Search NASA⌕ Search

Engineering topics

Smith, D.

Publications and source records attributed to Smith, D..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Probes For Measuring Changing Internal Temperatures

Improved thermocouple probes devised for measuring rapidly changing temperatures within layers of solid materials. In original application, layers in question are carbon-cloth phenolic liners in solid-rocket motor nozzles, and probes inserted in layers to various depths of order of 0.5 in. measure changing temperatures in layers during hot-fire tests. Probe concept adapted to measurements of temperatures inside various other layers, materials, and components, including material test specimens.

Hunt, S. B.↗
NASA NTRS1994

The Clementine mission: Initial results from lunar mapping

Clementine was a mission designed to test the space worthiness of a variety of advanced sensors for use on military surveillance satellites while, at the same time, gathering useful scientific information on the composition and structure of the Moon and a near Earth asteroid. Clementine was dispatched for an extended stay in the vicinity of Earth's Moon on 25 Jan. 1994 and arrived at the Moon on 20 Feb. 1994. The spacecraft started systematic mapping on 26 Feb., completed mapping on 22 Apr., and left lunar orbit on 3 May. The entire Clementine project, from conception through end of mission, lasted approximately three years. Topographic profiles derived from lidar laser altimetry permitted construction of a global topographic map of the Moon. Clementine also aimed at mapping the color of the Moon in eleven different wavelengths in the visible and near infrared parts of the system. With rock and soil samples of known geological context available from the Apollo and Lunar programs, the Clementine mission offers the data needed to construct a global digital image model of the Moon.

Spudis, P. D.↗
NASA NTRS1994

Microtechnology in Telecommunications for Spacecraft Cost and Mass Reduction

This paper examines the incorporation of both microelectronics and micromachining (termed microtechnologies) as applied to deep space telecommunication subsystems. Using the Pluto Fast Flyby Pre-Project as a main case study we have reduced the subsystem mass by 50%.

MCM amplifiers filters switches Goldstone Deep Spa↗
NASA NTRS1994

The Clementine Mission: Initial Results from lunar mapping

Clementine was a mission designed to test the space-worthiness of a variety of advanced sensors for use on military surveillance satellites while, at the same time, gathering useful scientific information on the composition and structure of the Moon and a near-Earth asteroid. Conducted jointly by the Ballistic Missile Defense Organization (BMDO, formerly the Strategic Defense Initiative Organization) of the US Department of Defense and NASA, Clementine was dispatched for an extended stay in the vicinity of Earth's moon on 25 January 1994 and arrived at the Moon on 20 February 1994. The spacecraft started systematic mapping on 26 February, completed mapping on 22 April, and left lunar orbit on 3 May. The entire Clementine project, from conception through end-of-mission, lasted approximately 3 years.

Spudis, P. D.↗
NASA NTRS1993

Novel miniaturised wideband baluns for MIC and MMIC applications

Very compact novel planar broadband baluns are described. Each balun consists of two Lange couplers. Less than 0.3 dB and 2.5 deg for the amplitude and phase balances, respectively, have been measured over the 1.0-2.2 GHz bandwidth for a microstrip balun. As compared with other reported baluns, these baluns are simpler, more compact, easier to design, and fabricated on only one side of the substrate. They are thus very attractive for microwave integrated and monolithic integrated circuit applications.

Nguyen, C.↗
NASA NTRS1991

Content addressable memory project

The progress on the Rutgers CAM (Content Addressable Memory) Project is described. The overall design of the system is completed at the architectural level and described. The machine is composed of two kinds of cells: (1) the CAM cells which include both memory and processor, and support local processing within each cell; and (2) the tree cells, which have smaller instruction set, and provide global processing over the CAM cells. A parameterized design of the basic CAM cell is completed. Progress was made on the final specification of the CPS. The machine architecture was driven by the design of algorithms whose requirements are reflected in the resulted instruction set(s). A few of these algorithms are described.

Hall, Josh↗
NASA NTRS1991

Report of the direct infrared sensors panel

The direct infrared sensors panel considered a wide range of options for technologies relevant to the science goals of the Astrotech 21 mission set. Among the technologies assessed are: large format arrays; photon counting detectors; higher temperature 1 to 10 micro-m arrays; impurity band conduction (IBC) or blocked impurity band (BIB) detectors; readout electronics; and adapting the Space Infrared Telescope Facility and Hubble Space Telescope. Detailed development plans were presented for each of these technology areas.

Mccreight, Craig↗
NASA NTRS1991

An observation of annihilation radiation from the Galactic center region

Results are reported from observations of the 511 MeV annihilation gamma-ray line from the Galactic center, made on May 22, 1989 with a high-resolution gamma-ray spectrometer on board a balloon launched from Alice Springs (Australia). The observations were made at about 4 gm/sq cm atmospheric depth for 6 hrs in a series of target and background pointings lasting 20 min each. The results obtained from multiparameter Gaussian fits to the data were as follows: 511 keV flux = 0.00089 + or - 0.00027 ph/sq cm per sec-rad, line width of about 1.1 keV, and less than 3.2 keV FWHM at 95 percent confidence.

Matteson, J.↗
NASA NTRS1991

An observation of the Galactic center region with the HEXAGONE high resolution gamma-ray spectrometer

The Galactic center region was observed for 6 hours on May 22, 1989 from a high altitude balloon with the HEXAGONE high resolution gamma-ray spectrometer. The instrument had a 285 sq/cm array of cooled germanium detectors with an energy resolution of 2.2 keV at 511 keV and an 18 deg FWHM field of view. The 511 keV gamma-rays from electron-positron annihilation and 1809 keV gamma-rays from the radioactive decay of Al-26 were observed to have fluxes of 8.9 x 10 exp -4 and 1.9 x 10 exp -4 ph/cm-s, respectively. Continuum emission was detected from 20 to 800 keV and preliminary results have been obtained for the spectrum. Below 120 keV this is well described by power law with a slope of -2.6. In the 120-250 keV band the spectrum contains a broad linelike feature. This is interpreted as the result of Compton backscattering of about 511 keV photons from a compact source of electron-positron annihilation radiation.

Matteson, J.↗
NASA NTRS1990

Space station automation of common module power management and distribution, volume 2

The new Space Station Module Power Management and Distribution System (SSM/PMAD) testbed automation system is described. The subjects discussed include testbed 120 volt dc star bus configuration and operation, SSM/PMAD automation system architecture, fault recovery and management expert system (FRAMES) rules english representation, the SSM/PMAD user interface, and the SSM/PMAD future direction. Several appendices are presented and include the following: SSM/PMAD interface user manual version 1.0, SSM/PMAD lowest level processor (LLP) reference, SSM/PMAD technical reference version 1.0, SSM/PMAD LLP visual control logic representation's (VCLR's), SSM/PMAD LLP/FRAMES interface control document (ICD) , and SSM/PMAD LLP switchgear interface controller (SIC) ICD.

Ashworth, B.↗
NASA NTRS1990

Precision orbit determination at the NASA Goddard Space Flight Center

This paper describes the GEODYN computer program developed by the Geodynamics Branch at the NASA Goddard Space Flight Center and outlines the procedure for accurate satellite orbit and tracking-data analyses. The capabilities of the program allow the development of gravity fields as large as 90 by 90, and a complete modeling of tidal parameters. It is also feasible to numerically integrate a continuous orbit of a satellite such as Lageos for up to 12 years. The evolution of the orbit can be studied, and, by comparison with locally determined orbits, force model improvements can be made. The GEODYN flow diagrams are presented.

Putney, B.↗
NASA NTRS1988

Responsivity of silicon photodiodes from 0.5 to 1.1 micron at 77 K

The responsivities of Si, Ge, and InSb photodiodes at 77 K are measured and compared. The results are used to determine the wavelength at which a change should occur in the detector materials used in the focal plan of the Mars Observer Visual and IR Mapping Spectrometer (VIMS). Quantitative responsivity data for Si photodiodes in the band from 0.5 to 1.1 were needed for the VIMS system analysis. The results show that the Si array for the focal plane should have two different antireflection coatings. It is found that the Si and InSb materials have equivalent quantum efficiencies at about 0.9 microns. Because of unknown signal chain complications that could be caused by a multiplexer accessing two different capacitances, the focal plane was designed with a change from Si to InSb at 1 micron.

Staller, C.↗
NASA NTRS1984

Feedthrough Seal For High-Pressure Vessel

Combination of ceramic and plastic withstands many depressurizations. Stack of washers surrounds leadthrough electrode. Under pressure washers expand to fill leadthrough hole in high-pressure vessel. Seal thus formed withstands 20 or more pressurization/depressurization cycles. Seal composed of neoprene, polytetrafluoroethylene, nylon and high-purity, high-density commercial alumina ceramic.

Williams, R.↗