The missions of the Voyager 1 and Voyager 2 probes have been extended by about another year by turning off one scientific instrument on each spacecraft. This will preserve power and continue collecting unique data about interstellar space. Both probes have already left the heliosphere – no man-made object has ever flown so far from Earth.
Image source: NASA
The Voyagers are powered by a radioisotope source: thermoelectric elements generate electricity when plutonium decays. However, the source’s power is declining by about 4 watts per year, and over time it will not be enough to maintain communication with Earth. To extend the spacecraft’s life, engineers are turning off less important or outdated scientific instruments.
After flying past Jupiter, Saturn, Neptune and Pluto, most of the equipment on board the Voyagers became obsolete. Until recently, each probe had four instruments that registered charged particles, which allowed them to study magnetic fields and plasma. These detectors helped scientists record the moment the devices left the heliosphere. However, if the instruments are not turned off, the energy supply will last no more than a year.
«Voyager 1 left the heliosphere in 2012, and Voyager 2 in 2018. The first device is currently 25 billion km from Earth, the second – 21 billion km. It takes a radio signal about 23 and 19 hours, respectively, to reach the probes and return back.
In October 2024, Voyager 2 turned off an instrument that measured the concentration and direction of plasma flow. It had collected only limited data in recent years due to its orientation relative to the motion of plasma in interstellar space. A similar instrument on Voyager 1 had been turned off earlier due to deteriorating performance.
Last week, Voyager 1 switched off its cosmic ray data collection system. It consisted of three sensors that recorded the energy and flow of protons coming from the Sun and the galaxy. This data allowed us to determine the moment when the probe exited the heliosphere.
Later this month, Voyager 2 will turn off its instrument for measuring low-energy charged particles. It detects electrons, ions, and cosmic rays from both our solar system and the galaxy’s depths.
Both systems use a rotating platform with a stepper motor that pulses at 15.7 watts every 192 seconds. The motor was designed to take 500,000 steps, enough for the 1980 flyby of Saturn. By the time it shuts down on Voyager 2, it will have taken more than 8.5 million steps.
March 1977. Probe assembly stage
Previously, engineers tried to keep all the scientific instruments running for as long as possible because the data from the Voyagers is unique. However, with current power consumption, turning off another instrument on each probe will be necessary in about a year.
Meanwhile, Voyager 1 will continue to use its magnetometer and plasma wave detection system. The low-energy charged particle detector will operate until the end of 2025, after which it will also be turned off. Voyager 2 will continue to study the magnetic field and plasma waves, and its cosmic ray detection system will be turned off in 2026.
According to engineers’ calculations, energy-saving measures will allow the probes to operate at least until the early 2030s — with at least one instrument on board. However, the devices have already been in outer space for 48 years, and unforeseen failures could shorten this period.