No human-made objects have traveled further into the final frontier than Voyager 1 and Voyager 2. However, both space probes are reaching the end of their service lives. NASA announced that engineers at the Jet Propulsion Laboratory are shutting off instruments on both spacecraft to limit energy use and prolong their time in operation. Since their launches in 1977, both Voyager probes have traveled over 12 billion miles from Earth and entered interstellar space.
Both Voyager probes are equipped with a radioisotope power system, a nuclear battery that uses the heat of decaying plutonium to generate electricity. The system produced 470 watts of power at launch, but that figure decreased over time as the plutonium deteriorated. NASA states the power output was 335 watts at the start of 1997, and it has fallen by 7 watts every year. With that information, the nuclear batteries are producing around 139 watts right now.
The Voyager twins are approaching their 50th birthday
NASA personnel have openly stated that the agency’s goal is to have both Voyager probes still operational for their 50th anniversary in 2027. The probes can only make it two more years by carefully managing the shrinking power supply. Each spacecraft launched with ten scientific instruments, and only three on each probe will be powered by the end of March after recent cullings. They’ll be down to two instruments by 2026. It’s not like flipping a light switch, though — there’s a good chance that the instruments won’t be able to be turned back on. Linda Spilker, a Voyager project scientist at JPL, said:
“Every minute of every day, the Voyagers explore a region where no spacecraft has gone before. That also means every day could be our last. But that day could also bring another interstellar revelation. So, we’re pulling out all the stops, doing what we can to make sure Voyagers 1 and 2 continue their trailblazing for the maximum time possible.”
The probes are surviving in interstellar space
Besides the fading nuclear batteries, the Voyager probes have also run into technical issues after nearly a half-century of hurtling through space. Voyager 1 has dealt with a degrading diaphragm clogging its thruster fuel tubes with silicon dioxide. The probe doesn’t use the thrusters to move but to keep its communication systems pointed toward Earth to send and receive data. Troubleshooting these problems can be an anxiety-inducing experience because it takes nearly an entire day to send a command to either probe with the vast distances involved.
It can’t be understated how monumental an effort the Voyager program has become to keep both probes still going outside of our Solar System for so long. As a point of reference, President Jimmy Carter was sworn into office in 1977, the same year as the Voyager launches, and died last year after being the first president to reach their 100th birthday. Voyager 1 and Voyager 2 are still exploring the unknown.