NASA probe: Voyager 1 (launched 1977)
On September 5th 1977 Voyager 1 was launched from Cape Canaveral, Florida. Originally designed to explore the outer planets of Jupiter and Saturn, the spacecraft is still functioning and transmitting back data to Earth.
Debate is still ongoing as to whether the probe has finally left the influence of the solar system and entered inter-stellar space. However regardless of this, Voyager is just passed a milestone. It is now more than 19.1 Billion kilometres from earth (at the time of writing),
One of the most compelling images collected from Voyager gives some idea of scale. As it reached the edge of the solar system, mission control pointed the on board imaging back at earth for one last photograph.
To give a further idea of scale, in the time it has taken you to read this post Voyager has moved another 4,000 km from Earth. Even at the speed of light an instruction to the probe now takes more than 30 hours to be received and acknowledged.