4 ms·

So why doesn’t Nasa use them all the time?

• AnkhMorporkian 11y ago
  Two reasons. One, in a lot of situations solar power is essentially guaranteed, and when there's no chance that there won't be sun solar panels are a hell of a lot cheaper. Second, there's a plutonium shortage in the US at the moment [1] making it really hard to secure an RTG. [1] http://www.wired.com/2013/09/plutonium-238-problem/ http://www.wired.com/2013/09/plutonium-238-problem/