The Pioneer Anamoly. An interesting article in the Seattle Times on gravity describes the "Pioneer Anamoly", which may point to something new in a field that had been thought to be settled for many years. The word "Pioneer" refers to the unmanned spacecraft we sent to deep space a couple of decades ago. Over the course of the many years during which those space-craft were tracked, they slowed down in a way inconsistent with our current theories of gravity. Thus the "Pioneer Anamoly".