Just like the Energizer Bunny, many of our early space probes seem to be ticking along way past their original lifetime estimates. According to

an article in Scientific American, the Deep Space Network recently reaquired the Pioneer 10 spacecraft which had not been contacted in nearly eight months. Not bad for a spacecraft that was launched on March 2, 1972.
But the professionals aren’t the only one’s who can make probes which last and last and last.

Radio amateurs have built and deployed satellites for decades. Each was constructed by a team
of volunteers and
deployed in orbit through the help of various space agencies. The first amateur satellite (designated
Oscar 1) was launched in 1961, weighed only five kilograms, and transmitted a Morse Code beacon for 18 days before its batteries were exhausted.
Subsequent satellites included repeater functions so that individuals on earth could make radio contact
with distant sights by using the satellite as a relay.

Oscar 7 was such a satellite, launched on November 15, 1974. It successfully operated for over six years, then fell silent due to a battery failure in mid 1981. The satellite was presumed lost.
On Jun 21, 2002, Pat Gown (G3IOR) was testing a new antenna on top of his tower, and began
receiving telemetry from a spacecraft. it was later determined that this spacecraft was the
assumed dead Oscar 7.

Oscar 7’s batteries are almost certainly depleted, so the spacecraft will only function when in
sunlight, but it is a remarkable achievement.

You can get the latest information and lots of background about Oscar 7 and amateur satellites in
general from the AMSAT website.