I have just finished to read the last Dan Simmons SF stories "Ilium" and "Olympos" in which a powerfull atomic propulsion system using atomic bombs explosions is described. A friend of mine told me that the system was indeed under studies in the fiftees and sixtees under the name "Orion project", name which is now used for the NASA Crew Exploration Vehicle:

http://en.wikipedia.org/wiki/Project_Orion...r_propulsion%29

"Orion was also the code name of an atomic Spaceship project [General
Dynamics Corporation/General Atomics] started in 1957 and declared dead
in 1965. A huge ship powered by hundreds of tiny atomic bombs!!! capable
of much greater lift and efficiency than chemically driven rockets.

Orion’s potential performance was stunning (could reach Pluto and return
to Earth inside of a year, or even travel to Proxima Centauri in 44
years at 10% the speed of light).

They hoped to put men on Mars by 1965 and on Saturn by 1970!"


"By using energetic nuclear power, Orion offered both high thrust and high specific impulse — the holy grail of spacecraft propulsion. It offered performance greater than the most advanced conventional or nuclear rocket engines now under study. Cheap interplanetary travel was the goal of the Orion Project. Its supporters felt that it had great potential for space travel, but it lost political approval because of concerns with fallout from its propulsion. The Partial Test Ban Treaty of 1963 is generally acknowledged to have ended the project."

I was really sceptic, but it seems to be serious.
Wouldn't it be an interesting way to clear the tremendous (and stupidly dangerous) stocks we have on Earth and send an unmanned spacecraft to the nearest stars ?
(At least, they could be used in a positive manner !!)

I'm aware about the political and ecological concerns about sending safely A/H bombs in space. I remember the trouble caused by the launch of Galileo or Cassini and their RTGs.

Do such kinds of projects still exist nowadays (even if they might not be politically correct) ?

Marc.

Marc, it would be nice but, I think, not practical... perhaps such a system could be used for a unmanned vehicle, wich can sustain stronger accelerations and radiation levels but, probably, no one would never allow to launch so many atomic bombs in space (is dangerous and violate also an international treaty...).
In fact, they abandoned the project!

IMO, such a naive idea recall me another couple of very popular beliefs:
1) world overpopulation issue can be resolved through solar system colonization;
2) far side of the Moon is the best place where to build large (optical/IR) astronomical observatories.
The former one is completely illusory (we MUST solve overpopulation and all consequent issues BEFORE to colonize space, otherwise we do not have time and resources). The latter could be true only for radioastronomy, but is false in other EM regions where a space free-fly telescope (eventually in the L2 region) is best choice, by far.

There actually does not seem to be any purely technical showstoppers to an Orion-type vessel and NASA has actually done some studies on the concept fairly recently (though it was more discreetly known as EPP (External Plasma Pulse) propulsion).

For details on the original Orion project I strongly recommend George Dyson's Project Orion (ISBN 0805072845).

tty

Marc, if you think Orion as a serious proposal for space transportation is outlandish, you ought to read up on the nuclear-powered aircraft they were trying to design back in the 1950s. The thing would have powered jet engines with a fission reactor, and IIRC, part of the process injected fissile material directly into the engines. The contrails of that airplane would have been so highly radioactive, they wouldn't have had to use it to drop bombs. They'd just have to overfly the enemy a few times and wait 15 years for them all to die of radiation poisoning and cancer.

-the other Doug

Talking about sending nuclear rockets to the stars: Here's links to a description of the British Interplanetary society study called Project Daedalus
and the proposal by the US Naval Academy called Project Longshot which was proposed to be sent to the Alpha Centauri tri-star system.

Direct fission drives like Orion are intriguing. It's the most efficient technology that is within our immediate grasp, if you wanted to approach relativistic speeds for example. There have also been proposals to burn fissionable fuel continuously in an engine. I suspect there are some serious engineering issues in building engines that can actually survive the impulse from thousands of nuclear explosions.

This reminds me of early speculative work on rocket engines. Some folks, like Oberth, designed engines that just melted or exploded when they were actually built. Annoying details like withstanding intense heat. Doh!

Ultimately, uranium is a very rare element. It's being used very wastefully now too, with U 238 being discarded or turned into artillery shells, when it should be bred to plutonium so it its energy can be exploited.

George Dyson's book is well worth a read. I have seen an interview with his father (Freeman Dyson), who said that when he worked out probability of causing additional deaths by cancer as a result of launching an Orion craft, he couldn't justify working on it any more.

I have seen it suggested that if we discovered an asteriod that looked certain to hit the earth in a few years, an Orion-type vehicle is about the only technology available to us that would allow us to reach it and nudge its orbit. In that case, the risk posed by the fallout from launch would probably be deemed to be irrelevant...

Chris

Niven and Pournelle fictionally figured out that an invasion by extraterrestrials would be a sufficient excuse to build and fly an Orion type launch vehicle/spacecraft.

See the collaborative novel Footfall, I believe.

Ah yes, Michael:

http://www.up-ship.com/apr/michael.htm

And then there is the Pluto of a different sort -

http://en.wikipedia.org/wiki/Project_Pluto

Seems everyone else already responded RE: the Orion project, but did you like the books? Dan Simmons is a favorite author of mine. His Hyperion Cantos is outstanding.

George Dyson has uploaded a set of previously "classified" images to flickr:
http://www.flickr.com/photos/xeni/sets/72157594329917915/
Click to view attachment

Cool -- cars and quonset huts and even a propeller-driven light plane taking off. Would that Mars actually had enough atmosphere for any of that...

-the other Doug

I think the 10%C figure is a bit generous. The Dyson book describes an Orion interstellar craft with a capability of a few percent C. Granted, since the 60's, there has been big improvements in material science and bomb technology, so 5%C or even a little higher might be possible.

Keep in mind, we are talking about detonating 20 million+ nukes for a flight plan like this. We are also talking about a vehicle with the potential to transport a viable human colony to the nearer stars.

While generally excellent, I found myself wishing for more info on the interstellar Orion vehicle in the Dyson book, though. It seems the original design (as best as I can garner) might be improved in some ways beyond material science and miniaturizing nuclear weapon technology. (how small and light can a 20 megaton nuke be?)

Perhaps as the bomb load is shot off, the mass of the pusher plate could be trimmed. It seems an approximation of 'fine tuning' the pusher plate diameter to the steadily decreasing mass of the vehicle could yield a big improvement in speed and/or payload. Additionally, rather than jettisoning unneeded pusher plate mass to space, it could be recycled into bomb casings and radiation channel filler materials rather having carried seperate materials from earth for this. This would allow more nukes/payload to be carried.

Additionally, perhaps bomb casings and weapon cores could be carried on the pusher plate. This would lighten the load on the suspension system, and result in less mass used for that. I am thinking that during the acceleration stages, on perhaps an annual basis, the outer annulus of the pusher plate could be unloaded, and recycled into the bomb casings. Also, by distributing bomb mass across the pusher plate, the pusher plate itself can be made lighter as the bending stresses will be reduced from the bomb impulses. Working on the pusher plate and assembling bomb units gives the crew (or the robots for an unmanned variant of this craft) something to do on the voyage. Note the acceleration might take 20 to 30 years.

At least it's kind of comforting to know that Orion technology is practical in a dire emergency...say, if we detect an imminent hypernova or a binary neutron star merger aimed our way some scary day...

I have a funny feeling that a "nearby" hypernova would first make itself known by how our upper atmosphere would flouresce so entertainingly -- as it blew off into space.

Not much time, in those cases, to re-route the entire industrial output of every nation to create an ark that would be able to save only a tiny fraction. Even if people could do such a thing, I dunno that there would be time.

-the other Doug

Well, the scenario I had in mind was the detection in the UV or IR bands of a dust or gas-occluded Eta-Carinae-type star that was maybe a hundred years from going blooey. Certainly there wouldn't be any time at all to build an Orion-type colony ship if the first warning we got was about three seconds of a pretty light show on the night side of the Earth before we all vaporize...

Well, not if the only plans around are the declassified "redacted" US versions.
Click to view attachment

...yeah, I saw that! Talk about marker-happy...

BTW, just to amplify my point, what if WISE finds an unpleasant surprise?

http://www.jpl.nasa.gov/news/news.cfm?release=2006-130

Since according to Dyson's book some of the technological legacies of the Orion project included techniques for making nuclear charges with amounts of fissile materials normally considered subcritical as well as a method to carry out undetectable nuclear tests I can understad that parts are still classified.

tty

I once did I research project about this, some time ago, I think the location is http://www.u.arizona.edu/~tuvas/, yep, that's the one. They were very serious about this kind of stuff. I first got into it when I heard about VASMIR rockets, and decided to look up on the net about them. I ran into a group by the name of Project Orion, they were cool. When I first heard them talk about Orion, I thought they were crazy... I found out later that this group was planning originally to build a fully functional Orion spacecraft, and use it as some kind of a museum on Earth until they could get the nukes to launch it. Just a few comments:

The 10%c orion is only acheivable when using H-bombs for detination. When your talking about bombs of that size, however, you want to have a very large spacecraft. The acceleration also is quite slow.

There exist several variations, which involve putting together a spacecraft much in the manner of the ISS, and using it in space.

Most of the nuclear bombs that countries have would be unsuitable for Orion. For an Orion rocket, you wan the blast to be shaped like a straw. For a weapon, you want the blast to be shaped like a pancake. Each will do it's job in the best way.

There's a book that Ted Taylor wrote, I don't know the name of it, but you might look into it. I think there's one written about Dyson by a third party, about him and his son, who built a very large canoe. It's been some time since I've read up on this stuff, however, so, I've forgotten the names... Still, they are fascinating books. Ted Taylorand Freeman Dyson were really incredible people, very much thinking outside the box.

The BBC did a great documentary about Project Orion. It's called "To Mars by A-bomb" and was broadcasted for the first time 2003 on BBC 4. The BBC webpage says the last time they broadcasted it was 08-FEB-2006. So it may be worth to keep checking the BBC webpage to see if they'll broadcast it again:

http://www.bbc.co.uk/bbcfour/documentaries...rs-a-bomb.shtml

This is actual test footage of a high-explosive Orion test:

http://paranoid.dechengst.nl/orion/oriontest.avi

I like the video, I used it in my presentations I gave on Orion, it was really cool!

I am not aware of a book written by Ted Taylor that was actually published. He was known to be writing a book before he died. You may be thinking of "The Curve of Binding Energy" which has a lot of nuclear anecdotes centered around Ted Taylor.

Don't know about an Orion book by Ted Taylor either, but I just watched the BBC Orion documentary again and Dyson's son did write a book about Orion:

http://www.amazon.com/Project-Orion-Story-...TF8&s=books

That must be it then, the curve of binding energy... Like I said, it's been a while, all I remember was reading a book with alot of references to him...