March 6, 2006 marked the final attempt by the Deep Space Network on Earth to acquire a signal from the Pioneer 10 spacecraft, launched back in March 1972.

Pioneer 10 was the first space probe sent to an outer planet - Jupiter. For some strange reason, Pioneer 10 has fallen behind in its projected travel by about 5,000 kilometers (3,000 miles) per year. Thus far, Scientists have been able to explain this "Pioneer Anomaly". No spacecraft behavior or previously unknown property of the outer solar system can explain the deceleration of the Pioneer spacecraft.

It is currently hurtling through interstellar space towards Aldebaran, the red star that forms the eye of the bull in Taurus.

Read the story at the The Planetary Society