Voyager 1, the farthest spacecraft from our planet, has powered down another science instrument as it explores uncharted interstellar space — a move that could call time for an ambitious effort to extend the probe’s impressive lifespan.
NASA sent orders on April 17 to deactivate the spacecraft’s low-energy charged particle experiment, or LECP, in hopes of saving power as Voyager 1 travels farther from Earth, the agency said. Voyager 1’s twin, Voyager 2, was launched in March 2025 with a single instrument measuring the composition of interstellar space.
The probes launched weeks apart in 1977, each carrying 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 about 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 extending beyond Pluto’s orbit. Keeping the probes operational much longer than their expected five-year lifespan means shutting down various instruments over time to conserve each spacecraft’s limited power supply.
“While shutting down the science instrument is not a priority, it is the best option available,” said Voyager mission manager Karim Badruddin of NASA’s Jet Propulsion Laboratory in Pasadena, California.
“Voyager 1 still has two operating science instruments — one to listen for plasma waves and one to measure magnetic fields. They’re still doing great work, sending back data from regions of space never explored by other manned spacecraft. The team is focused on keeping both Voyagers running as long as possible.”
Voyager 2 has three functional science instruments remaining.
Engineers hope the latest sacrificial move can keep Voyager 1 operating long enough for the team to potentially roll out an upgrade dubbed the “Big Bang” that would allow the record-breaking probe to continue exploring deeper into space — and perhaps even restart some of its science instruments.
The ‘big bang’ fix-up is breaking up
Both Voyager probes run on radioisotope thermoelectric generators, or devices that convert the heat from plutonium decay 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 a slow but steady power drain pushes engineers into a high-precision 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 will lose the ability to point its antennas toward Earth, and the NASA crews will lose contact with them — effectively ending the missions.
Engineers believe that turning off the majority of low-energy charged particles will enable Voyager 1 to continue flying with two functional instruments for about a year. Extending the mission’s life that long could bring Voyager 1 to its 50-year anniversary, a deadline that is setting the stage for one of the team’s most entrepreneurial steps yet.
The team will attempt a major swap in the Voyager probes, turning off some powered devices while turning on low-powered options — striking a balance between keeping each spacecraft warm while capturing scientific data.
This “big bang” would happen for one spacecraft at a time, at a time. Voyager 2, which has slightly more power and is relatively close to Earth, will initially serve as a test subject in May and June.
If the big bang on Voyager 2 succeeds, the team will try the same trick on Voyager 1 in July — and if it works, the low-energy charged particle experiment could give it a second chance to continue collecting important data in interstellar space.
“With the LECP we discovered the properties and effects of cosmic rays and solar particles, and ‘sense’ changes in our surroundings that determine when Voyager entered interstellar space from the Solar System,” wrote Matt Hill, principal investigator for the instrument at the Johns Hopkins Applied Physics Laboratory.
“We hope that the Voyager engineers’ latest plan will enable them to re-power the LECP on Voyager 1, allowing us to continue to learn any surprises that await Voyager in these distant regions of space,” he added. “They have a good track record of performing miracles with the rest of the power supply spread, but eventually this streak will end.”
Unexpected decline in power
An illustration shows some of the instruments on each Voyager spacecraft. – NASA/JPL-Caltech
During a scheduled roll maneuver on February 27, the mission team noticed that Voyager 1’s power level had dropped unexpectedly. The spacecraft regularly executes such maneuvers to calibrate its magnetometer instrument, which measures magnetic fields and environments in interstellar space..
If Voyager 1’s power level drops any further, such a decrease will trigger an autonomous failsafe known as the undervoltage fault protection system. The system will shut down components on Voyager, and recovering anything powered down during the automated process will require a lengthy and risky recovery effort by engineers on the ground.
“I think of fault protection as a safety net for the trapeze artist — it’s there but the trapeze artist should never actually let go of the trapeze,” Badruddin said. “Fault protection keeps the spacecraft in a safe state, but we have to recover from it and ‘return to trapeze’.”
Fault protection temporarily stops the transmission of science data from Voyager to Earth and adds the risk that the science instruments may not return properly, he said.
Mission engineers were ready to act and consulted a list they had compiled with the science team years earlier about the order in which they wanted to shut down various instruments while ensuring Voyager 1 could still complete a viable science mission.
Low energy charged particle experiments were at the top of the list. For nearly 49 years, the instrument has been measuring charged particles such as ions, electrons and cosmic rays from our Solar System and the Milky Way Galaxy. The measurements provided unprecedented data about regions of varying density beyond the heliosphere.
The instrument’s subsystems include a telescope and a magnetospheric particle analyzer, which has a 360-degree view, thanks to a rotating platform driven by a stepper motor.
That tiny motor, which only uses 0.5 watts, will stay on – meaning the device can be revived in the future if there’s enough power.
On Earth, the stepper motor was tested for about 250,000 steps, enough to drive Jupiter 1’s flybys of Jupiter and Saturn over a four-year period.
“The stepper has worked flawlessly for nearly 49 years and over 8.5 million steps,” Stamatios Krimigis, principal investigator for the device at the Johns Hopkins Applied Physics Laboratory, wrote in an email. “And, amazingly, it stepped up after we turned off the LECP supplemental heater to save power, and its temperature dropped to -62 degrees Celsius.
This is the stuff dreams are made of! “
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