Scientists Study Pioneer Anomalies

By Aussiegirl

Who can resist an article in which the very first sentence has the phrases "mysterious changes" and "point toward new ideas in physics"? I certainly can't.
Here is Wikipedia's article on the Pioneer anomaly , and here is the attention-grabbing first sentence: The Pioneer anomaly or Pioneer effect is the observed deviation from expectations of the trajectories of various unmanned spacecraft visiting the outer solar system, notably Pioneer 10 and 11. As of 2005, there is no universally accepted explanation for this phenomenon; while it is possible that the explanation will be prosaic—such as thrust from gas leakage—the possibility of entirely new physics is also being considered.
(The illustration is an artist's impression of Pioneer 10 orbiting Jupiter.)

Scientists Study Pioneer Anomalies

Scientists Study Pioneer Anomalies
by Staff Writers
Los Alamos (UPI) Aug 17, 2006

U.S. scientists say mysterious changes in acceleration seen in NASA's Pioneer 10 and 11 space probes might point toward new ideas in physics. During the 1980s, NASA researchers noticed the Pioneer 11 spacecraft was slowing more quickly than expected as it neared the edge of the solar system.

A similar effect occurred with the Pioneer 10 spacecraft, which was sent in the opposite direction. Finally, in 1998, John Anderson, then at the Jet Propulsion Laboratory in Pasadena, Calif., and colleagues made their findings public.

Since then, other NASA and European Space Agency probes have also exhibited unexplained changes in speed.

Anderson, now with the Global Aerospace Corp., says although it's possible an overlooked effect from ordinary physics might account for the anomalies, something more exotic could also be involved.

For example, the spacecraft trajectories could be influenced by the presence of dark matter in the solar system, says Michael Nieto of the Los Alamos National Laboratory. Or maybe the laws of gravity need reworking.

"We're just throwing it out as a possibility that the anomalies might have a single cause," said Anderson. "We thought it was really time to get the community thinking about it."