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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 523 records · Page 29

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NASA NTRS1981

Optimization of extended propulsion time nuclear-electric propulsion trajectories

This paper presents the methodology used in optimizing extended propulsion time NEP missions considering realistic thruster lifetime constraints. These missions consist of a powered spiral escape from a 700-km circular orbit at the earth, followed by a powered heliocentric transfer with an optimized coast phase, and terminating in a spiral capture phase at the target planet. This analysis is most applicable to those missions with very high energy requirements such as outer planet orbiter missions or sample return missions where the total propulsion time could greatly exceed the expected lifetime of an individual thruster. This methodology has been applied to the investigation of NEP missions to the outer planets where examples are presented of both constrained and optimized trajectories.

Sauer, C. G., Jr.↗

NASA NTRS1981

Spacecraft Dynamics as Related to Laboratory Experiments in Space

Proceedings are presented of a conference sponsored by the Physics and Chemistry Experiments in Space Working Group to discuss the scientific and engineering aspects involved in the design and performance of reduced to zero gravity experiments affected by spacecraft environments and dynamics. The dynamics of drops, geophysical fluids, and superfluid helium are considered as well as two phase flow, combustion, and heat transfer. Interactions between spacecraft motions and the atmospheric cloud physics laboratory experiments are also examined.

G. H. Fichtl↗

NASA NTRS1981

Is energy storage and release part of the substorm process?

Models for magnetospheric substorms were considered. A modified model which includes the growth phase, a time interval prior to the onset of the expansion phase, during which energy was transferred from a solar wind to the magnetosphere and stored for subsequent release, is discussed. Evidence for energy storage in the tail prior to substorm expansion for both isolated and moderate substorm activity is reviewed.

Clauer, C. R.↗

NASA NTRS1982

Effects of subsurface volume scattering on the lunar microwave brightness temperature spectrum

The effects of volumetric scattering on the lunar microwave brightness temperature are examined for a broad range of feasible lunar rock population distributions. Mie-scattering phase functions and the radiative transfer method are utilized. Surveyor and Apollo data relevant to lunar rock size distributions are discussed, and parameters are chosen for nine scattering models which liberally cover the range of studied rock population distributions. Scattering model brightness temperature predictions are analyzed in terms of the lunar disk center emission averaged over a lunation for wavelengths of 3-30 cm. The effects of scattering on the amplitude of disk center brightness temperature variations and resultant deductions of regolith electrical loss are examined. Constraints on the global scale variability of subsurface scatterers imposed by microwave brightness temperature maps are considered.

Keihm, S. J.↗

NASA NTRS1982

Launch vehicles for communications satellites

After giving brief development histories of the Delta and the Atlas Centaur launch vehicles, attention is given to the operational characteristics of the ascent, parking orbit, transfer orbit, and orbital insertion phases of the delivery of a communications satellite to a geostationary orbit by means of a Delta launch vehicle. NASA plans to employ Delta vehicles for as long as they are needed during the transition period to the Space Shuttle. NASA planning for Atlas Centaur includes launches through 1985 for INTELSAT-VA, and through 1986 for FLTSATCOM satellites.

Mahon, J. B.↗

NASA NTRS1985

From Algol to Beta Lyrae

Recognizing that the structure and evolutionary status of Beta Lyrae are much more complicated than for Algol, some of the problems of revealing its structure are discussed. The best model available at present considers Beta Lyrae as an Algol-type semi-detached system in a phase of fairly rapid mass transfer, i.e., younger than typical Algols. It is concluded that Beta Lyrae is not so special as it appears; some characteristics that are so puzzling in Beta Lyrae already appear in such classical Algols as U Cephei and RW Tauri. The mass-accreting components in these systems are surrounded by a hot, turbulent layer which probably expands and which is the seat of emission lines of fairly high ionization discovered in the far ultraviolet. In Beta Lyrae and the so-called W Serpenis stars, the circumstellar hot turbulent shell is much more extensive and probably also denser - a kind of 'superchromosphere'. In Beta Lyrae, a thick disk probably completely surrounds and hides the accreting star proper.

Plavec, M. J.↗

NASA NTRS1986

Alkali metal/halide thermal energy storage systems performance evaluation

A pseudoheat-pipe heat transfer mechanism has been demonstrated effective in terms of both total heat removal efficiency and rate, on the one hand, and system isothermal characteristics, on the other, for solar thermal energy storage systems of the kind being contemplated for spacecraft. The selection of appropriate salt and alkali metal substances for the system renders it applicable to a wide temperature range. The rapid heat transfer rate obtainable makes possible the placing of the thermal energy storage system around the solar receiver canister, and the immersing of heat transfer fluid tubes in the phase change salt to obtain an isothermal heat source.

Phillips, W. M.↗

NASA NTRS1989

Contact conductance evaluation for a full scale space erectable radiator pressurized interface

The baseline thermal control configuration for the Space Station Freedom includes a contact heat exchanger to provide efficient heat transfer between the two-phase thermal bus heat collection/delivery system and the radiator panel heat rejection system. The contact heat exchanger provides a dry interface for a modular radiator system with easy on-orbit panel replacement. July 1988 testing of the Space Erectable Radiator System (SERS) at NASA-JSC provided thermal/vacuum data for three full-scale prototype units of a pressurized dry contact heat exchanger design. Derived contact conductance values agreed with predictions and previous element tests and demonstrated high conductance for relatively low pressure levels. A limited amount of data was also obtained below the operating pressure, resulting in contact conductance trends with respect to interface pressure.

Duschatko, R. John↗

NASA NTRS1990

A pulsation phase-dependent dust shell model of OH 26.5 + 0.6

The spectral energy distribution of the radio-luminous OH/IR star 26.5 + 0.6 was modeled as a function of pulsation phase, using standard radiative-transfer techniques but with more self-consistent input parameters based partly on pulsation model calculations. The changes in spectral shape and overall intensity are easily explained in terms of the radial movement of the dust condensation radius with the changing luminosity of the star. The derived amplitude of the bolometric light curve is only 1.2 mag, considerably less than expected.

Suh, Kyung-Won↗

NASA NTRS1991

Preliminary thermal design of the COLD-SAT spacecraft

The COLD-SAT free-flying spacecraft was to perform experiments with LH2 in the cryogenic fluid management technologies of storage, supply and transfer in reduced gravity. The Phase A preliminary design of the Thermal Control Subsystem (TCS) for the spacecraft exterior and interior surfaces and components of the bus subsystems is described. The TCS was composed of passive elements which were augmented with heaters. Trade studies to minimize the parasitic heat leakage into the cryogen storage tanks are described. Selection procedure for the thermally optimum on-orbit spacecraft attitude was defined. TRASYS-2 and SINDA'85 verification analysis was performed on the design and the results are presented.

Arif, Hugh↗

NASA NTRS1991

Preliminary thermal design of the COLD-SAT spacecraft

Arif, Hugh↗

NASA NTRS1991

French direct TV broadcast satellite (TDF-1 and -2)

The French Direct TV Broadcast Satellite (TDF-1 and -2) missions are to provide three channels of TV and sound broadcasting to France within the 12 to 18 GHz bands. The satellites will be placed in a geostationary orbit at 19 degrees west longitude. The satellites will be launched from the Centre Spatial Guyanis in French Guiana on an Ariane launch vehicle. The Deep Space Network (DSN) will support the transfer and drift orbit mission phases. The coverage will consist of the 26-m antennas at Goldstone and Canberra as prime support. Maximum support will consist of two 8-hour tracks per station for a 7-day period, plus 14 days contingency support. Information is given in tabular form for DSN coverage, frequency assignments, telemetry, command, and tracking support responsibility.

Vacheyroux, R.↗

NASA NTRS1991

Geostationary Meteorological Satellite-5 (GMS-5)

The Geostationary Meteorological Satellite (GMS-5), which is being developed by the National Space Development Agency of Japan (NASDA), is the fifth geostationary, spin stabilized, weather satellite. Its purposes are to observe cataclysmic events such as hurricanes, typhoons, and regional weather phenomena; to relay meteorological data from surface collection points to the Data Processing Center in Japan; and to transmit processing imaging data for facsimile reproduction. The satellite will be launched from the Tanegashima Space Center (TaSC) in Japan by a type H-II launch vehicle. The Deep Space Network (DSN) will support the transfer and drift orbit mission phases. The coverage will consist of the 26-m antennas as prime and the 34-m antenna at Madrid as backup support for launch through drift orbit. Maximum support will consist of two 8-hour tracks per station for a seven day period, plus 23 days of contingency support from all complexes. Information is given in tabular form for DSN support, frequency assignments, telemetry, command and tracking station responsibility.

Horii, M.↗

NASA NTRS1991

Autonomous rendezvous and docking operations of unmanned expendable cargo transfer vehicles (e.g. Centaur) with Space Station Freedom

This paper describes the results of the feasibility study using Centaur or other CTV's to deliver payloads to the Space Station Freedom (SSF). During this study was examined the requirements upon unmanned cargo transfer stages (including Centaur) for phasing, rendezvous, proximity operations and docking/berthing (capture).

Emmet, Brian R.↗

NASA NTRS1991

Spectroscopic binary orbits from ultraviolet radial velocities. VIII - LZ Cephei (HD 209481)

We present a study of the double-lined spectroscopic binary LZ Cep based on high-resolution IUE spectra. We determine the radial velocities by using a cross-correlation technique incorporating profile fitting; this allows measurements of velocity separations down to unusually small values. The final velocity curve has a small but significant eccentricity. By considering other constraints, we construct a model for the system, which correctly predicts the light curve; in the model, the secondary fills its critical equipotential lobe. The secondary is conspicuously overluminous for its mass, and must have reached its present configuration following a phase of case A mass transfer.

Howarth, Ian D.↗

NASA NTRS1994

Adjustable Fiber Optic Microwave Transversal Filters

Microwave transversal filters implemented as adjustable tapped fiber optic delay lines developed. Main advantages of these filters (in comparison with conventional microwave transversal filters) are small size, light weight, no need for matching of radio-frequency impedances, no need for shielding against electromagnetic radiation at suboptical frequencies, no need for mechanical tuning, high stability of amplitude and phase, and active control of transfer functions. Weights of taps in fiber optic delay lines adjusted.

Shadaram, Mehdi↗

NASA NTRS1989

Fluid management in space construction

The low-g fluids management group with the Center for Space Construction is engaged in active research on the following topics: gauging; venting; controlling contamination; sloshing; transfer; acquisition; and two-phase flow. Our basic understanding of each of these topics at present is inadequate to design space structures optimally. A brief report is presented on each topic showing the present status, recent accomplishings by our group and our plans for future research. Reports are presented in graphic and outline form.

Snyder, Howard↗

NASA NTRS1990

NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 5: Aerospace librarians and technical information specialists as information intermediaries: A report of phase 2 activities of the NASA/DOD Aerospace Knowledge Diffusion Research Project

The objective of the NASA/DOD Aerospace Knowledge Diffusion Research Project is to provide descriptive and analytical data regarding the flow of scientific and technical information (STI) at the individual, organizational, national, and international levels, placing emphasis on the systems used to diffuse the results of federally funded aerospace STI. An overview of project assumptions, objectives, and design is presented and preliminary results of the phase 2 aerospace library survey are summarized. Phase 2 addressed aerospace knowledge transfer and use within the larger social system and focused on the flow of aerospace STI in government and industry and the role of the information intermediary in knowledge transfer.

Pinelli, Thomas E.↗