Ripley's Believe it or Not - We Own Weird. Accept No Substitutes

From global thermonuclear war to interplanetary exploration.

NASA is faced with a tricky problem when it comes to powering the craft that explore the outer reaches of the solar system.

First and foremost, it’s expensive as hell to launch anything into space.  We’re talking $5,000-10,000 per pound.   That means regular fuel, like gasoline, kerosine, etc. is not an option because they would be needed in ridiculously large amounts to power a craft on the years-long voyages.

Second, solar doesn’t work very well because the Sun gets very weak, very fast as you fly away from it ( Newton!).

With most of our usual answers for energy off the table, one source fits the bill particularly well:  radioactive decay.  You see, when radioactive materials fall apart, they give off heat.  Not only do they give off heat, but some can do it consistently, at high temperatures, for decades.  Plutonium-238 happens to be able to do exactly that.  A brick of it stays hot enough to give off a pleasingly dangerous red glow (like the picture above) and it has a half-life of 88 years, which means after that period of time, half the fuel will have been used up (and in 176 years, three-fourths).

The problem with Pu-238 is that it’s an extremely rare material.  There’s only one way to get it:  in nuclear chain reactions.  Back in the day, we used to be swimming in the stuff.  That’s because the US and Russia made a lot of it during the Cold War as a byproduct of nuclear weapons production and nuclear fuel reprocessing.  As it turns out, we haven’t made any since the 80’s, mainly because the US military has gotten out of the business of coming up with new and better ways to turn major metropolitan areas into glass bowls.

And that brings us to today, where NASA’s dropping bricks because they’re running out of Pu-238 bricks.  To make things worse, it may take a decade to get enough even if they get permission to start making more.