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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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NASA NTRS1986

Tethered satellite system

A reusable system is to be developed to enable a variety of scientific investigations to be accomplished from the shuttle, considering the use of a tethered system with manual or automated control, deployment of a satellite toward or away from the Earth, up to 100 km, and conducting or nonconducting tether. Experiments and scientific investigations are to be performed using the tether system for applications such as magnetometry, electrodynamics, atmospheric science, and chemical release. A program is being implemented as a cooperative U.S./Italian activity. The proposed systems, investigations, and the program are charted and briefly discussed.

Sisson, J.↗
NASA NTRS1986

Tethered satellite design

The capability of the satellite to perform a variety of space operations to be accomplished from the shuttle is reviewed considering use of the satellite with man-in-loop and closed loop modes and deployment (toward or away from Earth, up to 100 km), stationkeeping, retrieval and control of the satellite. Scientific payloads are to be used to perform experiments and scientific investigation for applications such as magnetometry, electrodynamics, atmospheric science, chemical release, communications, plasmaphysics, dynamic environment, and power and thrust generation. The TSS-S will be reused for at least 3 missions after reconfiguration and refurbishment by changing the peculiar mission items such as thermal control, fixed boom for experiments, aerodynamic tail for yaw attitude control, external skin, experiments, and any other feature. The TSS-S is to be composed of three modules in order to allow independent integration of a single module and to facilitate the refurbishment and reconfiguration between flights. The three modules are service, auxiliary propulsion, and payload modules.

Manarini, G.↗
NASA NTRS1986

Applications of tethers for planetary missions

Ideas of deep space exploration are considered. The role of tethers in deep space is of most concern. A proposal of a tethered instrument package in orbit about the Moon is explored. The idea of a sling on the surface of the Moon which would take solar energy and build up momentum of the sling is studied. The NASA idea of a Mars Aeronomy Orbiter which would use a tether to enhance the planned Mars Orbiter is reviewed. It is also proposed that a tether can be attached to an asteroid during a spacecraft flyby. The possibility of using tethers to provide a transportation system for payloads which are coming to the surface from escape, and which are leaving Mars and escaping from Mars itself is also studied. A proposal from the Jet Propulsion Lab. on collecting comet or asteroid samples and returning them to Earth is reviewed. A tethered penetrator which could collect core samples is the proposed way. Also considered is the area of electrodynamic tethers at Jupiter.

Penzo, P.↗
NASA NTRS1986

The Science and Applications Tethered Platform (SATP) project

The capabilities of tether systems in orbit are going to be demonstrated by the first planned flights of the Tethered Satellite System (TSS). These test flights will investigate the properties of tether systems as low altitude atmospheric research facilities and as electric power generators. Studies are being conducted with the purpose of testing a variety of concepts and approaches. A comparative analysis of results will allow the choosing of the most promising ideas for further development. The broad range of applications presently under study include applications in electrodynamics, transportation, microgravity in addition to basic research. The SATP project definition study is now about midway through its first phase. The analyses conducted have led to an appraisal of users interest in the project and to a deeper understanding of the problems associated with large, long-lived tether systems in space. In addition, two specialized platform designs, devoted to microgravity and precise pointing applications, are being studied because of their potential usefulness and the promise of technical feasibility.

Merlina, P.↗
NASA NTRS1986

Technology and test

The chairman of the Technology Applications in Space Working Group summarizes the technology issues for each of the disciplines in Tethered Satellite Systems. The disciplines are Tether Materials and Configurations, Tether System Dynamic Simulation Capability, Tether System Instrumentation, TAS Program Related Science Instrumentation, Atmospheric/Aerothermodynamic tethered system research, and TAS Discipline Program Accomplishment. To enable these tether applications, design and development programs have been recommended and are presently underway relative to the demonstration of the hollow cathode concept which is an enabling electrodynamic tether mission technology.

Siemers, P.↗
NASA NTRS1985

Bearing development program for a 25 kWe solar-powered organic Rankine-cycle engine

The bearing development program is summarized for a 25-kWe power conversion subsystem (PCS) consisting of an organic Rankine-cycle engine, and permanent magnetic alternator (PMA) and rectifier to be used in a 100-kWe point-focusing distributed receiver solar power plant. The engine and alternator were hermetically sealed and used toluene as the working fluid. The turbine, alternator, and feed pump (TAP) were mounted on a single shaft operating at speeds up to 60,000 rev/min. Net thermal-to-electric efficiencies in the range of 21 to 23% were demonstrated at the maximum working fluid temperature of 400 C (750 F). A chronological summary of the bearing development program is presented. The primary causes of bearing wear problems were traced to a combination of rotordynamic instability and electrodynamic discharge across the bearing surfaces caused by recirculating currents from the PMA. These problems were resolved by implementing an externally supplied, flooded-bearing lubrication system and by electrically insulating all bearings from the TAP housing. This program resulted in the successful development of a stable, high-speed, toluene-lubricated five-pad tilting-pad journal bearing and Rayleigh step thrust bearing system capable of operating at all inclinations between horizontal and vertical.

Nesmith, B.↗
NASA NTRS1985

A sun-aligned arc observed by DMSP and AE-C

On May 12, 1977, 8 minutes after a DMSP satellite photographed a sun-aligned auroral arc in the southern polar cap, AE-C crossed over the same arc. Precipitating electrons were observed with a peak energy flux of 0.94 erg per sq cm s but with no clear monoenergetic beam, and coincident ion precipitation was measured at energies of a few keV. A very sharp ion convection reversal was found coincident with the particle precipitation and embedded in a region of constant antisunward flow. Magnetic field data indicate that the arc occurred during the recovery phase of a weak magnetic storm, with the IMF in a toward sector and the Z component nearly zero. The data are consistent with a source of particles at altitudes of the order of 5-8 R(E) on field lines containing the plasma sheet boundary layer. The electron spectra do not indicate the existence of an electrostatic potential along the magnetic field lines projecting from the arc. The electrodynamic properties associated with the arc appear to be consistent with a simple model in which field-aligned currents are required along any boundary where the horizontal ionospheric current diverges.

Hoffman, R. A.↗
NASA NTRS1986

Development status of first Tethered Satellite System

An MOU between NASA and Italian research organizations has assigned the responsibilities for the development, payload integration, launch and operation of a Tethered Satellite System (TSS). The TSS will include a deployer mounted on a Spacelab pallet, science equipment on a customized mission support structure and a satellite connected to the Orbiter by a tether. The satellite is 1.6 m in diameter and can weight up to 500 kg. The deployer will be insulated from the Orbiter because of the conductive nature of the tether. The first mission is to demonstrate the TSS technology, perform electrodynamic investigations of the interaction of the tether with ambient space plasma, and gather data on atmospheric interactions in the lower thermosphere, geomagnetic phenomena and gravimetric characteristics. The first TSS will be deployed 20 km outward from the Orbiter and the earth on a strand of tin-coated copper wire wrapped in Teflon insulation, braided Kevlar and a Nomek jacket. The first strand is designed to accommodate 53 N tension. The satellite on the end of the tether will be a multimission platform for facile changeout of the scientific package from mission-to-mission.

Sisson, J. M.↗
NASA NTRS1986

Future applications of tethers in space

Various experiments with tethered satellite systems (TSS) have reached the stage of being considered for demonstration programs as follow-ups to the planned electrodynamic power system and atmospheric missions at the close of the 1980s. All TSS operations involve an initial separation thrust to a tethered object and then begin transferring angular momentum from one object to another while preserving the total angular momentum. The demonstrations include tethered launch of an Orbiter payload to a higher orbit, deployment of the Orbiter from the Space Station (SS), and launch of an Orbital Transfer Vehicle from the SS. The operations can be sequential, with the Orbiter providing the SS with an upward boost while being lowered to an easier deorbit position, followed by the SS releasing on OTV (or a repaired Space Telescope) to a higher orbit while the SS returns to a more favorable lower orbit.

Von Tiesenhausen, G.↗
NASA NTRS1986

Designing an electro-impulse de-icing system

Basic principles and parameters for a system to deice aircraft with electromagnetic impulses are described. The physical basis for deicing by such impulses is explained, and the requirements involved in the electrodynamic design, structural dynamic design, and system design are discussed. Some manufacturing and testing problems and techniques are described.

Zumwalt, G. W.↗
NASA NTRS1985

The perturbed neutral circulation in the vicinity of a symmetric stable auroral arc

In the present investigation, a sophisticated high-resolution time-dependent numerical model is used to study the neutral response to changes in the E region electrodynamical forcing and particle heating associated with the appearance of a stable auroral arc. The initial condition is a nighttime ionosphere in the presence of a background precipitation of electrons associated with diffuse auroras. A simulation study is conducted of the perturbation in the neutral circulation. The simulations were performed on the basis of a model which describes nonlinear, nonhydrostatic viscous flow on a rotating atmosphere.

Walterscheid, R. L.↗
NASA NTRS1986

Magnetic energy storage and conversion in the solar atmosphere

According to the approach employed in this investigation, particularly important simple configurations of magnetic field and plasma are identified, and it is attempted to achieve an understanding of the large-scale dynamic processes and transformations which these systems can undergo. Fundamental concepts are discussed, taking into account aspects of magnetic energy generation, ideal MHD theory, non-MHD properties, the concept of 'anomalous' resistivity, and global electrodynamic coupling. Questions of magnetically controlled energy conversion are examined, giving attention to magnetic modifications of plasma transport, the transition region structure and flows, channeling and acceleration of plasma, channeling and dissipation of MHD waves, and anomalous dissipation of field-aligned currents. A description of the characteristics of magnetohydrodynamic energy conversion is also provided, and outstanding questions are discussed.

Spicer, D. S.↗
NASA NTRS1986

The influence of scattering particles morphology on the characteristics of lidar signals

The characteristics of light scattering by a separate spherical particle are used as a priori information when interpreting the data on laser sounding of atmospheric aerosols. Analogously, it is necessary to have a priori information on the characteristics of light scattering by a single crystals in order to restitute the microstructure of crystal formation in the atmosphere. In contrast to the aerosol particles the crystals are of different shapes. On the one hand, this complicates the solution of electrodynamic problems on light scattering by such crystals. On the other hand, if obtaining such a solution is possible, one can determine the morphology of scattering particles accoring to the sounding data and this enables additonal information to be obtained on such meteorological parameters as temperature, pressure, and humidity. Using the geometric-wave approach the problem of scattering of plane electromagnetic wave on convex polyhedrons of arbitrary form was solved. As a result, the expressions were obtained for electric field components of perpendicular and parallel polarizations scattered in any given direction.

Zuev, V. E.↗
NASA NTRS1986

HISCAT: A proposed new scatter facility in Northern Scandinavia

It is proposed that a new versatile ionospheric and atmospheric scatter radar be constructed in northern Scandavia through a multinational collaborative effort. The new facility tentatively named HISCAT (High frequency, High power, High latitude, Heating and Ionospheric Scatter facility), should be used for scientific investigations of: the physics of the neutral (middle) atmosphere; fundamental plasma phenomena, natural or artificially induced in the ionosphere; electrodynamic conditions at high altitudes above the auroral region and in the polar cap ionosphere; plasma waves in the solar atmosphere. The system should thus be able to operate as a mesosphere-stratosphere-troposphere (MST) radar, a so-called ionospheric modification facility, incoherent-scatter radar, coherent-scatter radar, and solar radar. Basically, the new facility should be a device that can operate simultaneously on several frequencies in the frequency range 5 to 50 MHz not covered by other instruments. It should comprise: powerful transmitters, capable of delivering a total average power of several megawatts; an advanced phased antenna array of high gain forming one or two steerable and well collimated beams; and an advanced data collection and analysis system.

Bostrom, R.↗
NASA NTRS1986

Getaway Tether Experiment (GATE): A free flying tether experiment

Orbital reboost and power generation using electrodynamic tethers has been suggested as a means of increasing the operational flexibility and orbital lifetime of satellites. Excess energy generated by solar arrays can be stored as orbital energy and later extracted form the orbit during peak power demands. The Getaway Tether Experiment (GATE) will demonstrate this practical tether application and will measure the dynamic circuit impedance. The micrometeoroid hazard to tension members will be studied as will radio frequency propagation. The radar cross section of long wires will be calculated considering the effects of resistance.

Greene, M.↗
NASA NTRS1986

Working group report on advanced high-voltage high-power and energy-storage space systems

Space systems in the future will probably include high-voltage, high-power energy-storage and -production systems. Two such technologies are high-voltage ac and dc systems and high-power electrodynamic tethers. The working group identified several plasma interaction phenomena that will occur in the operation of these power systems. The working group felt that building an understanding of these critical interaction issues meant that several gaps in our knowledge had to be filled, and that certain aspects of dc power systems have become fairly well understood. Examples of these current collection are in quiescent plasmas and snap over effects. However, high-voltage dc and almost all ac phenomena are, at best, inadequately understood. In addition, there is major uncertainty in the knowledge of coupling between plasmas and large scale current flows in space plasmas. These gaps in the knowledge are addressed.

Cohen, H. A.↗
NASA NTRS1986

The Earth's magnetosphere as a sample of the plasma universe

Plasma processes in the Earth's neighborhood determine the environmental conditions under which space-based equipment for science or technology must operate. These processes are peculiar to a state of matter that is rare on Earth but dominates the universe as whole. The physical, and especially the electrodynamic, properties of this state of matter is still far from well understood. By fortunate circumstances, the magnetosphere-ionosphere system of the Earth provides a rich sample of widely different plasma populations, and, even more importantly, it is the site of a remarkable variety of plasma processes. In different combinations such processes must be important throughout the universe, which is overwhelmingly dominated by matter in the plasma state. Therefore, observations and experiments in the near-Earth plasma serve a multitude of purposes. They will not only (1) clarify the dynamics of the space environment but also (2) widen the understanding of matter, (3) form a basis for interpretating remote observations of astrophysical objects, thereby even (4) help to reconstruct events that led to the evolution of the solar system. Last but not least they will (5) provide know-how required for adapting space-based technology to the plasma environment. Such observations and experiments will require a close mutual interplay between science and technology.

Faelthammar, Carl-Gunne↗
NASA NTRS1987

Retarding potential analyzer research

Studies were continued in the areas of ionospheric electrodynamics, plasma irregularities, and ion-neutral coupling. The spectral characteristics of structure in the ion concentration and the electric field at high latitudes were examined. It was found that in the region of velocity shears the relationship between the slopes of the two spectra are dependent on the existence of large field-aligned currents and apparently large ionospheric conductivity gradients. The relationship between the Joule dissipation and the locally measured value of the ion temperature were studied by examining the horizontal ion drift velocity. The importance of ion-neutral coupling was investigated in additional studies involving the nature of the coupling at high latitude boundaries and during times of magnetic disturbances. Much of this behavior can be modeled using globular circulation models. In order to study the storm time response of the thermosphere the global ion convection pattern was derived from DE-2 measurements and used as input in a circulation model. The calculated variables of neutral velocity and composition and temperature were compared with measurements to validate the technique.

Hanson, W. B.↗