NASA turned off the plasma device to save the spacecraft 20.5 billion km away

Voyager 2 launched into space on August 20, 1977 and left the solar system on November 5, 2018. Currently, the ship is 20.5 billion km from Earth and uses 4 scientific instruments to study the space outside the heliosphere, the bubble of charged particles and the magnetic field surrounding the solar system. NASA believes Voyager 2 has enough power to keep a scientific instrument running until the 2030s, but that requires choosing what other devices to turn off.

The mission team sought to delay the device’s shutdown in the past because Voyager 1 and Voyager 2 are the only two probes operating in interstellar space, making any data they collect precious. To date, 6 of the spacecraft’s 10 original instruments have stopped working. Now, shutting down a seventh device is inevitable, and this time it’s the turn of the ship’s plasma science equipment. On September 26, engineers sent an order to turn off the device.

The plasma science instrument includes four cups that collect information about the amount of plasma, the flow of charged particles, moving through Voyager 2 and its direction. The three cups are angled toward the Sun, tracking charged particles in the solar wind while in the heliosphere. The fourth cup faces the other direction, observing plasma in the planet’s magnetic field and interstellar space. The device played a key role in detecting a decrease in the amount of charged particles from the Sun, proving that Voyager 2 flew across the boundary between the heliosphere and interstellar space in 2018.

“Engineers working on the mission carefully monitor changes to the 47-year-old spacecraft’s operations to ensure they do not create any unintended side effects,” said a representative of the Laboratory. NASA’s Jet Propulsion experiment shares. “The team confirmed that the command to shut down the device was processed without incident and the probe operated normally.”

The usefulness of the plasma science instrument is limited because the three sun-facing cups stop collecting plasma after leaving the heliosphere and going beyond the influence of the solar wind. Additionally, because of Voyager 2’s orientation, the data collected over the past few years is also more limited. A working cup only provides useful data once every three months, when the spacecraft rotates 360 degrees around its axis. This led to the decision to turn off the plasma device to preserve power instead of turning off other devices.

Both Voyager 1 and Voyager 2 operated on decaying plutonium and lost about 4 watts of power per year. In the 1980s, some of their instruments were turned off after two spacecraft completed exploration of the system’s giant planets. That helps increase power for the pair of probes, extending their lifespan. A few years ago, the two ships also turned off all unnecessary equipment. Voyager 1’s plasma equipment was decommissioned in 1980 and turned off in 2007.

NASA engineers are closely monitoring Voyager 2’s power source so they can decide which science instrument to turn off next to ensure the interstellar probe can provide science data for as long as possible.