Pioneer 8 Spacecraft

Instrument Host Overview
========================
Pioneer 8, also known as Pioneer C, was the third in a series of
solar-orbiting, spin-stabilized, and solar-cell- and battery-powered
satellites designed to obtain measurements of interplanetary phenomena from
widely separated points in space on a continuing basis. The spacecraft
carried experiments to study the positive ions and electrons in the solar
wind, the interplanetary electron density (radio propagation experiment),
solar and galactic cosmic rays, the interplanetary magnetic field, cosmic
dust, and electric fields. 

The main antenna for Pioneer 8 was a high-gain directional one. The
spacecraft was spin-stabilized at approximately 60 revolutions per minute,
with the spin axis perpendicular to the ecliptic plane and pointed toward
the south ecliptic pole. By ground command, one of five bit rates, one of
four data formats, and one of four operating modes could be selected. The
five bit rates were 512, 256, 64, 16, and 8 bits per second. Three of the
four data formats contained primarily scientific data and consisted of 32
seven-bit words per frame. One scientific data format was used at the two
highest bit rates. Another was used at the three lowest bit rates, and the
third contained data from only the radio-propagation experiment. The fourth
data format contained mainly engineering data. The four operating modes were
real-time, telemetry-store, duty-cycle store, and memory readout. In the
real-time mode, data were sampled and transmitted directly (without storage)
as specified by the data format and bit rate selected. In the
telemetry-store mode, data were stored and transmitted simultaneously in the
format and at the bit rate selected. In the duty cycle store mode, a single
frame of scientific data was collected and stored at a rate of 512 bits per
second. The time interval between collection and storage of successive
frames could be varied by ground command between 2 and 17 minutes to provide
partial data coverage for periods of up to 19 hours, as limited by the
bit-storage capacity. In the memory readout mode, data were read out at
whatever bit rate was appropriate to the satellite distance from the Earth.

Pioneer 8 was launched on 13 December 1967 into a 387.5-day heliocentric
orbit with radii of 0.99 x 1.09 AU and an inclination of 0.057 degrees.
The spacecraft was last tracked successfully on 22 August 1996, after
being commanded to the backup transmitter, a traveling wave tube (TWT).
There are no further plans to track or attempt communications with 
Pioneer 8.

Facts in Brief
==============
Mission Type: Orbiter
Launch Date: 1967-12-13 at 14:08:00 UTC
Launch Vehicle: Thor-Delta E-1 (no. 60 / Thor no. 479 / DSV-3E)
Launch Site: Cape Canaveral, USA / launch complex 17B
NASA Center: Ames Research Center
Mass: 146.0 kg
Spacecraft Instruments and Principal Investigator:
  Mono-axial Fluxgate Magnetometer, Norman Ness 
  Electrostatic Analyzer, John Wolfe
  Two-Frequency Beacon Receiver, Von Eshleman
  Cosmic Dust Detector, Otto Berg
  Cosmic Ray Anisotropy Experiment, Kenneth McCracken
  Cosmic Ray Gradient Detector, William Webber,
  Plasma Wave Detector, Frederick Scarf
  Celestial Mechanics Experiment, John Anderson
Spacecraft Power: Solar cells and batteries
Maximum Data Rate: 512 bits per second
NSSDCA/COSPAR Spacecraft ID: 1967-123A

References
==========
Siddiqi, A.A., Deep Space Chronicle: A Chronology of Deep Space and
Planetary Probes 1958-2000, Monographs in Aerospace History No. 24, NASA,
SP-2002-4524, Washington, D.C, 2002.