When we think about the milestones of the Voyager probes, it is practically impossible not to be amazed. Towards the end of the 1970s, a team from the California Institute of Technology built two spacecraft to explore the outer reaches of space. Despite the fact that both technological prodigies were launched by NASA in remote 1977, they continue to function today.
Voyager 1 and Voyager 2 are the only human-made devices that operate outside of the heliosphere, a region of our galaxy that is under the influence of the Sun and that shields us from cosmic radiation. The second of these ships, the protagonist of this article, is studying interstellar space more than 20,000 million kilometers from Earth.
The problem of power loss
It stands to reason that after so many years in space, Voyager 2 is facing some problems. The project engineers, however, have had sufficient expertise to make the best decisions and minimize their operational impact. In 2020, for example, we lost contact with the spacecraft for several months because the only antenna capable of doing so needed to undergo repairs.
One of the issues, if we could even call it that, that directly impacts mission life is power decline. Voyager 2, like its twin, is equipped with a radioisotope thermoelectric generator (RTG) that generates electricity from the heat produced by the decay of plutonium-238. The problem? Each year it produces 4 watts less power.
Faced with this scenario, engineers have faced the difficult challenge of deciding which parts of the ship to turn off in pursuit of electrical rationalization. As we can see on the mission status page, NASA has turned off several instruments over the years, including the Ultraviolet Spectrometer (UVS) and the Imaging Science Subsystem (ISS), that is, the one that took “Photographs”.
Currently, only five instruments are operational and, due to the need to reduce energy consumption, one of them was scheduled to stop working in 2026. But those responsible for the project were faced with a dilemma: the further Voyager 2 gets, the more valuable its data becomes, and turning off one of its instruments would reduce its valuable scientific power.
Fortunately, as they have done many times before, the talented team behind the aging spacecraft found a way around the problem, albeit with some level of risk as we’ll see below. It made available to the scientific systems a small reserve of power that was earmarked for a safety system designed to protect the instruments in the event of voltage fluctuations.
As a result of this change, Voyager 2 is expected to continue studying interstellar space with its five instruments. You may be wondering what has changed. The electrical voltage will now not be strictly regulated, but the engineers are confident that everything will work out, for after almost half a century they have determined that the ship’s power supply system is reliable and stable.
In any case, they explain, they will always have the possibility to make additional adjustments if something goes as they did not expect. If this solution is finally effective, the California Institute of Technology and NASA will implement it on Voyager 1, although we remember that this ship currently has four and not five instruments in operation, this because one of them broke down at the beginning of The mission.