Nearly 50 years and still going
Voyager 1 was launched on 5 September 1977. Voyager 2 launched 16 days earlier on 20 August 1977, but on a slower trajectory that took it past all four outer planets — the only spacecraft to visit Uranus and Neptune. Both were designed for a 5-year primary mission. Engineers have kept them alive for nearly 50, by periodically turning off heaters and instruments as their nuclear power sources (RTGs) gradually decay.
Into interstellar space
The heliopause is the boundary where the solar wind is matched by the pressure of interstellar gas. Beyond it lies the Local Interstellar Medium (LISM) — the material between the stars. Voyager 1 crossed this boundary in August 2012, confirmed by a dramatic change in the plasma density measured by its plasma wave instrument in 2013. Voyager 2 crossed it on 5 November 2018, giving scientists two simultaneous sampling points in different directions — a unique window into the boundary conditions of the heliosphere.
The distances involved put the light-year in perspective: at ~163 AU, Voyager 1 has covered only about 0.0026 light-years. The nearest star system (Alpha Centauri) is 4.24 light-years away — roughly 1,630 times further. Use the Distance Converter to compare.
The engineering challenge
Keeping Voyager alive requires constant ingenuity. In late 2023, Voyager 1 began transmitting garbled engineering data due to a corrupted memory chip. NASA engineers — working with 46-year-old code documentation and a 22-hour round-trip signal delay — devised a workaround that rerouted the data around the damaged memory, recovering science and engineering telemetry without a physical fix. It is one of the most remarkable remote-repair operations in the history of spaceflight. Details are at JPL News.