In the Cold Depths of Space: the True Pioneers

Far beyond the orbit of Pluto a small spacecraft wanders like a beacon in the night. Launched more than thirty years ago, Pioneer 10's mission was to become the first spacecraft to pass through the asteroid belt and then fly by Jupiter. The mission was designed for 21 months. Pioneer 10 continued functioning, and transmitting to Earth for over 30 years. The last feeble signal was received January 22 of this year but the radioisotope power source had decayed so much that the spacecraft could not transmit telemetry.

The entire Pioneer Program was a succession of firsts for spacecraft. Pioneers 6 through 9 were successfully launched in 1965-6 into circular solar orbits. Their purpose was to demonstrate the practicality of spinning a spacecraft to stabilize it and to simplify control of its orientation. These were vital steps in our beginning exploration of space. .

Originally designed to operate in space for at least 6 months, the Pioneers have proved to be remarkably reliable. Pioneer 9 failed in 1983. Pioneer 8 was last tracked successfully on 22 August 1996, after being commanded to the backup transmitter tube (TWT). Pioneer 7 was last tracked successfully in March 1995. Pioneer 6, the oldest operating spacecraft ever, had a track on the 70 meter Deep Space Station 43 in Australia on 6 October 1997.

Pioneer 10 was launched on 2 March 1972. During July 1972, the craft safely traversed the asteroid belt. On December 3, 1973, Pioneer 10 passed within 81,000 miles of Jupiter's cloudtops. Pioneer 10 obtained the first close-up images of the planet, charted Jupiter's intense radiation belts, located the planet's magnetic field, and discovered that Jupiter is predominantly a liquid planet.

After Jupiter, Pioneer 10 continued to make valuable scientific investigations in the outer regions of the solar system. The spacecraft studied the energetic particles from the Solar Wind and cosmic rays. Pioneer 10's science mission ended on March 31, 1997. Since then, its signal has been tracked by NASA's Deep Space Network. It had also been used to help train flight controllers how to acquire radio signals from space during the Lunar Prospector mission

Pioneer 11 was launched on 5 April 1973 and visited Jupiter and Saturn. By September 1995, Pioneer 11 could no longer make any scientific observations, and routine daily mission operations were stopped. Intermittent contact continued until November 1995, at which time the last communication with Pioneer 11 took place. There have been no communications since. The Earth's motion has carried it out of the view of the spacecraft antenna. The spacecraft cannot be maneuvered to point back at the Earth. It is not known whether the spacecraft is still transmitting a signal. No further tracks of Pioneer 11 are scheduled.

There were two additional Pioneer craft which, instead of heading out into the Solar System, instead, headed inward and visited Venus. Both missions were highly successful.

Pioneer 10 was once famed as the most remote object ever made by man until it was surpassed by Voyager I in 1998. It is now over 7.6 billion miles away. Pioneer 10 will continue to coast silently as a ghost ship through deep space into interstellar space, heading generally for the red star Aldebaran, which forms the eye of Taurus (The Bull). Aldebaran is about 68 light years away and it will take Pioneer over 2 million years to reach it.

Constellations

The Solar System