NASA engineers at the Jet Propulsion Laboratory (JPL) deactivated the Low-energy Charged Particles (LECP) instrument on the Voyager 1 spacecraft on April 17, 2025, to conserve the spacecraft’s diminishing power supply and prevent an automatic shutdown of critical systems.
The decision follows a power drop during a routine maneuver in February and is part of a long-established plan for balancing power conservation with scientific operations. Engineers are also developing a more comprehensive power-saving procedure, nicknamed "the Big Bang," which could extend the mission of both Voyager 1 and its twin, Voyager 2, into the 2030s.
Background and Timeline
The Voyager 1 and Voyager 2 spacecraft were launched in 1977. Their original mission was a five-year fly-by of Jupiter and Saturn. Both spacecraft have continued to operate for decades beyond their planned timelines.
Voyager 1 crossed the heliopause and entered interstellar space in August 2012. Voyager 2 followed approximately six years later. As of spring 2025, Voyager 1 is more than 15 billion miles (approximately 25 billion kilometers) from Earth. Radio signals traveling at the speed of light take approximately 23-24 hours one-way to reach Voyager 1.
Power System and Recent Incident
Both Voyager spacecraft are powered by radioisotope thermoelectric generators (RTGs), which convert heat from decaying plutonium into electricity. The power output from these generators decreases by approximately 4 watts per year.
On February 27, 2025, during a planned roll maneuver on Voyager 1, the spacecraft's power levels fell unexpectedly. NASA stated that any additional power drop could have triggered the spacecraft's undervoltage fault protection system, which would automatically shut down components to safeguard the probe. Recovery from such an event would be a lengthy process.
Instrument Shutdown
To prevent an automatic shutdown, mission operators sent commands to deactivate the Low-energy Charged Particles (LECP) instrument on April 17. The commands took approximately 23 hours to reach the spacecraft, and the shutdown sequence itself took more than three hours to complete.
Instrument Details
The LECP instrument measured low-energy charged particles, including ions, electrons, and cosmic rays. Its data included particles from the solar system and the galaxy, providing information about the structure of the interstellar medium, such as pressure fronts and regions of varying particle density. The Voyager spacecraft are the only operational probes positioned to collect this type of data.
Shutdown Sequence
The decision to deactivate the LECP was not made recently. Years ago, Voyager science and engineering teams established a predetermined order for deactivating spacecraft systems as power declined. This plan aimed to balance power conservation with the continuation of unique scientific operations.
Each Voyager spacecraft originally carried 10 identical instrument sets. Seven of these sets have now been deactivated on each spacecraft. For Voyager 1, the LECP was the next instrument scheduled for deactivation according to the established plan. The LECP on Voyager 2 was deactivated in March 2025. The last instrument to be shut down on Voyager 1 prior to the LECP was the cosmic ray subsystem experiment in February 2025.
Current Status
Voyager 1 now has two operational science instruments: one for detecting plasma waves (plasma wave subsystem) and one for measuring magnetic fields (magnetometer). Voyager 2 operates three instruments: the cosmic ray subsystem, magnetometer, and plasma wave subsystem.
A small motor within the LECP system, consuming approximately 0.5 watts, was left powered to preserve the possibility of restarting the instrument if additional power becomes available.
Future Plans: The "Big Bang" Procedure
Engineers at JPL are developing a more comprehensive power conservation plan, informally called "the Big Bang." This plan involves a coordinated swap of several powered components for lower-power alternatives. The procedure involves turning some devices off and replacing them with lower-power alternatives to maintain spacecraft warmth and continue science data collection.
Testing Timeline
- Testing of this procedure on Voyager 2 is scheduled for May and June 2026. Voyager 2 was selected for initial tests because it has more available power supplies and is slightly closer to Earth.
- If successful, the same procedure could be attempted on Voyager 1 no sooner than July 2026.
Engineers estimate that the shutdown of the LECP instrument provides approximately one year of operational margin, giving the team time to implement the "Big Bang" plan. JPL representatives stated the team hopes the procedure will recover enough power to potentially reactivate the LECP instrument on Voyager 1. Engineers aim to keep at least one instrument operating on each Voyager spacecraft into the 2030s.
Statements
Kareem Badaruddin, Voyager mission manager at JPL, stated: "While shutting down a science instrument is not anybody's preference, it is the best option available."
Badaruddin also noted that the two remaining instruments are "still working great, sending back data from a region of space no other human-made craft has ever explored."