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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Dark energy and the cosmic microwave background radiation

We find that current cosmic microwave background anisotropy data strongly constrain the mean spatial curvature of the Universe to be near zero, or, equivalently, the total energy density to be near critical-as predicted by inflation. This result is robust to editing of data sets, and variation of other cosmological parameters (totaling seven, including a cosmological constant). Other lines of argument indicate that the energy density of nonrelativistic matter is much less than critical. Together, these results are evidence, independent of supernovae data, for dark energy in the Universe.

Microwaves↗
NASA NTRS1991

Spectroscopic observations of bright and dark emission features on the night side of Venus

Near-infrared spectra of a bright and a dark thermal emission feature on the night side of Venus have been obtained from 2.2 to 2.5 microns at a spectral resolution of 1200 to 1500. Both bright and dark features show numerous weak absorption bands produced by CO2, CO, water vapor, and other gases. The bright feature emits more radiation than the dark feature throughout this spectral region, but the largest contrasts occur between 2.21 s 2.32 microns, where H2SO4 clouds and a weak CO2 band provide the only known sources of extinction. The contrast decreases by 55 to 65 percent at wavelengths longer than 2.34 microns, where CO, clouds, and water vapor also absorb and scatter upwelling radiation. This contrast reduction may provide direct spectroscopic evidence for horizontal variations in the water vapor concentrations in the Venus atmosphere at levels below the cloud tops.

Bell, J. F., III↗
DOE OSTI2026

Infrared freeze-in of magnetic dipole dark matter

We propose a novel mechanism for the cosmological production of keV–GeV mass dark matter that interacts with the Standard Model through a small effective magnetic dipole moment. Such an interaction can be radiatively generated if dark matter couples to heavier charged particles. Previous studies have focused on the case where these charged states are much heavier than the reheat temperature, such that freeze-in production of dark matter is sensitive to the ultraviolet details of reheating. Here, we instead consider the possibility that these heavy states have masses comparable to the dark matter mass and are charged under a new kinetically-mixed U (1)$^{′}$. As a result, dark matter production is dominated by the infrared freeze-in of the heavy charged states that subsequently thermalize the rest of the dark sector to a temperature much below that of the visible bath. We delineate regions of parameter space consistent with cosmological and astrophysical constraints and identify benchmark scenarios that can guide the next generation of direct detection experiments searching for spin-dependent scattering of sub-GeV dark matter.

Berlin, Asher [Fermilab] (ORCID:0000000211561482)↗
DOE OSTI2023

Fully depleted charge‐coupled device design and technology development

Abstract We describe the advancement of fully depleted charge‐coupled device (CCD) technology for scientific applications. Recent efforts on 650–725 m‐thick CCDs for direct dark‐matter and radiation detection with single‐electron sensitivity are described, as well as the technology transfer of the fully depleted CCD technology to 200 mm‐wafer fabrication facilities.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS2006

Radiator Development for Oxygen Storage on the Moon

Vision for Exploration includes "use of lunar resources to support sustained human space exploration". In a favorable orbit, dark sky could be a valuable resource. Spitzer Space Telescope dewar shell maintained at 35 K. Lunar orbit is favorable. Design of radiator to specific lunar environment. A large patch of lunar sky is permanently dark. Radiator provides reliable and un-interrupted cooling. Applications include: a) Zero-boil-off cryogen storage; b) Separation of lunar volatiles for resource utilization; c) Purify oxygen for astronauts; and d) Scrub air for habitation.

moon↗
NASA NTRS2014

The Affect of the Space Environment on the Survival of Halorubrum Chaoviator and Synechococcus (Nageli): Data from the Space Experiment OSMO on EXPOSE-R

We have shown using ESA's Biopan facility flown in Earth orbit that when exposed to the space environment for 2 weeks the survival rate of Synechococcus (Nageli), a halophilic cyanobacterium isolated from the evaporitic gypsum-halite crusts that form along the marine intertidal, and Halorubrum chaoviator a member of the Halobacteriaceae isolated from an evaporitic NaCl crystal obtained from a salt evaporation pond, were higher than all other test organisms except Bacillus spores. These results led to the EXPOSE-R mission to extend and refine these experiments as part of the experimental package for the external platform space exposure facility on the ISS. The experiment was flown in February 2009 and the organisms were exposed to low-Earth orbit for nearly 2 years. Samples were either exposed to solar ultraviolet (UV)-radiation (lambda is greater than 110 nm or lambda is greater than 200 nm, cosmic radiation (dosage range 225-320 mGy), or kept in darkness shielded from solar UV-radiation. Half of each of the UV-radiation exposed samples and dark samples were exposed to space vacuum and half kept at 105 pascals in argon. Duplicate samples were kept in the laboratory to serve as unexposed controls. Ground simulation control experiments were also performed. After retrieval, organism viability was tested using Molecular Probes Live-Dead Bac-Lite stain and by their reproduction capability. Samples kept in the dark, but exposed to space vacuum had a 90 +/- 5% survival rate compared to the ground controls. Samples exposed to full UV-radiation for over a year were bleached and although results from Molecular Probes Live-Dead stain suggested approximately 10% survival, the data indicate that no survival was detected using cell growth and division using the most probable number method. Those samples exposed to attenuated UV-radiation exhibited limited survival. Results from of this study are relevant to understanding adaptation and evolution of life, the future of life beyond earth, the potential for interplanetary transfer of viable microbes via meteorites and dust particles as well as spacecraft, and the physiology of halophiles.

space flight↗
NASA NTRS1991

Dark matter in the universe

What is the quantity and composition of material in the Universe? This is one of the most fundamental questions we can ask about the Universe, and its answer bears on a number of important issues including the formation of structure in the Universe, and the ultimate fate and the earliest history of the Universe. Moreover, answering this question could lead to the discovery of new particles, as well as shedding light on the nature of the fundamental interactions. At present, only a partial answer is at hand. Most of the radiation in the Universe does not give off detectable radiation; it is dark. The dark matter associated with bright galaxies contributes somewhere between 10 and 30 percent of the critical density; baryonic matter contributes between 1.1 and 12 percent of the critical. The case for the spatially flat, Einstein-de Sitter model is supported by three compelling theoretical arguments - structure formation, the temporal Copernican principle, and inflation - and by some observational data. If Omega is indeed unity, or even just significantly greater than 0.1, then there is a strong case for a Universe comprised of nonbaryonic matter. There are three well motivated particle dark matter candidates: an axion of mass 10 (exp -6) eV to 10 (exp -4) eV; a neutrino of mass 10 GeV to about 3 TeV; or a neutrino of mass 20 eV to 90 eV. All three possibilities can be tested by experiments that are either planned or are underway.

Turner, Michael S.↗
NASA NTRS1983

Apparatus for processing electromagnetic radiation and method

Measuring apparatus including a ruled member having alternate transparent and opaque zones. An optical coupler connecting the ruled member with electromagnetic radiation-conversion apparatus. The conversion apparatus may include a photomultiplier and a discriminator. Radiation impinging on the ruled member will, in part, be converted to electrical pulses which correspond to the intensity of the radiation. A method of processing electromagnetic radiation includes providing a member having alternating dark and light zones, establishing movement of the member through the beam of electromagnetic radiation with the dark zones interrupting passage of radiation through the rule, providing an optical coupler to connect a portion of the radiation with a conversion station where the radiation portion is converted into an electrical pulse which is related to the intensity of the radiation received at the conversion station. The electrical pulses may be counted and the digitized signals stored or permanently recorded to produce positional information.

Gatewood, George D.↗
DOE OSTI2023

A Step in understanding the S 8 tension

Models of dark sectors with a mass threshold can have important cosmological signatures. If, in the era prior to recombination, a relativistic species becomes nonrelativistic and is then depopulated in equilibrium, there can be measurable impacts on the cosmic microwave background as the entropy is transferred to lighter relativistic particles. In particular, if this “step” occurs near z~20, 000, the model can naturally accommodate larger values of H 0 . If this stepped radiation is additionally coupled to dark matter, there can be a meaningful impact on the matter power spectrum as dark matter can be coupled via a species that becomes nonrelativistic and depleted. This can naturally lead to suppressed power at scales inside the sound horizon before the step, while leaving conventional cold dark matter signatures for power outside the sound horizon. We study these effects and show such models can naturally provide lower values of S 8 than scenarios without a step. Furthermore, this suggests these models may provide an interesting framework to address the S 8 tension, both in concert with the H 0 tension and without.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2007

Deep Dielectric Charging of Spacecraft Polymers by Energetic Protons

The majority of research in the field of spacecraft charging concentrates on electron charging effects with little discussion of charging by protons. For spacecraft orbiting in the traditional LEO and GEO environments this emphasis on electrons is appropriate since energetic electrons are the dominant species in those orbits. But for spacecraft in orbits within the inner radiation belts or for interplanetary and lunar space probes, proton charging (center dot) effects may also be of concern. To examine bulk spacecraft charging effects in these environments several typical highly insulating spacecraft polymers were exposed to energetic protons (center dot) with energies from 1 Me V to lO Me V to simulate protons from the solar wind and from solar energetic proton events. Results indicate that effects in proton charged dielectrics are distinctly different than those observed due to electron charging. In most cases, the positive surface potential continued to increase for periods on the order of minutes to a day, followed by long time scale decay at rates similar to those observed for electron charging. All samples charged to positive potentials with substantially lower magnitudes than for equivalent electron doses. Possible explanations for the different behavior of the measured surface potentials from proton irradiation are discussed; these are related to the evolving internal charge distribution from energy dependent electron and proton transport, electron emission, charge migration due to dark current and radiation induced conductivity, and electron capture by embedded protons.

radiation induced conductivity↗
DOE OSTI2021

Demonstration of neutron radiation-induced nucleation of supercooled water

In this study, we present direct evidence for neutrons causing nucleation of supercooled water. Highly purified water (20 nm filtration) is cooled to well below freezing (as low as −20 °C) with a radioactive calibration source of neutrons/gamma-rays either present or removed during each of many control cooling runs for the same volume of water. When it is primarily neutrons irradiating the sample bulk, the non-equilibrium freezing point (also known as the “supercooling point”) is, on average, +0.7 °C warmer than the control equivalent, with a statistical significance of greater than 5 Sigma, with systematic uncertainty included. This effect is not observed with water in the presence of gamma-rays instead of neutrons. While these neutrons should have theoretically had sufficient energy to mount the energy barrier, corroborating our results, their raising of supercooling temperature has never been reported experimentally to the best of our knowledge. The potential to use deeply supercooled solutions, not only water, as metastable detectors for radiation and perhaps dark matter or neutrino physics presents now a new avenue for exploration.

Szydagis, Matthew↗
NASA NTRS1991

Migration and generation of contaminants from launch through recovery: LDEF case history

The migration of contaminants to and between Long Duration Exposure Facility (LDEF) surfaces reveals new information relevant to all future space missions. The surface of the LDEF satellite closely paralleled over seven meters of the shuttle during one launch and one reentry. Transfer of contaminants from the shuttle bay to the payload were documented and partially quantified for both the launch and recovery separately. LDEF carried a load of volatile silicones and hydrocarbons into orbit which were then polymerized by UV radiation into tough, dark brown stains on exposed surfaces. The distribution of these stains is providing new information on deposition mechanisms that should be studied on future missions. Electrostatic effects, diffusional flow, and effects due to small surface temperature differences at the time of UV exposure are suggested. The types of functional groups present in the LDEF deposit it nearly identical to stains recovered from other spacecraft. These stains were remarkably stable in low Earth orbit even with atomic oxygen exposure if the amount of silicones present was sufficient to create a sealing layer of silicon dioxide over the dark brown stain beneath.

Crutcher, E. Russ↗
NASA NTRS1994

Voyager investigation of the cosmic diffuse background: Observations of rocket-studied locations with Voyager

Attachments to this final report include 2 papers connected with the Voyager work: 'Voyager Observations of Dust Scattering Near the Coalsack Nebula' and 'Search for the Intergalactic Medium'. An appendix of 12 one-page write-ups prepared in connection with another program, UVISI, is also included. The one-page write-ups are: (1) Sky survey of UV point sources to 600 times fainter than previous (TD-1) survey; (2) Diffuse galactic light: starlight scattered from dust at high galactic latitude; (3) Optical properties of interstellar grains; (4) Fluorescence of molecular hydrogen in the interstellar medium; (5) Line emission from hot interstellar medium and/or hot halo of galaxy; (6) Integrated light of distant galaxies in the ultraviolet; (7) Intergalactic far-ultraviolet radiation field; (8) Radiation from recombining intergalactic medium; (9) Radiation from re-heating of intergalactic medium following recombination; (10) Radiation from radiative decay of dark matter candidates (neutrino, etc.); (11) Reflectivity of the asteroids in the Ultraviolet; and (12) Zodiacal light.

Henry, Richard C.↗
NASA NTRS1997

(abstract) 9 (micro)m Cutoff 640x480 Quantum Well Infrared Photodetector (QWIP) Focal Plane Array Camera

Long wavelength infrared (LWIR) detectors, 8 (micro)m to 12 (micro)m, are of great interest for a variety of ground-based and space-borne applications. These applications have placed stringent requirements on the performance of the infrared detectors and arrays including high detectivity, low dark current, uniformity, radiation hardness, and low power dissipation. I will discuss the development and progress of GaAs based long-wavelength quantum well infrared photodetectors (QWIPs) to meet those stringent requirements and the demonstration of a 9 (micro)m cutoff 640x480 QUIP focal plane array camera. The noise equivalent temperature difference of the focal plane array is 25 mK at 300 K background and the operating temperature is 70 K.

long wavelength infrared detectors LWIR detector a↗
NASA NTRS1995

16 Infrared Hot Electron Transistor

Very long wavelength infrared (VWIR) photodetectors, 14 20 , are of a great interest for variety of space-borne applications. These space applications have placed stringent requirements on the performance of the infrared detectors and arrays including high detectivity, low dark current, uniformity, radiation hardness and lower power dissipation. I will discuss the development and progress of AlxGal- xAs/GaAs VWIR quantum well infrared photodetectors (QWIPs) to meet those stringent requirements and the demonstration of a 15 128x128 QWIP focal plane array camera. The noise equivalent temperature difference of the focal plane array is 30 mK at 300 K background, and operating temperature is 45 K.

Electron Transistor↗