More than 30 years after launch, NASA received the magnificent Pioneer 10 spacecraft's last, very weak signal on January 23, 2003. NASA engineers believe that Pioneer 10's radioisotope power source had decayed to the point it did not possess enough power to send transmissions to Earth. The Deep Space Network (DSN), operated by NASA, did not detect a signal during a contact attempt on February 7, 2003. The three previous contacts, including those received on January 23, were faint, with no transmission information. April 27, 2002, was the last time a Pioneer 10 contact returned telemetry data. A final attempt to locate Pioneer 10's signal was made on March 3-5, 2006, but the attempt failed.
Pioneer 10 launched on March 2, 1972, on the top of an Atlas/Centaur/TE364-4 launch vehicle. This was the first of many historic and groundbreaking aspects of the Pioneer 10 mission, as it was the first use of the three-stage Atlas-Centaur launch vehicle. This third stage was necessary to force Pioneer 10 to the speed needed for the flight to Jupiter. This made Pioneer the fastest human-made object to leave the Earth, fast enough to pass the Moon in 11 hours and cross the Mars orbit, about 80 million kilometers (50 million miles) away, in just 12 weeks and would become the first spacecraft to obtain close-up images and make direct observations of Jupiter and the first to travel through the Asteroid belt. For a time, it was the most remote human-made object through most of its mission, now surpassed by the Voyager spacecrafts. Pioneer 10 is now well over 8 billion miles away from Earth.
Pioneer 10, on July 15, 1972, entered the Asteroid Belt, a doughnut-shaped area, which measures 280 million km wide and 80 million km thick. The material in the Asteroid Belt travels at nearly 20 km/sec, and the material ranges in size from rock chunks as large as Alaska dust particles. After safely making its way through the Asteroid Belt, Pioneer 10 headed toward Jupiter. It accelerated to a speed of 132,000 km/hr because of the massive planet's gravitational pull, and Pioneer 10 passed by Jupiter on December 3, 1973, within 130,000 km of the cloud tops. During this time, Pioneer 10 took the first close-up images of Jupiter, charted it's intense radiation belts, located the magnetic field around the planet, and discovered that Jupiter is predominantly a liquid planet. This was the first-ever approach to Jupiter. It opened the doors of exploration to the outer solar system. This enabled Galileo to investigate Jupiter, and its satellites, Cassini to go to Saturn and probe Titan, Voyager to tour the outer planets, and Ulysses to break out of the ecliptic. The measurements taken of the intense radiation environment near Jupiter were crucial in designing the Galileo and Voyager spacecrafts.
After Pioneer 10's encounter with Jupiter, the spacecraft explored the Solar system's outer regions, studying the energetic particles from the Sun and the Solar Wind produced in the outer reaches of the Solar System, as well as cosmic rays entering the Milky Way in our solar system. Valuable scientific investigations in the solar system's outermost regions continued to be conducted by the spacecraft until March 31, 1997, when its science mission ended. The DSN tracked the weak signal as part of an advanced concept study of communication technology, which supported NASA's future interstellar probe mission.
The power source on Pioneer 10 had been steadily degrading, but eventually, degradation was so severe, the signal dropped below the threshold for detection, and the connection was lost. The last time a Pioneer 10 returned telemetry data was April 27, 2002, and Pioneer 10's contact attempts on February 7, 2003, and March 3, 2006, were unsuccessful. The previous three contact attempts had very faint with no telemetry received, with the last weak signal received on January 23, 2003. Pioneer 10 is continuing to coast silently as a ghost ship through deep space into interstellar space, generally heading 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.
