What is the temprerature of the Voyagers 1 & 2?

Question

In the void of the universe, some 10 or so billion miles away, what is the temperature of the Voyagers? What is the temperature of their environment? Does the on-board radioisotope thermal electric generators (RTGs) keep them warm? In what temperature range do the electronics function?

Answer 1

They're both beyond the orbit of Pluto, whose temperature is about 35 kelvins.

Using an energy balance with the Stefan-Boltzmann radiation law http://en.wikipedia.org/wiki/Stefan-Boltzmann_Law , and assuming a power dissipation of 10W and emissivity of 0.3, the equilibrium temperature of a 3ft diameter object would be 122 kelvins, which is warm enough for satellite electronics to still work.

Answer 2

The primary mission of the Voyagers was to visit the giant planets in our solar system. They could only achieve this because of the way the planets were aligned, using their gravity to slingshot the probe from planet to planet. Neither one was capable of altering its course significantly without this gravitational assistance, and the last slingshot past the final planet on each flight sent it off in a direction that wasn't all that important, as the mission was over. Further, even at only 4.4 light years away, Voyager would still take thousands of years to reach Alpha Centauri. The chances of the probe still operating when it get there, or of us still listening for it down here, are so slim as to be not worth considering. By that time we are as likely to have found a way to overtake the probe and go their ourselves.

Answer 3

I don't know answers to all your questions, but since both Voyagers are pretty much beyond the reach of any significant sunlight (one is already past the outer orbit of Pluto), the temperature around them is probably pretty close to the temperature of interstellar space (a few Kelvin degrees above absolute zero).
Internally, they probably have some kind of thermal heating to some degree to keep their electronics functioning on minimal power.
But they aren't on full-blown "broadcast everything I see as soon as I see it" mode, since their radio antennas aren't always aimed at earth. And they likely have run low or out of thruster fuel to maintain orientation with earth to broadcast to us too often.
Check out nasa.gov to find out more.