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Fimmel, R. O.

Publications and source records attributed to Fimmel, R. O..

Pioneer to Venus - The multiprobe and orbiter missions

The missions of the Pioneer multiprobe and orbiter spacecraft to Venus are surveyed and illustrated with drawings, photographs, maps, and diagrams. The general characteristics of Venus and the pre-Pioneer missions are reviewed; the developmental history of the Pioneer project is traced; the spacecraft and their orbits and deployment are described; and the scientific findings on the planet surface, atmosphere, and ionosphere are summarized. The experiments planned for the extended mission of the orbiter (through reentry in 1992) are briefly characterized, includidng solar-wind-interaction studies, comet detection, ionosphere and aeronomy investigations, global lightning survey, optical observations, gamma-ray-burst detection, radar mapping, gravity measurements, and observations of Halley's Comet during February, 1986.

Craig, R. A.

Exploring beyond the planets - The Pioneer 10 and 11 missions

The Pioneer 10 and 11 missions are surveyed and illustrated with drawings, maps, graphs, and diagrams, with an emphasis on their present exploration of the outer heliosphere. The main goals of this exploration are examined (search for the heliospheric boundary, measurement of galactic cosmic radiation, and search for a trans-Neptunian planet); the ten scientific instruments carried by each spacecraft are characterized; and the results obtained so far with regard to the solar wind and interplanetary magnetic field, cosmic rays, and asteroid belt, Jupiter, and Saturn are summarized.

Dyal, P.

The continuing missions of Pioneer spacecraft

Pioneer spacecraft will continue as mankind's farthest explorer from the Sun and America's only operating planetary orbiter for many years in the future. The eleven-year old Pioneer 10 describes strong solar domination of the environment at its 29 astronomic units (AU) distance, and its sensitivity as a unique sensor of suspected gravitational phenomena is improving with distance. The four-year-old Pioneer Venus Orbiter increasingly defines the solar wind interaction with the nonmagnetic planet as its orbital axis precesses through the affected volume. Pioneer 10 promises data from 50 AU distance by 1991. The Venus Orbiter could operate until atmospheric entry in 1992.

Dyer, J. W.

A spacecraft computer repairable via command.

The MULTIPAC is a central data system developed for deep-space probes with the distinctive feature that it may be repaired during flight via command and telemetry links by reprogramming around the failed unit. The computer organization uses pools of identical modules which the program organizes into one or more computers called processors. The interaction of these modules is dynamically controlled by the program rather than hardware. In the event of a failure, new programs are entered which reorganize the central data system with a somewhat reduced total processing capability aboard the spacecraft. Emphasis is placed on the evolution of the system architecture and the final overall system design rather than the specific logic design.

Fimmel, R. O.