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Friday, November 29, 2013

Orion Revisited

    These are some excerpts from a review of George Dyson's book Project Orion about the Orion nuclear space ship project that could have done "Mars by 1965, Saturn by 1970".

The magnificent Orion ship of the 1960s would have cruised the solar system with a crew of hundreds of scientists living and working in large and luxurious rooms. On the first tour there would be a two-year stop at Mars before reaching Saturn in 1970. It was all so close.

Orion was space travel as imagined in the expansive 1950s. A big ship, with a crew of hundreds, exploring the entire solar system. Weight and size were not particularly pressing issues, miniaturization was not needed. In all the crew compartment designs there was always room for a dedicated barber’s chair – it was the designers way of indicating luxury. No one was going to be bolted into a chair and have to urinate in their spacesuit. Orion had all the comforts. Instead the issues were heavy engineering and nuclear science.

In George Dyson’s excellent 2002 book “Project Orion” he quotes Brian Dunne, the team’s lead experimentalist: “It was a crazy era. All our values were tweaked because of the cold war. It was a closed society and all kinds of strange ideas were able to grow.” (The author, George Dyson, is the son of the team’s leader, Freeman Dyson).

The idea of the Orion ship was fundamentally simple: Explode an atomic bomb behind a spaceship and the force of the explosion will push the ship forward. The idea was first proposed by Los Alamos mathematician Stanislaw Ulam at the end of World War II. Small scale tests were carried out using regular explosives to prove the concept.

The Orion project was started by a young colleague of Ulam, Ted Taylor, who was also the designer of both the smallest and largest fission bombs in the US atomic arsenal. It was calculated that it would take about 600 detonations, totalling 100 megatonnes, to boost a generous 20-story spaceship into a 300-mile Earth orbit. Said Taylor: “I used to have a lot of dreams about watching the flight, the vertical flight. The first flight of that thing doing its full mission would be the most spectacular thing that humans had ever seen.” get the ship into orbit would still require detonating 100 megatonnes in Earth’s atmosphere. That was a drawback of course, although supporters pointed out that it was no more than was already been detonated every year in routine above-ground nuclear testing,

......The scientists imagined a new Darwin-like “Beagle voyage” through the solar system with a two-year stop on Mars and visits to the moons of Saturn in 1970. General Thomas Power, head of Strategic Air Command saw a slightly different mission, the ability to deliver massive bombs on any target from orbit: “Whoever controls Orion will control the world.”

The team then began talking with Von Braun about putting a very small Orion atop a Saturn V rocket. The new plan would mean a 125-tonne Orion spaceship would be used only when lifted to orbit by the Saturn V. A crew of eight astronauts could reach the Moon in 1964. Never daunted by issues of scale, the team then calculated that a much larger conventional booster, such as a 4000-tonne “Super Nova”, might still get their beloved original 4000-tonne Orion into orbit as originally planned.

It was all getting too big and too challenging for the newly created NASA. Officials were daunted by its scale and worried how the system could ever be tested. NASA declined to fund the project. Only the Air Force remained in support. Their representative to NASA, Don Prickett, told the review committee: “There are always two philosophies encountered during the research phase of new concepts. One which says that if the concept has potential for a significant step forward it is worth a considerable effort to solve the problems even if this effort involves high risks. There is the other philosophy which approves only of research in which there are no real fundamental problems to be solved but rather improvement of established technology. What we need is more people working on novel ideas to solve some of the problems rather than viewing the problems as unsolvable.”

The outstanding engineering problems included the issue of how to get a bomb behind the pusher plate at exactly the right place, then a moment later another, and another, and another. While it might seem simple to send them straight out the back of the ship, that means creating a hole in the massive pusher plate which in turn leads to obvious safety concerns if the hatch was open when a bomb detonated on the plate. The there was the question of the pusher plate itself and whether the proposed ablative coatings would survive repeated atomic detonations.

Despite all this it was generally recognized that only the Orion program had the needed specifications for crewed missions in the solar system. The project was finally terminated in 1965 because, according Orion’s James Nance, NASA had “…no requirement for manned planetary missions.”

Freeman Dyson wrote the final report wrapping up the Orion Project in 1965. In it he wrote: “The men who began the project in 1958 aimed to create a propulsion system commensurate with the real size of the task of exploring the solar system, at a cost which would be politically acceptable, and they believe they have demonstrated the way to do it.” he went on to note that: “there was no more brave talk of Mars by 1965 and of sampling the rings of Saturn by 1970. What would have happened to us if the government had given full support to us in 1959, as it did to a similar bunch of amateurs in Los Alamos in 1943?”

Finally, Dyson told Ulam (Orion’s founder) that: “My concern is to make sure that the public knows what has happened, so that they will be ready to come back to these ideas when the time is ripe.”


   I have written of this before.

   With modern technology (ie neutron bombs) we can launch with far less radioactivity. The LNT theory that low level radiation has been as thoroughly disproven as is possible (the opposite, hormesis, that low level radiation improves health is clearly at least often true). Moreover launched from South Georgia or the South Sandwich Islands, with wind patterns circling the Antarctic almost no radiation would reach land. Taken all together radiation risk would be at least 3 orders of magnitude, and probably more, less than thought at the time.

    Bombs are certainly a quick and practical way to provide the massive power to get to orbit. I suspect that something more sophisticated, like an atomic powered ion engine, would be better for travelling across the solar system - though its thrust is far lower it can produce a steady thrust and a steady acceleration, even when it is very small, can cover a lot of space in a surprisingly short time. And acceleration on such an ion jet would be easily controllable, allowing it to match orbits with asteroids or even dock with other craft - something impossible for a craft powered by bombs.

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