On April 17, engineers at NASA’s Jet Propulsion Laboratory (JPL) in Southern California sent a command to power down Voyager 1’s instrument, known as the Low-Energy Charged Particle Experiment (LECP). Spacecraft powered by nuclear energy sources are gradually losing power, and shutting down this equipment is the most effective way to extend the life of humanity’s first mission to interstellar space.
LECP has operated almost continuously since Voyager 1 was launched in 1977, some 49 years ago. It studies low-energy charged particles such as ions, electrons, and cosmic rays that come from both our solar system and the wider galaxy. For decades, it has provided valuable insights into the interstellar medium, including detecting pressure waves and changes in particle density beyond the heliosphere. Voyager 1 and Voyager 2 are the only spacecraft far enough from Earth to collect this type of data.
Power supply shrinks after several decades in space
Voyager 1, like its twin Voyager 2, is powered by a radioisotope thermoelectric generator that converts heat from decaying plutonium into electricity. Each spacecraft loses about 4 watts of power each year. After nearly 50 years of operation, available electricity has been extremely limited. Engineers must carefully reduce energy usage by turning off heaters and instruments, while also preventing the spacecraft from getting so cold that the fuel lines freeze.
During a scheduled roll maneuver on February 27, Voyager 1 experienced an unexpected loss of power. Engineers realized that any further voltage drop could trip the spacecraft’s low-voltage fault protection system. The system automatically shuts down components to protect the probe, requiring a complex recovery process with additional risks.
The team decided to act before that happened.
“Turning down scientific instruments is not everyone’s preference, but it is the best option available,” said Kareem Badaruddin, Voyager mission manager at JPL. “There are still two working science instruments left on Voyager 1, one that listens to plasma waves and one that measures magnetic fields. They are still working well and sending back data from regions of space that no other artificial ship has ever explored. The team remains focused on keeping both Voyager 1 operational for as long as possible.”
Long-term planning strategies for equipment shutdowns
The decision to turn off LECP was not made suddenly. Several years ago, scientists and engineers developed a step-by-step plan to shut down systems in a specific order while preserving as much scientific capacity as possible. Each Voyager was originally equipped with 10 sets of instruments, but seven have already been powered down. Next on Voyager 1’s list was LECP. The same equipment was deactivated on Voyager 2 in March 2025.
Voyager 1 is currently more than 15 billion miles (25 billion kilometers) from Earth, so communications take time. It takes about 23 hours for the command to reach the spacecraft, and about 3 hours and 15 minutes after the command is received for the shutdown process to complete.
Parts of LECP will continue to operate. The motor that rotates the sensor and scans it in all directions uses very little power (0.5 watts) so it stays on. Leaving it on increases the chance that the equipment will restart if sufficient power becomes available in the future.
Future plans to expand the Voyager mission
Engineers expect Voyager 1 to be able to operate for about another year with LECP turned off. During this time, the team is preparing a more advanced power-saving strategy known as the “Big Bang.” This approach involves replacing multiple power-hungry components with more efficient alternatives at once to maintain sufficient warmth and functionality for continued scientific activity.
The Big Bang will first be tested on Voyager 2, which has slightly more available power and is closer to Earth, making it a lower-risk candidate. Tests are scheduled for May and June 2026, and if successful, the same approach will be applied to Voyager 1 by July.
If this plan works as expected, Voyager 1’s LECP device may even be activated again in the future.
