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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 NTRS1975

The pioneer projects: Economical exploration of the solar system

The interplanetary Pioneer missions are reviewed in terms of management implications and cost control. The responsibilities, organizational structure, and management practices of the Pioneer Projects are presented. The lines of authority and areas of responsibility of the principal organizational elements supporting the Pioneer missions are identified, and the methods employed for maintaining effective and timely interactions among these elements are indicated. The technical and administrative functions of the various organizational elements of the Pioneer Project Office at Ames Research Center are described in terms of their management responsibilities and interactions with other elements of the Project Office and with external organizations having Pioneer Project responsibilities. The management and control of activities prior to and during the hardware procurement phase are described to indicate the basis for obtaining visibility of the technical progress, utilization of resources, and cost performance of the contractors and other institutions supporting the Pioneer projects.

Spahr, J. R.↗
NASA NTRS1976

Results of the asteroid-meteoroid particle experiment on Pioneer 11

The Asteroid-Meteoroid Detector, an electro-optical instrument that detects and measures particles in space by sensing the sunlight reflected from them, is part of the payload of both the Pioneer 10 and 11 spacecraft. The Pioneer 11 instrument is essentially identical to that on Pioneer 10, with some minor modifications. Reduction of the Pioneer 11 data was complicated by the failure of one of the four sensor channels at about 1.1 AU from the sun. Detailed analysis yielded 51 events between 1.0 and 3.5 AU, which were used to determine the particle concentration distribution in that region of space. Weighted curve-fitting of the results shows agreement with the concentrations derived from Pioneer 10 to within about a factor of two. As with the Pioneer 10 results, the exponent of the size dependency varies from about -1.7 for 100-micron radius particles to about -3.2 for 10-cm bodies. The instrument, its operation, and the method of data analysis are reviewed.

Soberman, R. K.↗
NASA NTRS1978

Quiet time interplanetary cosmic ray anisotropies observed from Pioneer 10 and 11

Cerenkov counters on the Pioneer 10 and 11 spacecraft, capable of detecting alpha particles and protons with energies up to 480 MeV, and nucleons and electrons with energies up to 6 MeV, have yielded data on cosmic ray anisotropies during periods of low solar activity. Observations from Pioneer 11 place east-west anisotropy at 0.41 plus or minus 0.11%, and the north-south anisotropy at near zero; Pioneer 10 results show east-west anisotropy to be approximately 0.59 plus or minus 0.18%, and the north-south component at 0.25 plus or minus 0.08%. It is noted that the Pioneer 10 observations were obtained at the 6 AU range, while those from Pioneer 11 originated closer to the sun (1.1 to 2.7 AU). Attention is given to the ratio of the perpendicular to parallel components of the diffusion coefficient, and to the large north-south anisotropy reported by Pioneer 10, an effect due possibly to gradient drift, and to an additional streaming independent of the magnetic field polarity.

Ip, W.-H.↗
NASA NTRS1980

Pioneer Saturn

The Pioneer Saturn spacecraft, designated Pioneer 11 until its encounter with Jupiter, is presented, and its trajectory is reported. The 550-pound spin-stabilized spacecraft carries 12 scientific instruments, 11 of which were operational during its encounters with Jupiter and Saturn. After the successful completion of the Pioneer 10 Jupiter fly-by, for which Pioneer 11 was intended as a back-up, the Pioneer 11 spacecraft was committed to a Saturn-bound trajectory, and was sent on a spiral trajectory around Jupiter to approach Saturn. After mid-course maneuvers, the spacecraft arrived at Saturn on September 1, 1979, where it penetrated the ring plane outside of the visible rings, descending from above the ecliptic plane late in the morning quadrant, and making measurements of the planetary magnetosphere and its interaction with the solar wind, infrared radiation and gravitational and atmospheric effects on the radio signal. Pioneer Saturn departed from Saturn slightly above the ring plane, crossing the orbit of Titan 25 hr after Saturn flyby, and became the second spacecraft to escape the solar system.

Dyer, J. W.↗
NASA NTRS1981

Pioneers 6 through 12 mission support

The Deep Space Network support of Pioneer Mission Operations during the cruise phases of Pioneers 6 through 9, Pioneer 10, Pioneer 11, and the orbital operations of Pioneer 12 spacecrafts is described. All Pioneer spacecraft appear in good health and are operating nominally. Tracking coverage from June 1980 through March 1981 is shown.

Nevarez, R.↗
NASA NTRS1993

Geophysical Research Letters. Selected Papers on Pioneer Venus Orbiter: Entry Phase

Contents include the following papers which are comprised of subject matter related to the The Pioneer Venus Orbiter's Entry Phase: The Pioneer Venus entry phase; solar cycle variations of electron density and temperature in the Venusian nightside ionosphere; the magnetic state of the lower ionosphere during Pioneer Venus entry phase; the nightside ionosphere of Venus under varying levels of solar EUV flux; observation of the nightside Venus ionosphere; final encounter of the Pioneer Venus orbiter ion mass spectrometer; ion measurement during Pioneer Venus reentry; implications for solar cycle variation of ion composition and dynamics; evidence for day-to-night ion transport at low solar activity in the Venus pre-dawn ionosphere; model calculations of the dayside ionosphere of Venus at solar minimum; natural composition measurements by the Pioneer Venus neutral mass spectrometer during orbiter reentry; the Venus atmospheric response to solar cycle variations; and plasma waves observed at low altitudes in the tenuous Venus nightside ionosphere.

Source record↗
NASA NTRS1972

The interplanetary pioneers. Volume 1: Summary

The Pioneer Space Probe Project is explained to document the events which occurred during the project. The subjects discussed are: (1) origin and history of interplanetary Pioneer program, (2) Pioneer system development and design, (3) Pioneer flight operations, and (4) Pioneer scientific results. Line drawings, circuit diagrams, illustrations, and photographs are included to augment the written material.

Corliss, W. R.↗
NASA NTRS1973

Maneuver strategy for a possible Pioneer 11 extended mission

The Jupiter-bound Pioneer 11 spacecraft was launched in April 1973, eight months before the Jupiter encounter of the front-running twin spacecraft, Pioneer 10. Depending on the content of the Pioneer 10 science, the Pioneer 11 mission objectives may be modified to explore different regions about Jupiter, including an aimpoint region providing for an extended trajectory to Saturn. Following launch, early maneuver aiming strategies were designed to retain a later retargeting maneuver capability to repeat Pioneer 10 or to encounter alternate Jupiter aimpoints. This paper identifies the ground rules and information required for the adaptive design of these strategies, considering a variety of mission objectives and Project constraints for later retargeting maneuvers.

Frauenholz, R. B.↗
NASA NTRS1975

Jovian protons and electrons: Pioneer 11

A preliminary account of the Pioneer 11 passage through the Jovian magnetosphere as viewed by particle detector systems is presented. Emphasis is placed on the region well within the Jovian magnetosphere using data from the LET-II telescope, which measured the proton flux from 0.2 to 21.2 MeV in seven energy intervals and electrons from 0.1 to 2 MeV in four energy intervals. The relative trajectories of Pioneer 10 and 11 are discussed and indicate that Pioneer 11 was exposed to a much lower total radiation dose than Pioneer 10, largely as a result of the retrograde trajectory which approached and exited the inner region of the magnetosphere at high latitudes. Angular distributions, calculations from Pioneer 11 magnetic field data, and the low-energy nucleon component are included in the discussion.

Trainor, J. H.↗
NASA NTRS1975

Preliminary model studies of the magnetosphere of Jupiter: Pioneer 10

Observations of the Jovian magnetic field and its interaction with the solar wind plasma were made while the Pioneer 10 spacecraft was within about 100 R sub j of the planet. The magnetosphere was found to be severely stretched due to the presence of an intense current sheet, which was particularly evident during the outbound passage of Pioneer 10 near the dawn terminator. Plots of the angle between the orientation of the outbound field and the radius vector from the planet to the spacecraft showed a strong tendency for the field to become radial at large distances from the planet. A similar trend has also been seen in both the inbound and outbound Pioneer 11 data. Preliminary work on a mathematical model of the magnetosphere of Jupiter is given, based upon the Pioneer 10 outbound data. Some of the implications of the radial field configuration inferred from the Pioneer 10 and 11 data are also discussed.

Jones, D. E.↗
NASA NTRS1975

Pioneer 11 encounter - Preliminary results from the Ames Research Center plasma analyzer experiment

Pioneer 11 observations of the interaction of Jupiter's magnetosphere with the distant solar wind have confirmed the earlier Pioneer 10 observations of the great size and extreme variability of the outer magnetosphere. The nature of the plasma transitions across Jupiter's bow shock and magnetopause as observed on Pioneer 10 have also been confirmed on Pioneer 11. However, the northward direction of the Pioneer 11 outbound trajectory and the distance of the final magnetopause crossing (80 Jupiter radii) now suggest that Jupiter's magnetosphere is extremely broad with a half-thickness (normal to the ecliptic plane in the noon meridian) which is comparable to or greater than the sunward distance to the nose.

Mihalov, J. D.↗
NASA NTRS1976

Temperature of the atmosphere of Jupiter from Pioneer 10/11 radio occultations

Radio-occultation data from the Pioneer 10 and 11 flybys are analyzed using an integral inversion technique combined with a model for Jupiter's shape based on gravity data in order to account for the oblateness of the planet's atmosphere. The inversion technique defines the center of refraction in terms of the radius of curvature and the normal to the equipotential surface at the closest approach point of the ray. An Abelian inversion of the data obtained during the Pioneer 10 entry, the Pioneer 10 exit, and the Pioneer 11 exit is performed by fixing the center of refraction at some average value for each occultation event. The results for all three measurements are found to be consistent and to show a temperature inversion between the 10-mb and the 100-mb levels, with temperatures of 130 to 170 K at 10 mb and 80 to 100 K at 100 mb. Major sources of error are discussed, and it is concluded that the range of reasonable temperature uncertainties at these levels does not exceed 40 K. It is noted that the temperature inversion was also inferred from Pioneer 10 IR radiometric data.

Kliore, A. J.↗
NASA NTRS1980

Pioneers 6 through 9 support

The cruise phases of Pioneer 6 through 9 missions and the operations of the Deep Space Network in supoort of the Pioneer missions are reported for the period of 16 December 1979 through 31 May 1980. Pioneer 6 through 9 are in cruise mode and spacecraft appear to be operating nominally. Pioneer 8 continues to require the 100 kW transmitter from 64 m stations due to the spacecraft's degraded receiver. Difficulties in acquiring a downlink from the Pioneer 6 are discussed.

Nevarez, R. E.↗
NASA NTRS1984

The Z3 model of Saturns magnetic field and the Pioneer 11 vector helium magnetometer observations

Magnetic field observations obtained by the Pioneer 11 vector helium magnetometer are compared with the Z(sub 3) model magnetic field. These Pioneer 11 observations, obtained at close-in radial distances, constitute an important and independent test of the Z(sub 3) zonal harmonic model, which was derived from Voyager 1 and Voyager 2 fluxgate magnetometer observations. Differences between the Pioneer 11 magnetometer and the Z(sub 3) model field are found to be small (approximately 1%) and quantitatively consistent with the expected instrumental accuracy. A detailed examination of these differences in spacecraft payload coordinates shows that they are uniquely associated with the instrument frame of reference and operation. A much improved fit to the Pioneer 11 observations is obtained by rotation of the instrument coordinate system about the spacecraft spin axis by 1.4 degree. With this adjustment, possibly associated with an instrumental phase lag or roll attitude error, the Pioneer 11 vector helium magnetometer observations are fully consistent with the Voyager Z(sub 3) model.

Connerney, J. E. P.↗
NASA NTRS1984

The Z3 model of Saturn's magnetic field and the Pioneer 11 vector helium magnetometer observations

Magnetic field observations obtained by the Pioneer 11 vector helium magnetometer are compared with the Z(sub 3) model magnetic field. These Pioneer 11 observations, obtained at close-in radial distances, constitute an important and independent test of the Z(sub 3) zonal harmonic model, which was derived from Voyager 1 and Voyager 2 fluxgate magnetometer observations. Differences between the Pioneer 11 magnetometer and the Z(sub 3) model field are found to be small (approximately 1 percent) and quantitatively consistent with the expected instrumental accuracy. A detailed examination of these differences in spacecraft payload coordinates shows that they are uniquely associated with the instrument frame of reference and operation. A much improved fit to the Pioneer 11 observations is obtained by rotation of the instrument coordinate system about the spacecraft spin axis by 1.4 degree. With this adjustment, possibly associated with an instrumental phase lag or roll attitude error, the Pioneer 11 vector helium magnetometer observations are fully consistent with the Voyager Z(sub 3) model.

Connerney, J. E. P.↗
NASA NTRS1999

Cosmic Ray Telescope Experiment (CRT), Pioneer 10/11 Program

In May 1996 the electrical power on Pioneer 10 was no longer adequate to support the Cosmic Ray Telescope Experiment (CRT). In March 1997 ground based operations for the mission were terminated. The 25 years of Pioneer 10 were a remarkable voyage of discovery as it ventured into a vast new unexplored region of space. These observations by the Pioneer experiments led in the development of a new discipline of space science - heliospheric physics. For cosmic ray studies it was an incredible era, leading to the identification of new energetic particle populations and processes and initiating the study of the dynamics and large-scale structure and began the study of the dynamics and large-scale structure of the outer heliosphere. A summary of some of the principal scientific findings of the CRT experiment over this period is given in the next section. Even with the cessation of data from the Pioneer 10/11 mission there remained a great deal of scientific analysis and data archiving that required on the order of an additional three years of effort on the part of the CRT team. We have tried to select those tasks where the P10/11 CRT data have an important role to play. Special emphasis is placed on long-term synoptic studies that make use of the extended temporal and spatial coverage of the missions and the full capabilities of the CRT experiment. The major scientific objectives of this study are: (1) A phenomenological study of the modulation process in the heliosphere, thereby laying the foundation for developing a unified model of cosmic ray modulation over a complete 22 year heliomagnetic cycle; (2) These modulation studies and the temporal changes in the cosmic ray intensities also provide information on the large-scale structure and dynamics of the outer heliosphere; (3) use the galactic and anomalous cosmic ray data from Pioneer 10 to obtain a more accurate estimate of the distance to the modulation boundary and to the termination shock; (4) Use the results from (2) and from temporal variations to determine whether significant modulation occurs in the region of the heliosphere; (5)study the acceleration and transport of low energy solar interplanetary energetic particles and their relation to solar activity and interplanetary phenomena.

McDonald, Frank B.↗
NASA NTRS1980

Pioneer Venus Overview

A Pioneer Venus Overview is discussed. Pioneer Venus consists of two basic spacecraft: Orbiter and Multiprobe. The latter was separated into five separate vehicles near Venus. These were the probe transporter (called the Bus), a large atmospheric entry probe (dubbed Sounder) and three identical smaller probes (called North , Day, and Night in accordance with their entry locations). At Venus all six spacecraft communicated directly back to the Earth-based Deep Space Network (DSN) and, in the case of the Multiprobe mission, to two special receiving sites near Guam and Santiago (Chile). At the time this Special Issue was submitted for publication the nominal mission was complete and the Orbiter was continuing into an extended mission phase. It appears so that sufficient fuel remains to permit full operation through calendar year 1980, at least. The scientific payload, Principle Investigator, and his affiliation are listed for each Pioneer Venus spacecraft. This special issue is primarily devoted to short descriptions of the instruments listed with the exception of the Orbitor Cloud Photopolarimeter. Detailed instrument descriptions for this experiment have been published. Before proceeding with descriptions of the individual instruments, four special archival-type reports are included. The first deals with spacecraft design and operation. The Pioneer Venus spacecraft were unique and very special design features and operational modes needed to be incorporated. These are summarized therein. It should be noted that neither the scientific objectives nor the scientific results of the Pioneer Venus program are described or discussed in detail. The objectives have been published elsewhere.

Colin, Lawrence↗
NASA NTRS1971

Pioneer F/G: Spacecraft Operational Characteristics

The Pioneer F/G Spacecraft Operational Characteristics Study was performed by TRWS systems Group for the National Aeronautics and Space Administration, Ames Research Center (NASA/ARC) between Novembe1970 and April 1971, under contract NAS2-6255. The purpose of this study is to describe the operational characteristics of the Pioneer F and G spacecraft system and its subsystems to the NASA/ARC Pioneer Project personnel having the responsibility for conducting the Pioneer F/G flight mission operations. This report, "Pioneer F/G Spacecraft Operational Characteristics," is the final report of this study.

Hall, Charlie F.↗