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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 379 records · Page 21
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NASA NTRS1972

Study to adapt solar electric propulsion to the Pioneer F and G spacecraft

The addition of an electric thrust subsystem to the spin-stabilized Pioneer F and G spacecraft to improve performance capability for certain missions is discussed. The evaluation was performed for the Atlas and Titan launch vehicles with Centaur and TE-364-4 stages and for electric thrust stages of 8- and 5-kw with three 30- and five 15-cm thrusters respectively. The combination of a spinning spacecraft with electric propulsion is a concept only recently evaluated and the penalty from spinning over three-axis stabilized is not as significant as might initally be thought. There are major gains in weight, cost, and reliability, the disadvantages being lower data rate during the thrust phase and less efficient pointing. A variety of missions were evaluated from a solar approach mission into 0.14 AU to a flyby mission of Neptune at approximately 30 AU. Performance improvements were present for all missions evaluated.

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NASA NTRS1972

Star field attitude sensor study for the Pioneer Venus spacecraft

The characteristics of a star field attitude sensor for use with the Pioneer Venus spacecraft are presented. The aspects of technical feasibility, system interface considerations, and cost of flight hardware development are discussed. The tradeoffs which relate to performance, design, cost, and reliability are analyzed. The configuration of the system for installation in the spacecraft is described.

Rudolf, W. P.↗
NASA NTRS1973

Pioneer F and G mission to Juipter

The Pioneer missions to Jupiter in 1972 and 1973 are described along with the planet Jupiter. The spacecraft, navigation, attitude control, and propulsion are discussed along with the communications and data handling. The objectives of the missions are to map magnetic fields, solar wind, radiation belts and asteroids.

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NASA NTRS1972

The Interplanetary Pioneers. Volume 3: Operations

The operational aspects of the Pioneer program are described. The phases of the program discussed include: prelaunch operations, launch to DSS acquisition, near-earth operations, nominal and extended cruise, and scientific results.

Corliss, W. R.↗
NASA NTRS1973

Chemical pump study for Pioneer Venus program

Two chemical pumps were designed for the Pioneer Venus large probe mass spectrometer. Factors involved in the design selection are reviewed. One pump is designed to process a sample of the Venus atmosphere to remove the major component, carbon dioxide, so that the minor, inert components may be measured with greater sensitivity. The other pump is designed to promote flow of atmospheric gas through a pressure reduction inlet system. This pump, located downstream from the mass spectrometer sampling point, provides the pressure differential required for flow through the inlet system. Both pumps utilize the reaction of carbon dioxide with lithium hydroxide. The available data for this reaction was reviewed with respect to the proposed applications, and certain deficiencies in reaction rate data at higher carbon dioxide pressures noted. The chemical pump designed for the inert gas experiment has an estimated volume of 30 cu cm and weight of 80 grams, exclusive of the four valves required for the operation. The chemical pump for the pressure reduction inlet system is designed for a total sample of 0.3 bar liter during the Venus descent.

Rotheram, M.↗
NASA NTRS1973

Pioneer-10 measurements of the differential and integral cosmic-ray gradient between 1 and 3 AU

The cosmic-ray experiment on Pioneer has provided measurements of the differential radial gradient of cosmic-ray helium nuclei between 1 and 3 AU. Upper limits are quoted between 10 and 500 MeV/nuc which are everywhere 25%/AU and in some cases substantially smaller. The integral proton gradient ( 56 MeV) was also measured and found to have the following values: 2.4 + or - 0.3%/AU (1-2 AU), 7.6 + or - 0.7%/AU (2-3 AU).

Teegarden, B. J.↗
NASA NTRS1973

Effects of turbulence in the atmosphere of Venus on Pioneer Venus radio, phase 1

The prediction of the turbulence effects in the Venus atmosphere on Pioneer Venus radio was investigated. A careful investigation based on a theoretical and experimental study of the power spectrum of the Mariner 5 amplitude fluctuations is carried out and the results contribute considerably to our scientific knowledge of turbulence in the atmosphere of Venus. Fully developed turbulence is seen to exist predominantly in the altitude range of 41 - 49 km. This result is consistent with the high wind shear and wind velocities observed by Venera 4 for altitudes higher than 40 km. The outer scale size of turbulence is on the order of 100 m, the structure constant for the dayside atmosphere 3.9 x 10 to the -7 power m to the -1/3rd power, and that for the nightside atmosphere 2.9 x 10 to the -7 power m to the -1/3rd power.

Woo, R.↗
NASA NTRS1973

Mission Planning for Pioneer Saturn/Uranus Atmospheric Probe Missions

Mission planning for a series of atmospheric probe missions to Saturn and Uranus using a modified Pioneer spacecraft launched in 1979 and 1980 was examined. The operational options and the associated systems requirements consistent with the major scientific goals and spacecraft constraints of the missions is summarized. It is feasible to obtain in-situ atmospheric measurements in the atmosphere of Saturn and Uranus down to a pressure level of 10 bars using a common probe and spacecraft design. Spacecraft can be launched to both objectives with an adequate launch window in 1979 and 1980 using a Titan/Centaur launch vehicle with a TE-364-4 upper stage. Other scientific objectives can be accomplished by the flyby spacecraft. Encounters with the satellite Titan and RF occultations of Saturn, the ring system of Saturn, and Uranus can be obtained.

Swenson, B. L.↗
NASA NTRS1973

An estimate of particle flux from Pioneer 8 and 9 part 2

Five years of particle impact data obtained from Pioneer 8 and 9 have established reliable frequency levels for the near ecliptic region covered. This analysis is concerned with obtaining a multiplier which permits an estimate of the particle flux through a 1-A.U. sphere centered at the sun.

Wolf, H.↗
NASA NTRS1973

The Pioneer 11 high-field fluxgate magnetometer

The High Field Fluxgate Magnetometer Experiment flow aboard the Pioneer 11 spacecraft to investigate Jupiter's magnetic field is described. The instrument extends the spacecraft's upper limit measurement capability by more than an order of magnitude to 17.3 gauss with minimum power and volume requirements.

Acuna, M. H.↗
NASA NTRS1973

Pioneer Venus mechanical roots pump test and evaluation

A mechanical pump for use with the Pioneer-Venus probe mass spectrometer inlet system was obtained, and a limited performance testing program, including ultimate/compression ratio tests and throughput tests at three different pump speeds, was performed. Considerable operating experience with the pump was obtained over approximately 200 hours of running. The test results show general agreement with pump specifications.

Thomas, N. C.↗
NASA NTRS1972

Reinterpretation of the Pioneer 6 bow shock crossing.

This paper re-examines and reinterprets the interesting bow shock crossing of Pioneer 6 on December 16, 1965, by combining the high-resolution data for the magnetic field measurements with all the available plasma data. It is shown that, although a small correction of the magnetic field data improves the validity test of the MHD Rankine-Hugoniot (R-H) conditions, it is the plasma density measurements that are the principal source of the remaining inconsistencies. With the exception of the densities, the best agreement between the measurements and the R-H relations is obtained when the specific heat ratio is slightly less than the classical value of 5/3 expected for a magnetized plasma in the magnetosheath. A more accurate shock normal determination has been made, and it is found that the shock itself is possibly in motion with respect to the earth and that locally it may be approximated as a normal shock.

Mariani, F.↗
NASA NTRS1972

The zodiacal light as seen from the Pioneer F/G and Helios probes.

During the years 1972-1976 the first deep-space observations of zodiacal light will be made: from the Pioneer F/G Asteroid-Jupiter probes and from the Helios solar probes which will penetrate to 0.25 AU. These vehicles provide a unique opportunity to determine the spatial distribution of interplanetary dust throughout the region from 0.1 to 5 AU and its concentration toward the ecliptic plane. Zodiacal light models are used to discuss the accuracy with which the spatial distribution of the interplanetary dust may be inferred from deep-space observations of zodiacal light, with special emphasis on the effects of a dust-free zone near the sun and of a particle concentration in the asteroid belt.

Hanner, M. S.↗
NASA NTRS1972

The Pioneer Jupiter magnetic control program.

The Pioneer Jupiter spacecraft was required to have a sufficiently small magnetic field that accurate interplanetary-magnetic field measurements would not be compromised. In order to control the magnetic field throughout the program a running account of spacecraft magnetic fields was maintained by means of a periodically updated magnetic model. This model was used to make economic tradeoffs in subsystem magnetic moments within the allowed magnetic budget. The program was culminated with a measurement of the magnetic field of the spacecraft. A description of the magnetic tests and a comparison with estimates made with the magnetic model are also presented.

Sanders, N. L.↗
NASA NTRS1973

Preliminary Pioneer-10 intensity gradients of galactic cosmic rays.

Selected data from the University of Chicago charged-particle telescope on the Pioneer-10 spacecraft bound for Jupiter have been examined and compared with data from the University of Chicago charged-particle telescopes on the Earth satellites IMP-5 and IMP-6 at 1 AU to derive a preliminary integral intensity gradient for relativistic galactic protons and helium nuclei. The preliminary value obtained is (4.5 plus or minus 1.0) percent per AU over the radial range 1-2.8 AU. Preliminary differential gradients also have been obtained for the energy range 29-67 MeV per nucleon.

Mckibben, R. B.↗
NASA NTRS1973

Interplanetary radial gradients of galactic cosmic ray protons and helium nuclei - Pioneer 8 and 9 measurements from 0.75 to 1.10 AU.

We report measurements of the radial interplanetary cosmic ray gradient made with cosmic ray instruments aboard the Pioneer 8 and 9 spacecraft. The time period covered in these studies is from January 1968 to June 1969. During this time, the radial separation of these two spacecraft varied from 0.75 to 1.10 AU from the sun. This study includes detailed measurements of the differential spectra and gradients of protons and helium nuclei from 2 to 1200 Mev/nucleon. The differential gradient for each species is observed to go through a broad maximum of about 50%/AU at energies corresponding to about 1 BV rigidity, decreasing at both lower and higher rigidities. The proton and helium nuclei gradients are small down to the lowest energies we measure.-

Webber, W. R.↗
NASA NTRS1973

Pioneer imaging photopolarimeter optical system.

The imaging photopolarimeter aboard the Pioneer 10 spacecraft en route to the vicinity of Jupiter is described. This instrument is capable of moderate resolution spin-scan imaging and high precision polarimetric and photometric mapping of Jupiter in red and blue light. The field of view can be selectively changed from 0.50 mrad square to 40 mrad square to accommodate resolution and radiance combinations ranging from the zodiacal background to that of Jupiter. Optical materials were chosen to survive, with minimum degradation, the rigors of a nearly 2-year journey to Jupiter including transit through the Jovian trapped radiation belts. The optics are described in detail, and the operational system is outlined. The procedures for preflight and in-flight calibration are described, and some performance characteristics and preliminary flight results are presented.

Pellicori, S. F.↗
NASA NTRS1973

The Pioneer 9 electric field experiment. III - Radial gradients and storm observations.

We present a detailed analysis of the Pioneer 9 VLF electric field observations for 20 selected storm periods covering a heliocentric range extending from 0.754 AU to 0.99 AU. Although data from only two low frequency channels are available, the results of the present study tend to confirm the preliminary speculation by Scarf and Siscoe (1971) that the turbulent E-field spectrum in the disturbed solar wind has a significant radial gradient.

Scarf, F. L.↗