Pluto is Much Colder Than Expected
IZ Reloaded writes "Any would be travellers to Pluto should bring extra winter gear. The new temperature on Pluto according to scientists is 43 degrees Kelvin. That's 10 degrees Kelvin colder than expected. From CNN: "Astronomers think Pluto's colder than expected temperature reading involves interactions between nitrogen ice on the planet's surface and the nitrogen gas that makes up its atmosphere...Pluto is a dynamic example of what we might call an anti-greenhouse effect...""
so it says that Charon, Pluto's moon, is warmer than the planet. Since Charon is almost as big as Pluto, I am sure this new tidbit will add more to the deabte concerning what relation the two celestial bodies have with each other and how they came to be paired.
Well, from what I know the reason that RTG generators are used is because of the extremely low light levels so far from the sun, not cold. The Mars rovers for instance use solar panels with batteries and heaters. I'd bet batteries+solar panel+heaters is a LOT cheaper than an RTG.
But you're right, on a mission to pluto they'd have to use an RTG for power, so chemical batteries wouldn't be needed. I hadn't thought of the low light levels. But, the original point is that a heat source is important because electronics don't work the same at such extremely low temperatures.
AccountKiller
That's an interesting point. From the article, Pluto receives about 1/1000th as much sunlight as the Earth. From here http://www.powerfromthesun.net/chapter1/Chapter1.h tm we see that the Earth receives 1367 watts per square meter, so we can assume that Pluto typically receives only 1.367 watts per square meter. Dumping the heat from a single P4EE into Pluto's surface could be pretty disruptive, hundreds of watts over a small surface area. The rush of nitrogen vapor would be like a bomb exploding.
-- *My* journal is more interesting than *yours*...