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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

On the sources of ultraviolet absorption in spectra of Titan and the outer planets

In response to observations of the ultraviolet deficiencies shown by all of the outer planets and Titan, models have been proposed to explain the low albedos in terms of absorption by particles in the upper atmospheres of these objects. These particles are generally believed to be photochemically formed from gases in the upper atmospheres, primarily methane and hydrogen. Such processes may also be operative on Titan. Results of some laboratory experiments on proton irradiation of mixtures of gases including CH4, H2, and NH3 have shown that liquid and solid materials are produced that are strong ultraviolet absorbers. However, the material produced from the CH4 + H2 mixture was colorless, indicating that species containing elements other than carbon and hydrogen are necessary for the production of color. Two such elements are nitrogen (as NH3 or N2) and sulfur (as H2S); colored materials have been produced from such mixtures. None of these materials has spectral properties identical to those shown by the planets. Therefore it is necessary that mixtures (and/or cloud layers) of the photochemical materials be present.

Scattergood, T.↗
NASA NTRS1976

Heat shield characterization: Outer planet atmospheric entry probe

A full scale carbon phenolic heat shield was fabricated for the Outer Planet Probe in order to demonstrate the feasibility of molding large carbon phenolic parts with a new fabrication processing method (multistep). The sphere-cone heat shield was molded as an integral unit with the nose cap plies configured into a double inverse chevron shape to achieve the desired ply orientation. The fabrication activity was successful and the feasibility of the multistep processing technology was established. Delaminations or unbonded plies were visible on the heat shield and resulted from excessive loss of resin and lack of sufficient pressure applied on the part during the curing cycle. A comprehensive heat shield characterization test program was conducted, including: nondestructive tests with the full scale heat shield and thermal and mechanical property tests with small test specimen.

Mezines, S. A.↗
NASA NTRS1976

Biology on the outer planets

A brief review is given of information on the structure and composition of the outer planets and the organic reactions that may be occurring on them. The possibility of life arising or surviving in the atmospheres of these planets is considered, and the problem of contamination during future unmanned missions is assessed. Atmospheric models or available atmospheric data are reviewed for Jupiter, Saturn, Uranus, Neptune, Pluto, the Galilean satellites, and Titan. The presence of biologically interesting gases on Jupiter and Saturn is discussed, requirements for life on Jupiter are summarized, and possible sources of biological energy are examined. Proposals are made for protecting these planets and satellites from biological contamination by spacecraftborne terrestrial organisms.

Young, R. S.↗
NASA NTRS1993

Dynamics of the atmospheres of the outer planets - Post-Voyager measurement objectives

Current knowledge about dynamics and thermal structure on the outer planets is reviewed with the aim of identifying important measurements which should be made in the post-Voyager era. The existence of jets and cloud bands is the puzzle that underlies all others. Discussion focuses on the particular case of Jupiter because documentation is most complete. Recent dynamical work has successfully reproduced much of the behavior of jets and spots with simple models that contain few parameters. It is argued that the gross dynamical parameters, such as density stratification and rotation rate, are the keys to their behaviors, rather than the particular specifics of radiative forcing, cloud distributions, thermodynamic transformations. Voyager data have shown that the jet systems decay with height in the region above the visible clouds. Therefore the highest priority must be given to establishing dynamical parameters that characterize levels within and beneath the clouds. These require determination of the deep structure of the jets, of the density stratification, and of the horizontal density contrasts. The deep regions are not easily accessible, and these measurements present challenging opportunities. Indirect inferences about the controlling processes may sometimes be possible by observing waves and other activity in the more easily accessible stratosphere, and some of these issues are also discussed.

Gierasch, Peter J.↗
NASA NTRS1996

The Outer Planets: Getting There Fast

In this paper, a brief review is given of NASA's outer planet missions as performed with chemical propulsion systems. The Kuiper Express is discussed as an illustration of the integrated approach that should be used in mission and spacecraft design to maximize science return.

velocities↗
NASA NTRS1981

Numerical integration of the satellites of the outer planets

The formulation of a numerical integration program, used to construct ephemerides for satellites of the outer planets, is described. The equations of motion are derived, including (1) n massive integrated satellites, (2) m massive perturbing planets, (3) J2, J4 oblateness coefficients of the primary and each satellite, and (4) a barycentric coordinate system. Variational equations are also found: (1) 6n initial states and n masses of the integrated satellites, (2) J2, J4 of the primary planet, (3) the mass of the system, and (4) right ascension and declination of the pole. The formulation was used to construct the satellite ephemerides of Saturn for the Voyager mission.

Peters, C. F.↗
NASA NTRS1991

Near infrared imaging of the outer planets

In the last year we have continued our program of near infrared imaging of the outer planets of the solar system. Uranus is virtually invisible at 2.3 microns, showing that the methane is an effective absorber of the incident sunlight and that there is very little aerosol content in the upper atmosphere. On the other hand, Neptune shows a haze present over the entire Northern Hemisphere at 2.3 microns. This leads to the inference that there is an aerosol layer at a high altitude. We have recovered the Neptune satellite, 1989 N1, which was first discovered in Voyager images. The satellite is exceedingly faint in the near infrared, and was detectable only because the planet itself was comparatively faint at this wavelength. Observations of this satellite, coupled with the Voyager images, permit us to substantially refine the satellite's orbit, and hence carefully probe the gravitational field of Neptune.

Matthews, K.↗
NASA NTRS1972

Power conditioning equipment for a thermoelectric outer planet spacecraft, volume 1, book 2

The design and development of power conditioning equipment for the thermoelectric outer planet spacecraft program are considered. One major aspect of the program included the design, assembly and test of various breadboard power conditioning elements. Among others these included a quad-redundant shunt regulator, a high voltage traveling wave tube dc-to-dc converter, two-phase gyro inverters and numerous solid state switching circuits. Many of these elements were arranged in a typical subsystem configuration and tests were conducted which demonstrated basic element compatibility. In parallel with the development of the basic power conditioning elements, system studies were continued. The salient features of the selected power subsystem configuration are presented.

Andrews, R. E.↗
NASA NTRS1973

Study of meteoroid detection systems applicable to the outer planets missions

Modifications to the Pioneer 10/11 meteoroid detection experiment to allow it to be used for outer planet missions were investigated. Both pressurized cells and metal-oxide silicon (MOS) penetration detectors are considered. Both the sensors systems and the electronics are treated. Investigation of the calibration and characterization of the MOS penetration detector is reported.

Brooks, A. D.↗
NASA NTRS2005

Ground Based Studies of the Outer Planets

This report covers progress to date under this grant on our continuing program to conduct ground based studies of the outer solar system planets and satellites, with emphasis on spectroscopy and atmospheric phenomena. The research continues under our new PAST grant, NNG04G131G beginning 5/1/2004. The original period of performance of the subject grant was 3/1/2001 to 2/28/2004, but was extended one year at no cost. Although there is some overlap in the scientific projects conducted during the extended year with those of the new grant, this report is confined to the portion of the work funded under NAG5-10435. The primary goals for this grant period were a comparative study of outer planet thermospheres/ionospheres near solar maximum, extended to the mid-IR, and the investigation of molecular dimers in outer solar system atmospheres. This project supports NASA's planned space missions, Jupiter Polar Orbiter, outer Planet Microprobes, and the recent Cassini flyby of Jupiter. It also supports the OSS strategic plan themes, The Exploration of the Solar System and The Sun-Earth Connection/ Understanding comparative planetary space environments.

Trafton, Laurence M.↗
NASA NTRS1985

Wave observations in outer planet magnetospheres

The first measurements of plasma waves and wave-particle interactions in the magnetospheres of the outer planets were provided by instruments on Voyager 1 and 2. At Jupiter, the observations yielded new information on upstream electrons and ions, bow shock dissipation processes, trapped radio waves in the magnetospheres and extended Jovian magnetotail, pitch angle diffusion mechanisms and whistlers from atmospheric lightning. Many of these same emissions were detected at Saturn. In addition, the Voyager plasma wave instruments detected dust particles associated with the tenuous outer rings of Saturn as they impacted the spacecraft. Most of the plasma wave activity at Jupiter and Saturn is in the audio range, and recordings of the wave observations have been useful for analysis.

Scarf, F. L.↗
NASA NTRS1970

Guidance and Navigation Requirements for Unmanned Flyby and Swingby Missions to the Outer Planets: Low Thrust Missions, Phase B - Volume 3

The guidance and navigation requirements for unmanned missions to the outer planets, assuming constant, low thrust, ion propulsion are discussed. The navigational capability of the ground based Deep Space Network is compared to the improvements in navigational capability brought about by the addition of guidance and navigation related onboard sensors. Relevant onboard sensors include: (1) the optical onboard navigation sensor, (2) the attitude reference sensors, and (3) highly sensitive accelerometers. The totally ground based, and the combination ground based and onboard sensor systems are compared by means of the estimated errors in target planet ephemeris, and the spacecraft position with respect to the planet.

Source record↗
NASA NTRS1972

Outer planets grand tours: Planetary radio astronomy team report

Requirements related to scientific observations of planetary radio emissions during outer planets grand tours are discussed. Observations at low frequencies where non-thermal cooperative plasma phenomena play a major role are considered for determining dynamical processes and magnetic fields near a planet. Magnetic field measurements by spacecraft magnetometers, and by radio receivers in their harmonic modes are proposed for interpretation of planetary radio emission.

Warwick, J. W.↗