NASA engineers at the Jet Propulsion Laboratory successfully executed a power-saving maneuver known as the Big Bang
on the Voyager 2 probe, shifting devices and lower-power alternatives to keep its three remaining science instruments running for at least another year while planning a similar sequence for Voyager 1.
Operating at an astonishing distance of roughly 13.3 billion miles from Earth, the Voyager 2 spacecraft continues its journey through interstellar space. Its survival now depends on micro-management of a steadily fading power source. Both Voyager probes rely on radioisotope thermoelectric generators, which convert the heat generated by the natural radioactive decay of plutonium into electricity.
That plutonium isotope decays toward its 88-year half-life, causing each spacecraft to lose about 4 watts of power every year. After nearly a half-century in flight, those energy reserves have dwindled so severely that mission operators face constant operational trade-offs, deciding instrument by instrument what stays active and what powers down.
The Mechanics of the Big Bang Maneuver
To prevent the premature shutdown of another instrument on Voyager 2, engineers at NASA’s Jet Propulsion Laboratory devised a delicate sequence nicknamed the Big Bang
. The strategy involved turning off certain powered devices and simultaneously substituting them with lower-power alternatives while ensuring the spacecraft maintained enough internal warmth to survive the frigid environment of interstellar space.
Engineers carefully tested the procedure on Voyager 2 before implementing it in May and June. The savings should provide power to keep its three instruments operating for at least an extra year, averting a shutdown that was otherwise scheduled for later in the year.
A Dwindling Instrument Manifest Across the Twin Probes
The twin Voyagers originally launched in the late summer of 1977 with 10 science instruments apiece. Many of those devices served their purpose during the historic Grand Tour
planetary alignments of the outer gas giants—Jupiter, Saturn, Uranus, and Neptune—before being powered down. However, recent losses stem strictly from energy starvation.
Since 2024, the shrinking power supply has forced mission operators to turn off two science instruments on each spacecraft. Voyager 2 now operates with only three remaining active sensors: the Cosmic Ray Subsystem, Magnetometer, and Plasma Wave Subsystem. These instruments measure high-energy particles, local magnetic fields, and ripples in charged gas.
Voyager 1 is in even tighter straits. Situated further out at roughly 15.9 billion miles from Earth, it was forced to shut down its low-energy charged-particle instrument in April, leaving it with only two functioning science instruments.
The High-Stakes Plumber’s Dilemma on Voyager 1
Buoyed by the success of the Voyager 2 test, mission controllers are preparing to execute the same Big Bang power swap on Voyager 1 in the coming months. But operating the farther twin carries steeper risks.
Every device or heater turned off saves electrical current, but it also allows parts of the spacecraft to cool down.
Milestones Approaching Across the Interstellar Void
Communication with the probes grows increasingly challenging as distance stretches radio signal travel times. A signal sent from Earth takes nearly 24 hours to reach Voyager 1, meaning a single troubleshooting exchange consumes two full days. Despite these barriers, the spacecraft continue pushing boundaries into regions no other human-made artifact has reached.
Voyager 1 crossed into interstellar space in August 2012, followed by Voyager 2 in 2018. In November, Voyager 1 will reach a historic milestone by passing a distance of one light-day from Earth. Both spacecraft are also hurtling toward their 50th anniversaries in 2027, with mission planners hoping the probes might extend their historic data collection into the next decade.
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