Pioneer 10 [NASA]

ThePioneer 10 mission was the first to be sent to the outer solar system and the firstto investigate the planet Jupiter, after which it followed an escape trajectory from thesolar system. The spacecraft achieved its closest approach to Jupiter on 3 December 1973,when it reached approximately 2.8 Jovian radii (about 200,000 km).

Pioneer 11 was the second mission to investigate Jupiter and the outer solar system andthe first to explore the planet Saturn and its main rings. Pioneer 11, like Pioneer 10,used Jupiter's gravitational field to alter its trajectory radically. It passed close toSaturn and then it followed an escape trajectory from the solar system.

Fifteen experiments were carried to study the interplanetary and planetary magneticfields; solar wind parameters; cosmic rays; transition region of the heliosphere; neutralhydrogen abundance; distribution, size, mass, flux, and velocity of dust particles; Jovianaurorae; Jovian radio waves; atmosphere of Jupiter and some of its satellites,particularly Io; and to photograph Jupiter and its satellites. Instruments carried forthese experiments were: 

• Asteroid/Meteroid Detector (non-imaging telescopes with overlapping fields of view to detect sunlight reflected from passing meteoroids)
• Meteroid Detector (sealed pressurized cells of argon and nitrogen gas for measuring the penetration of meteoroids)
• Helium Vector Magnetometer (HVM)
• Infrared Radiometer
• Imaging Photopolarimeter (IPP)
• Trapped Radiation Detector (TRD)
• Plasma Analyzer (PA)
• Charged Particle Instrument (CPI)
• Cosmic Ray Telescope (CRT)
• Geiger Tube Telescope (GTT)
• Ultraviolet Photometer (UV)

The spacecraft body was mounted behind a 2.74-m-diameter parabolic dish antenna thatwas 46 cm deep. The spacecraft structure was a 36-cm-deep flat equipment compartment, thetop and bottom being regular hexagons. Its sides were 71 cm long. One side joined asmaller compartment that carried the scientific experiments. The high-gain antenna feedwas situated on three struts, which projected forward about 1.2 m. This feed was toppedwith a medium-gain antenna. A low-gain omnidirectional antenna extended about 0.76 mbehind the equipment compartment and was mounted below the high-gain antenna. Power forthe spacecraft was obtained by four SNAP-19 radioisotope thermonuclear generators (RTG),which were held about 3 m from the center of the spacecraft by two three-rod trusses 120deg apart. A third boom extended 6.6 m from the experiment compartment to hold themagnetometer away from the spacecraft. The four RTG's generated about 155 W at launch anddecayed to approximately 140 W by the time the spacecraft reached Jupiter, 21 months afterlaunch. There were three reference sensors: a star sensor for Canopus which failed shortlyafter Jupiter encounter and two sun sensors. Attitude position could be calculated fromthe reference directions to the earth and the sun, with the known direction to Canopus asa backup. Three pairs of rocket thrusters provided spin-rate control and changed thevelocity of the spacecraft, the spin period near the end of the mission being 14.1seconds. These thrusters could be pulsed or fired steadily by command. The spacecraft wastemperature-controlled between minus 23 deg C and plus 38 deg C. A plaque was mounted onthe spacecraft body with drawings depicting a man, a woman, and the location of the sunand the earth in our galaxy.

Communications were maintained via 

• the omnidirectional and medium-gain antennas which operated together while connected to one receiver and
• the high-gain antenna which was connected to another receiver.

These receivers could be interchanged by command to provide some redundancy. Two radiotransmitters, coupled to two traveling-wave tube amplifiers, produced 8 W at 2292 MHzeach. Uplink was accomplished at 2110 MHz, while data transmission downlink was at 2292MHz. The data were received by NASA's Deep Space Network (DSN) at bit rates up to 2048 bpsenroute to Jupiter and at 16 bps near end of the mission.

A third set of parts has been assembled as a third probe,Pioneer H, as potential a back-up and was considered later for a Jupiter fly-by with a subsequent out-off-ecliptic mission. This mission was never approved and the probe is now on diplay at the National Air and Space Museum in Washington, D.C.

Launch Sites:

• CC =   Cape Canaveral Air Force Station, Eastern Test Range, Cape Canaveral, Florida, USA   

References:

• NSSDC Master Catalog:Pioneer 10
• NSSDC Master Catalog:Pioneer 11

• Pioneer 0, 1, 2
• Pioneer 3, 4
• Pioneer P1, P3, P30, P31
• Pioneer 5 (P 2)
• Pioneer 6, 7, 8, 9, E
• Pioneer 10, 11, H
• Pioneer 12 (Pioneer-Venus 1)
• Pioneer 13 (Pioneer-Venus 2)

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