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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Electrons at low altitudes: A difficult background problem for soft X-ray astronomy

Quasi-trapped and precipitating electrons have been observed with rocket-borne X-ray astronomy detectors in the altitude range 150 to 500 km. Because the flights occured at low magnetic latitudes the electrons were unexpected. Data from many flights are combined to derive altitude dependence, an average electron spectrum, and variation with solar activity. Development of electron-rejecting collimators is discussed, and laboratory and flight data on these collimators are presented.

Seward, F. D.↗
NASA NTRS1974

Post-flight differential correction analysis using Vinti's spheroidal method for the small astronomy satellite orbit

The results of an intensive analysis of a differential orbit improvement method utilizing observational data for a 550-kilometer altitude, near-circular, near-equatorial satellite orbit are presented. Observations of the Small Astronomy Satellite (SAS-1) are in the form of direction cosines as measured at two ground interferometer tracking stations near the Equator during the first 22 orbital revolutions (approximately 37 hours) after launch of the spacecraft. Numerical results, in both tabular and graphical form, are displayed for numerous iterated fittings of various observational arcs by differential correction of the orbital elements. Parameters varied in these comparative cases include the time duration of the observational data block, the number of pairs of direction cosine data and the number of tracking station passes included in the solution, the distribution of such passes between the two available tracking stations, and the acceptance criterion for the observational residuals in the least squares fitting procedure. It was found that three observational pairs of direction cosine data, the minimum number possible for a uniquely determined solution in theory, are sufficient to promote covergence to an accurate solution, if properly selected.

Walden, H.↗
NASA NTRS1974

Radio astronomy Explorer-B postlaunch attitude operations analysis

The attitude support activities of the Radio Astronomy Explorer-B are reported. The performance of the spacecraft hardware and software are discussed along with details of the mission events, from launch through main boom deployment. Reproductions of displays are presented which were used during support activities. The interactive graphics proved the support function by providing the quality control necessary to ensure mission success in an environment where flight simulated ground testing of spacecraft hardware cannot be performed.

Werking, R. D.↗
NASA NTRS1973

Multidisciplinary research in the space sciences. Scope B: Experimental X-ray astronomy

A research program to design and develop instruments suitable for rocket-borne X-ray astronomy experiments is discussed. Successful designs that were implemented are summarized. The designs include the following: (1) a large area modular X-ray focusing system, (2) incoherent scattering polarimeters, (3) Bragg crystal spectrometers and polarimeters, and (4) a focusing collector for long wavelength. The applications of these instruments to the observation of X-ray sources in rocket-borne experiments are analyzed.

Novick, R.↗
NASA NTRS1974

The liquid-xenon Compton telescope - A new technique for gamma-ray astronomy

We propose a new technique for gamma-ray astronomy in the difficult but important energy decade from 0.3 to 3.0 MeV. Cosmic gamma rays Compton scatter in a liquid-xenon wire proportional chamber recently developed at Lawrence Berkeley Laboratory (Derenzo, et al., 1972; Muller, et al., 1971) and then are totally absorbed in a second chamber. The energy and position of each interaction is recorded for each gamma ray. This information determines a circle on the celestial sphere which must intersect the source position. A localized source of gamma-rays would show itself as the intersection of many such circles. We expect to locate sources to a fraction of a square degree in a balloon-borne sky survey experiment using an instrument with a one steradian acceptance.

Dauber, P. M.↗
NASA NTRS1973

Spacecraft control section for the improved Small Astronomy Satellite /SAS-C/

The upgraded spacecraft control section for the Small Astronomy Satellite (SAS-C) incorporates a remarkable amount of flexibility for a small satellite. Able to point its thrust axis to any direction in space, it can also spin or slow its outer body rotation to zero for star-locked pointing of side viewing experiments. A programmable telemetry system and delayed command system enhance the inherent capability of a spacecraft designed to be used for a variety of experiments, each of which can be built independently and attached just prior to final acceptance testing and launch. The design of this new spacecraft, whose first launch is scheduled for 1975, is provided in sufficient detail to permit the reader to ascertain its suitability for specific experiments.

Townsend, J. R.↗
NASA NTRS1974

Infrared astronomy and the Shuttle

The infrared spectral range extends approximately from 1 micron to 1000 microns. Observations in infrared astronomy are made with the aid of ground-based telescopes and telescopes flown in aircraft, balloons, or rockets. Advantages and drawbacks of infrared studies conducted by different approaches are discussed. Infrared astronomers are looking forward to observations made from orbiting spacecraft. Present plans call for placing a large telescope aboard the Space Shuttle Orbiter for short missions lasting from seven days to three weeks several times a year. However, the occurrence of a pollution of the spacecraft environment by dust particles and gases coming from the spacecraft might present a problem for the observations. Possible approaches for solving this problem are discussed.

Harwit, M.↗
NASA NTRS1974

A balloon-borne 1 meter telescope for far-infrared astronomy

The flight of a balloon-borne one-meter telescope for infrared astronomy in the wavelength interval of 40 to 240 microns is discussed. The gyro-stabilized telescope mapped the intensity of the far infrared radiation from NGC 7538, Mars, the Orion Nebula, and W3 with a resolution of one minute and from selected regions of these sources with a resolution of 30 seconds. The infrared detection is described and its capabilities are analyzed. The instrumentation, orientation system, and modes of observation of the telescope are defined.

Fazio, G. G.↗
NASA NTRS1975

X-ray and gamma-ray astronomy

Accomplishments in the fields of X-ray and gamma ray astronomy are discussed. Data obtained from IMP and OGO satellites are analyzed to determine the sources of interplanetary radiation bursts. The energy spectrum of cosmic gamma ray bursts as observed by IMP-6 is described. The application of cooling blackbody techniques as a method for examining cosmic gamma ray bursts is reported. The experimental results and theoretical interpretation of high energy diffuse gamma rays are investigated. The structure of the SAS-2 satellite is depicted and the accomplishments are examined. Other sources of gamma radiation to include galactic fermi, Cygnus X-1, supernovae, and the planet Jupiter are proposed. Data obtained from the Pioneer 10 space probe are presented in graph form.

Source record↗
NASA NTRS1974

Thunderstorms observed by radio astronomy Explorer 1 over regions of low man made noise

Radio Astronomy Explorer (RAE) I observations of thunderstorms over regions of low man-made noise levels are analyzed to assess the satellite's capability for noise source differentiation. The investigation of storms over Australia indicates that RAE can resolve noise generation due to thunderstorms from the general noise background over areas of low man-made noise activity. Noise temperatures observed by RAE over stormy regions are on the average 10DB higher than noise temperatures over the same regions in the absence of thunderstorms. In order to determine the extent of noise contamination due to distant transmitters comprehensive three dimensional computer ray tracings were generated. The results indicate that generally, distant transmitters contribute negligibly to the total noise power, being 30DB or more below contributions arriving from an area immediately below the satellite.

Caruso, J. A.↗
NASA NTRS1974

MSFC Skylab ground-based astronomy program

The Skylab Ground-Based Astronomy Program (SGAP) was conducted to enhance the data base of solar physics obtained during the Apollo Telescope Mount (ATM) mission flown in conjunction with the Skylab orbital station. Leading solar physicists from various observatories obtained data from the ground at the same time that orbital data were being acquired by ATM. The acquisition of corollary solar data from the ground simultaneously with the ATM orbital observations helped to provide a broader basis for understanding solar physics by increasing spectral coverage and by the use of additional sophisticated instruments of various types. This report briefly describes the individual tasks and the associated instrumentation selected for this ground-based program and contains as appendices, the final reports from the Principal Investigators.

Duncan, B. J.↗
NASA NTRS1975

A timeline algorithm for astronomy missions

An algorithm is presented for generating viewing timelines for orbital astronomy missions of the pointing (nonsurvey/scan) type. The algorithm establishes a target sequence from a list of candidate targets in a way which maximizes total viewing time. Two special cases are treated. One concerns dim targets which, due to lighting constraints, are scheduled only during the antipolar portion of each orbit. They normally require long observation times extending over several revolutions. A minimum slew heuristic is employed to select the sequence of dim targets. The other case deals with bright, or short duration, targets, which have less restrictive lighting constraints and are scheduled during the portion of each orbit when dim targets cannot be viewed. Since this process moves much more rapidly than the dim path, an enumeration algorithm is used to select the sequence that maximizes total viewing time.

Moore, J. E.↗
NASA NTRS1975

Small Astronomy Payloads for Spacelab

The workshop to define feasible concepts in the UV-optical 1R area for Astronomy Spacelab Payloads is reported. Payloads proposed include: high resolution spectrograph, Schmidt camera spectrograph, UV telescope, and small infrared cryogenic telescope.

Bohlin, R. C.↗
NASA NTRS1975

Potential usefulness of CCD imagers in astronomy

Two dimensional detectors have been important in astronomy since the earliest days of the science. Recently, the requirements for greater photometric accuracy, sensitivity and spectral coverage have driven the search for better imaging devices. Electron beam readout devices with a variety of target materials and intensification schemes, including the SEC and silicon vidicons, have been used successfully. The CCD as an image detector has several potential advantages over electron beam readout devices; low noise, simple construction and geometric stability are among them.

Mccord, T. B.↗
NASA NTRS1974

Small astronomy satellite-A, Uhuru data analysis

Objectives were to conduct observations with the first satellite entirely devoted to X-ray astronomy and to analyze the results obtained. A catalog of X-ray sources was generated, and results of discoveries and further detailed observations of sources were presented in scientific journals and meetings. A list of how objectives were met, a brief description of the instrument, significant results, the X-ray catalog, and a complete bibliography of results are included.

Koch, D.↗
NASA NTRS1975

Gamma ray astronomy

A survey of the instruments developed for gamma ray astronomy is given together with a brief summary of the current status of the observational results. These include the studies of galactic gamma ray emission, the diffuse, presumably extragalactic, gamma radiation, and localized gamma ray sources. The study of the spatial distribution of galactic gamma radiation is beginning to provide a new means for the study of galactic structure and dynamics. The diffuse emission may provide evidence of gamma ray emission in the cosmological past, although improved observations must be obtained before the picture can be clarified. The study of localized sources has shown NP0532, the Crab radio pulsar, to be a gamma ray pulsar also and strong emission from Vela may be due to supernova produced cosmic rays interacting with the remnant gas.

Kniffen, D.↗
NASA NTRS1975

High-energy gamma-ray results from the second small astronomy satellite

Data are reported which were obtained with a high-energy (exceeding 35 Mev) gamma-ray telescope flown on the second Small Astronomy Satellite (SAS-2). The high-energy galactic gamma radiation is observed to dominate over the general diffuse radiation along the entire galactic plane, and its longitudinal and latitudinal distributions appear to be generally correlated with galactic structural features, particularly with arm segments. Principally on the basis of its angular distribution and magnitude, it is suggested that this radiation results primarily from cosmic-ray interactions with interstellar matter. A uniform celestial gamma radiation appears to have been detected; the form of its differential spectrum over the energy range from about 35 to 170 MeV is obtained, and a cosmological origin is suggested for this radiation. In addition to the general galactic emission, high-energy gamma radiation was detected from the Crab Nebula, Vela X, a general region toward the galactic center, and a region located a few degrees north of the galactic plane. Upper limits to the high-energy gamma ray fluxes are set for a number of localized sources.

Fichtel, C. E.↗