Pioneer 10 became the first spacecraft to cross the asteroid belt, something scientists thought was impossible * The spacecraft is now investigating the mystery of gravity at the edge of the solar system
NASA engineers this month managed to receive a radio signal from the first spacecraft to pass the orbit of Pluto. Pioneer 10 is now 12.1 billion kilometers from Earth and has been quiet since March of this year (2002). Currently, a radio signal traveling at the speed of light takes 11 hours to reach Earth from Pioneer 10, a spacecraft launched from here in 1972.
The deep space receiving station near Madrid detected the signal but could not lock the receiver on it, Pioneer 10 project manager Larry Lasher said in a status report. The antenna in Spain is one of several large dishes that, together with NASA's network of satellites, make it possible to contact the spacecraft located throughout the solar system.
Additional antennas located in Goldstone, California and Arecibo, Puerto Rico, confirmed that the radio signal was coming from Pioneer 10. However, the transmission was so weak that scientists were unable to take any scientific readings from the spacecraft's instruments.
Pioneer 10 and its sister Pioneer 11, launched in 1973, earned their names during decades of record-breaking discoveries.
The spacecraft moved in opposite directions and were the first to cross the asteroid belt, the first to explore the outer solar system and the first to send images of the gas giants Jupiter and Saturn.
Radio contact with Pioneer 11 was lost in 1995. In April 2001, Pioneer 10 surprised astronomers when it successfully sent a signal back to Earth as requested. In 1998, one of the older Voyager spacecraft passed Pioneer 10 and became the most distant man-made spacecraft in space.
But Pioneer 10, now twice as far from the Sun as Pluto, continues to serve as a scientific asset as it reaches the edge of the Solar System. On the rare occasions that scientists are able to extract crisp data from Pioneer 2 in the coming years, they will need to use those readings to study everything from cosmic rays to chaos theory and the mechanisms of gravity.
Facts about Pioneer 10
• The spaceship includes a small sign designed by Carl and Linda Sagan, and Frank Drake intended to be used as a greeting card for extraterrestrial civilizations.
• In its current orbit, Pioneer 10 will reach the human planet Aldebaran - the eye of the Taurus group, in over 2 million years.
• The spacecraft weighing 270 kilograms travels at a speed of 44 thousand km/h relative to the sun.
• The spacecraft is now 82 AU from the center of the solar system. An astronomical unit is the average distance between the Earth and the Sun - 150 million km.
