Pioneer Anomoly

I heard Bill Nye talk about the Pioneer Anomoly back in July 2005 at the Comet Bash. It apears the Pioneer Probes are speeding up rather than slowing down as they exit the Solar System. JPL engineer John Anderson held back on this information for almost ten years (From a Seattle Times article) Three reasons could be:

One possibility is that dark matter is holding the spacecraft back. Some cosmologists believe dark matter exists because only 10 percent of the expected mass of the universe has been found. If 90 percent of the universe's mass and energy is invisible, maybe it could exert gravitational pull on spacecraft.

Another possibility, even more fanciful, is that invisible dimensions are tugging at the Pioneers. This idea has its origin in string theory, a two-decade-old school of thought that suggests we are surrounded by more than the three dimensions we know about. Some versions of string theory suggest there could be as many as 11 dimensions, most of which are curled up and hidden from us.

A third possibility is that gravity has been hiding secrets that three centuries of research have failed to uncover.

Too bad Pioneer 11 in 1995 communication stopped, Pioneer 10 last communication was in 2003. To fully study this Anomoly is to send another probe, but NASA has said no and ESA won't send one untill 2015. Most JPL Pioneer project scientist's won't be around to look at the data.