NASA has turned off one of Voyager 1’s remaining science instruments to conserve power as the spacecraft’s nuclear battery dwindles after nearly 50 years in space.
The decision, announced this week by engineers at NASA’s Jet Propulsion Laboratory, shuts down the probe’s plasma wave subsystem, which measured the density of ionized gas in interstellar space. Voyager 1, now over 15 billion miles from Earth, continues to return data from its remaining instruments, including the magnetometer and cosmic ray detector, but its power supply declines by about 4 watts each year.
Why engineers are shutting down instruments one by one
The spacecraft’s three radioisotope thermoelectric generators, fueled by decaying plutonium-238, now produce less than 250 watts — barely enough to preserve critical systems and a handful of science tools running. Mission managers have prioritized keeping the spacecraft’s ability to communicate with Earth, which requires power for its transmitter and antenna pointing system. Last time a similar power crisis arose, in 2019, NASA shut down Voyager 2’s heater for its ultraviolet spectrometer to save energy.
What Voyager 1 has already taught us about interstellar space
Since crossing the heliopause in 2012, Voyager 1 has provided the first direct measurements of the interstellar medium, revealing that plasma density outside the Sun’s influence is higher than expected and that cosmic rays are modulated by solar activity in ways not fully predicted by models. Its data has shown that the Sun’s magnetic field extends far beyond the planets, shaping a vast bubble that deflects galactic radiation. These findings have reshaped scientific understanding of the boundary between solar and interstellar space.
How long the mission might still last
With current power levels and consumption rates, engineers estimate Voyager 1 could continue operating at least one science instrument until around 2025, after which even the magnetometer may necessitate to be shut down to preserve contact. The spacecraft will then continue its silent journey, carrying the Golden Record toward a close approach with the star Gliese 445 in roughly 40,000 years. No further instrument shutdowns are planned before mid-2025, but the timeline remains dependent on actual power decay.
Why did NASA choose to turn off the plasma wave instrument specifically?
NASA selected the plasma wave subsystem because it consumes about 1.2 watts of power and its data, while valuable, is considered less critical for maintaining the spacecraft’s core mission of studying magnetic fields and cosmic rays in interstellar space.
Can Voyager 1’s power be replenished or repaired?
No, the spacecraft’s power source cannot be replenished or repaired. its decline is due to the natural radioactive decay of plutonium-238 in its generators, an irreversible process that has been predictable since launch.
