There’s a reason that “rocket science” is the gold standard metaphor for complex, difficult tasks. Rockets are finicky creatures as likely to blow up as they are to work — something SpaceX learned the hard way when their Falcon 9 rocket exploded on the launch pad in September, a blast so concussive it was picked up on radar. And it turns out the explosion was because of a problem that had literally never happened before in the history of rocketry.
The Falcon 9 is largely powered by liquid oxygen, also known as LOX, which has to be kept at a temperature of about -340 degrees Fahrenheit, which is fairly close to the temperature it freezes solid at, -362. It’s shoved out of the rocket by liquid helium, which is much colder and may have leaked into the fuel tank. While Space X is shy about the details, an interaction between the carbon fiber tank, the liquid helium, and the LOX meant that essentially, the fuel froze solid and the ignition phase, not being able to go down, instead went everywhere. Yes, the rocket exploded because it froze solid.
The good news is that this bizarre accident is unlikely to happen again. SpaceX engineers, having figured it out, will ensure it doesn’t. Not least because frozen things shouldn’t explode. Come on, popular science is annoying enough sometimes without being that counterintuitive!