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NASA has switched off one of Voyager 2’s science instruments as the spacecraft struggles with dwindling power while continuing its decades-long mission in interstellar space. The decision was made on September 26, 2024, to preserve energy for the remaining instruments as the probe travels more than 12.8 billion miles (20.5 billion kilometers) from Earth.
Voyager 2, launched on August 30, 1977, crossed into interstellar space in November 2018 after more than 41 years of exploration. It remains the only spacecraft besides Voyager 1 to pass beyond the heliosphere, the bubble of charged particles surrounding the Sun.
NASA engineers turned off the plasma science instrument (PLS), which had played a critical role in confirming Voyager 2’s exit from the heliosphere. In a statement posted on X, the Voyager account said, “In 2018, the PLS was critical in determining that I had left the heliosphere, but power management is a major challenge when you’ve been exploring for 47 years. I will, however, still be monitoring plasma in the interstellar medium with my plasma wave subsystem (PWS).”
The command to shut down the instrument was sent on September 26 and took 19 hours to reach the spacecraft, followed by another 19 hours for confirmation to return to Earth. With this change, only three of the probe’s original ten instruments remain active.
The plasma science instrument was designed to measure the density and direction of plasma in space using four cups; three facing the Sun to analyze solar wind, and one pointed in the opposite direction to detect plasma from planetary magnetic fields and interstellar space.
After Voyager 2 crossed into interstellar space, the readings from the Sun-facing cups dropped sharply, while the fourth cup provided limited data during occasional spacecraft rotations.
NASA explained that with the limited return from the instrument and rising power demands, it was no longer sustainable to keep it active. Even so, Voyager 2 continues to provide rare and vital data about conditions beyond the solar system, where sunlight is too weak to provide meaningful energy.
Mission managers say the spacecraft has enough power to operate at least one science instrument into the 2030s, continuing to extend humanity’s reach deeper into the galaxy.
