are planned in order to reduce uncertainty to the 0.1% level required for climatological studies. A comparison of the measurement and models of solar spectral irradiance obtained by Thekaekara (1969, 1974), Arvesen (1969) and Labs and Neckel (1968, 1975) shows that the spectrum of Labs and Neckel is most accurate in the 0.4 to 1.25 micron range, that of Arvesen is best in the 0.3 to 0.4 abd 1.25 to 2.5 micron ranges and the model of Labs and Neckel is best at wavelengths greater than 2.5 microns.

Willson, R. C.↗
NASA NTRS2005

Tumbleweed Rovers

Tumbleweed rovers, now undergoing development, are lightweight, inflatable, approximately spherical exploratory robotic vehicles designed to roll across terrain, using only wind for propulsion. Tumbleweed rovers share many features with beach-ball rovers, which were discussed in several prior NASA Tech Briefs articles. Conceived for use in exploring remote planets, tumbleweed rovers could also be used for exploring relatively inaccessible terrain on Earth. A fully developed tumbleweed rover would consist of an instrumentation package suspended in an inflated twolayer (nylon/polypropylene) ball. The total mass of the rover would be of the order of 10 kg, the diameter of the ball when inflated would be 2 meters, and the minimum wind speed needed for propulsion would be about 5 m/s. The instrumentation package would contain a battery power supply, sensors, a Global Positioning System (GPS) receiver, and a radio transmitter that would send the sensor readings and the GPS position and time readings to a monitoring station via a satellite communication system. Depending on the specific exploratory mission, the sensors could include a thermometer, a barometer, a magnetometer (for studying the terrestrial magnetic field and/or detecting buried meteorites), a subsurface radar system (for measuring ice thickness and/or detecting buried meteorites), and/or one or two diametrally opposed cameras that would take the part of sending two side-looking images out. In the planned Antarctic field test, a prototype tumbleweed rover was released at a location near the South Pole. Using the global Iridium satellite network to send information about its position, the rover transmitted temperature, pressure, humidity, and light intensity data to NASA s Jet Propulsion Laboratory. The rover reached speeds of 30 km per hour over the Antarctic ice cap, and traveled at an average speed of about 6 km per hour. The test was designed to confirm the rover s long-term durability in an extremely cold environment, with the goal being eventual use of the device to explore the Martian polar caps and other planets in the solar system. On future Antarctic exploratory missions, tumbleweed rovers might be used to acquire sensor data for studies of global warming, ozone depletion, and impacts of meteorites.

Behar, Alberto↗
DOE OSTI2025

Agrivoltaic Grazing Systems for a Sustainable Future: A Multi‐Disciplinary Review & Gap Analysis

Solar photovoltaics (PV) is the fastest growing source of electricity in the world, however, its expansion has raised concerns about the displacement of agriculture and the degradation of rangeland ecosystems. This has prompted research and development of multi-land-use systems that co-prioritize energy production alongside agriculture, commonly referred to as agrivoltaics. Currently, agrivoltaic grazing (also called solar grazing) is one of the most common forms of these systems. However, peer-reviewed research on these systems is limited. This review synthesizes research on agrivoltaic grazing systems, drawing upon literature addressing agrivoltaics broadly and considering relevant literature in adjacent fields of study. Based on this review, we identify six key gaps and priority directions for future research. These include foundational fieldwork to characterize the layered ecological impacts of solar PV and grazing and understand PV-livestock integration from both an animal welfare and a PV infrastructure perspective. This will facilitate the development of biogeochemical and economic models that improve our predictive capacity and ability to compare system designs. We also identify gaps in understanding the human aspects of these systems and emphasize the importance of utilizing collaborative research methods and increasing research on the social dimensions of agrivoltaic grazing systems.

14 SOLAR ENERGY↗
DOE OSTI2023

Subordinated Gaussian Processes for Solar Irradiance

Traditionally the power grid has been a one-way street with power flowing from large transmission-connected generators through the distribution network to consumers. This paradigm is changing with the introduction of distributed renewable energy resources (DERs), and with it, the way the grid is managed. There is currently a dearth of high fidelity solar irradiance datasets available to help grid researchers understand how expansion of DERs could affect future power system operations. Realistic simulations of by-the-second solar irradiances are needed to study how DER variability affects the grid. Irradiance data are highly non-stationary and non-Gaussian, and even modern time series models are challenged by their distributional properties. We develop a subordinated non-Gaussian stochastic model whose simulations realistically capture the distribution and dependence structure in measured irradiance. We illustrate our approach on a fine resolution dataset from Hawaii, where our approach outperforms standard nonlinear time series models.

MATHEMATICS AND COMPUTING,SOLAR ENERGY↗