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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Science Enabled by the Ares V: A Large Monolithic Telescope Placed at the Second Sun-Earth Lagrange Point

The payload mass and volume capabilities of the planned Ares V launch vehicle provide the science community with unprecedented opportunities to place large science payloads into low earth orbit and beyond. One example, the outcome of a recent study conducted at the NASA Marshall Space Flight Center, is a large, monolithic telescope with a primary mirror diameter of 6.2 meters placed into a halo orbit about the second Sun-Earth Lagrange point, or L2, approximately 1.5 million kin beyond Earth's orbit. Operating in the visible and ultraviolet regions of the electromagnetic spectrum, such a large telescope would allow astronomers to detect bio-signatures and characterize the atmospheres of transiting exoplanets, provide high resolution imaging three or more times better than the Hubble Space Telescope and the James Webb Space Telescope, and observe the ultraviolet light from warm baryonic matter.

Hopkins, Randall C.↗
NASA NTRS1999

Observation and Modeling of the Solar Transition Region: Multi-Spectral Solar Telescope Array Observations - 1

We report on observations of the solar atmosphere in several extreme-ultraviolet and far-ultraviolet bandpasses obtained by the Multi-Spectral Solar Telescope Array, a rocket-borne spectroheliograph, on flights in 1987, 1991, and 1994, spanning the last solar maximum. Quiet-Sun emission observed in the 171-175 Angstrom bandpass, which includes lines of O v, O VI, Fe IX, and Fe X, has been analyzed to test models of the temperatures and geometries of the structures responsible for this emission. Analyses of intensity variations above the solar limb reveal scale heights consistent with a quiet-Sun plasma temperature of 500,000 less than or equal to T (sub e) less than or equal to 800,000 K. The structures responsible for the quiet-Sun EUV emission are modeled as small quasi-static loops. We submit our models to several tests. We compare the emission our models would produce in the bandpass of our telescope to the emission we have observed. We find that the emission predicted by loop models with maximum temperatures between 700,000 and 900,000 K are consistent with our observations. We also compare the absolute flux predicted by our models in a typical upper transition region line to the flux measured by previous observers. Finally, we present a preliminary comparison of the predictions of our models with diagnostic spectral line ratios from previous observers. Intensity modulations in the quiet Sun are observed to occur on a scale comparable to the supergranular scale. We discuss the implications that a distribution of loops of the type we model here would have for heating the local network at the loops' footpoints.

Oluseyi, Hakeem M.↗
DOE OSTI2021

Development of a cosmic ray oriented trigger for the fluorescence telescope on EUSO-SPB2

The Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2), in preparation, aims to make the first observations of Ultra-High Energy Cosmic Rays (UHECRs) from near space using optical techniques. EUSO-SPB2 will prototype instrumentation for future satellite-based missions, including the Probe of Extreme Multi-Messenger Astrophysics (POEMMA) and K-EUSO. The payload will consist of two telescopes. The first is a Cherenkov telescope (CT) being developed to quantify the background for future below-the-limb very high energy (E 10 PeV) astrophysical neutrino observations, and the second is a fluorescence telescope (FT) being developed for detection of UHECRs. The FT will consist of a Schmidt telescope, and a 6192 pixel ultraviolet camera with an integration time of 1.05 s. The first step in the data acquisition process for the FT is a hardware level trigger in order to decide which data to record. In order to maximize the number of UHECR induced extensive air showers (EASs) which can be detected, a novel trigger algorithm has been developed based on the intricacies and limitations of the detector. Finally, the expected performance of the trigger has been characterized by simulations and, pending hardware verification, shows that EUSO-SPB2 is well positioned to attempt the first near-space observation of UHECRs via optical techniques.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1975

Multiple detector focal plane array ultraviolet spectrometer for the AMPS laboratory

The possibility of meeting the requirements of the amps spectroscopic instrumentation by using a multi-element focal plane detector array in a conventional spectrograph mount was examined. The requirements of the detector array were determined from the optical design of the spectrometer which in turn depends on the desired level of resolution and sensitivity required. The choice of available detectors and their associated electronics and controls was surveyed, bearing in mind that the data collection rate from this system is so great that on-board processing and reduction of data are absolutely essential. Finally, parallel developments in instrumentation for imaging in astronomy were examined, both in the ultraviolet (for the Large Space Telescope as well as other rocket and satellite programs) and in the visible, to determine what progress in that area can have direct bearing on atmospheric spectroscopy.

Feldman, P. D.↗
NASA NTRS1976

Instrumentation for solar spectrophotometry at extreme ultraviolet and soft X-ray wavelengths

The solar extreme ultraviolet and soft X-ray (XUV) spectrum at wavelengths between 20 and 300 A contains a wealth of emission lines from ions formed at temperatures from 10 to the 5th K to greater than 2 x 10 to the 7th K. The requirements for high resolution spectrophotometric instrumentation are discussed in the light of data obtained with extreme ultraviolet and X-ray telescopes flown on Skylab. The design of a grazing-incidence spectroheliometer for active region and flare studies over the wavelength range from 40 to 630 A is presented and recently developed high-efficiency detectors and detector-arrays for use at XUV wavelengths are described.

Timothy, J. G.↗
NASA NTRS1995

Late-time spectra and type Ia supernova models: New clues from the Hubble Space Telescope

Calculated late-time spectra of two classical hydrodynamical models for Type Ia supernovae (deflagration model W7 of Nomoto, Thielemann, & Yokoi, and delayed detonation model DD4 of Woosley & Weaver) are compared with observations of SN 1992A and other spectroscopically normal SNe Ia. An important new piece of information is provided by observations done with the Hubble Space Telescope (HST) which cover the ultraviolet range at the nebular phase of a SN Ia: SN 1992A in NGC 1380. For the first time a picture of SN Ia emission from the ultraviolet through the optical is obtained at these phases. Predictions of the classical model (W7 and DD4) are compared with the observed spectrum of SN 1992A and with the optical spectra of SN 1989M in NGC 4579 and SN 1990N in NGC 4639 at similar epochs. The absolute B and V magnitudes of the models are also estimated at these late phases. Taken at face value the nebular spectra of these 'classical' models are more consistent with the long extragalactic distance scale, pointing to distances to NGC 4579 around 21 +/- 3 Mpc and a slightly larger distance, 22 +/- 3 Mpc, to NGC 4639, on the back side of the Virgo Cluster. However, the calculated Fe(+3) luminosity as predicted from the models exceeds the observed limit from the HST data of SN 1992A. Other differences in the ratios of the line intensities between calculated and observed spectra, show some disagreement with the observed spectra at the nebular phases. They may not be the best choice for spectroscopically normal SNe Ia, and their use as an independent calibration of the extragalactic distance scale should be viewed with caution.

Ruiz-Lapuente, P.↗
NASA NTRS1999

A Multiwavelength Search for Correlated Time Variations in the Brightest Egret Blazers

The February 1996 flare of 3C279 peaked at the highest gamma-ray intensity ever recorded for this object. Compton Gamma Ray Observatory (CGRO), Rossi X-Ray Timing Explorer (RXTE), Advanced Satellite For Cosmology and Astrophysics (ASCA), Roentgen Satellite (ROSAT), International Ultraviolet Explorer (IUE), Hubble Space Telescope (HST), Infrared Space Observatory (ISO) and 18 ground-based observatories participated in observations at various times during January and February 1996. The CGRO EGRET and RXTE light curves are correlated during the flare without any lag larger than the temporal resolution of about 1 day. We present simultaneous spectral energy distributions prior to and near the flare peak. The gamma-rays vary by more than the square of the observed infrared-optical flux change, which poses some problems for specific blazar models.

Urry, C. Megan↗
NASA NTRS2005

Comparison of Newly Acquired Lunar Spectra with the Titanium Abundance Maps Derived from Clementine

The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) is one of seven science instruments onboard NASA's MESSENGER mission, currently en-route to the planet Mercury. One of MASCS s components, referred to as the Visible and Near Infrared Spectrograph (VIRS), will record reflectance spectra of the surface in order to characterize the mineralogy of the planet [1]. The lunar highlands and the average mercurian crust are proposed to be compositionally similar [i.e. 2]. In preparation to interpret VIRS reflectance spectra of Mercury to be first obtained in 2008, the Moon has been observed with an engineering model of the VIRS from a ground-based telescope. In this study, the ultraviolet and visible region of the spectrum is compared with titanium content in the lunar regolith.

Holsclaw, G. M.↗
NASA NTRS2011

Fabrication and Calibration of FORTIS

The Johns Hopkins University sounding rocket group is entering the final fabrication phase of the Far-ultraviolet Off Rowland-circle Telescope for Imaging and Spectroscopy (FORTIS); a sounding rocket borne multi-object spectro-telescope designed to provide spectral coverage of 43 separate targets in the 900 - 1800 Angstrom bandpass over a 30' x 30' field-of-view. Using "on-the-fly" target acquisition and spectral multiplexing enabled by a GSFC microshutter array, FORTIS will be capable of observing the brightest regions in the far-UV of nearby low redshift (z approximately 0.002 - 0.02) star forming galaxies to search for Lyman alpha escape, and to measure the local gas-to-dust ratio. A large area (approximately 45 mm x 170 mm) microchannel plate detector built by Sensor Sciences provides an imaging channel for targeting flanked by two redundant spectral outrigger channels. The grating is ruled directly onto the secondary mirror to increase efficiency. In this paper, we discuss the recent progress made in the development and fabrication of FORTIS, as well as the results of early calibration and characterization of our hardware, including mirror/grating measurements, detector performance, and early operational tests of the micro shutter arrays.

Fleming, Brian T.↗
NASA NTRS2017

Physical Properties of Sub-Galactic Clumps at 0.5 ≤ Z ≤ 1.5 in the UVUDF

We present an investigation of clumpy galaxies in the Hubble Ultra Deep Field at 0.5 equal to or less than z equal to or less than 1.5 in the rest-frame far-ultraviolet (FUV) using Hubble Space Telescope Wide Field Camera 3 broadband imaging in F225W, F275W, and F336W. An analysis of 1404 galaxies yields 209 galaxies that host 403 kpc scale clumps. These host galaxies appear to be typical star-forming galaxies, with an average of 2 clumps per galaxy and reaching a maximum of 8 clumps. We measure the photometry of the clumps and determine the mass, age, and star formation rates (SFR) using the spectral energy distribution fitting code FAST (Fitting and Assessment of Synthetic Templates). We find that clumps make an average contribution of 19% to the total rest-frame FUV flux of their host galaxy. Individually, clumps contribute a median of 5% to the host galaxy SFR and an average of approximately 4% to the host galaxy mass, with total clump contributions to the host galaxy stellar mass ranging widely from lower than 1% up to 93%. Clumps in the outskirts of galaxies are typically younger, with higher SFRs, than clumps in the inner regions. The results are consistent with clump migration theories in which clumps form through violent gravitational instabilities in gas-rich turbulent disks, eventually migrate toward the center of the galaxies, and coalesce into the bulge.

galaxies: structure↗
NASA NTRS2018

Development of Transition Edge Sensor Detectors Optimized for Single-Photon Spectroscopy in the Optical and Near-Infrared

The search for biosignatures in the atmospheres of exoplanets will be a key focus of future space telescopes that operate in the ultraviolet, visible, and near-infrared bands. Detection of biosignatures requires an instrument with moderate spectral resolving power ($R \sim 100$) and a large bandwidth ($\sim 400$ nm -- $\sim 1.8$ $\mu$m). Additionally, biosignature detection is a photon-starved science; instruments designed for these measurements would ideally combine high optical efficiency with quantum-limited photon detectors (i.e., detectors that exhibit zero dark current). In this work, we report on our efforts to develop energy resolving transition edge sensor (TES)-based detectors designed for biosignature detection. TESs operated as microcalorimeters are compelling detectors for this application. Unlike semiconductor detectors, TESs eliminate the need for dispersive optics and are truly single photon detectors -- fundamental TES noise yields uncertainty in the energies of detected photons, not in the number of detected photons. We introduce TESs designed for this application and discuss the path toward realizing a TES-based dispersionless spectrometer optimized for biosignature detection.

Instrumentation and Photography↗
NASA NTRS2018

Development of Transition Edge Sensor Detectors Optimized for Single-Photon Spectroscopy in the Optical and Near-Infrared

The search for biosignatures in the atmospheres of exoplanets will be a key focus of future space telescopes that operate in the ultraviolet, visible, and near-infrared bands. Detection of biosignatures requires an instrument with moderate spectral resolving power (R ~ 100) and a large bandwidth (~ 400 nm – ~ 1.8 µm). Additionally, biosignature detection is a photon-starved science; instruments designed for these measurements would ideally combine high optical efficiency with quantum-limited photon detectors (i.e., detectors that exhibit zero dark current). In this work, we report on our efforts to develop energy resolving transition edge sensor (TES)-based detectors designed for biosignature detection. TESs operated as microcalorimeters are compelling detectors for this application. Unlike semiconductor detectors, TESs eliminate the need for dispersive optics and are truly single photon detectors – fundamental TES noise yields uncertainty in the energies of detected photons, not in the number of detected photons. We introduce TESs designed for this application and discuss the path toward realizing a TES-based dispersionless spectrometer optimized for biosignature detection.

Instrumentation and Photography↗
NASA NTRSDate not supplied

Solar Flare Catalog for SPICE Instrument on the Solar Orbiter

Studying the solar corona, the outermost layer of solar atmosphere, is a pivotal part of understanding the dynamic relations between solar activity and the solar wind, which can disrupt the near-Earth environment. Solar flares emit electromagnetic radiation in the solar corona, capable of releasing large amounts of energy in a matter of minutes. Flares can also be associated with Coronal Mass Ejections (CMEs) and affect Earth’s ionosphere. One instrument that can be used to study flares is the Spectral Imaging of the Coronal Environment (SPICE) instrumentaboard the Solar Orbiter (SolO). SPICE is a high-resolution extreme ultraviolet stigmatic slit spectrometer that covers emission lines formed from the solar chromosphere to corona. Since SPICE is a stigmatic slit spectrometer, the instrument can only take in data from a small spatial area on the Sun at a time. Due to the fast and unpredictable nature of flare events, it can be difficult to determine if and when SPICE has observed a flare. For this reason, we have created a catalog of flares observed by SPICE. This catalog of observational data was assembledby cross referencing data between different solar missions, including data from SolO’s E xtreme Ultraviolet Imager (EUI) and Spectrometer Telescope for Imaging X-rays (STIX), Solar Dynamics Observatory’s Atmospheric Imaging Assembly (SDO/AIA) instrument, and the Geostationary Operational Environmental Satellite (GOES-R). Supplemental analysis of the SPICE solar flare data includes Gaussian line fitting for flares of particular interest. The catalog can be utilized to locate and study coronal loop structures and flare ribbons. This SPICE solar flare catalog and additional supplemental analysis allows for the ease of identification of useful SPICE spectral data and multi-instrument analysis in order to study solar flare activity. It will be open for use by the Solar Orbiter and broader Heliophysics communities.

Anneliese L. Schmidt↗
NASA NTRS2015

Advanced UVOIR Mirror Technology Development for Very Large Space Telescopes

The Advanced Mirror Technology Development (AMTD) project is in phase 2 of a multiyear effort, initiated in FY 2012. This effort is to mature, by at least a half Technology Readiness Level step, the critical technologies required to enable 4-meter or larger ultraviolet, optical, and infrared (UVOIR) space telescope primary mirror assemblies for both general astrophysics and ultra-high contrast observations of exoplanets. AMTD continues to achieve all of its goals and has accomplished all of its milestones to date. This has been achieved by assembling an outstanding team from academia, industry, and government with extensive expertise in astrophysics and exoplanet characterization, and in the design/manufacture of monolithic and segmented space telescopes; by deriving engineering specifications for advanced normal-incidence mirror systems needed to make the required science measurements; and by defining and prioritizing the most important technical problems to be solved. Our results have been presented to the CoPAG and Mirror Tech Days 2013, and proceedings papers of the 2013 and 2014 SPIE Optics & Photonics Symposia have been published.

Effinger, Mike↗
NASA NTRS2001

Ultraviolet-Optical Space Astronomy Beyond HST Conference (Origins Conference and UV-Optical Working Group Support)

This grant supported three major activities, from 1997-2001. (1) Origins Conference. The funds from this grant were used, initially, to support a Conference on "Origins", held May 19-23, 1997 at Estes Park, CO and attended by a wide range of astronomers, planetary scientists, and astrobiologists. The scientific proceedings of this meeting were published in 1998 by the Astronomical Society of the Pacific: "Origins" (1998) "Proceedings of the International Origins Conference". (2) UV-Optical Space Astronomy. Conference Additional funds provided by the NASA Office of Space Science were used to support a meeting held August 5-7, 1998 at Boulder, CO and attended by ultraviolet and optical astronomers and instrumentalists interested in a UV-O successor to the Hubble Space Telescope. The scientific proceedings of this meeting were published in 1999: "Ultraviolet-Optical Space Astronomy Beyond the Hubble Space Telescope" (1999), NASA provided funds and commissioned the UVOWG (Ultraviolet-Optical Working Group), charged with recommending a set of fundamental scientific problems and new space missions in the UV/Optical wavelength bands. The working group was chaired by J. M. Shull, and included ten other astrophysicists. Their report was published as a "White Paper" (Nov. 1999) entitled "The Emergence of the Modern Universe: Tracing the Cosmic Web" available. The results of this report were used in the NASA Strategic Planning ("Roadmap") exercise and by the NRC Astronomy/Astrophysics Decade Committee.

Shull, J. Michael↗
NASA NTRS1976

Extreme ultraviolet survey experiment MA-083

A grazing incidence telescope sensitive to radiation in the 5- to 100-nanometer band was flown in the Apollo service module. On 10 nighttime revolutions, the command and service module was maneuvered to point the instrument at 30 different stellar targets for periods of 1 to 20 minutes, thus constituting the first sensitive search for extreme ultraviolet radiation from nonsolar sources. Several hours of supplementary data were also obtained during nighttime orbits when other experiments in the scientific instrument module bay were operating. Preliminary analysis of a small fraction of the total data indicates the definite detection of a strong source of extreme ultraviolet radiation during observations made during revolution 109. The source is located in Coma Berencies. The suggested optical identification is the white dwarf HZ 43. If this association is correct, the star has the highest temperature of any known white dwarf. Regardless of the optical identification, however, this object is the first nonsolar source to be detected in the extreme ultraviolet band.

Bowyer, S.↗
NASA NTRS1984

Images in the rocket ultraviolet - Photometry of M101

It is pointed out that ultraviolet imagery of spiral galaxies is a sensitive probe of the large-scale morphology of the star-forming regions and the associated interstellar dust. A rocket-borne Ritchey-Chretien telescope was employed to obtain three ultraviolet images of the Sc 1 galaxy M101 (NGC 5457). The present investigation is concerned with the procedures for reduction and absolute calibration of the obtained images and an analysis in terms of discrete sources. Attention is also given to the radial variation and the azimuthal variation of disk and arms. It is found that the emission from M101 in the UV bandpass is dominated by extreme Population I, in the form of discrete OB/H II complexes.

Hill, J. K.↗