Supplies of NASA's go-to fuel for space exploration, plutonium-238, are dwindling. The U.S. stopped making it 20 years ago and now NASA's Russian suppliers are running out after production shut down.

The problem? Nobody makes nukes anymore.

    Deep space probes

beyond Jupiter can't use solar power because they're too far from the sun. So they rely on a certain type of plutonium, plutonium-238. It powers these spacecraft with the heat of its natural decay. But plutonium-238 isn't found in nature; it's a byproduct of nuclear weaponry.

So where can NASA turn to in order to get the 11lbs of plutonium it needs each year? Fortunately, the Department of Energy has come to the rescue and decided to spend the $150 million or so it would take to re-start production. Man, it feels like the Cold War all over again. [Yahoo]