Voyagers 1 and 2 are the only spacecraft yet outside the heliosphere, the Sun’s “bubble” of space. This detail from our new Five Escapers poster shows how their flights past Saturn flung Voyager 1 (orange) northward and sent Voyager 3 (red) on to Uranus.
Each Voyager carries five instruments to study interstellar space. Scientists want these instruments to last as long as possible; the data they transmit are more valuable the farther they are from the Sun.
Power for operating the instruments comes from “radioisotope thermoelectric generators,” which convert heat from decaying plutonium into electricity. As the decay continues, the amount of power declines. Eventually one of the instruments will have to be turned off so that the others can continue; later, another… The engineers who manage the mission have saved some power by turning off heaters and other non-essential systems. Now they have found another trick.
There is a small reserve of power set aside for safety. A damaging fluctuation in the spacecraft’s electric voltage would trigger a mechanism that allows access to this reserve. But there has been no such emergency in the nearly 46 years of the Voyagers’ life. So the team decided to switch off that system in Voyager 2. The power reserve becomes available to the instruments, and the deactivation of the first of them can be postponed from 2023 to 2026. If the strategy proves successful with Voyager 2, it will be extended to Voyager 1.
This is all described in a NASA article that Daniel Cummings told me about.
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