Inside the plan to propel spacecraft to other planets by riding the shockwaves of nuclear bombs
We all know how rockets work. Set off a big explosion underneath one, and try to keep it under control. The more powerful the explosion, the more thrust you get.
So wouldn’t it be a fantastic idea to set off a nuclear bomb about sixty metres below a spacecraft and ride the blast wave to other planets? That was the thinking behind a research effort to power US spacecraft with atomic bombs, known as Project Orion.
The plan was the brainchild of mathematician Stanisław Ulam, at the Los Alamos National Labratory in 1946. He worked with noted physicist and eventual Nobel Prize-winner Frederick Reines on developing the preliminary calculations on how it could work.
The attraction was that a nuclear drive could deliver two things at once — thrust and efficiency. Many spacecraft propulsion systems can manage one or the other. Nuclear engines are the only technology that could meet the power requirements to achieve both at the same time.
For example, a traditional chemical rocket — like the Saturn V that took Neil Armstrong and his crew to the Moon — is extremely inefficient but is capable of tremendous thrust. An ion engine, on the other hand, like those that nudge satellites into the right orbit, can’t manage much thrust but is capable of efficiencies as high as eighty percent.
Ulam and Reines’ designs were formalised in a memo in 1947, and Ulam worked with Cornelius Everett to put together a report in 1955 titled ‘On a Method of Propulsion of Projectiles by Means of External Nuclear Explosions’.
Originally the plan had been to detonate a series of small nuclear devices, about one per second, inside a forty-metre-wide ‘combustion chamber’, with water injected to serve as a propellant.
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