3 ms·
The plutonium 238 decays according to a curve, and the thermocouples are degraded as well by heat and radiation according to a curve. So the power output drops
by retrac 3y ago
The plutonium 238 decays according to a curve, and the thermocouples are degraded as well by heat and radiation according to a curve. So the power output drops rather predictably: "The radioisotope thermoelectric generator on each spacecraft puts out 4 watts less each year." [1]
The Voyagers will soon no longer have enough power to operate any of their instruments. They'll have enough power to continue operating the transmitter (which serves as a science experiment of its own) into the 2030s. The power of the signal will drop before the electronics and control brown out (if it works as designed), and it the signal might become too weak to detect before the probe completely stops operating. Such a fate befell Pioneer 11, who may yet still be warbling away at low power no longer pointed at Earth; its carrier was last detected in 2003.
[1] https://voyager.jpl.nasa.gov/frequently-asked-questions/ https://voyager.jpl.nasa.gov/frequently-asked-questions/
- wolverine876 3y ago> [1] https://voyager.jpl.nasa.gov/frequently-asked-questions/ https://voyager.jpl.nasa.gov/frequently-asked-questions/ Also: Even if science data won't likely be collected after 2025, engineering data could continue to be returned for several more years. The two Voyager spacecraft could remain in the range of the Deep Space Network through about 2036, depending on how much power the spacecraft still have to transmit a signal back to Earth. That FAQ covers a lot of interesting ground (though it talks about 2020 in the future tense). After Voyager 1 took its last image (the "Solar System Family Portrait" in 1990), the cameras were turned off to save power and memory ... I didn't realize that was the last image. ... it is very dark where the Voyagers are now. While you could still see some brighter stars and some of the planets with the cameras, you can actually see these stars and planets better with amateur telescopes on Earth.
- xattt 3y ago> the cameras were turned off to save power and memory Since it’s powered by an RTG, how does the power get “used up”? I assume that this refers to the available power budget at a given moment versus some sort of expendable power reserve.
- Yossarrian22 3y agoProbably a physical relay to deal with parasitic power draw
- xcv123 3y agoYes the power budget is decreasing as the generator output decreases over time.
- 8bitsrule 3y agoIt's the first question at the top of that ^ FAQ page. One of their comments is : "Mission managers removed the software from both spacecraft that controls the camera." Makes me wonder if that unused RAM came in handy lately!
- wkat4242 3y agoIt's radioactive so the half-life has a serious effect. Its half-life is 87 years so it's not even used up one. I guess it wasn't really very overdimensioned. But it wasn't meant to last this long.
- exitb 3y ago> The two Voyager spacecraft could remain in the range of the Deep Space Network through about 2036 It would be quite depressing if it was us failing to receive a fainter signal, rather than Voyager failing to send it.
- gpvos 3y agoI think the reverse would be more depressing. There will inevitably come a time when the signal will be indiscernible from the background noise.
- wolverine876 2y agoIs that strictly true? Doesn't it depend on the signal processing power of the receiver?
- dmurray 3y ago> the transmitter (which serves as a science experiment of its own) into the 2030s. One of the longest-running scientific experiments, too. It's already about as old as the Queensland pitch drop experiment was when Voyager I was launched.