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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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NASA NTRS1991

Performance characteristics of the imaging MAMA detector systems for SOHO, STIS, and FUSE/Lyman

Imaging Extreme Ultraviolet (EUV) Multi-Anode Microchannel Array (MAMA) detector systems with formats of 360 x 1024 pixels and pixel dimensions of 25 x 25 sq microns are being fabricated and tested for flight in two instruments on the ESA/NASA Solar and Heliospheric Observatory (SOHO). In addition, very-large-format (1024 x 1024)- and (2048 x 2048)-pixel Far Ultraviolet (FUV) and EUV MAMA detectors with pixel dimensions of 25 x 25 sq microns are being fabricated and tested for use in the NASA Goddard Space Flight Center's Hubble Space Telescope Imaging Spectrograph (STIS), a second-generation instrument scheduled for in-orbit installation in 1997. Finally, FUV MAMA detectors with formats of 224 x 960 pixels and pixel dimensions of 14 x 14 sq microns are being evaluated as prototypes of the detector for the prime FUV spectrograph of the Far Ultraviolet Spectroscopic Explorer (FUSE/Lyman) mission. The configurations and performance characteristics of the different detector systems are described, and the plans for further development of the Advanced Technology MAMA detector system discussed.

Timothy, J. G.↗

NASA NTRS1991

Gamma Ray Observatory (GRO) Prelaunch Mission Operations Report (MOR)

The NASA Astrophysics Program is an endeavor to understand the origin and fate of the universe, to understand the birth and evolution of the large variety of objects in the universe, from the most benign to the most violent, and to probe the fundamental laws of physics by examining their behavior under extreme physical conditions. These goals are pursued by means of observations across the entire electromagnetic spectrum, and through theoretical interpretation of radiations and fields associated with astrophysical systems. Astrophysics orbital flight programs are structured under one of two operational objectives: (1) the establishment of long duration Great Observatories for viewing the universe in four major wavelength regions of the electromagnetic spectrum (radio/infrared/submillimeter, visible/ultraviolet, X-ray, and gamma ray), and (2) obtaining crucial bridging and supporting measurements via missions with directed objectives of intermediate or small scope conducted within the Explorer and Spacelab programs. Under (1) in this context, the Gamma Ray Observatory (GRO) is one of NASA's four Great Observatories. The other three are the Hubble Space Telescope (HST) for the visible and ultraviolet portion of the spectrum, the Advanced X-ray Astrophysics Facility (AXAF) for the X-ray band, and the Space Infrared Telescope Facility (SIRTF) for infrared wavelengths. GRO's specific mission is to study the sources and astrophysical processes that produce the highest energy electromagnetic radiation from the cosmos. The fundamental physical processes that are known to produce gamma radiation in the universe include nuclear reactions, electron bremsstrahlung, matter-antimatter annihilation, elementary particle production and decay, Compton scattering, synchrotron radiation. GRO will address a variety of questions relevant to understanding the universe, such as: the formation of the elements; the structure and dynamics of the Galaxy; the nature of pulsars; the existence of black holes; the possible existence of large amounts of antimatter, energetic and explosive phenomena occurring in galactic nuclei; the origin of the cosmic diffuse background; particle acceleration in the Sun, stars and stellar systems; processes in supernovae; and the origin and evolution of the universe itself.

Source record↗

NASA NTRS1979

Overview of NASA solar physics programs

The program of solar physics missions for the 1980's will include earth-orbiting and solar-orbiting free flying satellites as well as Shuttle sorties carrying large facility instruments and smaller PI-class investigations. Individual missions will have specific, unifying objectives in contrast to the exploratory nature of missions of the 1960's and 70's. The Solar Maximum Mission will study solar flares in 1980 and 1981. The International Solar Polar Mission will swing past Jupiter and traverse the Sun's polar caps in 1986, measuring the high-latitude solar wind. Three of the early Shuttle flights will carry PI-class solar experiments, and the Solar Optical Telescope, to fly in about 1984, will provide extremely high spatial resolution of solar features. Possible future missions include the Solar Cycle and Dynamics Mission to study the Sun's magnetic cycle, and the Solar Probe, which will pass within 4 solar radii of the Sun's surface.

Chipman, E.↗

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.↗

NASA NTRS1988

Large aperture scanning airborne lidar

A large aperture scanning airborne lidar facility is being developed to provide important new capabilities for airborne lidar sensor systems. The proposed scanning mechanism allows for a large aperture telescope (25 in. diameter) in front of an elliptical flat (25 x 36 in.) turning mirror positioned at a 45 degree angle with respect to the telescope optical axis. The lidar scanning capability will provide opportunities for acquiring new data sets for atmospheric, earth resources, and oceans communities. This completed facility will also make available the opportunity to acquire simulated EOS lidar data on a near global basis. The design and construction of this unique scanning mechanism presents exciting technological challenges of maintaining the turning mirror optical flatness during scanning while exposed to extreme temperatures, ambient pressures, aircraft vibrations, etc.

Smith, J.↗

NASA NTRS1999

Effects of Heating on Teflon(Registered Trademark) FEP Thermal Control Material from the Hubble Space Telescope

Metallized Teflon(Registered Trademark) FEP (fluorinated ethylene propylene) thermal control material on the Hubble Space Telescope (HST) is degrading in the space environment. Teflon(Registered Trademark) FEP thermal control blankets (space-facing FEP) retrieved during the first servicing mission (SM1) were found to be embrittled on solar facing surfaces and contained microscopic cracks. During the second servicing mission (SM2) astronauts noticed that the FEP outer layer of the multi-layer insulation (MLI) covering the telescope was cracked in many locations around the telescope. Large cracks were observed on the light shield, forward shell and equipment bays. A tightly curled piece of cracked FEP from the light shield was retrieved during SM2 and was severely embrittled, as witnessed by ground testing. A Failure Review Board (FRB) was organized to determine the mechanism causing the MLI degradation. Density, x-ray crystallinity and solid state nuclear magnetic resonance (NMR) analyses of FEP retrieved during SM1 were inconsistent with results of FEP retrieved during SM2. Because the retrieved SM2 material curled while in space, it experienced a higher temperature extreme during thermal cycling, estimated at 200 C, than the SM1 material, estimated at 50 C. An investigation on the effects of heating pristine and FEP exposed on HST was therefore conducted. Samples of pristine. SM1, and SM2 FEP were heated to 200 C and evaluated for changes in density and morphology. Elevated temperature exposure was found to have a major impact on the density of the retrieved materials. Characterization of polymer morphology of as-received and heated FEP samples by NMR provided results that were consistent with the density results. These findings have provided insight to the damage mechanisms of FEP in the space environment.

deGroh, Kim↗

NASA NTRS2009

MESSENGER Observations of Mercury's Dynamic Magnetosphere

MESSENGER's 14 January and 6 October 2008 encounters with Mercury have provided new measurements dynamic variations in the coupled atmosphere magnetosphere system. The two flybys took place under very different interplanetary magnetic field (IMF) conditions. The northward IMF during the first encounter produced a very quiet, stable magnetosphere. Neutral sodium atoms and photo-ions were observed to high altitudes ; > 2000 km, even in the subsolar region demonstrating the important role played by more energetic neutral atom production processes such as sputtering. Consistent with predictions of magnetospheric models for northward IMF, the neutral atmosphere was observed to have its strongest sources in the high latitude northern hemisphere for the first flyby. The southward IMF for the second encounter revealed a highly dynamic magnetosphere. Reconnection between the interplanetary and planetary magnetic fields is known to control the rate of energy transfer from the solar wind and to drive magnetospheric convection. The MESSENGER magnetic field measurements revealed that the rate at which interplanetary magnetic fields were reconnecting to planetary fields was a factor of 10 greater than is usually observed at Earth. This extremely high reconnection results in a large magnetic field component normal to the magnetopause and the formation of flux transfer events that are much larger relative to the size of the forward magnetosphere than is observed at Earth. The resulting magnetospheric configuration allows the solar wind access to much of the dayside surface of the Mercury. This widespread impingement of the solar wind on Mercury's surface is a likely source of the less structured sodium exosphere imaged during the second flyby and quite possibly the high degree of exospheric temporal variability observed by ground-based telescopes.

Slavin, James A.↗

NASA NTRS2016

Multilayer Active Shell Mirrors for Space Telescopes

A novel active mirror technology based on carbon fiber reinforced polymer (CFRP) substrates and replication techniques has been developed. Multiple additional layers are implemented into the design serving various functions. Nanolaminate metal films are used to provide a high quality reflective front surface. A backing layer of thin active material is implemented to provide the surface-parallel actuation scheme. Printed electronics are used to create a custom electrode pattern and flexible routing layer. Mirrors of this design are thin (< 1.0 mm), lightweight (2.7 kg/m2 ), and have large actuation capabilities. These capabilities, along with the associated manufacturing processes, represent a significant change in design compared to traditional optics. Such mirrors could be used as lightweight primaries for small CubeSat-based telescopes or as meter-class segments for future large aperture observatories. Multiple mirrors can be produced under identical conditions enabling a substantial reduction in manufacturing cost and complexity. An overview of the mirror design and manufacturing processes is presented. Predictions on the actuation performance have been made through finite element simulations demonstrating correct abilities on the order of 250−300× for astigmatic modes with only 41 independent actuators. A description of the custom metrology system used to characterize the active mirrors is also presented. The system is based on a Reverse Hartmann test and can accommodate extremely large deviations in mirror figure (> 100 µm PV) down to sub-micron precision. The system has been validated against several traditional techniques including photogrammetry and interferometry. The mirror performance has been characterized using this system, as well as closed-loop figure correction experiments on 150 mm dia. prototypes. The mirrors have demonstrated post-correction figure accuracies of 200 nm RMS (two dead actuators limiting performance).

Reverse Hartmann↗

NASA NTRS1978

On the distribution of sodium in the vicinity of Io

The contribution of scattering in a telescope to measurements of the size of Io's sodium cloud and to the distribution of emission intensity in the cloud is investigated. The brightest regions, within 30 arcsec of Io near opposition and along the equatorial plane, are relatively undistorted, but regions further than 45 arcsec away and not close to the equatorial plane are very likely to consist mainly of scattered light. Portions of the cloud in the vicinity of the magnetic equator are also mostly scattered light when Io is near extreme magnetic latitude. The equatorial torus, however, extends up to 20 arcmin from Jupiter. The large size of the cloud is thus confirmed. High-resolution line profile shapes indicate that sodium streams from Io preferentially in the forward direction with velocities distributed up to 18 km/sec. The observed wavelength shifts of the peak intensities from Io's rest frame are compatible with a cloud streaming through a bound atmospheric component, but they could also be caused by a velocity distribution peaked at very low velocities.

Trafton, L.↗

NASA NTRS1993

Development of a tool-set for simultaneous, multi-site observations of astronomical objects

A network of ground and space based telescopes can provide continuous observation of astronomical objects. In a 'Target of Opportunity' scenario triggered by the system, any telescope on the network may request supporting observations. We propose to develop a set of data collection and display tools to support these observations. We plan to demonstrate the usefulness of this toolset for simultaneous multi-site observations of astronomical targets. Possible candidates for the proposed demonstration include the Extreme Ultraviolet Explorer, International Ultraviolet Explorer, ALEXIS, and sounding rocket experiments. Ground based observations, operated by the University of California, Berkeley; the Jet Propulsion Laboratory; and Fairborn Observatory, Mesa, Arizona will be used to demonstrate the proposed concept. Although the demonstration will involve astronomical investigations, these tools will be applicable to a large number of scientific disciplines. the software tools and systems developed as a result of our work will be made available to the scientific community.

Chakrabarti, Supriya↗

NASA NTRS1992

Lidar measurements using large liquid mirror telescopes

It is a well accepted practice in the discussion of lidars to compare systems by a performance factor given by the product of the transmitter power and receiver aperture. This form of the performance factor reflects the two key parameters that determine the amount of photons recorded from a given range bin; the amount of transmitted photons and the probability of collecting a scattered photon. We are interested in studying the propagation and breaking of gravity waves typically generated in the lower atmosphere. To study these waves requires high temporal and spatial resolution, as they have frequencies as high as 500 mHz and generate turbulent structures with vertical scales of less than 25 m. In the 80 - 100 km region of the atmosphere these measurements are most efficiently obtained by using resonance scattering from sodium atoms deposited by meteors. However, in the 30 - 80 km region, the most efficient scattering arises from molecules (Rayleigh scattering). Since the atmospheric scale height is nominally 7 km, this scattering becomes extremely weak above 60 km. Furthermore, present laser technology limits the power available for Rayleigh-scattering experiments to about 0.5 - 50 W. The transmitter for the lidar system under development at the University of Western Ontario uses a two-beam transmitter to simultaneously measure density perturbations and temperature from both Rayleigh and resonance scattering.

Sica, R. J.↗

NASA NTRS1992

Development of a tool-set for simultaneous, multi-site observations of astronomical objects

A network of ground and space based telescopes can provide continuous observation of astronomical objects. In a 'Target of Opportunity' scenario triggered by the system, any telescope on the network may request supporting observations. We propose to develop a set of data collection and display tools to support these observations. We plan to demonstrate the usefulness of this tool set for simultaneous multi-site observations of astronomical targets. Possible candidates for the proposed demonstration include the Extreme Ultraviolet Explorer, International Ultraviolet Explorer, ALEXIS, and sounding rocket experiments. Ground based observations operated by the University of California, Berkeley; the Jet Propulsion Laboratory; and Fairborn Observatory, Mesa, Arizona will be used to demonstrate the proposed concept. Although the demonstration will involve astronomical investigations, these tools will be applicable to a large number of scientific disciplines. The software tools and systems developed as a result of our work will be made available to the scientific community.

Chakrabarti, Supriya↗

NASA NTRS2004

Evidence for Gradual External Reconnection Before Explosive Eruption of a Solar Filament

We observe a slowly evolving quiet-region solar eruption of 1999 April 18, using extreme-ultraviolet (EUV) images from the EUV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO) and soft X-ray images from the Soft X-ray Telescope (SXT) on Yohkoh. Using difference images, in which an early image is subtracted from later images, we examine dimmings and brightenings in the region for evidence of the eruption mechanism. A filament rose slowly at about 1 km/s for 6 hours before being rapidly ejected at about 16 km/s leaving flare brightenings and postflare loops in its wake. Magnetograms from the Michelson Doppler Imager (MDI) on SOHO show that the eruption occurred in a large quadrupolar magnetic region with the filament located on the neutral line of the quadrupole s central inner lobe between the inner two of the four polarity domains. In step with the slow rise, subtle EIT dimmings commence and gradually increase over the two polarity domains on one side of the filament, i.e., in some of the loops of one of the two sidelobes of the quadrupole. Concurrently, soft X-ray brightenings gradually increase in both sidelobes. Both of these effects suggest heating in the sidelobe magnetic arcades. which gradually increase over several hours before the fast eruption. Also, during the slow pre- eruption phase, SXT dimmings gradually increase in the feet and legs of the central lobe, indicating expansion of the central-lobe magnetic arcade enveloping the filament. During the rapid ejection. these dimmings rapidly grow in darkness and in area, especially in the ends of the sigmoid field that erupts with the filament. and flare brightenings begin underneath the fast-moving but still low-altitude filament. We consider two models for explaining the eruption: "breakout. which says that reconnection occurs high above the filament prior to eruption, and tether cutting, which says that the eruption is unleashed by reconnection beneath the filament. The pre-eruption evolution is consistent with gradual breakout that led to (and perhaps caused) the fast eruption. Tether-cutting reconnection below the filament begins early in the rapid ejection. but our data are not complete enough to determine whether this reconnection began early enough to be the cause of the fast-phase onset. Thus, our observations are consistent with gradual breakout reconnection causing the long slow rise of the filament, but allow the cause of the sudden onset of the explosive fast phase to be either a jump in the breakout reconnection rate or the onset of runaway tether-cutting reconnection. or both.

Sterling, Alphonse C.↗

NASA NTRS2005

A New Large-Well 1024x1024 Si:As Detector for the Mid-Infrared

We present a description of a new 1024x1024 Si:As array designed for ground-based use from 5 - 28 microns. With a maximum well depth of 5e6 electrons, this device brings large-format array technology to bear on ground-based mid-infrared programs, allowing entry to the mega-pixel realm previously only accessible to the near-IR. The multiplexer design features switchable gain, a 256x256 windowing mode for extremely bright sources, and it is two-edge buttable. The device is currently in its final design phase at DRS in Cypress, CA. We anticipate completion of the foundry run in October 2005. This new array will enable wide field, high angular resolution ground-based follow up of targets found by space-based missions such as the Spitzer Space Telescope and the Wide-field Infrared Survey Explorer (WISE).

astronomy↗

NASA NTRS2013

Hubble Tarantula Treasury Project: Unraveling Tarantula's Web. I. Observational Overview and First Results

The Hubble Tarantula Treasury Project (HTTP) is an ongoing panchromatic imaging survey of stellar populations in the Tarantula Nebula in the Large Magellanic Cloud that reaches into the sub-solar mass regime (<0.5 Stellar Mass). HTTP utilizes the capability of the Hubble Space Telescope to operate the Advanced Camera for Surveys and the Wide Field Camera 3 in parallel to study this remarkable region in the near-ultraviolet, optical, and near-infrared spectral regions, including narrow-band H(alpha) images. The combination of all these bands provides a unique multi-band view. The resulting maps of the stellar content of the Tarantula Nebula within its main body provide the basis for investigations of star formation in an environment resembling the extreme conditions found in starburst galaxies and in the early universe. Access to detailed properties of individual stars allows us to begin to reconstruct the temporal and spatial evolution of the stellar skeleton of the Tarantula Nebula over space and time on a sub-parsec scale. In this first paper we describe the observing strategy, the photometric techniques, and the upcoming data products from this survey and present preliminary results obtained from the analysis of the initial set of near-infrared observations.

Tarantula↗

NASA NTRS2019

Challenges and Potential Solutions to Develop and Fund NASA Flagship Missions

Large, strategic "Flagship" missions have unique characteristics that lead to challenging developmental difficulties for the National Aeronautics and Space Administration (NASA). Missions such as the Hubble Space Telescope (HST), James Webb Space Telescope (JWST), and the Mars Science Laboratory (MSL) had technical and programmatic challenges that led to significant schedule delays and subsequent cost growth. Although NASA has instituted policies that have reduced cost growth for more "typical" NASA science missions, NASA Flagship missions remain a distinct challenge due to their requirement to provide unprecedented science or tackle bold exploration goals, typically while concurrently developing new technologies. The unique challenges presented by Flagship missions make it extremely difficult to fully predict cost and schedule given that the technical and programmatic advances needed to meet performance requirements are unprecedented. This paper addresses why Flagship missions are unique and proposes a new programmatic approach to develop and fund Flagship missions.

Develop↗

NASA NTRS2019

Challenges and Potential Solutions to Develop and Fund NASA Flagship Missions

flagship missions↗

NASA NTRS2016

First Peek of ASTRO-H Soft X-Ray Telescope (SXT) In-Orbit Performance

ASTRO-H (Hitomi) is a Japanese X-ray astrophysics satellite just launched in February, 2016, from Tanegashima, Japan by a JAXA's H-IIA launch vehicle. It has two Soft X-ray Telescopes (SXTs), among other instruments, that were developed by the NASA Goddard Space Flight Center in collaboration with ISAS/JAXA and Nagoya University. One is for an X-ray micro-calorimeter instrument (Soft X-ray Spectrometer, SXS) and the other for an X-ray CCD camera (Soft X-ray Imager, SXI), both covering the X-ray energy band up to 15 keV. The two SXTs were fully characterized at the 30-m X-ray beam line at ISAS/JAXA. The combined SXT+SXS system effective area is about 250 and 300 cm(exp 2) at 1 and 6 keV, respectively, although observations were performed with the gate valve at the dewar entrance closed, which blocks most of low energy X-rays and some of high energy ones. The angular resolution for SXS is 1.2 arcmin (Half Power Diameter, HPD). The combined SXT+SXI system effective area is about 370 and 350 cm (exp 2) at 1 and 6 keV, respectively. The angular resolution for SXI is 1.3 arcmin (HPD). The both SXTs have a field of view of about 16 arcmin (FWHM of their vignetting functions).The SXT+SXS field of view is limited to 3 x 3 arcmin by the SXS array size. In-flight data available to the SXT team was limited at the time of this conference and a point-like source data is not available for the SXT+SXS. Although due to lack of attitude information we were unable to reconstruct a point spread function of SXT+SXI, according to RXJ1856.5-3754 data, the SXT seems to be working as expected in terms of imaging capability. As for the overall effective area response for both SXT+SXS and SXT+SXI, consistent spectral model fitting parameters with the previous measurements were obtained for Crab and G21.5-0.9 data. On the other hand, their 2-10 keV fluxes differ by about 20% at this point. Calibration work is still under progress. The SXT is the latest version of the aluminum foil X-ray mirror, which is extremely light-weight and very low cost, yet produces large effective area over a wide energy-band. Its area-mass ratio is the largest, 16 cm(exp 2)/kg, among ASTRO-H, Chandra, and XMM-Newton mirrors. The aluminum foil mirror is a still compelling technology depending on the mission science goal.

X-rays↗