Made to last only five years, the two Voyager spacecraft are still passing through the void of space, representing humanity beyond the influence of the Sun. Both Voyager 1 and Voyager 2 were launched in 1977, just 15 days apart, with the goal of exploring the gas giants of our solar system: Jupiter and Saturn. To NASA’s surprise, space probes revealed new secrets even from Uranus and Neptune and became the first man-made objects to reach interstellar space.
Interstellar space is the cold region beyond the heliosphere, the hot plasma bubble on the edge of our solar system. While Voyager 1 made its historic entry into interstellar space in August 2012, its twin Voyager 2 crossed the heliosphere in November 2018.
After being exposed to such harsh conditions for more than four decades, the effects are being felt now, which is why NASA is considering closing the spacecraft. Recently, NASA physicist Ralph McNutt told Scientific American that scientists will continue to shut down both probes.
(Illustration of the position of Voyager 1 and Voyager 2; Image: NASA)
What makes Voyagers work?
Both Voyagers are equipped with an energy source called radioisotope thermoelectric generators (RTGs). This propulsion system uses plutonium to convert the heat produced by its natural radioactive decay into electricity to power spacecraft instruments, computers, radio, and other systems.
Each of the space probes is equipped with instruments such as television cameras, infrared and ultraviolet sensors, magnetometers, plasma detectors, and cosmic and charged particle sensors. However, after 44 years, Voyager 1 has only four functional instruments, while Voyager 2 has only five.
NASA will change instruments one by one
Decades have passed since NASA turned off the probe’s camera to save energy for other necessary operations. Going forward, the engineers will turn off the rest of the instruments one by one until the Voyagers lose communication and head into the nothingness of space.
Currently, 23.3 billion kilometers from Earth, it takes 20 hours of light and 33 minutes to make contact with Voyager 1, while it takes just under 18 hours of light to contact Voyager 2, which is about 19.5 billion miles away.
A Scientific American report suggested that scientists have estimated that the plutonium that powers the probes could be depleted as early as 2025 or perhaps the 2030s at the latest. Most recently, NASA revealed that Voyager 1’s articulation and attitude control (AACS) system, which helps the spacecraft maintain its orientation, suffered a mysterious error.