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Comment by berntb | Hacker News Reader

Since it seems we could have had viable colonies outside the atmosphere by now, this should have implications for Fermi's Paradox.

If Fermi's Paradox comes from a limiting factor "removing" civilizations (a physics experiment, etc), it should need to destroy a whole solar system and not only a planet. Otherwise it would only remove the fraction of civilizations that didn't develop an Orion before that experiment.

IIRC, NASA killed Orion politically? They might have exterminated humanity -- for job security...

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I'm guessing that civilizations on some other planets probably have a much easier time of colonizing space than we do. We have the misfortune of finding ourselves in the only vaguely-habitable rock in our own solar system, but some other systems must have multiple habitable planets, even multiple life-supporting ones.

Imagine if the moon had been several times bigger -- it would have an atmosphere, and thanks to panspermia might even have picked up enough life from Earth to give it a breathable atmosphere. The Apollo Project would have immediately been followed by a project to kill and eat the local wildlife to see what it tastes like. Or suppose we'd evolved on a moon of a Jupiter-like planet in the habitable zone -- there'd be a whole bunch of other equally habitable moons just a short flight away.

Instead we're stuck on a big rock, looking at a bunch of other rocks which are fairly useless to us. Sigh.

I'm fuzzy on this so I may be wrong, but wouldn't the moon require a metal core to create a magnetic field to hold the atmosphere (or protect it from being bombarded by radiation)?

Quite likely, yes.

If Fermi's Paradox comes from a limiting factor "removing" civilizations (a physics experiment, etc), it should need to destroy a whole solar system and not only a planet.

Maybe the economic hurdles are the limiting factors? Economics seems to be closely related to game theory. I bet a lot of the principles apply to all civilizations.

Space access can be much cheaper, even without nuclear launch.

They talked of building the Orion the same way as submarines, iirc. I've read Henry Spencer argue that modern rockets and payloads are so expensive to make because they have to save on every gram.

Actually, it's good they killed the Orion.

Can you imagine a streak of detonating nukes all the way to LEO?

>>Actually, it's good they killed the Orion.

Extreme, world changing (in more than one way) and mind blowing (also in more than one way!) technological marvels might not be your cup of tea?

Edit: I might add -- if you can't handle tea, stay with the boiled water...

>>Can you imagine a streak of detonating nukes all the way to LEO?

I can imagine it -- all the way to Saturn's moons, by way of the asteroid belt. What a beautiful dream.

But certainly, a careful analysis of the failure modes might be considered prudent. An infrastructure outside the atmosphere would easily arguably be worth at least a small increase in cancer risk.

(Today is a different matter of course, since it would be detrimental to lots of very expensive satellites' health.)

Don't get me wrong. I would love the aircraft-carrier sized spacecraft and the sheer demonstration of power of it reaching orbit and leaving to deep space.

What I don't like is the huge EMP destroying electronics across half a planet and the fallout making three-eyed fish.

Orion is great, but we would have to find cleaner propellants if we really want to build a lot of them ;-)

It's also unclear how many we could propel with the amount of fissiles we have on Earth.

>>It's also unclear how many we could propel with the amount of fissiles we have on Earth.

Was that a joke? Can you give a reference which discusses how many thousands ton of nukes that are limiting...?

(Hint, not that much uranium is needed for those bombs. Also, from what I've read -- if the Uranium prices go up a bit, there will be much more mined.)

Each Orion mission would require a couple dozen explosions to reach LEO, plus several (according to the delta-v you require for the specific journeys) for propelling them.

Don't forget the technology is not ready yet - it would be a lot harder than following the blueprints and building it naval ship style. Specific nukes would have to be developed for this project, nuclear fuel to be diverted from military uses, the environmental risks be measured and, possibly, an acceptable death toll would have to be determined. An astronaut blown to pieces is a very different thing than a mutant boy half a planet away whose lack of luck can be somewhat blamed on increased environmental radiation.

Orion is a great idea. Perhaps some aspects of it could be salvaged, but I seriously doubt we will see one ground-launched unless we develop pure fusion bombs. OTOH, if we are to bang our heads developing pure fusion bombs (which we can agree are a very bad idea), we could as well develop some other form of propulsion, nuclear fusion or not.

As for the number of nukes, just imagine how many a small fleet of them would require to haul itself around the solar system and other uses. Launching them (and their nukes) would be the easy part.

Orion is insanely cool and I am a bit ashamed we cannot build one, but I am not attached to it in any special way. This is not the way to go. It was not practical in the 50's and it's not practical now. We still must find a better way.

>>Each Orion mission would require a couple dozen explosions to reach LEO

Huh? Values I've seen talks about a nuclear explosion around per second. You'd need a few minutes to reach LEO.

>>nuclear fuel to be diverted from military uses

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

"The decommissioning programme of Russian nuclear warheads accounted for about 13% of total world requirement for enriched uranium leading up to 2008."

Etc.

(And of course it isn't a simple decision. Few interesting ones ever are.)

This is the second discussion in a short time where you obviously don't know anything at all but still write.

Personally, if I don't know anything about a subject, I just read and/or ask. Since I know my opinions will change when I know more, anyway.

There was a pretty good article I read a few years ago about the technical problems with Orion. It wasn't just politics which killed it:

http://www.alternatehistory.com/gateway/essays/OrionProblems...

The main problem is the fact that hydrogen bombs sans fission trigger turned out not to be possible [] which increases the amount of radiation released per launch from "modest" to "really quite excessive".

[] Or if they are possible then the folks who know how to build them certainly aren't interested in letting on. There'd be nothing worse for nonproliferation than hydrogen bombs without a U or Pu trigger.

After a quick browse, that reference seems quite good -- but with a lot of spin. Who wrote the article?

Can you get me a REAL reference for "really excessive" radiation? IIRC, it contradicts both Dyson's son's book and most everything else I've read.

Edit: The Wikipedia page on project Orion (http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsi...) contradicts the claim that the radiation estimation is based on fusion only bombs. ("Freeman Dyson, group leader on the project, estimated back in the '60s that with conventional nuclear weapons, that each launch would cause on average between 0.1 and 1 fatal cancers from the fallout"). Also see "Edit 2" below. That fits with my memories, too. A serious error on the page -- to make a point... a pity, the author was obviously knowledgeable but seems dishonest. (I won't bother checking the rest of the reference, if that got through.)

Regarding costs, the Orions were thought to be built like a water going ship out of steel. That means orders of magnitudes less cost. Also, many problems just go away in designing equipment if you can throw weight at it (common example is heat distribution.)

(Was there even serious discussion about making ion drive research in the 1960s? Ah, another thing NASA should have founded -- but used all the money for the shuttle instead. :-( )

Also, the whole point with Orion was that you could literally go in person all over the solar system 30+ years ago -- which we still won't do inside decades...

Edit 2: Also from the Wikipedia page discussed in the edit above:

The fallout for the entire launch of a 6000 short ton (5500 metric ton) Orion is only equal to a ten-megaton (40 petajoule) blast, assuming the use of pure fission weapon-type nuclear explosives.

With special designs of the nuclear explosive, Ted Taylor estimated that it could be reduced tenfold, or even to zero if a pure fusion explosive could be constructed

wasn't it the 1963 nuclear test ban treaty? basicaly, after that, you could only detonate nukes during peacetime underground, right?

and orion would have been detonating them not-too-distant from earth when ramping up for interstellar voyages.

No. Kennedy was shown a design for an Orion well before that, and was freaked out by the possibility of one hovering over an enemy city, per Ted Taylor, the project leader. The test ban treaty signing might have actually been partially a result of Orion, rather than an unrelated activity that shut it down.

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