Project Orion: The True Story of the Atomic Spaceship

Johnzo writes: "It seems ludicrous to imagine that a spaceship could ascend into orbit and beyond by riding the impulses produced by a series of external atomic explosions. Such an idea would perhaps be more properly confined to science fiction -- like the Niven & Pournelle classic Footfall. But Footfall drew its inspiration from a real-life project, a project that, according to George Dyson's Project Orion: The True Story of the Atomic Spaceship, continues to offer exciting possibilities for space exploration." This sounds like a fascinating book; read on below for johnzo's full review.

Project Orion: The True Story of the Atomic Spaceship
author	George Dyson
pages	345
publisher	Henry Holt & Company
rating	9/10
reviewer	johnzo
ISBN	0805059857
summary	An excellent high-level introduction to the characters, engineering, culture, and future of the Orion project, and an ideal jumpoff point to other readings about the atomic age.

The chief advantage of an Orion-style spaceship can be explained in terms of specific impulse, which is the time during which a mass of fuel will produce enough mass x g thrust. Conventional chemical rockets, constrained by exhaust temperature, can produce specific impulses of about 430 seconds. Orion-style engines promised a specific impulse that was an order of magnitude higher than that--"2000 to 3000 seconds for first-generation designs, 4000 to 6000 for larger vehicles using existing bombs." The combination of long specific impulse and high thrust was unique to Orion, and would have allowed for the sustained high-acceleration maneuvers necessary for long-range manned space flight. And, like nuclear bombs in general, Orion scaled up more easily than it scaled down. The original Orion reference design massed 4,000 tons, and unlike the Apollo missions, which sent 600 lbs into space for every pound that came home, more than half of Orion's launch weight would have returned to Earth from a voyage to Saturn. Had it fulfilled its promises, Orion would have enabled manned space travel on a grand scale, with thousands of tons of payload and year-plus mission durations. It would have let us go into deep space in spaceships instead of mere disposable, unmanned spacecraft.

From 1958 to 1965, a team of physicists and engineers at General Atomic in California pursued the Orion dream. Project Orion tells their story ably. Dyson explores high-minded science and baroque bureaucracies in short, manageable, anecdote-loaded chapters. It's a terrifically easy read; with just freshman physics and a passing knowledge of 1950's America, I was able to follow along with no problems. The book begins by explaining the basics of Orion, the 1950's atomic establishment, the dot-com-like culture at General Atomic, the experiments that gave rise to the Orion idea, and the seed funding from ARPA. Dyson moves on to introduce us to some of Orion's chief characters, notably Stanislaw Ulam, who originally patented the atomic-pulse-drive idea, Ted Taylor, the Orion project leader and namer (he "just picked a name out of the sky," says the book) and Freeman Dyson, the celebrated scientist who was on board for the first two years -- and, who, not coincidentally, is George Dyson's father.

From there, it's on to the fun parts, beginning with the chapters detailing the engineering problems that Orion's designers faced. Most obviously, how do you design a pusher plate that won't shake itself apart or ablate under repeated impacts of nuclear plasma? (answer: with a thin coat of oil, reapplied between each atomic pulse.) How do you cushion the crew from the hundred-g shock of the pulse-unit explosions? (answer: with two-stage shock absorbers.) How do you shape the expansion of the propellant plasma so that you hit the pusher plate right? (answer: you take advantage of directed-energy weapons research to shape your atomic charges.) How do you eject your atomic charges from around the rim and orient them so that they explode correctly? (answer: you talk to Coca-Cola about bottling plant design.) And how do you cope with a pulse-unit misfire that sprays your pusher plate with jagged shrapnel instead of friendly plasma? (no answer given.)

Since GA's Orion program was a small shop that wasn't straightjacketed by job descriptions, the physicists were free to envision operational details and space missions for their baby. After concluding its engineering coverage, Project Orion looks at some of these missions. Freeman Dyson proposed a mission that would have landed on the moon, orbited Venus, Earth, and Mars, and then gone out to to Enceladus, Saturn's second-innermost satellite. The mission would have made clever use of tricks like planetary gravity boosts, in-atmosphere decelerations, and propellant harvesting to stretch its range. The senior Dyson was vexed by the problem of atomic contamination, though; even if it used the cleanest bombs available in the late fifties, an Orion launch would still introduce considerable amounts of toxic fission products into the Earth's magnetosphere. Dyson estimated that about ten people would die from atomic contamination for every Orion launch. This was about one percent of the estimated fatalities attributed to the atomic tests of the day. Instead of waiting for cleaner bombs to solve this problem, GA collaborated with friendly factions inside NASA--including rocket pioneer Wernher von Braun, who was an enthusiastic supporter of Orion--to discuss rocket-boosted Orion models. Proposals were made to either loft Orion into orbit wholesale or to boost it in pieces and conduct final assembly in orbit. Rocket-powered auxiliaries were also discussed; these would serve as landing craft and inter-Orion taxis.

In the end, of course, all of this work amounted to nothing. For various reasons -- nuclear test bans, lack of funding, and indifferent brass -- the Orion project was never permitted to conduct any of the nuclear test shots necessary to advance its work. The Orion staff made only a single successful test flight during the entire duration of the project, and this was conducted with 1m-diameter model powered by C4 charges. By 1959, Freeman Dyson had left the effort; he had seen that NASA wasn't going to budge away from Von Braun's giant rockets, and he knew that NASA was the only agency that would be able to support Orion. The project staggered on for four more years under Air Force funding, but the Air Force wasn't the right fit for Orion; no one could figure out a clear and present military use for all that lifting power. The USAF repeatedly approached NASA for money, but NASA was interested only in the conservatively incrementing known technologies, not in wholesale revolution. Orion was orphaned by 1965, its knowledge scattered through hundreds of classified documents and dozens of scientist's brains.

The book ends on a fascinating note, with modern-day retrospectives from various Orion staff. Some of them--including Ted Taylor--have renounced the idea of atomic weapons entirely. Some of them are convinced that Orion could never be made to work safely and reliably. Others believe that Orion is an idea whose time will come. NASA agrees with them, in some small measure; they're looking at Orion again as a space-exploration and asteroid-intercept technology. They're having a tough time finding details and data from the General Atomic project, though -- much of Orion's data is still classified. Dyson has had more success in hunting down those documents than NASA. When he contacted them in the course of his research, they begged him for copies!

I greatly enjoyed reading Project Orion. The only disappointment it held for me was its heavy reliance on Freeman Dyson's recollections, and the consequent weighting of the book towards Dyson's year of involvement. I suspect there's a lot of interesting detail missing from the latter six years of the project. That aside, Project Orion is an excellent high-level introduction to the characters, engineering, culture, and future of the Orion project, and an ideal jumpoff point to other readings about the atomic age.

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You can purchase Project Orion: The True Story of the Atomic Spaceship from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

Deep Impact

[TheCrazyFinn]

Deep Impact also used Orion.

Nice to see a book on Ol' Bang Bang.

The Crazy Finn

politics vs. science

[NixterAg]

I read this book a few months ago and I agree with the reviewer that this is an excellent book. However, it tends to concentrate a great deal more on the politics surrounding Project Orion than the science much to my chagrin. Much of the information surrounding Project Orion is still classified so I don't necessarily blame the author for this, but those intending on reading the book should qualify their expectations.

I did get a great appreciation for the sheer size and magnitude of truly difficult engineering problems and the organizations and minds assigned to solving them.

All in all, it's a quick and easy interesting read that engineers and NASA junkies will likely enjoy.

Re:politics vs. science

[Jack William Bell]

I know George and have met his father Freeman Dyson. And I can tell you that Freeman is still very reticent about the scientific details of the project, mostly because of the work they did designing miniature atomic weapons. Plus it is kind of a cold war mindset/cultural thing. Really it is amazing how much detail George was able to pull out of the hat when researching this book. He even came up with some test video (which I have seen). According to him the goverment attempted to re-restrict some of the information he collected after he got it via the Freedom of Information Act. Too late... Heh heh.

Still the politics of the project are illuminating themselves in how they show changing attitudes in the US and the US government over those crucial years.

Note for the interested: George Dyson lives in Bellinham WA (from where the fictional Orion-based spacecraft was launched in 'Footfall') and was GoH (Guest of Honor) at Vikingcon 17 [bsffc.org] there in the summer of 2000. Freeman Dyson has been a GoH at Vikingcon many times. Jerry Pournelle has been GoH at Vikingcon once and Larry Niven has been GoH twice, including 17. As you can guess 17 was a very cool con for Orion-based sychronicity and George gave a wonderful presentation there on the research he was doing at the time for this book.

Jack William Bell, who must admit to being the Vikingcon 18 [bsffc.org] chairvictim...

Would a reactor-style system work better?

[Whispers_in_the_dark]

I'm not a physicist, but I would think that the majority of the energy from the explosion would not propel the spaceship but would be emitted in perpendicular directions, escecially as the blast grew in size (let's not forget the sudden G forces involved here). Wouldn't using the resulting hot gasses/radiation from a nuclear reactor provide a smoother, more efficient burn?

Re:Would a reactor-style system work better?

[nrd907s]

I'm not a physicist but I'm assuming the reason for the conical shape of the bottom of thrusters is to allow for perpendicular exploded particles to also help propel the ship. (something like why satellite dishes are conical/parabolic)

Re:Would a reactor-style system work better?

[RocketJeff]

The majority of the energy does go in other directions, but the typical nuclear explosive has more then enough energy to spare. The pusher-plate on the bottom of the Orion ship was designed to cushion the ship from the raw acceleration (as well as the radiation).

The typical nuclear reactor rocket (like the NERVA) was designed for space-only operations and didn't have the power to lift-off from the Earth's surface. Remember, the Orion ship itself is the size of a large skyscraper.

blasts stay the same size as i understand it.

[Unknown Poltroon]

Use a hemispherical plate, explode them at teh focus, enough of the energy pushes on the plate to make this worthwile. The key here is BIG OVERKILL not efficient.

Re:blasts stay the same size as i understand it.

[sphealey]

Use a hemispherical plate, explode them at teh focus, enough of the energy pushes on the plate to make this worthwile. The key here is BIG OVERKILL not efficient.

Ted Taylor, the master of the elliptical, evasive non-release of classified information, hinted that it is possible to direct the energy release of an atomic explosion (hard as that may be to believe). So possibly some of the classified Orion knowledge concerns how to direct the energy in the desired direction.

sPh

Re:Would a reactor-style system work better?

[DonkeyJimmy]

but I would think that the majority of the energy from the explosion would not propel the spaceship but would be emitted in perpendicular directions

You could always direct the explosions using the same design as a rocket engine.

Wouldn't using the resulting hot gasses/radiation from a nuclear reactor provide a smoother, more efficient burn?

It sounds like they're trying to make a practicle design, and leaving a trail of radiation may not be the best solution for that.

I think the best concern you raise is the G force issue, which I'm also curious about. Anyone know any details on that?

Re:Would a reactor-style system work better?

[breadbot]

You could always direct the explosions using the same design as a rocket engine.

You might have a hard time finding nozzle material that could stand up to a fusion explosion! A pusher plate seems like about the best you could do -- you might actually want to allow some of that force to dissipate.

Re:Would a reactor-style system work better?

[spike hay]

You could always direct the explosions using the same design as a rocket engine.

Rocket nozzles would not be able to withstand the force of a nuclear explosion. However, there is a different concept that even gets a greater ISP than Orion. It is called the Nuclear Salt Water Rocket.

This uses plutonium salts dissolved in ordinary water. In the fuel tank, there are lots of boron rods to keep the fuel from fissioning. But then the fuel is fed into the combustion chamber, which has no moderator. Here, the nuclear salts explode, producing a high speed jet of water from a constant nuclear explosion.

This would get a specific impulse of around 10,000. It has an even bigger advantage over Orion: Orion's fuel is uranium or plutonium. That's very expensive. However, the vast majority of the NSWR's fuel mass is just water. This makes it quite a bit cheaper than Orion.

However, we already have had the tech for Orion since the 60's. (In fact, the completely designed a craft to reach Saturn) So, maybe we could get an exemption from the test ban treaty and build and launch one.

Re:Would a reactor-style system work better?

[ryanwright]

Is the quality of this cocaine satisfactory, Mr. Delorian?

You should get your facts straight and learn to spell before slandering a man who was acquitted of all charges due to entrapment. In other words, a government setup: John DeLorean was not a coke head nor did he traffic in it.

Orion was never about efficiency

[Bingo Foo]

The Orion project was about getting to another star as fast as possible. Consider though, that "as fast as possible" means on a historic timescale, not merely short transit time. Given the technology we have (and had at the birth of Orion), making x BTU's worth of thermonuclear bombs and utilizing them at even 5% efficiency was a faster way to get a working craft to Sirius than trying to design an engine with controlled fusion.

Keep in mind that all controlled, sustained nuclear reactions we have engineered to date are fission reactions. An inefficiently converted but uncontrolled fusion reaction (aka Hydrogen bomb) will still give more "bang for the buck," literally and figuratively.

Orion vs NERVA vs VASIMIR

[Latent Heat]

Way I see it there are three approaches to nuclear propulsion: 1) Orion -- putty-putty bang-bang, 2) NERVA -- high power density reactor which heats up hydrogen that squirts out a conventional rocket nozzle, and 3) VASIMIR (Variable specific impulse magnetic rocket) -- use the nuclear reactor for an electric power station and accelerate hydrogen or other gas with a magnetic rocket nozzle (there is also ion drive, but VASIMIR is popular these days because it offers the greatest thrust of all the electric schemes). The book, in talking the politics, indicated that NASA Huntsville though that Orion was pie-in-the-sky before doing something like NERVA first. VASIMIR is a more recent proposal and was not under consideration in that era. My understanding is that NERVA would be a replacement 3rd stage to a Saturn V -- that way the reactor would not be turned on until you got into space. One thing about NERVA is that its propellant is stores as liquid hydrogen, which is one of the bulkiest, least dense liquids around. The NERVA stage would have been huge, essentially the same diameter as the S-IC and S-II rocket stages below it, making the nuclear Saturn V one continuous cylinder until you got to the payload fairing. Given the weight of the reactor and given the bulk of the hydrogen tank, I am wondering if the 800-second specific impulse compared to the 430-second specific impulse of the regular Saturn S-IVB upper stage would have been a wash. Orion had a bulk problem too. If it was ground launched, if could have had a much bigger diameter pusher plate to capture more of the nuclear explosion and be more efficient (or perhaps less inefficient). Its efficiency came from the ultra-high temps of a nuclear blast compared to a sustained nuclear reactor and its inefficiency came from most of that efficiency being wasted apart from the little bit captured by the pusher plate, and the bigger the pusher plate the better. I thought they said a ground launch Orion could be in the 10000-second specific impulse range while the Orion launched as a third stage of a Saturn V was reduced to about 2000-second specific impulse because of the smaller pusher plate -- you start getting into the is it worth the bother range. I actually think that the Orion approach would be by far the easiest from the engineering standpoint, given how much work and testing went into bomb making. The only holdup is the idea of polluting even space let alone the Earth with that much fission fragments.

Re:Orion vs NERVA vs VASIMIR

[WolfWithoutAClause]

"but VASIMIR is popular these days because it offers the greatest thrust of all the electric schemes"

Ahem. Actually, it gives less thrust than most ion drives per kilowatt, noteably Hall effect thrusters.

Part of the problem is energy- for a given megawatt of power, with VASIMR most of it ends up in the extremely high velocity exhaust (5400 seconds == 54000 m/s) where you don't want it, rather than the vehicle, which you do.

There's a theorem that says that if you keep your ISP constant there is an optimum exhaust velocity for minimum energy- it's about 2/3 of the mission delta-v. To get to mars you need a delta-v of about 5 km/s not 54km/s. The reason minimum energy is important is because nuclear reactors are not noted for having a light weight- there's no point saving fuel at the cost of extra overall weight.

Of course VASIMR varies its ISP, which helps, but it goes from very-high, to way-too-high ;-)

Re:Would a reactor-style system work better?

[Louis_Wu]

Good theory, wrong application. Using a conical shape to control explosions is a well known and widely practiced technique, but it isn't used in rockets or thrusters.

The reason that a rocket engine has a conical 'bell' is to control the behavior of the exhaust gases. Specifically, the shape of the exhaust bell controls the efficiency of the gas flow, and prevents losses which could reduce thrust. All of the exploding happens inside the rocket, and it is the escaping gasses which the exhaust bell is designed to affect.

FYI, one of the main uses of explosion control is shaped charges, the kind that police special units use to get through walls/roofs/ceilings. A simple shaped charge can be made by placing two explosives in a 'V' shape, the resulting explosion will be pointed toward the opening in the 'V'. It's not magic, the explosion is very radial, but more heads toward the open end of the 'V' than any other direction. To get a charge which points most (nearly all?) of the explosion in one direction, put something strong and heavy around the explosive where you don't want damage. Example - a piece of angle iron (an 'L' shape of steel) with strips of C4 along the inside of the 'V' will shape the explosion and direct it toward the open end. Unfortunately, Newton's Third Law still applies (for every action there is an equal and opposite reaction), so the force of the explosion will want to move the angle iron. So you weight it down with sandbags. This is pretty much how LAPD started using shaped charges to enter buildings through the roof. A few pieces of angle iron with explosive in them, some sandbags, arrange on the roof, get behind something and BOOM. This was later refined - the shaped charges (iron pieces, wiring, & everything) were attached to a piece of particle board, placed on the roof, a few sandbags were dropped on top, and you could create yourself a nice entry hole for your SWAT team in a few seconds.

Caveat: I haven't experimented with shaped charges, I've just read about them.

Re:Would a reactor-style system work better?

[XNormal]

Wouldn't using the resulting hot gasses/radiation from a nuclear reactor provide a smoother, more efficient burn?

Smoother? Yes. More efficient? definitely not.

Specific impulse depends on exhaust velocity. Exhaust velocity depends on temperature. The maximum achievable temperature for a nuclear thermal rocket is limited by the reactor construction materials to a few thousand degrees. With an Orion rocket, even if it loses a significant percentage of of thrust sideways the temperature is still orders of magnitude higher.

The Ultimate Frat-Boy Vehicle

[Hack Shoeboy]

A Spaceship that lights its own farts???

Other nuclear propulsion...

[wowbagger]

If you are ever in Idaho, you should visit EBR-1 [atomictourist.com], the world's first breeder reactor. It is decommissioned, cold, and open for tourists during the summer season. Outside, they have some prototype nuclear jet engines - devices that took in air, heated it with a fission reactor, and expelled it for thrust. Neat stuff - would have been nasty as hell had it ever gone into service, but neat none the less.

EBR-1 is about 4 hours drive from the west entrance of Yellowstone National Park [nps.gov], and about 45 minute from Craters of the Moon National Park [nps.gov], so there's plenty of other stuff to do in the area.

Re:Other nuclear propulsion...

[dpbsmith]

Well, actually even though it never did go into service, it WAS nasty as hell when it experienced a partial core meltdown on November 29, 1955.

For some reason, most of the sites like this [atomictourist.com] that show it lighting four light bulbs or mention Arco, Idaho as "the first city to be lit by atomic power" don't seem to mention this...

Re:Other nuclear propulsion...

[Fesh]

I thought that sounded familiar. We Almost Lost Detroit had a rather detailed treatment of the incident, if I recall.

Someone explain this to me please

[Winterblink]

I've heard of the Orion concept before and quite frankly I can't understand how you build something to withstand an atomic explosion for propulsion purposes and not have it blow itself to smithereens. I DO realize that we're not talking about megaton sized explosions here. :) However I'm still fuzzy on how a very low power explosion could keep the damage to the craft down while still providing an effective means of propulsion. Or is this similar to the impulse engines of star trek (the greatest scientific precursor ever, *snicker*), where the nuclear reaction is fed constantly by small amounts of reactive mass?

Re:Someone explain this to me please

[RocketJeff]

Or is this similar to the impulse engines of star trek (the greatest scientific precursor ever, *snicker*), where the nuclear reaction is fed constantly by small amounts of reactive mass?

Nope, Orion was designed to use atomic bombs for propulsion.

They wern't meant to be exploded directly against the ship, but a 'safe' distance away. The blast/shock wave is what actually propels the ship. The pusher-plate absorbs the shock and transmits it to the rest of the ship like a giant shock-absorber.

Re:Someone explain this to me please

[Winterblink]

They wern't meant to be exploded directly against the ship, but a 'safe' distance away. The blast/shock wave is what actually propels the ship. The pusher-plate absorbs the shock and transmits it to the rest of the ship like a giant shock-absorber.

Thanks! I guess my followup question to that would be: how "clean" can that possibly be? I imagine using nukes to break earth orbit can't be too good for those of us on the ground. :)

Re:Someone explain this to me please

[benwb]

It's attitudes like this that explain why my children won't have mutant powers.

Re:Someone explain this to me please

[Winterblink]

Hey I'm no treehugger, I just know that airbursts and spacebursts are bad for my computers. :)

Re:Someone explain this to me please

[RocketJeff]

I imagine using nukes to break earth orbit can't be too good for those of us on the ground. :)

The surface bursts used to get Orion off the ground would have been bad - lots of fallout and other nasty stuff. The air bursts (when the blast doesn't actually touch the ground) wouldn't have been that bad except for the initial EMP and radiation burst. Air bursts don't create fallout and are thus much cleaner then surface bursts (but I still wouldn't want to be around one).

Oh, really?

[fnj]

The air bursts (when the blast doesn't actually touch the ground) wouldn't have been that bad except for the initial EMP and radiation burst. Air bursts don't create fallout and are thus much cleaner then surface bursts (but I still wouldn't want to be around one).

Oh, really? Hiroshima was an air burst (around 2000 feet; no crater was created). Are you really saying there was no fallout at Hiroshima? I know there is less fallout than there is with ground bursts, but none?

Re:Oh, really?

[RocketJeff]

Fallout is caused by matter being caught-up in the nuclear fireball.

Air bursts create some fallout, but very little. In this case it's only the air/dust/smoke that's already in the air (or kicked up into the fireball by the blast).

Hiroshima was actually a very clean explosion (for the time). Notice that most of the deaths from Hiroshima (even those from cancer today) are caused from exposure to the initial explosion, not from being in the area afterwards. If there was significant fallout, Hiroshima wouldn't have been habitible for quite a while (months at least) afterwards.

Re:Oh, really?

[mesocyclone]

Yes. There was NO fallout from Hiroshima - in the sense of local, deadly fallout. There was dispersed, low level worldwide fallout.

All of the radiation deaths in Hiroshima were a result of what is called "prompt radiation." This is the radiation dose delivered in the first minute of a blast. It includes the immediate radiation released by the fission reaction, and exposure to radiation from the very short lived elements in the fireball before they rise high enough and decay enough that the radiation flux is negligible.

I say aain. There was NO localized fallout from Hiroshima. In fact, the first time fallout was recognized as a serious problem was after a south pacific test, when fallout, in the form of white flakes falling from the sky, fell on people outdoors on a relatively nearby island. They reported skin burns from the fallout, but there were no significant injuries.

Ground bursts produce fallout because the radioactive elements (which are all vapor after the blast) are mixed with large amounts of particulate matter, condense on it, and fall from the sky from ground zero outwards downwind.

Note also that there is controversy over whether low levels of radiation, such as what you get with distributed world-wide fallout (from stratsopheric transport of long lived radioactive elements from a fireball), is even harmful. There is little evidence that low doses are harmful, and there is some evidence that they are not (for example, on a county by county basis in the US, lung cancer rates are INVERSELY proportional to household radon levels). Almost all radiation dosage standards (such as the EPA 4picoCuries/liter - or is it m^2... oh well) are a result of extreme extrapolation from high dosage exposures. BTW... the same is also true of some toxic chemicals, although most toxic chemical recommendations come from extrapolating downward from lethal-dose 50% levels in animals - an even more fragile exercise.

The term you are looking for is "ablation"

[Howzer]

It's the way the shielding on every spacecraft before the Shuttle worked.

The shielding burns up, but at a predicted rate, and it lasts long enough to get the craft on the ground. Shuttle shielding is the opposite, it's a ceramic that simply "holds" the heat (vast simplification there, but well).

And it's ablation again with Orion. Sure, the explosions ablate part of the shielding, but it lasts long enough to get the craft where you want it to be.

And to answer your other question, the idea is like the engine of a car. If you can hear the individual pistons firing, then you've probably got a problem! But they do fire individually. Same thing with Orion (or similar) - the bombs are chucked out the back at a pretty rapid rate. At least in the designs I remember - I haven't read the book but I will based on the review. It sounds fascinating!

Re:The term you are looking for is "ablation"

[Winterblink]

Heh, good analogy with the car (Futurama: "Like putting too much air in a balloon!")

In the case of interstellar travel though, that'd bite if you get to where you're going and realize they don't have the raw materials to build more ablative shielding. How do you get back? :)

You're right though, the concept is extremely fascinating. The best part of the posting was the bit about us travelling through space in SHIPS, not CRAFT. Once we start building vehicles that essentially aren't "disposable", there'll be a heck of a space rennaissance.

Re:The term you are looking for is "ablation"

[Queuetue]

Most likely, we'll find carbon and steel wherever we go - that's what they used for the plate and "grease" in the tests...

Re:The term you are looking for is "ablation"

[3waygeek]

IIRC, Ted Taylor discussed the ablation issue in The Curve of Binding Energy, referred to in several other posts. During their tests, someone had left a thumbprint on the pusher plate; they discovered that there was less (or maybe no) ablation in the area of the thumbprint. So they came up with the idea of spraying the pusher plate with oil between explosions; ablation problem solved.

FWIW, they consulted with the Coca-Cola company to determine the mechanism for dispensing the nuclear charges -- Coke, having lots of vending machines, knows a thing or two about dispensing cylindrical objects reliably. Taylor didn't say how many quarters it'd take to get to Alpha Centauri, however.

Re:The term you are looking for is "ablation"

[Daetrin]

No, that's not the term that's being looked for, or at least not exactly. From the article itself:

"Most obviously, how do you design a pusher plate that won't shake itself apart or ablate under repeated impacts of nuclear plasma? (answer: with a thin coat of oil, reapplied between each atomic pulse.)"

So the ship itself isn't really undergoing any ablation. I'm not sure if the term could be properly applied to a continuously resupplied coat of oil.

Re:Someone explain this to me please

[spike hay]

I've heard of the Orion concept before and quite frankly I can't understand how you build something to withstand an atomic explosion for propulsion purposes and not have it blow itself to smithereens.

It is exploded some distance behind the craft. The Orion has an ultra-heavy pusher plate (one of it's main drawbacks) that has a thick coating of graphite. With each blast, some of the graphite is ablated.

Re:Someone explain this to me please

[Phurd Phlegm]

It is exploded some distance behind the craft. The Orion has an ultra-heavy pusher plate (one of it's main drawbacks) that has a thick coating of graphite. With each blast, some of the graphite is ablated.

You should read the book. A suprising result was that with a little bit of an oil coating, there would be no ablation. Well, I was suprised, anyway.

Re:Someone explain this to me please

[spike hay]

Hmm. You'd think an oil coating would just vaporize. That's amazing.

All this and more...

[bourne]

Another good book that bears on this subject is Robert Zubrin's Entering Space: Creating a Spacefaring Civilization [amazon.com]. He discusses the atomic bomb drive as well as other postulated ideas for interstellar craft, such as solar wings and some trick with laser and mirrors (IIRC).

Even better, for slashdot folks, is that Zubrin takes this stuff seriously in a scientific sense. He discusses the energy needs and expected capabilities of the various craft, and in general covers a lot of "practical" ground. This is the same guy who is behind The Mars Society [marssociety.org], which actively works to enable and encourage mannned missions to Mars.

Slashdot has covered Zubrin and Mars Society before; see this [slashdot.org] and that [slashdot.org]. He also has a mars-specific book titled The Case for Mars: The Plan to Settle the Red Planet and Why We Must [amazon.com]. I recommend both his books to anyone who thinks we need to get off this rock.

I concur and wish to add...

[Howzer]

The Mars Society [marssociety.org], in the process of encouraging and enabling manned missions to Mars, is currently doing this project [senecac.on.ca] among others.

Cool hack if ever I have seen one! Build-your-own Mars Base in one of the most Mars-Like places on Earth, and do real research on how to operate said base when (not if) we get to Mars.

If you keep up with the web traffic on this project, NASA's position seems to be basically "Great work guys!" and "Can we send our best people?" to which request the Mars Society seems to graciously and intelligently accede.

Crazier than Orion

[Latent Heat]

Zubrin had a crazier idea than Orion -- the nuclear salt water rocket.

The idea is that you would have a tank of water with uranium salt in solution along with enough boron so the thing would go off at once. You piped this salt water into a reactor chamber where you somehow extracted the boron so that you would get a nuclear chain reaction inside the chamber and then the super heated salt water would squirt out the back.

As somewhat less crazy idea is that you would entrain uranium hexafluoride gas in a vortex in a reactor and pump hydrogen through it -- kind of a look-Ma-no-walls version of NERVA.

Costs:

[Unknown Poltroon]

Feasable nuclear engineering: 500 billion
Buncha rocket scientists: 10 millon
Building the engine: 1 billion
Putting Manhattan into orbit:Priceless.

The Nuclear Salt Water Rocket

[XNormal]

This is a design by Robert Zubrin [wikipedia.com] for a rocket that produces a continous atomic blast using water with a high concentration of Uranium or Plutonium salts.

Nuke Your Way to the Stars [washington.edu]

Re:The Nuclear Salt Water Rocket

[Chris Y Taylor]

The article at washington.edu about Zubrin's nuke designs says:

"He has used a simplified model to show that the distribution of fission-inducing thermal neutrons in the reaction chamber depends critically on the velocity of the liquid fuel as it passes through the reaction chamber. This dependence occurs because the moving salt water fuel is also the medium in which the neutrons are slowed. If the liquid is at rest, the maximum flux occurs at the center of the cylinder, but if the moderating fuel liquid is in motion, the point of maximum flux is skewed downstream and also rises to a much higher maximum. If the right fuel velocity is chosen, the thermal neutron flux (and therefore the site of maximum fission energy release) can be made to peak very sharply just outside the exit end of the cylindrical reaction chamber."

That is true only when the system is operating at a steady state condition. This means that, as with liquid fuel rockets, starting and shutting down the engine is going to be a difficult trick. It might be accomplished using a chemical shim to inhibit the nuclear reaction duirng startup and shutdown, but that is probably the sort of thing that would need experimental testing to prove (I don't trust computer models quite that much).

Chris Y Taylor

Warp drive when?

[little1973]

You can find more info about advanced propulsion techniques (like the Orion-project) and other interesting space-science stuff at Warp Drive When? [nasa.gov].

Also on Sagan's Cosmos

[GuyMannDude]

One of the episodes of Carl Sagan's Cosmos series [carlsagan.com] dealt with long distance space travel and showed examples of proposed starship design and the Orion was one of them. He, of course, had to insert one of his typical comments about how that would be a much better use for nuclear technology than bombs, but the episode is worth watching anyhow.

It seems ludicrous to imagine that a spaceship could ascend into orbit and beyond by riding the impulses produced by a series of external atomic explosions.

I wish that submitters would really refrain from inserting their own editorial comments and judgements in the stories they submit. Cosmos was aired over two decades ago. So the idea for Orion did not seem ludicrous to me. Couldn't this guy just comment on the book instead of making a guess as to how knowledgable the entire slashdot community is on starship design?

GMD

We have nuclear submarines/carriers, why not ?

[qurob]

Those things go 25 years without needing to be refilled, or whatever.

Re:We have nuclear submarines/carriers, why not ?

[RobertNotBob]

They also turn a propeller as a means to go for place to place. And then there's the 30 knots (unclassified) top speed.

Hmmmm, propeller driven spacecraft... Neat idea you have there. All we have to do is find a intersteller river.

fission blowtorch

[Anonymous Coward]

Dissolved uranium salts in water ejected by a magnetohydrodynamic drive (think linear accelerator for saltwater) with a neutron emitter to initiate fission at the egress point: that's the way to go. Any comments?

Nukes for Nasa

[Angus McNitt]

The only question I would have about using Nuclear power for space launch woudl be not only be residual radiation at the launch site, but the weight of the craft itself. Too much weight and it won't lift, too little and you cook the occupants. Even a minimal craft woudl have to be very heavy. I would think re-entry would be very problematic. How do you retard you downward velocity enough not to destroy yourself landing. Make a blast chamber that stayed in space or burned up in atmosphere? Would be a great way to lauch heavy componants to a large space station thouhg.

Also if you had an interuption in the blast progression, what would keep you from falling like the giant lead weight the craft would be? To use the Footfall reference again, wasn't that their major concern after the first one when off; keeping them going at the correct rate? Too little you fall, to fast and you either pulp your occupants or start to damage the "bomb guns". I guess now that part would be safer to test due to computer modeling. You wouldn't have to convert hundreds of tons of Nevada's sand into glass.

Now, if you used it as a space based propulsion, that would be great. It would also help get rid of all those old Russian and American nukes that have been removed due to Anti-Balistic Missle treaties. Also any background radiation would disapate failry quickly.

I'm not a physicist, so feel free to pick holes in this.

Project Thunderwell

[ek_adam]

It's been done. Short story, in the 1950's they were still testing nuclear weapons. They put one at the bottom of a long mine shaft and put a heavy metal plate on top to partially contain the explosion. The plate was last seen moving at about six times escape velocity.

On the other hand, it probably vaporized before leaving the atmosphere, see Operation Plumbob [enviroweb.org] for more information.

Re:Project Thunderwell

[grossinm]

Check out project Gasbuggy as well. Small device was used to help extract natural gas from the ground. DOE Site here [doe.gov]

Ted Taylor and THE CURVE OF BINDING ENERGY

[Lumpish Scholar]

For more on Ted Taylor -- his work on fission bombs, his participation in Project Orion, his speculations on how small a nuclear bomb could topple the World Trade Center towers (decades ago), and his concerns about nuclear proliferation -- I strongly recommend John McPhee's The Curve of Binding Energy [amazon.com] (BN [barnesandnoble.com]). McPhee [amazon.com] (BN) [barnesandnoble.com] is an excellent writer, and this is one of his books I enjoyed the most.

Good interview with the Dysons about Project Orion

[jimkski]

NPR's TOTN Science Friday broadcast an interview with Freeman and George Dyson a month or two ago. You can hear the interview at the NPR Archives:

http://search.npr.org/cf/cmn/segment_display.cfm?s egID=145345

The interview is great for conveying the commitment and enthusiasm Freeman felt for the Orion Project. They really believed that the ship would be build and flown to Mars last century. With NASA's new administrator Sean O'Keefe talking about alternative propulsion systems (including nuclear), who knows maybe Dyson's ideas will actually see the light of day.

Dyson Sphere

[Anonymous Coward]

Remember the 'Dyson Sphere' episode of ST:TNG where Scotty had been trapped in a regenerative transporter cycle for 75 years in his ship, stuck on the sphere?

Well, Freeman Dyson is that Dyson.

See the Dyson Sphere FAQ [d.kth.se] for details.

Sort of! Re:Dyson Sphere

[StefanJ]

In the essay "Extraterrestrials," Dyson specifically denies having come up with the Dyson Sphere.

He gives credit for the concept of a star-swaddling energy collector to a book he found in a London subway stop book stall: the quasi-novel Star Maker by SF writer and philosopher Olaf Stapledon:

http://www.amazon.com/exec/obidos/tg/detail/-/0486 219623/

Freeman Dyson is best known to SF fans because of the "Sphere" concept and the Orion drive. But please check out the guy's actual writing. There's a lot more to him than this eye-candy.

Re:Sort of! Re:Dyson Sphere

[DNS-and-BIND]

The politically correct name should then be Stapledon Sphere, not Dyson Sphere.

Don't tell me The Next Generation got its facts wrong, AND passed up an opportunity to be politically correct? It pushes the limits of believability, you understand.

Not intended for launch

[elh102]

"It seems ludicrous to imagine that a spaceship could ascend into orbit and beyond by riding the impulses produced by a series of external atomic explosions...."

That's because it IS ludicrous, at least the "ascend into orbit" part. It has been a while since I read anything about Project Orion, but I'm pretty confident that this propulsion technique was intended for use only in space. The spacecraft would most likely have been assembled in orbit, or possibly launched from Earth by one mother of a big chemical rocket.

Re:Not intended for launch

[sphealey]

That's because it IS ludicrous, at least the "ascend into orbit" part. It has been a while since I read anything about Project Orion, but I'm pretty confident that this propulsion technique was intended for use only in space. The spacecraft would most likely have been assembled in orbit, or possibly launched from Earth by one mother of a big chemical rocket.

Interestingly, that turns out not to be the case.

First, the starting point of Orion was asking the question, "How do we get multi-ton payloads into space?". Chemical rockets, then and today, take tremendous amounts of resources to get a few hundred kg into space. Then and now, that doesn't really do much for anyone.

Second, you have to remember that the Orion project started during the era of above-ground nuclear testing. Yes, an Orion launch would have created some fallout and upper-atmosphere contamination. But compared to the 10 MT (US) and 60 MT (USSR) monsters that were being fired for test purposes, the pollution wouldn't have seemed so bad.

Of course, times have changed, and I doubt anything like this will be ever be used in the atmosphere except in dire circumstances (Footfall, Deep Impact).

sPh

Nitpick

[roystgnr]

Of course, times have changed, and I doubt anything like this will be ever be used in the atmosphere except in dire circumstances (Footfall, Deep Impact).

They said in Deep Impact that the Orion ship was assembled in orbit (although it looked like a close enough orbit to create hell with EMP, at least).

They also didn't talk about Orion propulsion at all, which was just horribly disappointing. Yes, it was a long movie, but couldn't they have spared 60 seconds to show us the astronaut's reactions to riding a nuclear arsenal? It could have been made part of the plot, too: "We've used up all our bombs that we tried to destroy the comet with, but we still have a ton of bombs that were intended to decelerate us when we returned to Earth..."

Re:Nitpick

[sphealey]

They said in Deep Impact that the Orion ship was assembled in orbit (although it looked like a close enough orbit to create hell with EMP, at least).

Sorry, I should worded my reference more carefully. I meant that if the Earth actually faced a real asteroid impact scenario with enough time to respond, as illustrated in the fictional movie Deep Impact, the inhabitents of Earth might be willing to eat the fallout from an Orion launch to avoid total destruction.

sPh

No Nukes!

[mustangdavis]

First, like many people here, I don't understand how a nuclear explosion won't destroy the ship it is trying to move through Space at "warp speed". This seems pretty dangerous to me. Good luck finding anyone to fly that thing!

Second, haven't scientists just discovered how to have the same piece of matter in two locations at one time? In theory, this means that we might be able to "beam" things, rather than blow them up while trying to move them.

I seriously think we need to consider non-tradional methods of relocating ourselves rather than blowing ourselves up.

Besides, what would happen if a large nuclear powered space craft had a mishap and crashed into the earth? (or Mars??) ... do we really want to destroy the places we are trying to explore?

C'mon karma points!!

Re:No Nukes!

[Gilmoure]

While a nuclear explosion is rather devastating, it doesn't totally vaporize everything. H bomb tests at Bikini atoll included Navy ships so we could see how they weathered the explosion. I think there's a picture with one cruiser lifted hundreds of feet up in the air with one of these tests.

For an Orion, you build a really thick plate (it will slowly wear away) with some ablative surface (carbon, oil?) and set off the nuke some distance from it. You don't capture all the force of the explosion but what you do bumps you along.

Re:No Nukes!

[sphealey]

While a nuclear explosion is rather devastating, it doesn't totally vaporize everything. H bomb tests at Bikini atoll included Navy ships so we could see how they weathered the explosion. I think there's a picture with one cruiser lifted hundreds of feet up in the air with one of these tests.

The original "Bikini" test that you refer to was a shot of a 20 kt fission weapon - essentially the same as the one used at Hiroshima. The first test of a fusion weapon, the "Mike" shot, ended up being a bit larger than predicted at 10 MT. It vaporized an entire island about 2 km in diameter to a depth of about 100 m! That's a lot of vaporized rock.

sPh

Re:No Nukes!

[autopr0n]

First, like many people here, I don't understand how a nuclear explosion won't destroy the ship it is trying to move through Space at "warp speed". This seems pretty dangerous to me. Good luck finding anyone to fly that thing!

That's because you're stupid, not because it isn't possible.

Hrmmm, I wonder

[splume]

if the Rocket Guy [slashdot.org] would be interested in something like this?

Side note: Esther Dyson.

[autopr0n]

I remember reading an interview with Freeman Dyson a couple years ago in wired. He mentioned a week he visited his Daughter, Esther, at Harvard. During the time, she never attended a single class.

When he asked her about it, she said something like "you don't go to Harvard to study, you go to meet people."

It's interesting that she was one of the fist heads of ICANN.

The Curve of Binding Energy

[Zergwyn]

This is one of the books you should read if you are interested in research, both with weapons and peaceful purposes, that was done with nuclear weapons. Theodore B. Taylor was one of the most interesting and ingeninous nuclear researchers ever, and had many ideas for using directed charge nuclear devices for everything from rockets to digging subways that would span the entire continent. He also discusses how easily nuclear devices can be made, and a lot of the current state-of-the-art in devices. A definite good read. More info about the book can be found on amazon here. [amazon.com]

Metroid?

[Ill_Omen]

I hope I'm not the only one reminded of Metroid and the bomb-climbing trick.

Artificial Gravity

[IMarvinTPA]

If we were to develop a ship that accelerated at 9.8 m*m for the first half of a trip, and then slowed at the same rate for the second half of a trip, would that be sufficient for artificial gravity?

Andy

Re:Artificial Gravity

[Pig Hogger]

If we were to develop a ship that accelerated at 9.8 m*m for the first half of a trip, and then slowed at the same rate for the second half of a trip, would that be sufficient for artificial gravity?

Read Georges Rémi's (Hergé) Objectif Lune ( Destination Moon [daimi.aau.dk]) and On a marché sur la Lune (Explorers on the Moon [daimi.aau.dk]) comic books for an excellent story on the design, building and use of an atomic-powered rocket to the moon (and back - including an attempt at spacejacking) which provides artificial gravity through continuous 1G acceleration.

The fact that it was written 50 years ago in Belgium does not remove much of it's scientific accurary.

Aliens plan revenge for steel plate destroying...

[Kristoffor]

planet. AT 3:am GMT today the governments of most of the nations of earth received a formal declaration of war from an alien race who claims we fired the first shot. After many hours of discussion it was determined that this "first shot" was a large steel plate intended to dampen the effects of a nuclear explosion test performed by the United States many years ago. The steel plate propelled by the explosion escaped the earth's gravity at a heading that led it on a collision course with an unsuspecting race of aliens, almost wiping them out to the last being. The American government has made plans to compensate the few surviving members of the afflicted race by granting them naturalized citizen status and homes in Los Angeles where their outer worldly looks and nature is unlikely to be noticed.

A Family of Incredible Minds

[merger]

Just briefly I had the opportunity to meet George Dyson (a really nice down to earth guy). If the name sounds at all familiar, his sister is Ester Dyson (used to be chairperson of ICANN) and father is Freeman Dyson (a well known theoretical physicist). From what I've heard, George was always the odd one out in the family taking his own path. He used to live in a great looking tree house on the north end of Vancouver Island and then went on to research and build baidarkas (an Aleut Kayak).He has a great book on the kayaks called "Baidarka" which in the first half covers the history of the their development and Aleuts interaction with Russian traders and then moves on to cover the vessels themselves and his work.

He then went on to research and write a book on A.I. titled "Darwin Among the Machines: The Evolution of Global Intelligence". In addition to the original theories about using nuclear explosions to propel space ships, his father had the concept of building a huge structure around a star that people would live on the inside of and the star would provide the energy. You may remember this from a Star Trek Next Generation where they brought back Scotty, it was the Dyson Sphere. A final interesting tidbit is that George Dyson's grandfather Sir George Dyson was an English composer and founder of the National Federation of Music Societies.

Overall, it's an interesting family with some incredible minds in it. The BBC [bbc.co.uk] has a short piece on his AI book and on the left hand column is a real audio interview with George. There are also plenty of other links on google if you plug in his name.

Re: vacuum energy, QM

[guybarr]

also, It is not so well known that Freeman Dyson, among his many other ideas, also suggested a device to store vacuum energy (Casimir Force) known (IIRC) as Dyson-Plates.

His biggest contribution (AFAIK) is the Dyson Interaction picture of QM and QFT, on which Feynman diagrams are built. (they were friends and coworkers, BTW).

personal note: for me it was significant to know about a person in the context of a Sci-Fi writer, and then study some of his (considerable) contributions to other fields ... sort of a geekish sense of closure ;)

A good related book

[phr2]

is "The Starship and the Canoe" by Kenneth Brower. It's actually about Freeman Dyson (the "starship" refers to the Orion project) and George Dyson (who at the time was living in the Alaska wilderness). It's not really a techie book about specific impulses or engineering history, but a good read about these two very interesting people.

The elder Dyson's books

[StefanJ]

Project Orion is in the honored last position of my read-me stack. I save the most interesting stuff for last.

I feel compelled to plug Freeman Dyson's semi-autobiographical Disturbing the Universe:

http://www.amazon.com/exec/obidos/ASIN/0465016774/

I like the very earliest review. Mine's the one after.

Dyson's books are as interesting as science fiction, but without the cranky politics and cluelessness about the human condition that pervades much of the genre. Imagined Worlds is a sort of lite version of Disturbing the Universe; Weapons and Hope is a still-relevant book about arms control from the mid eighties.

Re:The elder Dyson's books

[geekoid]

"Project Orion is in the honored last position of my read-me stack. I save the most interesting stuff for last."

So, after you die you can look back and say "Man, there was a lot of interesting stuff I was going to read"?

Personal, I read the interestng stuff first, then after I die I can say "look at all the unintersting stuff I didn't have to read, WOOT!"

OTOH I can't understand why someone would read something they don't find interesting, unless mandated by a high force, such as school.

Reading Order Re:The elder Dyson's books

[StefanJ]

I recommend a lot of books to people; to maintain karma, I try to respect others' recommendations, and check out and buy books I might not normally read.

Per my rule above, I try to read these "should reads" before I read the books I really look forward to.

Generally, it works out. I've often surprised myself. The Immense Journey by Loren Eiseley was on my "should read" list, and it turned out to be a gas; a really deep and portenteous nature book.

And then there's Understanding Comics. That was on my "should read" list too. I hated and despised most comic books, but enough people recommended McCloud's book that I thought I should give it a try. DAMN! What a book. I buy a lot of way freaky comics, now.

Or: Marketing Mishaps. I found this slim paperback in a Goodwill store. It is literally a textbook; case studies on companies gone wrong. I thought it would be a good "medicine" read, for understanding why products and companies fail. It was a gas! Now I know why A.C. Gilbert, highly respected maker of Erector Sets and Chemistry Sets, is now longer around.

Clear enough?

Stefan

The Binding Curve Of Energy

[ronaldcromwell]

A book by John A. McPhee, written in 1979, called The Curve Of Binding Energy gives an excellent account of this project, including an inverview with one of it's cheif designers. It's a fabulous book, and it's short, so you could read it in a night (a long night, but hey :>) Check it out at borders [amazon.com].

Space travel isn't feasible

[Animats]

Space travel with chemical fuels isn't feasible.

After half a century of building big rockets, we now know that they don't work very well. Half a century ago, they were use-once-and-throw-away devices, and they still are. Payloads are still tiny compared to the launch weight, even for the Shuttle. Compare the figures for jet aircraft, which can be half payload.

Reliability is still lousy, too. This is because so much weight reduction is required just to get the things off the ground that they don't have adequate safety margins. About 10-20% of satellite launches still fail, almost half a century after the first one. That number isn't improving, either; in fact, it was a little better in the 1970s. There have only been a few hundred Shuttle flights, and it's blown up once. Commercial aircraft flights, by comparison, fail a few times per year, out of millions of flights.

Half a century in aviation took us from the Wright Brothers Flyer to the B-52. Half a century in rocketry took us from the Atlas I to the Atlas V. There's been little progress in launch vehicles since the 1960s. All the major launch systems were created decades ago.

So chemical fuels just don't have the power-to-weight ratio for useful space travel. People knew this in the Orion days; it's a straightforward calculation. It's unfortunate that an Orion wasn't launched once or twice, just to demonstrate that nuclear propulsion is possible.

Re:Space travel isn't feasible

[Caradoc]

SSTO (or Single Stage to Orbit) vehicles still use chemical fuels - they just use them more efficiently.

I think we're going to see some progress in this field over the next few years, assuming that the American Taxpayers don't start squawking that the money for the space program would be better used to feed people who're too lazy to work.

SSTO vehicles are vaporware

[Animats]

What SSTO vehicles? None exist.

Remember Rotary Rocket [archive.org], with their commercial SSTO vehicle They're dead. Just a little bit of weight growth in the engine, and the design became unable to make it to orbit.

Re:SSTO vehicles are vaporware

[Caradoc]

I'd agree that with current materials, SSTO vehicles won't work.

With harder ceramics, lighter composites, et cetera ad absurdum, they *will* be feasible.

The problem is that research projects keep getting killed in favor of feeding the breeders.

Re:SSTO vehicles are vaporware

[Animats]

Weight reduction is tough when well over 90% of vehicle weight at launch is fuel and oxidizer. Almost all of the fuel is used to lift fuel.

If We Build a Space Elevator

[invid]

and an atomic rocket then we'll be in business people! It will finally be here--we'll finally have an interplanetary civilization! This is what we need to aspire to. This is our destiny. Let's make it happen people. Go! Go! Go!

Just like rocket-jumping?

[t_allardyce]

So basically, they want to propel a ship by blowing up nuke... Has someone been rocket-jumping in quake too much? or maybe thats grenade jumping... Either way, you end up getting damaged :)

Freeman Dyson

[Pig Hogger]

Freeman Dyson (Freeman Dyson!) had no trouble believing in Ringworld.

Introduction to The Ringworld Engineers (Larry Niven)

We should use Orion as a contingency

[Chairboy]

I'd like to suggest the following: BUILD an Orion ship in the middle of the desert over a period of years. Whenever a big piece of military hardware is decommissioned, install it somewhere on this Orion ship. Sidewinders, old A-10 guns that fire depleted uranium, hell, even ICBMs.

Why? Just in case.

Let's say an asteroid or comet threatens civilization: You'd have a solution that, as messy as it would be, would at least be superior to millions of people getting killed.

What if aliens threaten us? We'd have SOME sort of defense.

What if some unforseeable natural disaster takes place in space and only a big old spaceship will solve it? I'd rather we be prepared then not.

Store is unfueled, keep the nukes where they are now. This way, it's no real threat to anyone. Keep the warheads off the ICBMs it has onboard, all this stuff could be installed in a day or so, if we were properly motivated.

Have schools and colleges build simple re-entry capsules that don't have to be super lightweight.

Put one or two submarine reactors onboard along with a big resevoir of water. Like Niven-Pournelle's Archangel, you could use water for attitude control. For 'precision' maneuvering, you could fire off an ICBM (properly aligned, of course).

This would be neat, and it could be done a LOT cheaper then when you use purpose built components.

Re:Wont work.

[guybarr]

why ? verification.

It's the oldest engineering axiom, but it seems to need to be stressed out more (in bold font, even :) ):

if it is not tested, it doesn't work !!!

and verifying orion means you need many test flights (for statistical confidence).

So your attitude of "build it just in case, but don't fly it." although a nice idea, is impractical. to build it requires that you test it.

Re:We should use Orion as a contingency

[Chairboy]

Sidewinders might be short range in atmosphere, but in space.... c'mon, don't people watch anime any more?

Niven and Pournelle said it best

[TheConfusedOne]

From Footfall:

THOOM

THOOM

THOOM

God was knocking,

and he wanted in...

BAD

Re:Wow

[spike hay]

It seems that blowing stuff up under you could be painful.

These bombs are small enough that they only produce a large thud after each explosion. IIRC, they also have shock absorbers to cushion the crew area. Still though, losing your lunch in space would not be very fun.

Re: A Mote in God's Eye

[RobertNotBob]

While I enjoyed A Mote in God's Eye enough to finish it, you have to admit that the author is not looking for laurels to rest on when he writes; (not quoted directly)

All of the best engineers come from the planet New Scotland, and most starship captains accept the notion that they intentionally speak with such a heavy accent that they are nearly unintelligable.

I do not have enough of a memory to quote it directly, but that is almost it.

Re:Footfall a classic?

[foistboinder]

Much of Footfall was a rehash of Lucifer's Hammer.

Re:Footfall a classic?

[DuckDuckBOOM!]

Lucifer's Hammer is an offshoot/expansion/whatever of the asteroid impact scene in Footfall. According to N&P in a making-of article (source escapes me, but I think was an old Analog,) they were pitching the story outline for Footfall, and the editor wrote back, "Forget about alien invasion. Write about asteroid impact."
The rest, as they say, is history.

Re:Footfall a classic?

[Caradoc]

The "smart crowbars" were discussed in depth as a possibility for the SDI projects - see references for "brilliant pebbles" as opposed to "smart rocks."

Re:Footfall a classic?

[Nyarly]

Still think they'd be a good idea if lifting them into space didn't cost so much. I don't know that they'd hit with quite as much force as the authors described, but hey, cool idea.

Actually, IIRC, I remember reading an article about Thor-like non-explosive deorbited projectiles that would release energy like a 10 megaton nuke. Something about building them out of tungsten, and contructing them in such a way that they conversed the jerk of their impact into outward force. My understanding was that the result of suddenly accellerating on impact would be sufficient to cause solid tungsten to explode. Nutty, crazy stuff.

Also, IIRC the Thor devices had nothing more than a radio-controlled rocket to deorbit. Niven's favorite gravitational phenomenon (tidal force) keeps them aligned like spokes around the Earth, and you scatter them in varying orbits. All the intelligence is on the ground: you need to deorbit the right thor at the right moment in order to hit your target. On the other hand, it's the technological equivalent to hurling a metal projectile ten years ago only to snap your fingers today and have it fall out of the sky on your enemy.

'rare' is a bit weak...

[autopr0n]

Hope out to particleadventure.com to read up real quick on the physics behind anti-matter. With an anti-matter drive, where the matter is anihalated into pure energy (momentarly) why both at this point dealing with nuclear? Yes I know AM is somewhat rare but jeez you think the leftist,socialist, posing as demoncrate fool tree-huggers are going to allow a nuclear drive?

Eventualy all of those afraid of nukes will die off. There's no rational reason to be afraid of them.

Anyway, antimatter is a bit more then 'rare' a single atom of antihydrogen costs something like $100,000 to produce. A billion dolars gets you just ten thousand atoms worth. that's about 1.5*10^(-10) jouls of energy.

In other words, not a lot. Even if it just cost $1 to produce a single hydrogen atom of antimater, it would require $7.2 billion to get as much energy as a watch battery. But it dosn't, it costs ~ $100,000.

Re:Nuclear Propulsion in "2001"

[spitzak]

I think that was the "Discovery", the ship going to Jupiter, that they considered making bomb-powered, and in the end certainly had some sort of nuclear engines. They tried to put the huge fins needed for heat dispersal onto it but they never looked good so they left them off in the movie.

The shuttle was always intented to be chemical powered, I think, unless those are some sort of nuclear rockets.

Re:Ion engines are better

[StefanJ]

Actually, the early concept Orion ships WOULD be launched from the ground.

As I recall, the Isp for the larger versions of Orion STARTED at 10,000 seconds.

Ion drives are great for unmanned flights, but the low thrust is a problem. You spend a lot of time just building up to escape velocity. During this time your crew is exposed to cosmic rays, are consuming expendables, and perhaps going stir-crazy. (Space . . . MADnesss!)

For this reason, higher thrust at a lower Isp can be preferable. The trip costs more in terms of reaction mass, but you get there faster.