NASA engineers have halted the operation of one of the science instruments on Voyager 2 due to declining power supplies as the spacecraft explores deep space. Launched on August 20, 1977, Voyager 2 left the solar system on November 5, 2018, and is currently over 20.5 billion kilometers (12.8 billion miles) from Earth, using four scientific instruments to study the heliosphere surrounding the solar system.
NASA believes Voyager 2 has enough power to continue running one scientific instrument into the 2030s, but this requires shutting down other instruments. Mission specialists have attempted to delay this shutdown as Voyager 2 and its twin Voyager 1 are the only active probes humanity has in interstellar space, making any data they collect unique.
So far, six of the spacecraft's ten primary instruments have been deactivated, and the loss of the seventh instrument became inevitable when engineers ordered the shutdown of the plasma science instrument on September 26. This instrument was crucial in detecting a decrease in charged particles from the sun, indicating that Voyager 2 crossed the boundary between the heliosphere and interstellar space in 2018.
Officials at NASA's Jet Propulsion Laboratory, which oversees the mission, stated, “Mission engineers are always closely monitoring changes to the operations of the 47-year-old spacecraft to ensure that they do not generate any undesirable secondary effects. The team confirmed that the shutdown command was executed without incident and that the probe is operating normally.”
Recently, the instrument was used only once every three months during a 360-degree rotation of the spacecraft toward the sun. This limited use was a key factor in scientists' decision to shut down the plasma instrument to conserve power rather than disable another instrument on Voyager 2.
Both Voyager missions operate on decaying plutonium and lose about 4 watts of power each year. In the 1980s, many of their instruments were turned off after the spacecraft completed their investigations of the giant planets in the solar system. A few years ago, both spacecraft also turned off all non-essential instruments. The plasma instrument on Voyager 1 ceased operations in 1980 and was shut down in 2007 to conserve power.
Meanwhile, NASA engineers are closely monitoring Voyager 2's resources to determine when to shut down the next science instrument to ensure the interstellar explorer can continue providing science for as long as possible from this 'final frontier' beyond the solar system.