Nearly half a century ago, a spacecraft about the size of a small car left Florida atop a rocket on what was meant to be a five-year mission. This week, NASA announced it had turned off one of that craft’s remaining science instruments — not because the mission failed, but to extend its life.
Voyager 1 is the most distant human-made object. Engineers at NASA’s Jet Propulsion Laboratory are working to keep it operating as its power supply dwindles.
Built for five years, operating for nearly fifty
Voyager 1 launched on Sept. 5, 1977, from Cape Canaveral on a Titan-Centaur rocket. It weighs about 1,797 pounds and carries a 12-foot dish antenna to communicate with Earth. Built at JPL, it has been running almost continuously for nearly 49 years.
In the late 1960s scientists noticed the outer planets—Jupiter, Saturn, Uranus and Neptune—would briefly align, enabling spacecraft to use gravity assists to gain speed and change direction without extra fuel. NASA scaled an ambitious “Grand Tour” down to the Voyager program, designed for an intensive five-year flyby of Jupiter and Saturn. Voyager 1 far exceeded that lifespan.
Voyager 1 flew past Jupiter in March 1979, revealing active volcanism on the moon Io—the first observation of volcanoes beyond Earth. It reached Saturn in November 1980 and returned detailed data on Saturn’s rings and the moon Titan. A close Titan encounter sent Voyager 1 out of the plane of the solar system and toward interstellar space.
In 1990 the mission was extended as the Voyager Interstellar Mission, with a new goal: study the edge of the Sun’s influence and the space beyond. On Aug. 25, 2012, Voyager 1 crossed the heliopause—the boundary where the Sun’s charged-particle wind yields to interstellar space—becoming the first human-made object in interstellar space. Voyager 2 followed in 2018.
More than 15 billion miles away, running on borrowed power
As of this spring, Voyager 1 is over 15 billion miles from Earth. Radio signals take more than 23 hours one way. The spacecraft runs on a radioisotope thermoelectric generator (RTG), which converts heat from decaying plutonium into electricity. There are no solar panels; the RTG’s output falls by about 4 watts per year. After decades, that decline is now critical.
During a routine maneuver in late February, Voyager 1’s power dropped unexpectedly, bringing it near an automatic fault-protection shutdown. That safety response would have required a lengthy, risky recovery, so engineers acted proactively.
Turning off history to preserve the mission
On April 17, mission engineers sent commands to deactivate the Low-Energy Charged Particles experiment (LECP), one of Voyager 1’s remaining science instruments. LECP measures ions, electrons and cosmic rays from the heliosphere and interstellar space, helping map interstellar structure. Its counterpart on Voyager 2 was turned off in March 2025.
Years ago Voyager teams agreed on an order to power down instruments to conserve energy while keeping the most valuable science. The LECP was next on that list. “While shutting down a science instrument is not anybody’s preference, it is the best option available,” said Kareem Badaruddin, Voyager mission manager at JPL.
Voyager 1 now has two operational science instruments: a plasma-wave detector and a magnetometer. Engineers estimate the LECP shutdown could buy roughly another year of operation.
A bigger conservation plan and hopes for the future
The team is also preparing a broader power-saving maneuver nicknamed “the Big Bang,” which swaps several older, higher-power components for lower-power alternatives in a coordinated sequence. Tests on Voyager 2 planned for May and June 2026 will inform whether the procedure can be applied to Voyager 1 as soon as July. If successful, there’s a small chance the LECP could be returned to service.
Engineers aim to keep at least one instrument running on each Voyager into the 2030s, allowing both probes to continue reporting from regions no machine has ever explored.