The Voyager Probes Are Running Low on Plutonium 48 Years Later. NASA Has Just Taken Extreme Measures

The iconic Voyager 1 and Voyager 2 space probes, launched nearly 50 years ago, are running out of power. To avoid losing communication with them, NASA has decided to shut down two additional instruments to extend their operational life.

One less instrument on each Voyager probe. NASA announced that the mission team turned off the cosmic ray subsystem on the Voyager 1 probe on Feb. 25. This instrument was designed to study high-energy particles in interstellar space.

The cosmic ray subsystem has conducted scientific observations throughout its mission. In 2020, it detected for the first time how electrons from the Sun are accelerated by shock waves as they travel out of the solar system. Voyager 1 is currently the farthest human-made object from Earth and has traveled the longest distance into interstellar space.

On March 24, NASA plans to shut down the instrument that measures low-energy charged particles aboard Voyager 2. These actions are meant to reduce the power consumption of both probes, which operate on a radioisotope generator fueled by decaying plutonium. Each probe loses about 4 watts of power every year.

Very few instruments are active. NASA has been gradually shutting down functions on the Voyager spacecraft to extend their operational lifespan. Out of the original 10 science instruments, only three remain operational on each of the twin probes:

1. Magnetometer: This instrument measures the strength and direction of the magnetic field at the outer reaches of the solar system. It helps researchers understand how the Sun’s magnetic field interacts with the magnetic field of interstellar space.
2. Plasma wave subsystem: This device detects electromagnetic and plasma waves, providing valuable information about the density and temperature of plasma in interstellar space.
3. On Voyager 1, the low-energy charged particle instrument is expected to be deactivated by the end of 2025. On Voyager 2, the cosmic ray subsystem will continue to operate until 2026.

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A growing history of repairs. In May 2024, after six months without receiving readable science data due to Voyager 1’s internal memory degradation, NASA successfully restored data transmission through a complex software upgrade. A similar situation occurred in 2010 with Voyager 2, but that was resolved through a simple reboot.

However, the issues aren’t limited to memory. In September 2024, engineers were required to activate Voyager 1’s secondary thrusters, which had been dormant for decades. This corrected the probe’s orientation due to a blockage in its main engines–a problem attributed to their prolonged use. This procedure involved carefully warming up the inactive engines. In the end, it was successful, allowing the mission to continue.

NASA expects the probes to keep functioning until 2030. Voyager project manager Suzanne Dodd said on Wednesday that turning off certain instruments is a crucial step to avoid a premature end to the mission. With these adjustments, both spacecraft will be able to send scientific data at least until the 2030s, although their capabilities will gradually decrease over time.

It’s important to note that the Voyager missions have far exceeded their original goals, which were to explore Jupiter and Saturn. The probes continue to perform beyond expectations thanks to engineering excellence and ongoing adjustments. They still provide unique insights into interstellar space and the heliopause, the region where the solar wind loses its influence.

Image | NASA

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