
Engineers work on NASA’s Voyager 2 at JPL in March 1977, ahead of the spacecraft’s launch that August. The probe carries 10 science instruments, some of which have been turned off over the years to save power. [Credit: NASA]
On Tuesday, Oct. 1 engineers at Pasadena’s Jet Propulsion Laboratory announced they had made a difficult but necessary decision to turn off a key science instrument aboard NASA’s Voyager 2 spacecraft. This move aims to conserve power and extend the mission’s lifespan as the probe continues its unprecedented journey through interstellar space.
“Mission engineers have taken steps to avoid turning off a science instrument for as long as possible because the science data collected by the twin Voyager probes is unique,” states the NASA document. It further notes, “No other human-made spacecraft has operated in interstellar space, the region outside the heliosphere.”
On September 26, Jet Propulsion Laboratory engineers issued a command to switch off the plasma science instrument, one of Voyager 2’s ten original science tools. This decision comes as the spacecraft, now over 12.8 billion miles from Earth, grapples with a gradually diminishing power supply. Both Voyager probes are powered by decaying plutonium and lose about 4 watts of power each year.
The plasma science instrument, consisting of four “cups,” has played a crucial role in Voyager 2’s mission. Three cups face the Sun, while the fourth is positioned at a right angle. In 2018, it helped determine that the spacecraft had left the heliosphere — the protective bubble of particles and magnetic fields created by the Sun. The boundary is marked by changes in atoms, particles, and magnetic fields detectable by the Voyagers’ instruments.
Jet Propulsion Laboratory’s engineering team has been working diligently to postpone instrument shutdowns.
After completing giant planet exploration in the 1980s, they turned off several science instruments. More recently, they’ve switched off all non-essential onboard systems and adjusted how Voyager 2’s voltage is monitored. These efforts have allowed the spacecraft to continue its exploration with at least one operational science instrument, potentially extending its mission into the 2030s.
The command to power down the plasma science instrument took 19 hours to reach Voyager 2, with an additional 19-hour delay for the return signal to reach Earth. Jet Propulsion Laboratory engineers carefully monitored the process to ensure the 47-year-old spacecraft executed the command without any unwanted side effects.
While the plasma science instrument on Voyager 2 has been turned off, four other instruments aboard the spacecraft continue to collect valuable data about the interstellar medium. Another instrument, the plasma wave subsystem, can estimate plasma density when solar eruptions drive shocks through the interstellar medium.
It’s worth noting that the plasma science instrument on Voyager 1 stopped working in 1980 and was turned off in 2007 to save power.
As Voyager 2 continues its journey, the team at Jet Propulsion Laboratory remains committed to maximizing the mission’s scientific output. Their ongoing efforts ensure that this remarkable spacecraft, launched from Earth nearly half a century ago, continues to push the boundaries of human exploration and scientific discovery.