FILE – This illustration provided by NASA depicts Voyager 1.
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Nearly 50 years ago, a spacecraft the size of a small car launched from the Florida coast on a mission intended to last five years. This week, NASA revealed it had powered down one of the spacecraft’s remaining science instruments—not due to mission failure, but to prolong its life.
Voyager 1, humanity’s most distant creation, is nearing the end of its power supply. Engineers at NASA’s Jet Propulsion Laboratory (JPL) in Southern California are striving to delay its shutdown as long as possible.
A spacecraft built for five years that has lasted nearly fifty
Voyager 1, a robotic space probe, was launched on September 5, 1977, from Cape Canaveral aboard a Titan-Centaur rocket. It weighs approximately 1,797 pounds—similar to a midsize sedan—and is equipped with a 12-foot-wide dish antenna to communicate with Earth. Constructed at JPL, managed by the California Institute of Technology, it has been in nearly continuous operation for almost 49 years.
The mission was sparked by a unique astronomical event: in the late 1960s, scientists identified an alignment of the outer planets—Jupiter, Saturn, Uranus, and Neptune—that occurs once every 175 years. This alignment allowed a spacecraft to utilize each planet’s gravitational pull to increase speed and alter its trajectory without additional fuel, a technique known as gravity assist.
NASA’s initial plan was an extensive exploration of all outer planets, termed the “Grand Tour.” However, budget constraints led to a scaled-down version called the Voyager program, focusing on intensive fly-bys of Jupiter and Saturn. The two spacecraft involved were designed to last five years but have endured nearly ten times longer.
In March 1979, Voyager 1 passed by Jupiter, discovering active volcanoes on the moon Io, marking the first observation of volcanic activity beyond Earth. It reached Saturn in November 1980, providing detailed studies of the planet’s rings and its large moon Titan. The close encounter with Titan altered Voyager 1’s path upwards, out of the solar system’s plane, ending its planetary journey and propelling it toward the stars.
In 1990, NASA extended the mission under the Voyager Interstellar Mission, aiming to reach and study the boundary of the Sun’s influence and beyond. On August 25, 2012, Voyager 1 crossed the heliopause, the boundary where solar wind yields to interstellar space, becoming the first human-made object to enter the space between stars. Voyager 2 followed in 2018.
Workers near the top of the 526 ft. Vehicle Assembly Building at the Kennedy Space Center spruce up the NASA logo standing on scaffolds in Cape Canaveral, Fla., Wednesday, May 20, 2020.
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More than 15 billion miles away, on borrowed power
As of this spring, Voyager 1 is over 15 billion miles from Earth. At that distance, a radio signal traveling at light speed takes over 23 hours to reach the probe one way. Every command engineers send and each piece of data they receive crosses this immense distance.
The spacecraft is powered by a radioisotope thermoelectric generator, which converts heat from decaying plutonium into electricity. It has no solar panels or rechargeable batteries, relying solely on the gradual release of nuclear heat, which declines by about 4 watts annually. After nearly fifty years, this reduction in power has become critical.
In late February, a routine maneuver revealed a sudden drop in Voyager 1’s power levels, nearly triggering an automatic shutdown meant to protect the probe, which would have necessitated a lengthy and risky recovery process. The engineering team had to act quickly.
Switching off a piece of history to preserve the whole
On April 17, engineers sent commands to deactivate the Low-energy Charged Particles experiment (LECP), one of Voyager 1’s remaining science instruments. The LECP measured ions, electrons, and cosmic rays from our solar system and beyond, aiding scientists in mapping interstellar space uniquely. Its counterpart on Voyager 2 was turned off in March 2025.
Years ago, the Voyager science and engineering teams agreed on a sequence for shutting down instruments to conserve power while maintaining critical scientific capabilities. The LECP was next. “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, in a NASA blog post on Friday.
Voyager 1 now operates with two science instruments: one for detecting plasma waves and another for measuring magnetic fields. The latest shutdown could extend the mission by about another year.
The team is also crafting a comprehensive power conservation strategy called “the Big Bang,” which involves swapping several powered components for lower-power alternatives. If testing on Voyager 2, planned for May and June 2026, succeeds, the same procedure will be tried on Voyager 1 no sooner than July. If successful, there is a slight chance the LECP could resume functioning.
Engineers aim to keep at least one instrument operational on each spacecraft into the 2030s, allowing both to continue sending data from uncharted regions of space.
