Want to stay on top of all the space news? Follow @universetoday on TwitterThe Pioneer group of missions was designed to obtain measurements of interplanetary phenomena from widely separated points in space and return non-stop data. Pioneer 9 was the fourth in the series. Each satellite orbited the Sun and was spin-stabilized and was powered by solar-cells and battery-power. Pioneer 9 carried experiments to study the positive ions and electrons in the solar wind, the interplanetary electron density using a radio propagation experiment, solar and galactic cosmic rays, the interplanetary magnetic field, cosmic dust, and electric fields. Pioneer 9 introduced a new coding process. Along with Pioneer 6, 7, and 8 the vehicle acted as the world’s first space-based solar weather network, providing practical data on the solar storms that interfere with communications and power on Earth.
Pioneer 6, 7, 8, and 9 were identical in design. They each carried many of the same instruments aloft. Pioneer 9 featured the instruments: Cosmic-Ray Anisotropy, Celestial Mechanics, Two-Frequency Beacon Receiver, Cosmic Dust Detector, Cosmic Ray Gradient Detector, Triaxial Magnetometer, Solar Plasma Detector, and the Electric Field Detector.
Communication was achieved through the spacecraft’s high-gain directional antenna. 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 bps. 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 by the specified data format and bit rate. 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 bps. The time period between collection and storage of successive frames could be varied by ground command between 2 and 17 min to provide partial data coverage for periods of up to 19 h, 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.
Contact with Pioneer 9 was maintained until May 1983. Mission controllers made an unsuccessful attempt in 1987 to contact the spacecraft. Pioneer’s 6-9 have been touted as the least expensive of NASA’s spacecraft in terms of science per dollar spent. The spacecraft have not been regularly tracked for science data return in recent years, a successful telemetry contact with Pioneer 6 was made on December 8, 2000 to celebrate 35 years of continuous operation since launch. That is quite tremendous considering its original design life expectancy was only 6 months. As of March 26, 2007, Pioneer 6 is still described as viable and is the oldest operating space probe. Scientists also believe that contact is still possible with Pioneers 7 and 8. Unfortunately, Pioneer 9 is definitely out of commission.
We have written many articles about Pioneer 9 for Universe Today. Here are some space probe pictures, and here’s an article about Pioneer 11.
We’ve also recorded an entire episode of Astronomy Cast all about Interstellar Travel. Listen here, Episode 145: Interstellar Travel.