Curiosity's RTG?

[VenomousRequiem]

So, the Curiosity gets it's electricity from an RTG mounted on the back, right? I don't know much about how the RTGs work, but they degrade after time if I'm not mistaken.

How long will it take for Curiosity's RTG to degrade and have it's electrical system's grind to a halt because of this?

[SargeRho]

14 years at least.

[Brethern]

That depends on how much power curiosity needs to function. assuming it needs only %50 of the power it's RTG creates it could probably work for 15 years more or so.

[VenomousRequiem]

Ah, okay.

Another question answered... ​FOR SCIENCE!

[SargeRho]

The rate at which an RTG decays isn't controllable, increasing the power draw won't make it decay faster, since an RTG's heat comes from radioactive decay, not fission.

[Camacha]

The rate at which an RTG decays isn't controllable, increasing the power draw won't make it decay faster, since an RTG's heat comes from radioactive decay, not fission.

I assume Brethern referred to the degree of overdimensioning of the RTG. If it can function with half the power output of a new RTG, it can still function to full capacity after many years, until the power output drops below 50% of the RTG when it was new.

[VenomousRequiem]

I assume Brethern referred to the degree of overdimensioning of the RTG. If it can function with half the power output of a new RTG, it can still function to full capacity after many years, until the power output drops below 50% of the RTG when it was new.

So like the half-life of the element decaying in the RTG?

[Camacha]

So like the half-life of the element decaying in the RTG?

In this scenario yes, but it really depends on the over-dimensioning. If you know the minimal power requirements (which can also vary, depending on the instruments you run) to run Curiosity, the original output of the RTG, the half life value of the isotope plus the expected wear of the thermocouples (decreasing thermocouple efficiency actually is a larger loss than the radioactive decay) you can calculate the life span.

Pete Theisinger, from MSL project manager at NASA's Jet Propulsion Laboratory says the RTG might have 10-15 years based on the Plutonium, but that other components are far more likely to spoil the party. Which is a good point: mechanicals are much more likely to fail than the RTG itself. On reason he gives exact numbers are not knows is that parts are only tested to two to three times the mission time span. Anything beyond that is a guessing game, so part wear might level off, increase dramatically or anything in between.

Edited August 13, 2015 by Camacha

[PB666]

The rate at which an RTG decays isn't controllable, increasing the power draw won't make it decay faster, since an RTG's heat comes from radioactive decay, not fission.

What he is saying is that if solar adds X and RTG adds Y and the rover needs X + 0.5Y to function, then when the power output drops by 50% the craft will cease to function.

But the reality is the curiosity has a bigger problem, its wheels are wearing out. And it probably will always have enough power to function, but to move and do new things it may have a difficult time of things.

Voyager for instance has either cut functions, or others have simply died, As long as voyager still has enough power to dial home, its considered functional, but after its experiments fail it will probably be abandoned.

[Rakaydos]

Even if it's not producing practical power, at the very least a dying RTG shuld nicely cover the energy costs of keeping the electronics warm enough to reboot, for a very long time.