Surfing the nuclear blast wave – with science!

I saw a documentary the other day about Project Orion – which to me underscored just how much times have changed since the 1960s.

Owing to a severe attack of geekiness, I already knew quite a bit about the idea, but this added interviews with project scientists such as Freeman Dyson. What was it? On the surface, Project Orion looked like the maddest of the mad atomic projects to emerge from an atom-mad 1950s. It envisaged sending 10,000 ton ‘space cruisers’ to Mars and Saturn (the calculations were actually done) – this when the Soviets had just launched Sputnik 1 and the best US rockets had yet to orbit anything.

Project Orion. Public domain, via Wikipedia.
Project Orion. Public domain, via Wikipedia.

What’s more, it wasn’t science-fiction. It was do-able with 1950s technology. How? By surfing the blast waves of atomic bombs, that’s how.

See what I mean about ‘mad’?

Lots of nukes. Up to 1000 of them with yield of between 5 and 15 kilotons for an orbital mission alone, lobbed out the back and detonated against a ‘pusher plate’ that would intercept some of the energy and protect the crew from the radiation.

Incredibly, scale tests using conventional explosives showed that the principle was feasible.  Work began under the auspices of the General Atomic division of General Dynamics in the late 1950s. By the early 1960s the project team was under USAF control. They had to tackle such problems as finding ways of storing vast numbers of miniature nukes in magazine-type systems that could then throw them out the back at a rate of up to four a second – all the while dynamically correcting for loss of thrust by selecting a bigger bomb on the fly, if the prior one failed to properly detonate. To develop machinery for that they apparently looked for technical inspiration from the Coca Cola corporation, whose bottling plants were designed to manipulate and select product at a colossal rate.

Paradoxically, the spaceship design itself was remarkably simple. One of the biggest problems confronting spaceship designers – then and now – is that chemical and even nuclear-thermal propulsion has severe energy limits. Mass is an issue and the onus is on to keep structural weight down. That, in part, is why rockets and spacecraft are so fiendishly expensive.

Not so Project Orion. The spaceship could be built using structural steel – like a submarine, and submarine makers such as General Dynamics’ Electric Boat Division were envisaged as the potential builders of the first Orion rockets. There was no need for exotic materials or bespoke super-lightweight fittings. Early planning envisaged living space for 50 people for up to four years. Even an ordinary commercial barber’s chair was going to be fitted, just because they could.

The declassified papers are at:
The declassified papers are at:

To give that a bit of science, one measure of rocket propulsion efficiency is specific impulse. The Rocketdyne F-1 motor that took US astronauts to the Moon – the most powerful rocket motor ever made – had a specific impulse of 263. Five drove the Saturn V first stage, lifting the 3,300 ton Moon rocket skywards. The USAF’s 1963 Orion 4,400 ton space-dreadnought had a specific impulse of (wait for it) 3,976. And the design team thought the system could be stretched to specific impulses of 20,000 or more ‘for the post-1980 era’. Woah!

Of course Orion never happened. The problem, it seems, was twofold. One of them was that space-dreadnought – the weaponisation of Orion envisaged by the USAF. This took the form of a space battleship orbiting Earth, bristling with nuclear armaments and virtually immune to countermeasures. Even a nuke couldn’t stop it – all the ship had to do was turn its nuke-proof pusher plate into an incoming Soviet missile. President John F. Kennedy was apparently shown a car-sized model of it during a demonstration of new Air Force weaponry, and was horrified.

Then, as strontium-90 began appearing in milk supplies on the back of world atmospheric nuclear tests, the project team (whose concepts were peaceful – they thought they’d found a way to use nukes to support scientific exploration) began to have second thoughts about the wisdom of nuking their way into space. Miniature or not, Orion’s propulsion-bombs were still nukes; and like the atmospheric nuclear tests they would deliver both background radiation and physical fallout to the atmosphere. It turned out that between 1-10 people would eventually fall victim to fallout, per launch. As far as the Orion team were concerned that was 1-10 too many, of course. And then the 1963 atmospheric test ban treaty made atmospheric nuclear tests illegal and that was that.

It was the right decision. Orion was a stupid idea – not least because every launch would have required 1000 nuclear weapons just to reach orbit – let alone any destination. You don’t have to be a rocket scientist to figure out the implications which, needless to say, ran well beyond the fallout provoked by legitimate use of the system. If we wanted to commit planetary suicide on the back of the human condition, this would have been one quick way to do it. The mere act of developing the technology to build the propulsion-nukes would have been incredibly risky, given the way humans so often turn knowledge to evil purpose.

Yet for me the story is extraordinary – not because of the lost sci-fi possibilities involving 10,000 ton interplanetary vessels, but because of the way the project encompassed the attitudes of the 1950s – and the way those attitudes so quickly changed.

Humanity always does this. We invent something new and immediately our imaginations are seized by possibilities that inevitably outstrip the reality of whatever the new thing happens to be. Later, reality bites and our imaginary concepts come crashing down to Earth. The issue has been at the back of bubbles such as the railway boom of the 1840s, the ‘dotcom’ boom of the 1990s and so forth – and it also underpinned Project Orion.

There is a lesson there about ourselves. And history is full of them, if we know how to look.

Copyright © Matthew Wright 2016

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