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An artist’s impression of Pioneer 10 heading out of the solar system towards the galactic center.
Image credit: NASA Ames
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Pioneers 10 and 11 both carried small metal plaques identifying their time and place of origin for the benefit of any other spacefarers that might find them in the distant future. Pioneer 10 is heading towards the star Aldebaran in the Taurus constellation and will take more than two million years to reach it.
Image credit: NASA Ames
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On December 4, 1973, excitement rose as the Pioneer 10 spacecraft sent back images of a Jupiter of ever-increasing size as it plunged at high speed toward its closest approach to the planet. PICS (Pioneer Image Converter System) began to show a few spots on the screens, which gradually built up into a very distorted crescent-shaped Jupiter. “Sunrise on Jupiter,” exclaimed a scientist excitedly. Subsequent PICS images were of a crescent Jupiter gradually decreasing in size as the spacecraft sped away out of the Jovian system.
Image credit: NASA Ames
The unexpected slowing of NASA’s Pioneer 10 and 11 spacecraft – the so-called “Pioneer Anomaly” – turns out to be due to the slight, but detectable effect of heat pushing back on the spacecraft, according to a recent paper. The heat emanates from electrical current flowing through instruments and the thermoelectric power supply. The results were published on June 12 in the journal Physical Review Letters.
“The effect is something like when you’re driving a car and the photons from your headlights are pushing you backward,” said Slava Turyshev, the paper’s lead author at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “It is very subtle.”
Launched in 1972 and 1973, Pioneer 10 and 11 are on an outward trajectory from our sun. In the early 1980s, navigators saw a deceleration on the two spacecraft, in the direction back toward the sun, as the two spacecraft were approaching Saturn. They dismissed it as the effect of dribbles of leftover propellant still in the fuel lines after controllers had cut off the propellant. But by 1998, as the spacecraft kept traveling on their journey and were over 8 billion miles (13 billion kilometers) away from the sun, a group of scientists led by John Anderson of JPL realized there was an actual deceleration of about 300 inches per day squared (0.9 nanometers per second squared). They raised the possibility that this could be some new type of physics that contradicted Einstein’s general theory of relativity.
In 2004, Turyshev decided to start gathering records stored all over the country and analyze the data to see if he could definitively figure out the source of the deceleration. In part, he and colleagues were contemplating a deep space physics mission to investigate the anomaly, and he wanted to be sure there was one before asking NASA for a spacecraft.
Read More:
http://www.nasa.gov/centers/ames/news/features/2012/pioneer_anomaly_jpl.html
