Scott Manley
1 HN recommender · recommended in 3 months, 2020–2026
11:17 · 737K views · Jul 10, 2020
Scott Manley explains the Cold War experiments in which steel and aluminium spheres, known as Lew Allen's Balls, were placed near nuclear detonations. The spheres survived the fireball, and he walks through what the declassified results show.
Cited as a fun, well-explained account of objects surviving nuclear blasts, relevant to Orion-style and spacecraft survivability discussions.
3 comments from Hacker News
You might also be interested in the story of Lew Allen's Balls (which is much less prurient than the name might suggest). These were pumpkin-sized steel spheres, coated in a thin layer of graphite, that were suspended as close as 10 meters from one of the Teapot nuclear explosions (22 kT) in Nevada. The explosion vaporized about 1 mm of graphite but otherwise didn't damage the spheres much at all. this video (starting around 5:50).
Medusa Drive is interesting, and so are lots of other space propulsion idea, like the nuclear light bulb [1], the direct fusion drive [2], the fission fragment rocket [3] or the pulse nuclear thermal rocket [4]. The difference is that Project Orion was actually funded, and some of the smartest nuclear scientists worked on it for a few years. Of course, they never built the actual rocket, but they carried out a tremendous amount of theoretical and experimental work. All other designs were only done on paper. For Project Orion, they put actual spheres coated in graphite next to nuclear bombs to see if they withstand the explosion, while being inside the fireball. They did, and Scott Manley covered this in one of his youtube videos [5] (see 9:30 where he mentions the Orion project). They got a little island from the Navy where they could carry explosive tests. They built a conventionally powered version of the rocket. They found out by accident that adding a bit of oil on the pusher plate reduces the ablation significantly. They did a lot of testing to see if the pusher plate can withstand the various stresses. When someone comes up with a new idea for interstellar travel, they spend a few days thinking of a few aspect of the design, and then they publish a paper or write a novel. For Project Orion, they hired Ted Taylor, one of the greatest minds in nuclear weapons design, and they also hired Freeman Dyson, one of the greatest minds in the world in general. [1] [LINK] [2] [LINK
To add to this, given what we're learn about nuclear weapons in school/media, you'd think a small fission device would convert the entire mass of the satellite into a ball of mixed plasma and vapour. A lot of the non-metallic mass of the satellite would probably vaporize, but any surviving bits would have a bunch of added kinetic energy. Especially for things that reflect both infrared and soft x-rays, with pretty high melting points and pretty high thermal masses, nuclear explosions do less damage than you'd think. There was a nuclear test where they put a steel sphere about the size of a bowling ball pretty close to a device similar to Gadget / Fat Man. Spoiler alert: it survived barely scratched.[0] You could probably design a satellite with thin enough pieces of metal and add carbon black / carbon fiber to any polymers too transparent to IR/soft x-rays. You could probably also use a thermonuclear device, but the particle steams caught in the earth's magnetic field would damage satellites, and there's also the EMP to worry about. [0] this video