Integration of radioisotope thermoelectric generators for the Pioneer F/G program
Radioisotope thermoelectric generators integration for Pioneer 6/7 program, discussing design requirements
Nothwang, G. J.↗
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Pioneer-class mission capabilities
Pioneer Jupiter spacecraft, noting low weight, radioisotope thermoelectric generators and gyroscopic stabilization by spinning with antenna pointed at earth
Jackson, R. W.↗
More than two years of micrometeorite data from two Pioneer satellites
Pioneer 8 and 9 micrometeorite measurements of particles kinetic energy, momentum, velocity and direction, correlating measured particle flux rates with predictions based on zodiacal light
Berg, O. E.↗
A model for predicting the results of in situ meteoroid experiments - Pioneer 8 and 9 results and phenomenological evidence
Qualitative micrometeoroid model for predicting results of in situ experiments, considering correlation to Pioneer 8 and 9 results
Berg, O. E.↗
Magnetic field measurements by Pioneer 7. 1: Hourly averages of the field elements from 17 August 1966 to 29 October 1967 (Bartel's Solar Rotation 1820 to 1836)
The magnetic observations of Pioneer 7, located in the aftward portion of the disturbed solar plasma caused by interaction with the geomagnetic field, are summarized in graphical form. Hourly averages of the magnetic field elements for Bartel's solar rotation number are shown for each month from August 1966 to October 1967.
Ness, N. F.↗
Magnetic field measurements by Pioneer 6. 1: Hourly averages of the field elements from 17 December 1965 to 5 September 1967 (Bartels solar rotation 1811 to 1834)
Magnetic field data obtained on Pioneer 6 flights are presented in graph form as hourly averages. The spacecraft and magnetic field detector are described. The standard data analysis procedures are also given.
Ness, N. F.↗
Reentry thermal protection from Pioneer F RTG insulation material
Ablation tests were performed on the insulation material used in the Pioneer F radioisotope thermoelectric generator (RTG) in the Ames Arc-Heated Planetary-Gas Wind Tunnel. Test results indicate that the material, trade name Min-K 1301, should experience little ablation for heat transfer rates below 40 BTU/sq ft-sec. If the current design were to be changed so that the various pieces of Min-K were fastened or interlocked together the total amount of heat delivered to the RTG heat source during an earth orbital decay reentry would be reduced by at least 22.7%.
Vorreiter, J. W.↗
Pioneer F mission to Jupiter
The experimental designs for the Pioneer F mission to Jupiter are described. The spacecraft is designed to make measurements of the planet's atmosphere, radiation belts, heat balance, magnetic fields, moons, and other related phenomena. The mission also characterizes the heliosphere, the interstellar gas, cosmic rays, asteroids, and meteoroids between the earth and 2.4 billion kilometers from the sun.
Allaway, H. G.↗
Pioneer F/G feed movement mechanism
The Pioneer F/G spacecraft achieves the desired earth-pointing direction through a system requiring the shifting of the main antenna feed 1 in. off axis. The feed is pivoted to this position by an electrically heated thermal actuator consisting of an electroless nickel bellows in a copper housing and filled with Freon 21. The actuator overtravels and maintains the feed in the offset position in a thermostatic limit cycle operation mode until commanded off. The mechanism is expected to operate in a -240 F environment near Jupiter and was successfully tested at such temperatures.
R. M. Acker↗
Pioneer F/G appendage deployment
An integrated program of testing and analysis is described for developing and flight-qualifying the appendage deployment systems of Pioneer F/G, a spin-stabilized spacecraft which will fly by Jupiter. A combination of deployment system component tests, simplified nonspinning deployment tests, and analyses were used to develop the deployment system hardware. Analytical deployment models, verified by correlation with deployment test performance data and incorporating measured system parameters, were used to project in-flight deployment system performance over the expected range of environmental and hardware extremes.
Hesprich, G. V.↗
Assessment of Jupiter's trapped radiation by pioneer
The experiments planned for Pioneers F and G during their Jupiter flybys are discussed. The complement includes four energetic charged particle experiments: University of Iowa package consisting of Geiger-Mueller tubes; University of California, San Diego, trapped radiation package consisting of solid state detectors, thin scintillators, and an alcohol water Cerenkov radiator; University of Chicago package containing charged particle detectors; and a Goddard Space Flight Center package containing solid state, cosmic ray detectors. Other experiments are the Jet Propulsion Laboratory magnetometer and the Ames Research Center plasma analyzer. Pitch angle distributions at Jupiter, and the capabilities for unambiguous identification of energetic protons at Jupiter are also discussed.
Mihalov, J. D.↗
Pioneer 8 plasma-wave measurements at distant bow-shock crossings.
Evaluation of enhanced low-frequency plasma-wave levels detected near the Pioneer 8 multiple bow-shock crossings encountered beyond 120 earth radii (Bavassano et al., 1971) and of high-frequency plasma waves detected in the upstream region. It is suggested that the distant interaction of the solar wind and the magnetosheath produced nonthermal electrons of the type commonly found upstream from the subsolar shock. The bow-shock position is compared with fluid model predictions, and some distinctions between the standing bow shock and the propagating interplanetary shock are considered.
Scarf, F. L.↗
The electrical power subsystem of the Pioneer F/G spacecraft.
The Pioneer F/G spacecraft is the first to use radioisotope thermoelectric generators (RTG's) for a long duration interplanetary mission. This paper describes the design of the spacecraft power subsystem which meets the unique requirements of such a mission. The primary power source consists of four SNAP 19 RTG's. The 4.2 volt dc outputs of the RTG's are inverted to higher voltage ac by four inverters which are connected in parallel at their outputs. A power control unit (PCU) regulates the ac output of the inverters such that the RTG's are operated at near maximum power voltage throughout the mission. The PCU also contains charge and discharge controls for a silver cadmium battery which supplements the RTG's if load requirements temporarily exceed RTG power output. Battery reliability is enhanced by overcharge and cell reversal protection electronics which are provided for each cell. Multiple, low voltage, regulated dc outputs which supply power to the spacecraft subsystems are provided by a central transformer-rectifier-filter unit (CTRF). The CTRF operates directly from the regulated ac bus.
Reppucci, G. M.↗
Structure and orientations of solar-wind interaction fronts - Pioneer 6.
An analysis is given of five stream-stream interaction events observed in the Pioneer 6 plasma and field data. That the time profiles of all the parameters are consistent among the events and with previous descriptions given in the literature substantiates the notion of a common interaction type. The velocity variations in four of the events tend to lie in planes approximately parallel to the corotation spiral; thus it is implied that the events are reasonably stationary in time in the corotating frame. The data are interpreted in terms of a corotating interaction front, which is a ridge of high pressure parallel to a corotating spiral. The increased pressure is due to radial compression of the streams. The east-west (zonal) flow directions also occur in the front and are shown to be produced by the zonal pressure gradient of the pressure ridge.
Siscoe, G. L.↗
Average solar wind proton properties from Pioneers 6 and 7.
Distributions and average values for the proton speed, azimuthal and polar flow directions, and the proton temperature and density in the solar wind are presented. The data are obtained from the Ames plasma probes on Pioneers 6 and 7. The time periods covered include Dec. 18, 1965 to mid-February 1966, and mid-August to mid-October 1966. The distributions of the parameters, except for the polar flow direction, are skewed, partially because of stream-stream interactions in the solar wind. The average values of the basic plasma parameters from the two spacecraft are different which could be due partially to different solar activity at the two times, and partially to sector and beam structure dependence.
Mihalov, J. D.↗
Anomalous type III bursts explained in terms of intermittent solar wind streams observed by Pioneer spacecraft.
Occasional solar radio bursts drift downward in frequency (like type III bursts), but the drift slows or ceases or it may even reverse. These anomalous forms are called L-bursts, U-bursts, etc., and are observed as low as 1 MHz by spacecraft. The conventional explanation involves guidance of relativistic exciting particles by solar magnetic fields that do not have the spiral shape expected in undisturbed conditions. A reasonable alternative explanation is possible and, indeed, it follows directly from the inferences which have been drawn from the Stanford dual-frequency experiment flown on four Pioneer spacecraft. Analysis of temporal variations in these data leads to the conclusion that narrow streams of enhanced concentration have lifetimes which are typically about one day and the streams seem to be intermittently ejected by long-enduring sources at the sun. Each enhancement is thought to lie along a spiral and to have a beginning and an end. It may happen that relativistic exciters encounter the tail of such a discrete streamer; the concentration encountered by such exciters would initially decline but, at the streamer tail, it would level off and perhaps increase. The plasma frequency versus time (the burst frequency) would then cease to drop in the typical type III profile and would level off or increase (as in a U-burst).
Croft, T. A.↗
An analysis of Pioneer 9 low-frequency wave observations near interplanetary discontinuities.
Observation of an unusually complex sector boundary on Feb. 2, 1969. Within a single seven-hour period the Pioneer 9 magnetometer and plasma probe detected a reverse shock, a slow shock, and a conventional fast shock. During this interval the electron gyrofrequency and the ion plasma frequency each varied by more than a factor of 10, and the low-frequency (broadband and 400-Hz) electric field wave levels were high and variable. It is shown that, near the discontinuities, enhanced 400-Hz wave levels were not generally associated with field gradients or current layers, but elevated 400-Hz wave levels were detected when the ion density fell within a fairly well-defined window. This suggests that modes related to ion sound waves were detected, and the observations are assessed in terms of various theories for interplanetary wave generation.
Scarf, F. L.↗
Pioneer 7 observations of the August 29, 1966, interplanetary shock-wave ensemble.
The detailed plasma (except for electrons) and magnetic field data from Pioneer 7 are presented for a proposed double-shock ensemble. The Ames Research Center plasma probe data are compared with that of the MIT probe. These data are compared with MHD theory to show that the discontinuities themselves satisfy the magnetic Hugoniot equations. The data are also compared with the theoretical predictions for the double-shock structure. The theory requires as input only the forward shock velocity, the original ambient solar wind conditions, and a reasonable assumption regarding the density and azimuthal magnetic field in the 'new' solar wind which is detected after passage of the reverse shock. A unique solution is then obtained for the theoretical piston and reverse shock positions as well as for the temporal plasma behavior for both infinite and finite electrical conductivities.
Dryer, M.↗