Voyager 1 has little time left in interstellar space. An ambitious "Big Bang" solution could save it.

 

Voyager 1, currently the most distant spacecraft from our planet , has turned off another scientific 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 Particle Experiment, or LECP, in hopes of conserving energy as Voyager 1 moves further and further away from Earth, according to the agency . The same instrument, which measures the structure of space between stars, was switched off on Voyager 1's twin, Voyager 2, in March 2025.

The probes were launched weeks apart in 1977, each equipped with a suite of 10 scientific instruments designed to aid their passages past 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 bubble of magnetic fields and particles from the Sun that extends far beyond the orbit of Pluto. Keeping the probes operational for much longer than their projected five-year lifespan has meant turning off different instruments over time to preserve each spacecraft's limited power supply.

"While turning off a scientific instrument is not anyone's preference, it is the best option available," explains Kareem Badaruddin, Voyager mission manager at NASA's Jet Propulsion Laboratory in Pasadena, California.

"Voyager 1 still has two functioning scientific instruments—one that listens to plasma waves and another that measures magnetic fields. They continue to function very well, sending back data from a region of space that no other human spacecraft has ever explored. The team remains focused on keeping both Voyagers operational for as long as possible."

Voyager 2 still has three scientific instruments in operation.

Engineers hope that this final sacrificial maneuver will keep Voyager 1 running long enough for the team to launch an upgrade, dubbed "Big Bang," that could allow the record-breaking probe to continue exploring space more deeply—and perhaps even reset some of its scientific instruments.

Preparing to correct the "Big Bang"

The two Voyager probes operate using radioisotope thermoelectric generators, that is, devices that convert the heat supplied by decaying plutonium into electricity. Since the probes began flying, almost half a century ago, they have been losing about 4 watts of energy per year.

Managing the slow but steady depletion of energy forces engineers into a high-risk balancing act. Shutting down instruments and heaters in the frigid temperatures of interstellar space risks cooling the probes beyond repair. If the fuel lines freeze, the spacecraft will lose the ability to keep their antennas pointed at Earth, and NASA teams will lose contact with them—effectively ending the missions.

Engineers believe that shutting down most of the low-energy charged particle experiment will allow Voyager 1 to continue flying with two functional instruments for about a year.

Extending the mission's life for so long could bring Voyager 1 to its 50th anniversary, a timeline that is setting the stage for one of the team's most ambitious moves.

The team will attempt a major swap on the Voyager probes, switching off some electrical devices and switching on others that consume less energy—maintaining a balance between keeping each spacecraft warm and continuing to collect scientific data.

This "Big Bang" would occur all at once, for one spacecraft at a time. Voyager 2, which has slightly 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 it works, the Low-energy Charged Particles experiment may have a second chance to continue its crucial data collection in interstellar space.

"With LECP we discovered the properties and effects of cosmic rays and solar particles, and 'felt' the changes in the region around us that determined when Voyager passed from the solar system to interstellar space," writes Matt Hill, principal investigator of the instrument at the Johns Hopkins Applied Physics Laboratory, in an email.

"We hope that the Voyager engineers' latest plan can reactivate the LECP on Voyager 1, so that we can continue to learn about the surprises that await Voyager in these distant regions of space," he adds. "They have a good track record of seemingly performing miracles that stretch the remaining power supply, but eventually this series will end."

An unexpected power outage

An illustration shows some of the instruments located on each Voyager spacecraft. NASA/JPL-Caltech

During a scheduled rotation maneuver on February 27, the mission team noticed that Voyager 1's energy levels had unexpectedly dropped. The spacecraft routinely performs this type of maneuver to calibrate its magnetometer instrument, which measures magnetic fields and environments in interstellar space.

If Voyager 1's power levels were to drop further, this decrease would trigger an autonomous safety system called the undervoltage fault protection system.

The system would shut down Voyager's components, and recovering anything that was shut 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's there, but the artist should never actually let go of the trapeze," says Badaruddin. "Fault protection puts the spacecraft in a safe state, but we have to recover it and 'get back on the trapeze'."

The fault protection also temporarily interrupts any transmission of scientific data from Voyager to Earth and increases the risk that the scientific instruments will not reconnect correctly, he said.

The mission engineers were ready to act and consulted a list they had compiled with the science team years earlier regarding the order in which they wanted to turn off various instruments, while ensuring that Voyager 1 could still carry out a viable scientific mission.

The "Low-energy Charged Particles" experiment was at the top of the list. For almost 49 years, the instrument measured charged particles such as ions, electrons, and cosmic rays originating from our solar system and the Milky Way galaxy in general.

The measurements provided unprecedented data on regions of varying density beyond the heliosphere. The instrument's subsystems include a telescope and a magnetospheric particle analyzer, which have a 360-degree view thanks to a rotating platform driven by a stepper motor.

This small motor, which consumes only 0.5 watts, will remain on – meaning the instrument itself can be reactivated in the future if there is sufficient power.

On Earth, the stepper motor was tested for approximately 250,000 steps, enough to function during Voyager 1's flybys of Jupiter and Saturn over a period of four years.

"The stepper motor has functioned flawlessly for almost 49 years and more than 8.5 million steps," writes Stamatios Krimigis, principal investigator of the instrument at the Johns Hopkins Applied Physics Laboratory, in an email message.

"And, surprisingly, it continued to run after we switched off the LECP's supplementary heater to save energy, and its temperature dropped to -62 degrees Celsius. This is what dreams are made of!"