Note on the collapse of magnetic interstellar clouds
Explore the source record for details and available documents.
Mouschovias, T. CH.↗
SEARCH · Engineering Papers
Results for “Spitzer”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
High-velocity interstellar clouds
Interstellar absorption line studies have revealed that rapidly moving clouds within one kiloparsec of the sun have considerably less depletion of heavy elements than in the low-velocity diffuse clouds, and their density is somewhat greater and their thickness smaller. Evaporation of interstellar grains, resulting from grain-grain collisions in interstellar shocks, may provide a possible explanation for the observations. Some problems involved in this mechanism are discussed, particularly the likely dominant importance of the interstellar magnetic field in confining the grains within the shocked layer and in accelerating them through the associated electric field, thus offsetting the frictional force of the gas.
Spitzer, L.↗
Surface materials of the Viking landing sites
In the present paper, the soil characteristics at the Viking sites are discussed in terms of bulk density, particle size, angle of internal friction, cohesion, and moisture content. At the Viking Lander-1 site, there is a relatively weak drift material, along with more cohesive materials of a rocky area, and rocks. A variety of materials are present also at the Lander-2 site. Moisture content is low as compared to terrestrial soils. Current estimates of some of the physical properties are tabulated and discussed.
Moore, H. J.↗
The Viking magnetic properties experiment - Primary mission results
Three permanent magnet arrays were mounted on each Viking lander: a strong array fixed on a photometric reference test chart on top of the landers; and two arrays, one strong and one weak, incorporated into the backhoe of the surface sampler. Some or all of the magnetic particles detected could be highly magnetic unoxidized mineral grains (metallic Fe, magnetite, pyrrhotite) forming the core beneath a reddish coating of limonite or hematite; or grains composed of gamma-Fe2O3, with and without other iron oxides; or igneous rock (or mineral particles) which consist of an admixture of unweathered silicate material or minerals with a significant fraction of highly magnetic phase, again with a reddish coating; they could be also igneous rock or mineral particles, intrinsically nonmagnetic, but having a reddish coating containing gamma-Fe2O3; or clay mineral particles which contain and/or are coated with Fe2O3, of which a substantial fraction is in the gamma-Fe2O3 form.
Hargraves, R. B.↗
JSC interactive basic accounting system
Design concepts for an interactive basic accounting system (IBAS) are considered in terms of selecting the design option which provides the best response at the lowest cost. Modeling the IBAS workload and applying this workload to a U1108 EXEC 8 based system using both a simulation model and the real system is discussed.
Spitzer, J. F.↗
Cost and performance characteristics of data system configurations for processing remotely sensed data
Some alternative approaches to constructing a large remote-sensing data system are explored. The cost and performance implications of using a collection of 'small' computers versus using one large computer are examined. Several architectures and associated costs for the large data system supporting a single data center are presented. Recurring cost factors (maintenance and operations) currently slightly favor the single large-machine architecture, but other factors may dictate the choice of one of the two multimachine architectures discussed.
Gregor, P. J.↗
Sample fields of the Viking landers, physical properties, and aeolian processes
Surface sampler activities on Mars during the Viking extended mission are considered, including excavation of deep trenches, construction of conical piles of materials, backhoe touchdown experiments, and acquisition of contiguous pictures of the surface beneath number 2 terminal descent engines using mirrors. Results of the Physical Properties Investigation that are relevant to aeolian processes are also discussed. Both pictures and surface sampler data indicate that the surface materials in the sample fields of the Viking landers may be grouped, in order of increasing strength, into drift material, crusty to cloddy material, blocky material and rocks.
Moore, H. J.↗
Surface erosion caused on Mars from Viking descent engine plume
During the Martian landings the descent engine plumes on Viking Lander 1 (VL-1) and Viking Lander 2 (VL-2) eroded the Martian surface materials. This had been anticipated and investigated both analytically and experimentally during the design phase of the Viking spacecraft. This paper presents data on erosion obtained during the tests of the Viking descent engine and the evidence for erosion by the descent engines of VL-1 and VL-2 on Mars. From these and other results, it is concluded that there are four distinct surface materials on Mars: (1) drift materials, (2) crusty to cloddy material, (3) blocky material, and (4) rock.
Hutton, R. E.↗
Recommendations for the NASA Avionics program for the 1980's
NASA is examining the merits of a significant expansion of its avionics, controls, and human factors technology program for the 1980's. The rationale for an expanded program is related to two factors. One factor is related to a utilization of recent and anticipated significant advances in microelectronics. The second factor is the need to develop new concepts in avionics and control systems for more efficient aircraft operation and better utilization of extremely limited airport capacity. Substantial benefits could be realized in three major categories, including improved aircraft efficiency, improved flight operations, and improved/extended operational capability. The NASA Avionics, Controls, and Human Factors Technology Plan is the report of a task force of agency personnel working in close cooperation with industry, DOD, and FAA. Attention is given to the NASA role, aircraft controls, crew station technology, flight management, integration and interfacing, commercial transports, general aviation, rotorcraft, V/STOL, and high performance aircraft.
Spitzer, C. R.↗
Development of a large area space solar cell assembly
The development of a large area high efficiency solar cell assembly is described. The assembly consists of an ion implanted silicon solar cell and glass cover. The important attributes of fabrication are the use of a back surface field which is compatible with a back surface reflector, and integration of coverglass application and cell fabrications. Cell development experiments concerned optimization of ion implantation processing of 2 ohm-cm boron-doped silicon. Process parameters were selected based on these experiments and cells with area of 34.3 sq cm wre fabricated. The average AMO efficiency of the twenty-five best cells was 13.9% and the best bell had an efficiency of 14.4%. An important innovation in cell encapsulation was also developed. In this technique, the coverglass is applied before the cell is sawed to final size. The coverglass and cell are then sawed as a unit. In this way, the cost of the coverglass is reduced, since the tolerance on glass size is relaxed, and costly coverglass/cell alignment procedures are eliminated. Adhesive investigated were EVA, FEP-Teflon sheet and DC 93-500. Details of processing and results are reported.
Spitzer, M. B.↗
Non-mass-analyzed ion implantation from a solid phosphorus source
A phosphorus ion beam, extracted from a Freeman ion source charged with elemental phosphorus, has been investigated for use in solar cell fabrication. Mass spectroscopy of the beam indicates the absence of both minority-carrier lifetime degrading impurities and hydrogen. The ion beam, without mass analysis, was used for ion implantation of solar cells, and performance for all cells was found to be equivalent to mass-analyzed controls.
Spitzer, M. B.↗
Large area space solar cell assemblies
Development of a large area space solar cell assembly is presented. The assembly consists of an ion implanted silicon cell and glass cover. The important attributes of fabrication are (1) use of a back surface field which is compatible with a back surface reflector, and (2) integration of coverglass application and call fabrication.
Spitzer, M. B.↗
Evaluation of the ion implantation process for production of solar cells from silicon sheet materials
For the ion implantation tooling was fabricated with which to hold dendritic web samples. This tooling permits the expeditious boron implantation of the back to form the back surface field (BSF). Baseline BSF web cells were fabricated.
Spitzer, M. B.↗
Evaluation of the ion implantation process for production of solar cells from silicon sheet materials
The objective of this program is the investigation and evaluation of the capabilities of the ion implantation process for the production of photovoltaic cells from a variety of present-day, state-of-the-art, low-cost silicon sheet materials. Task 1 of the program concerns application of ion implantation and furnace annealing to fabrication of cells made from dendritic web silicon. Task 2 comprises the application of ion implantation and pulsed electron beam annealing (PEBA) to cells made from SEMIX, SILSO, heat-exchanger-method (HEM), edge-defined film-fed growth (EFG) and Czochralski (CZ) silicon. The goals of Task 1 comprise an investigation of implantation and anneal processes applied to dendritic web. A further goal is the evaluation of surface passivation and back surface reflector formation. In this way, processes yielding the very highest efficiency can be evaluated. Task 2 seeks to evaluate the use of PEBA for various sheet materials. A comparison of PEBA to thermal annealing will be made for a variety of ion implantation processes.
Spitzer, M. B.↗
Acoustic waves in supernova remnants
When the Mach number of a supernova shock wave, propagating through the hot interstellar gas, is less than the critical value 2.76, the interaction of the shock with an interstellar cloud produces a reflected pressure pulse that propagates away from the cloud as an acoustic wave. A preliminary analysis indicates that about 4% of the energy of an exploding supernova shell is converted into such waves. When the postshock gas temperature exceeds 2 x 10 to the 6th K, waves as short as 6 pc are damped in less than a wavelength, returning the energy to the hot gas. Longer waves, especially at late stages, are less strongly damped, and are superposed in the hot gas to create a fluctuating magnetoacoustic field, with typical periods of about 100,000 years. In the warm neutral clouds at temperatures of about 8000 K these waves are rapidly damped by plasma slip (ambipolar diffusion), providing a heat source that may account for the temperatures of these clouds.
Spitzer, L., Jr.↗
A survey of ultraviolet interstellar absorption lines
A telescope-spectrometer on the Copernicus spacecraft made possible the measurement of many ultraviolet absorption lines produced by the interstellar gas. The present survey provides data on ultraviolet absorption lines in the spectra of 88 early-type stars. The stars observed are divided into four classes, including reddened stars, unreddened bright stars, moderately reddened bright stars, and unreddened and moderately reddened faint stars. Data are presented for equivalent width, W, radial velocity V, and rms line width, D, taking into account some 10 to 20 lines of N I, O I, Si II, P II, S II, Cl I, Cl II, Mn II, Fe II, Ni II, Cu II, and H2. The data are based on multiple scans for each line. Attention is given to details of observations, the data reduction procedure, and the computation of equivalent width, mean velocity, and velocity dispersion.
Bohlin, R. C.↗
Interstellar abundances of oxygen and nitrogen
Neutral nitrogen and oxygen column densities or limits are derived for 53 path lengths through the diffuse interstellar medium and compared with column densities of neutral hydrogen. For neither N nor O is a systematic increase of depletion found as reddening increases. The value found for forbidden O/N is 8, and the abundances of N and O are both between 40% and 70% of the solar values. Implications of these results for models of interstellar grains are briefly discussed.
York, D. G.↗
The all electric airplane-benefits and challenges
The all electric aircraft considered in the present investigation is an aircraft which has digital flight crucial controls, electromechanical actuators, and electrical secondary power. There are no hydraulic or pneumatic systems. The characteristics of an all electric aircraft are related to reduced acquisition cost, reduced weight, reduced fuel consumption, increased reliability, reduced support equipment, simpler maintenance, an expanded flight envelope, and improved survivability. An additional benefit is the dramatically increased design flexibility and mission adaptability. However, the implementation of the all electric aircraft concept requires the resolution of a number of major technology issues. Issues in the digital flight controls area are related to achieving the required levels of safety and reliability in a cost effective manner. Other challenges which have to be met are concerned with electromechanical actuators, environmental control and ice protection systems, and engine technology.
Spitzer, C. R.↗