Huh. I took that to mean that it’s still unexplained, but here’s a reasonable supposition. But we’re working on it.
Why did communication with the Pioneers stop, but the Voyagers are still talking to us?
Probably their power supplies just ran too low. That’s the problem with RTGs: They don’t need sunlight, but they have a very definite expiration date (given mission parameters, etc.).
What are RTGs? And why would the Pioneers power supply run too low, but not the Voyager power supply?
RTG stands for Radioisotope thermoelectric generator. How much power they can produce is directly related to the isotope’s half-life. Voyagers’ RTGs no longer have enough power to run their cameras anymore, I believe. Eventually, they won’t have any power left to communicate at all.
So the Pioneers RTG’s ran out of energy faster than the Voyagers?
Any estimate for when the Voyagers will stop transmitting?
Half life of the Plutonium used in all RTGs is 87 years, so that isn’t the limiting factor. Degradation of the thermocouples seems to be what limits the lifetime. The Pioneers RTGs were a different design to the Voyagers, and this may have a lot to do with the relative lifetimes. Apparently the ones used for the Pioneers only had a design life of five years.
Half-life of the plutonium can be a limiting factor, since it won’t necessarily be enough for a full half-life. It depends on the margins you design into your spacecraft. If, say, your spacecraft needs 100 watts to operate at full functionality, and you build it with an (initially) 200 watt power supply, then you’d be fine for a full half-life. If you built it with only a 100 watt supply, though, it’ll drop below nominal values immediately. And of course there’s always room to stretch things by running at less than full functionality: Maybe you can save some power by shutting down less-essential instruments, for example, or slowly charge a battery for infrequent transmissions so you don’t have to power the antenna continuously.
Oh, great. Earth is going to get a ticket now for littering the galaxy with plutonium.
Bad news!
Hopefully they can fix it, but at 46 years old some of us are pessimistic.
At least it still has power. I wonder if an SEU (single event upset) finally got to it.
46? You’re still a kid. Why so pessimistic?
Voyager 1 is 46 years old; I am not. The reason I am pessimistic is that they don’t build things to last anymore–especially stuff like electronics–as well as it being subjected to radiation, etc.
I guess the best case scenario is they eventually recover a useful signal.
Maybe the worst case scenario is the gobbledegook turns out to be Vogon poetry.
Realistically, the worst-case scenario is that it only lasts for nine times as long as it was meant to, instead of quite getting to ten times. The Voyager missions are already resounding successes, and have been for decades.
There are little reaction jets on Voyager to orient and point the craft in the correct direction to perform various space probe duties.
When do the little gas tanks run out fuel?
If a bald lady shows up looking for the creator I’m running.
(Well, it is a zombie)
As noted upthread, this is not a zombie, since Voyager 1 is still going. Well OK, if it doesn’t transmit data ever again, values of zombieness are reached.