NASA Voyager 1 & 2 Owners' Workshop Manual - 1977 onwards (VGR77-1 to VGR77-3, including Pioneer 10 & 11): An insight into the history, technology, ... sent to study the outer planets and beyond

Voyager 1 has recently crossed the boundary of our solar system and passed into interstellar space, and Voyager 2 is likely to follow suit, on a different path, between 2016 and 2017. The two Voyager probes will continue to transmit details of discoveries beyond our solar system until at least 2020.