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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 1,153 records · Page 64
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Study of alternate optical and fine guidance sensor designs for the space infrared telescope facility (SIRTF)

A unique optical design was developed that compensates for the coma degraded images caused by field chopping in SIRTF. The conic constants of a Cassegrain telescope were altered to compensate for the coma induced by the secondary mirror tilt. The modulation transfer function is essentially independent of secondary mirror tilt, and diffraction limited image quality is maintained over a several arcminute field during chopping. With an untilted secondary mirror, the coma compensated (CC) design has a smaller field than the unchopped Ritchey-Chretien design; but use of relay optics, such as the inverted Cassegrain design developed for the fine guidance sensor (FGS), can increase the CC telescope's field size. A reactionless secondary mirror chopper mechanism that uses superconducting magnets was studied. The heart producing elements are confined to a reaction plate that is not directly viewed by the IR focal plane. A design was also developed for a low moment of inertia, reticulated HIP beryllium secondary mirror consistent with blank fabrication technology and optical finishing requirements.

Wissinger, A.↗
NASA NTRS1985

Study of application of space telescope science operations software for SIRTF use

The design and development of the Space Telescope Science Operations Ground System (ST SOGS) was evaluated to compile a history of lessons learned that would benefit NASA's Space Infrared Telescope Facility (SIRTF). Forty-nine specific recommendations resulted and were categorized as follows: (1) requirements: a discussion of the content, timeliness and proper allocation of the system and segment requirements and the resulting impact on SOGS development; (2) science instruments: a consideration of the impact of the Science Instrument design and data streams on SOGS software; and (3) contract phasing: an analysis of the impact of beginning the various ST program segments at different times. Approximately half of the software design and source code might be useable for SIRTF. Transportability of this software requires, at minimum, a compatible DEC VAX-based architecture and VMS operating system, system support software similar to that developed for SOGS, and continued evolution of the SIRTF operations concept and requirements such that they remain compatible with ST SOGS operation.

Dignam, F.↗
NASA NTRS1985

A normal incidence, high resolution X-ray telescope for solar coronal observations

The following major activities were advanced or completed: complete design of the entire telescope assembly and fabrication of all front-end components; specification of all rocket skin sections including bulkheads, feedthroughs and access door; fabrication, curing, and delivery of the large graphite-epoxy telescope tube; engineering analysis of the primary mirror vibration test was completed and a decision made to redesign the mirror attachment to a kinematic three-point mount; detail design of the camera control, payload and housekeeping electronics; and multilayer mirror flats with 2d spacings of 50 A and 60 A.

Golub, L.↗
NASA NTRS1984

Science with the Solar Optical Telescope (SOT)

Use of the Solar Optical Telescope (SOT) to study the energetics and dynamics of the solar atmosphere is described. Studies include the origin and evolution of the Sun's magnetic field, the structure of solar subsurface convection, the heating of the outer solar atmosphere, and sources of the solar wind in the lower lying regions of the outer atmosphere. To achieve the scientific goals of the SOT, it is necessary to observe features in the solar atmosphere on the scale of a typical photon mean-free-path in continuum radiation and also of the hydrodynamic or density scale-height. The 1.3 m telescope, of a Gregorian configuration, achieves close to 0.1 arcsec angular resolution on the Sun in visible and ultraviolet wavelengths.

Jordan, S. D.↗
NASA NTRS1985

Telescope in lunar orbit

The use of a large telescope in high lunar orbit 4000 km above the Moon's equator is proposed. It is recognized that the Hubble Space Telescope (ST), will provide the necessary capabilities if it can be transferred to lunar orbit. The Orbital Transfer Vehicle (OTV), will be able to scan the lunar surface, locate small outcrops of minerals important to base development, support early base operations and undertake detailed geophysical exploration of the whole lunar surface.

Page, T.↗
NASA NTRS1985

A balloon-borne imaging gamma-ray telescope

A balloon-borne coded-aperture gamma-ray telescope for galactic and extragalactic astronomy observations is described. The instrument, called GRIP (Gamma Ray Imaging Payload), is designed for measurements in the energy range from 30 keV to 5 MeV with an angular resolution of 0.6 deg over a 20 deg field of view. Distinguishing characteristics of the telescope are a rotating hexagonal coded-aperture mask and a thick NaI scintillation camera. Rotating hexagonal coded-apertures and the development of thick scintillation cameras are discussed.

Althouse, W. E.↗
NASA NTRS1985

High Resolution Telescope and Spectrograph (HRTS)

The major objectives of the high resolution telescope and spectrograph (HRTS) are: (1) the investigation of the energy balance and mass balance of the temperature minimum, chromosphere, transition zone, and corona in quiet regions on the Sun as well as in plages, flares, and sunspots; (2) the investigation of the velocity field of the lower corona to study the origin of the solar wind; (3) the investigation of preflare and flare phenomena. The HRTS instruments consists of a telescope, an ultraviolet spectrograph, and ultraviolet spectroheliograph, and an H alpha slit display system, all housed in a thermal control canister mounted on an instrument pointing system.

Moore, R. L.↗
NASA NTRS1985

A balloon-borne imaging gamma-ray telescope

A balloon-borne coded-aperture gamma-ray telescope for galactic and extragalactic astronomy observations is described. The instrument, called Gamma Ray Imaging Payload (GRIP), is designed for measurements in the energy range from 30 keV to 5 MeV with an angular resolution of 0.6 deg over a 20 deg field of view. Distinguishing characteristics of the telescope are a rotating hexagonal coded-aperture mask and a thick NaI scintillation camera. Rotating hexagonal coded-apertures and the development of thick scintillation cameras are discussed.

Althouse, W. E.↗
NASA NTRS1985

Modeling a high energy gamma-ray telescope

A Monte Carlo program was developed to simulate a high energy gamma-ray telescope using a coded aperture mask (CAMTRAC). The ultimate purpose of the calculation will be to determine the optimum design parameters for such an instrument. The model can also used to ascertain under what conditions CAMTRAC performance is superior to that of conventional telescopes which employ electron-positron pair direction as the sole means of determining gamma ray direction.

Jenkins, T. L.↗
NASA NTRS1985

GeV gamma-ray astronomy telescopes with high angular resolution

Gamma-ray telescopes flown on satellites have poor angular resolution with typical point source error circles of a few square degrees. It is shown that a major improvement in angular resolution for the detection of gamma-rays in the GeV region can be obtained with a single crystal as converter. The electron produced by a gamma ray incident at a small angle to a major crystal axis or plane is captured into channeling and radiates gamma rays. The channeling radiation and the electron-positron pair can be detected and yield point source locations with a precision of 5 arcseconds at 10 GeV. This is an improvement of three orders of magnitude on the angular precision of telescopes sensitive to gamma-rays above 50 MeV flown on Satellites.

Mcbreen, B.↗
NASA NTRS1985

Angular resolution of air-shower array-telescopes

A fundamental limit on the angular resolution of air shower array-telescopes is set by the finite number of shower particles coupled with the finite thickness of the particle swarm. Consequently the angular resolution which can be achieved in practice depends in a determinant manner on the size and number of detectors in an array-telescope, as well as on the detector separation and the timing resolution. It is also necessary to examine the meaning of particle density in whatever type of detector is used. Results are given which can be used to predict the angular resolution of a given instrument for showers of various sizes, and to compare different instruments.

Linsley, J.↗
NASA NTRS1985

Construction of a cosmic ray air shower telescope

The telescope under construction is mainly for the purpose of locating the arrival directions of energetic particles and quanta which generate air showers of sizes 10 to the 5th power to 10 to the 6th power. Both fast timing method and visual track method are incorporated in determining the arrival directions. The telescope is composed of four stations using scintillators and neon flash tubes as detectors. The system directional resolution is better than 1.5 deg.

Ng, L. K.↗
NASA NTRS1985

An underground cosmic ray muon telescope for observation of cosmic ray anisotropy

A telescope housed in a tunnel laboratory has an overburden of 573 hg cm(-2) and is located under the center of a saddle-shaped landscape. It is composed of triple layers of proportional counters, each layer of area approx. 4m x 2m and their separation 0.5m. Events are selected by triple coincidence and software track identification. The telescope is in operation for over a year and the overall count rate is 1280 hr(-1). The structure and operation of the system is reported.

Lee, Y. W.↗
NASA NTRS1984

Glancing incidence EUV telescopes - Analysis and comparison

Steps in the derivation of generalized surface equations describing either a Wolter or Wolter-Schwarzschild type II extreme ultraviolet telescope are outlined. These surface equations are incorporated in an optical design program where first-order design parameters are varied to produce a number of different series of type II telescopes. These series are then ray traced to compare and analyze the geometric image quality for different designs in terms of minimum rms angular blur and field curvature. Results of an analysis illustrating the dependence of effective area on first-order design parameters are also presented. The differences and similarities between equivalent Wolter and Wolter-Schwarzschild designs are discussed.

Davila, P. M.↗
NASA NTRS1983

Telescope-optical system performance analysis for the Cryogenic Limb Array Etalon Spectrometer (CLAES) on the Upper Atmospheric Research Satellite

A first-order performance analysis of the CLAES telescope-optical system is presented. The experiment involves the passive measurement of earth-limb radiance over a 10-60 km tangent altitude range, and is based on a solid Fabry-Perot spectrometer which provides spectral resolution of 0.25/cm for atmospheric emission spectroscopy over the 3.5-12 micron IR range. The optical system is required to provide a high degree of off-axis rejection and stray-light control, primarily to suppress intense emission from the earth surface. The astigmatism and other geometric aberrations are corrected by a secondary mirror which produces an excellent image of the primary one, allowing for location of a diffraction control or Lyot stop. The off-axis scattering performance of the telescope is examined in terms of the mirror scatter coefficient and point source rejection ratio. A mirror bidirectional reflectance distribution function of 0.0001 at 1 deg with a 1/theta-squared roll-off between 1 and 0.2 deg is realizable based on recent measurements. This results in an off-axis radiance term that is generally small in comparison with the system-limiting NER.

Roche, A. E.↗
NASA NTRS1983

System design parameter study for Shuttle Infrared Telescope Facility (SIRTF)

SIRTF is a high-sensitivity, cooled astronomical telescope operating from 2 to 1000 microns. The techniques used in analyzing the sensitivity of the SIRTF system performance to several technical issues are presented. Lowering the telescope temperature to near 4K is found to produce margin in several areas. A refined observing requirements model relieves the hardware performance requirements, and identifies extended source size/observing strategy as an important system specification. Other major conclusions are presented.

Mord, A. J.↗
NASA NTRS1983

The GSFC Advanced Compton Telescope (ACT)

A new telescope is being developed at GSFC for the study of point sources of gamma rays in the energy range 1-30 MeV. Using the detection principle of a Compton scatter in a 2.5 cm thick NaI(Tl) detector followed by absorption in a 15 cm thick NaI(Tl) detector, the telescope uses a rocking collimator for field-of-view reduction and background subtraction. Background reduction techniques include lead-plastic scintillator shielding, pulse shape discrimination and Anger camera operation to both NaI detectors, as well as a time-of-flight measurement between them. The instrument configuration and status is described.

Hartman, R.↗
NASA NTRS1983

Cerenkov detectors for cosmic ray telescopes employing the Cerenkov x total energy technique of mass identification

Considerable progress has been made regarding the evolution of the 'Cerenkov x total energy technique' for mass identification of cosmic ray nuclei since the introduction of telescopes employing this technique by Webber et al. (1973). Thus, significant improvements in mass resolution have been made. These improvements are mainly related to the resolution of the Cerenkov counter. The present investigation is, therefore, concerned with the properties of various types of Cerenkov detectors. In addition, a description is provided of the characteristics of a large area (approximately 0.5 sq m-ster) cosmic ray isotope telescope, which is being developed for use on balloons or spacecraft.

Webber, W. R.↗