Pioneer 10 is heading towards the asymptote of a hyperbolic trajectory. The vehicle is spin stabilized with its main antenna pointed at the Earth. However as Pioneer 10 proceeds along its hyperbolic trajectory, the Earth leaves its antenna's field of view. This means that about once a year the vehicle has to be tweeked ever so slightly such that the Earth is recentered in its field of view. Supposably its RTGs are producing so little power that most of the vehicle has been shutdown. It's almost like a stroke victim who can communicate only by blinking its eyes.

It's a tough call concerning which was NASA Ames' greatest technical achievement, i.e. Pioneer 10 or the Galileo Probe.

Gary