Voyager 1, the farthest spacecraft from our planet, has powered down another science instrument as it explores uncharted interstellar space — a move that could buy time for an ambitious attempt to extend the probe’s impressive lifespan.
NASA sent a command on April 17 to deactivate the spacecraft’s Low-energy Charged Particles experiment, or LECP, in the hopes of saving power as Voyager 1 journeys farther from Earth by the day, according to the agency. The same instrument, which measures the structure of the space between stars, was turned off on Voyager 1’s twin, Voyager 2, in March 2025.
The probes launched weeks apart in 1977, each outfitted with a suite of 10 science instruments intended to aid their flybys of Jupiter, Saturn, Uranus and Neptune. Voyager 1 is currently about 25.40 billion kilometers (16 billion miles) from Earth, while Voyager 2 is roughly 21.35 billion kilometers (13 billion miles) away.
They are the only active spacecraft beyond the heliosphere, the sun’s bubble of magnetic fields and particles that extends well beyond the orbit of Pluto. Keeping the probes operating far longer than their expected lifespan of five years has meant shutting down different instruments over time to preserve each spacecraft’s limited power supply.
“While shutting down a science instrument is not anybody’s preference, it is the best option available,” said Kareem Badaruddin, Voyager mission manager at NASA’s Jet Propulsion Laboratory in Pasadena, California.
“Voyager 1 still has two remaining operating science instruments — one that listens to plasma waves and one that measures magnetic fields. They are still working great, sending back data from a region of space no other human-made craft has ever explored. The team remains focused on keeping both Voyagers going for as long as possible.”
Three functioning science instruments remain on Voyager 2.
Engineers hope the latest sacrificial move can keep Voyager 1 operating long enough for the team to potentially roll out an upgrade, nicknamed “the Big Bang,” that could allow the record-breaking probe to continue exploring deeper into space — and perhaps even restart some of its science instruments.
Both Voyager probes run on radioisotope thermoelectric generators, or devices that convert the heat provided by decaying plutonium into electricity. Since the probes began flying nearly half a century ago, they have been losing an estimated 4 watts of power per year.
Managing the slow but steady power drain pushes engineers into a high-stakes balancing act. Turning off instruments and heaters in the frigid temperatures of interstellar space risks chilling the probes beyond repair. If the fuel lines freeze, the spacecraft would lose the ability to keep their antennas pointed toward Earth, and NASA teams would lose contact with them — effectively ending the missions.
Engineers believe that shutting down the majority of the Low-energy Charged Particles experiment will enable Voyager 1 to keep flying with two functional instruments for about one year. Extending the life of the mission for that long could bring Voyager 1 to its 50-year anniversary, a deadline that’s setting the stage for one of the team’s most enterprising steps yet.
The team will attempt to make a big swap on the Voyager probes, turning off some powered devices while turning on alternatives that draw less power — maintaining that balance of keeping each spacecraft warm while continuing to capture scientific data.
This “Big Bang” would occur all at once, for one spacecraft at a time. Voyager 2, which has a bit more power and is relatively closer to Earth, will initially serve as a test subject during May and June.
If the Big Bang is successful on Voyager 2, the team will attempt the same maneuver on Voyager 1 in July — and if that works, the Low-energy Charged Particles experiment may get a second chance to continue its crucial collection of data in interstellar space.
“With LECP we discovered properties and effects of cosmic rays and solar particles, and ‘sensed’ the changes in the region around us that determined when Voyager had crossed from the solar system into interstellar space,” wrote Matt Hill, principal investigator for the instrument at the Johns Hopkins Applied Physics Laboratory, in an email.
“We hold out hope that the Voyager engineers’ latest plan will be able to power up LECP on Voyager 1 again, to let us continue to learn whatever surprises await Voyager in these distant regions of space,” he added. “They have a good track record of seeming to perform miracles that stretch the remaining power supply, but eventually this streak will end.”
During a scheduled roll maneuver on February 27, the mission team noticed that Voyager 1’s power levels dropped unexpectedly. The spacecraft routinely executes such maneuvers to calibrate its magnetometer instrument, which measures magnetic fields and environments in interstellar space.
If Voyager 1’s power levels dropped any lower, such a decrease would trigger an autonomous failsafe called the undervoltage fault protection system. The system would shut down components on Voyager, and recovering anything that was powered down during the automatic process would require a lengthy and risky recovery effort by engineers on the ground.
“I think of fault protection as a safety net for a trapeze artist — it is there but really the trapeze artist should never let go of the trapeze,” Badaruddin said. “Fault protection puts the spacecraft in a safe state, but we must recover from it and ‘get back on the trapeze.’”
Fault protection also temporarily halts any transmission of science data from Voyager to Earth and adds the risk that science instruments may not properly turn back on, he said.
Mission engineers were ready to act and consulted a list they had compiled along with the science team years before about the order in which they wanted to shut down various instruments, while ensuring Voyager 1 could still carry out a viable science mission.
The Low-energy Charged Particles experiment was at the top of the list. For nearly 49 years, the instrument has measured charged particles like ions, electrons and cosmic rays coming from our solar system as well as the Milky Way galaxy more broadly. The measurements have provided unprecedented data about regions of varying density beyond the heliosphere.
The subsystems of the instrument include a telescope and magnetospheric particle analyzer, which have a 360-degree view, thanks to a rotating platform powered by a stepper motor.
That tiny motor, which only uses 0.5 watts, will remain turned on — which means the instrument itself could be revived in the future if there is enough power.
On Earth, the stepper motor was tested to about 250,000 steps, enough to operate during Voyager 1’s flybys of Jupiter and Saturn over a four-year span.
“The stepper has worked flawlessly for nearly 49 years and over 8.5 million steps,” wrote Stamatios Krimigis, principal investigator for the instrument at the Johns Hopkins Applied Physics Laboratory, in an email. “And, amazingly, it continued to step after we turned-off the LECP supplemental heater to save power, and its temperature dropped to –62 degrees Centigrade.
This is the stuff that dreams are made of!”
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