Following in Pioneer's footsteps -- Calls grow for a mission to find out why old space probes are slowing down.

"Does the puzzling behaviour of the Pioneer spacecraft at the edge of the solar system reveal new laws of physics? Space scientists are calling for a deep-space mission to find out. Even if there is no revolutionary physics involved, they say that results could be vital for engineers designing future deep-space probes."

Here's a link to the original article I posted about the anomaly.