xkcd.WTF!?

Explanation ➲

White Hat and Cueball are having a conversation. In the first panel, Cueball is telling White Hat about his gardening experiences. White Hat tunes out for the middle two panels, and when he starts paying attention again, Cueball is discussing Project Orion.

Project Orion was an ambitious idea, funded briefly by the US government in the 1960s, to launch enormous spaceships into orbit by detonating a series of nuclear bombs below them. The force from the explosions would be absorbed by a pusher plate on the bottom of the rocket, which is the detail Cueball is sharing when White Hat tunes back in. In Ad Astra, Roy McBride uses a similar mechanism to get from Neptune back to Earth. It was considered feasible for construction, but abandoned because of the 1963 Partial Test Ban Treaty as well as out of concerns for both cost and the idea of spaceships literally armed with atomic bombs. People probably daydream about this project because it seems like it could provide for rapid and massive entry into space, but it was halted due to the intense danger. We may have sufficient technology to somehow make this safe with extensive additional engineering, but the risk is still so large it has not been pursued.

The fact that physicists' conversations tend to converge towards Project Orion is similar to how Randall's conversations tend to converge towards carcinization in 2418: Metacarcinization. Cueball turned into a crab (i.e., he carcinized) when Megan first told him about carcinization in 2314: Carcinization; hopefully physicists don't do something analogous when discussing Project Orion.

The title text transitions to another cool nuclear rocket technology, dusty plasma fission fragment rockets, which also uses nuclear energy, and would fit well in the 2326: Five Word Jargon collection.

Project Orion has been mentioned before, in 786: Exoplanets, where Beret Guy sums it up as "nuke-riding city ships", and in the what if? article Everybody Out.