Finding the source of the pioneer anomaly

Some 40 years ago, a quarter-ton lump of circuits and sensors slipped Earth´s surly bonds, sped past the moon and Mars, and hurtled toward Jupiter. The probe, Pioneer 10, and its sister ship, Pioneer 11, which followed a year later, were true trail blazers . They gave humanity its first close-up glimpses of worlds beyond the solar system´s asteroid belt. They also left behind a mystery-one that has simultaneously baffled and inspired as trophysicists for years.