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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Thermal structure and heat balance of the outer planets

Current knowledge of the thermal structure and energy balance of the outer planets is summarized. The Voyager spacecraft experiments have provided extensive new information on the atmospheric temperatures and energetics of Jupiter, Saturn and Uranus. All three planets show remarkably small global-scale horizontal thermal contrast, indicating efficient redistribution of heat within the atmospheres or interiors. Horizontal temperature gradients on the scale of the zonal jets indicate that the winds decay with height in the upper troposphere. This suggests that the winds are driven at deeper levels and are subjected to frictional damping of unknown origin at higher levels. Both Jupiter and Saturn have internal power sources equal to about 70 percent of the absorbed solar power. This result is consistent with the view that significant helium differentiation has occurred on Saturn. Uranus has an internal power no greater than 13 percent of the absorbed solar power, while earth-based observations suggest Neptune has an internal power in excess of 100 percent of the absorbed solar power.

Conrath, B. J.↗
NASA NTRS1991

Voyager plasma wave observations near the outer planets

With the completion of the reconnaissance of the magnetospheres of the outer planets by Voyager, a first-order view is obtained of the existence of plasma waves in a wide variety of settings with which to begin the task of intercomparison. Voyager carried the first plasma-wave receivers to Jupiter, Saturn, Uranus, and Neptune and some very strong statements can be made about the likelihood of several types of plasma-wave modes and where in a planetary magnetosphere these emissions will occur. Further, the role of plasma waves can be understood, in general, in the physics of the magnetospheres and their effects on the energy budget, plasma energization and transport, and the generation of planetary radio emissions.

Kurth, W. S.↗
NASA NTRS1992

Comparative observations of plasma waves at the outer planets

Observations of the plasma-wave spectra from the four major outer planets are examined with particular attention given to the instabilities related to the precipitation of energetic particles. Wave-particle interactions involving hiss, chorus, and electron-cyclotron harmonic emissions are studied. These interactions contribute about 10 exp 13 W into the Jovian atmosphere, and the electron-cyclotron emissions on Saturn are shown to contribute significantly to the precipitation of energetic electrons. Whistler-mode waves are shown to exist at Uranus with intensities that could put 3-40 keV electrons on strong diffusion, but the amplitudes of the emissions are not sufficient to make them a significant part of precipitation. Weak electron-cyclotron harmonic emissions and whistler modes are detected at Neptune, suggesting that the present dataset is based on regions of low wave intensities.

Kurth, W. S.↗
NASA NTRS2003

Revolutionary Concepts for Human Outer Planet Exploration (HOPE)

This paper summarizes the content of a NASA-led study performed to identify revolutionary concepts and supporting technologies for Human Outer Planet Exploration (HOPE). Callisto, the fourth of Jupiter's Galilean moons, was chosen as the destination for the HOPE study. Assumptions for the Callisto mission include a launch year of 2045 or later, a spacecraft capable of transporting humans to and from Callisto in less than five years, and a requirement to support three humans on the surface for a minimum of 30 days. Analyses performed in support of HOPE include identification of precursor science and technology demonstration missions and development of vehicle concepts for transporting crew and supplies. A complete surface architecture was developed to provide the human crew with a power system, a propellant production plant, a surface habitat, and supporting robotic systems. An operational concept was defined that provides a surface layout for these architecture components, a list of surface tasks, a 30-day timeline, a daily schedule, and a plan for communication from the surface.

Power electronics↗
NASA NTRS1973

Interaction of the solar wind with the outer planets.

The hypersonic analog for the interaction of the solar wind with Jupiter, Saturn, Uranus, Neptune, and Pluto is used to provide estimates of shock shapes and locations, as well as average magnetosheath and/or ionosheath properties for these planets. Several representative spacecraft flyby trajectories (designed for outer-planet 'Grand Tour' simulations) are superimposed upon a series of figures in order to provide estimates of potential plasma and field parameters which may be encountered. Consideration is given first to the possibility that several of these planets have intrinsic magnetic fields and, secondly, to the interaction of the solar wind directly on the ionosphere should there actually be no intrinsic field. Saturn and Pluto are chosen as examples of this latter case.

Dryer, M.↗
NASA NTRS1972

The outer planets - Fly-by prospects

The projected benefits of flyby missions to the outer planets are discussed. Possible changes in existing theories of planetary composition as a result of such missions are also discussed.

Demarcus, W. D.↗
NASA NTRS1972

Definition phase of Grand Tour missions/radio science investigations study for outer planets missions

Scientific instrumentation for satellite communication and radio tracking systems in the outer planet exploration mission is discussed. Mission planning considers observations of planetary and satellite-masses, -atmospheres, -magnetic fields, -surfaces, -gravitational fields, solar wind composition, planetary radio emissions, and tests of general relativity in time delay and ray bending experiments.

Tyler, G. L.↗
NASA NTRS1974

Fluxgate magnetometers for outer planets exploration

The exploration of the interplanetary medium and the magnetospheres of the outer planets requires the implementation of magnetic field measuring instrumentation with wide dynamic range, high stability, and reliability. The fluxgate magnetometers developed for the Pioneer 11 and Mariner-Jupiter-Saturn missions are presented. These instruments cover the range of .01 nT to 2 million nT with optimum performance characteristics and low power consumption.

Acuna, M. H.↗
NASA NTRS1974

Proceedings: Outer Planet Probe Technology Workshop, summary volume

A summary report and overview of the Outer Planet Probe Technology Conference are given. Summary data cover: (1) state of the art concerning mission definitions, probe requirements, systems, subsystems, and mission peculiar hardware, (2) mission and equipment trade-offs associated with Saturn/Uranus baseline configuration and the influence of Titan and Jupiter options on mission performance and costs, and (3) identification of critically required future R and D activities.

Source record↗
NASA NTRS2002

Outer planet spacecraft temperature testing and analysis

Unmanned spacecraft flown on missions to the outer planets of the solar system have included flybys, planetary orbiters, and atmospheric probes during the last three decades. The thermal design, test, and analysis approach applied to these spacecraft evolved from the passive thermal designs applied to the earlier lunar and interplanetary spacecraft. The inflight temperature data from representative sets of engineering subsystems and science instruments from a subset of these spacecraft are compared to those obtained during the ground test programs and from the prelaunch predictions. Several lessons are presented with specific recommendations for considerations for new projects to aid in the planning of cost effective temperature design, test, and analysis programs.

temperature testing planetary spacecraft Voyager G↗
NASA NTRS1997

Self-Organization of Zonal Jets in Outer Planet Atmospheres: Uranus and Neptune

The statistical mechnical theory of a two-dimensional Euler fluid is appleid for the first time to explore the spontaneous self-oganization of zonal jets in outer planet atmospheres. Globally conserved integralls of motion are found to play a central role in defining jet structure.

Euler Fluid Self-organization outer planet↗
NASA NTRS1972

Estimating trajectory correction requirements for multiple outer planet missions.

General approach to the problem of estimating trajectory correction requirements for multiple outer planet flyby missions when the navigation system uses onboard optical measurements made during approach to each target planet to complement the ground-based radio measurements. The accuracy and reliability of the onboard measurement system plays a critical role in sizing the trajectory correction capability required. An illustration of the combined use of radio and optical measurements is provided for the particular case of a Jupiter-Uranus-Neptune mission. Use of the statistical technique developed for computing the trajectory correction margin required to account for uncertainties in subsystem performance, permits trajectory correction savings of 100 to 20 m/sec over 'worst case' designs. This represents weight savings of about 50% of the science payload. For the example case trajectory correction requirements are estimated for two candidate optical systems and the radio alone case. The use of onboard measurements allows a trajectory correction savings of approximately 140 m/sec.

Friedman, L. D.↗
NASA NTRS1975

Test evaluation of potential heatshield contamination of an outer planet probe's gas sampling system

The feasibility of retaining the heat shield for outer planet probes was investigated as a potential source of atmospheric sample contamination by outgassing. The onboard instruments which are affected by the concept are the pressure sensor, temperature sensor, IR detector, nephelometer, and gas sampling instruments. It was found that: (1) The retention of the charred heatshield and the baseline atmospheric sampling concepts are compatible with obtaining noncontaminated atmospheric samples. (2) Increasing the sampling tube length so that it extends beyond the viscous boundary layer eliminates contamination of the atmospheric sample. (3) The potential for contamination increases with angle of attack.

Kessler, W. C.↗
NASA NTRS1974

Outer planet probe cost estimates: First impressions

An examination was made of early estimates of outer planetary atmospheric probe cost by comparing the estimates with past planetary projects. Of particular interest is identification of project elements which are likely cost drivers for future probe missions. Data are divided into two parts: first, the description of a cost model developed by SAI for the Planetary Programs Office of NASA, and second, use of this model and its data base to evaluate estimates of probe costs. Several observations are offered in conclusion regarding the credibility of current estimates and specific areas of the outer planet probe concept most vulnerable to cost escalation.

Niehoff, J.↗