Pioneer 10 beyond Neptune orbit
In 1983, space probe vehicle Pioneer 10 crossed the orbit of Neptune and became the first man-made object to leave our Solar System. It was launched 2 Mar 1972. It is moving in a straight line away from the Sun at a constant velocity of about 12 km/sec. Some 30 years after its launch, on 27 Apr 2002, NASA made successful contact with telemetry received from Pioneer 10 when it was at a distance from Earth of 7.57 billion miles, and the round-trip time for the signal (at the speed of light) was 22-hr 35-min. The probe sent information from the one scientific instrument that was still working, the Geiger Tube Telescope. The spacecraft is heading generally towards the red star Aldebaran, which forms the eye of Taurus (The Bull).