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Homer Hickam Speaks Out For Fission Rockets
jonerik writes: "Former NASA engineer Homer Hickam (perhaps best known for his 1998 memoir "Rocket Boys," which was turned into the 1999 motion picture "October Sky") has this article in Technology Review in which he advocates that the U.S. revive its nuclear rocket program of the '50s and '60s, arguing that nuclear-powered rockets are the only realistic way of opening up the rest of the solar system - particularly Mars - to human exploration."
He is 100% correct in his assessment that nuclear power is our only currently viable option to explore the rest of the solar system.
Unfortunately, people are so freaked out about anything with the word "nuclear" or "reaction" attached to it the only way they would ever put a dime in it is if it was called "The Wonder Drive" or "Warp Drive". The really sad part about that is nuclear powered rockets really wouldn't be that dangerous. The most dangerous part about them would be getting the fuel off planet, which is not as dangerous as it sounds.
Beer Die is the game of champions Learning To walk my own path.
Nice to see an old-timer get a little coverage on /., but he really covers no new ground in that short article.
The major objections then, as now, are:
- What happens if fission powered rockets crash? Instant nuclear disaster, unless the containment vessel holds (and it might, but the public will not be convinced it would).
- Other countries fears that fission powererd rockets are actually orbiting nuclear weapons, able to be dropped on them at will. And again, even if they weren't bombs, orbiting fission rockets would be nuclear weapons: all you have to do is build the containment vessel so it can be blown apart on impact via conventional explosives, leaving a cloud of contamination.
I don't predict these space nukes are coming any time soon. Better to invest in laser propultion and linear magnetic launchers.
Here is a link to that : here
Anyway, nuclear rockets are a great idea. A better one, you may have heard me harp on this before, is VASIMR. It is a plama rocket with a nuke power source. It will be around ten times as efficient as the nuke rockers. However, the VASIMR, unlike the nuclear rocket, it does not have enough thrust to launch from earth. It is more a slow and steady engine that runs for weeks instead of minutes. But the burnout velocity of a VASIMR can be vastly higher than a chemical rocket.
The nuclear rocket can provide cheap, efficient space launches with not too much radioactive fallout. In fact, if a nuclear rocket using helium as a propelent will produce no fallout at all. Since a nuclear rocket is about twice or three times as efficient as a chemical rocket, the amount of fuel you'd need would be slashed dramatically. A nuke rocket launch might only use 10% or less of the fuel that a conventional booster would.
It's under R&D.
It ionizes hydrogen with microwaves an then accelerates them with magnetic fields. While it doen't provide thrust like a chemical rocket, it certainly has many, many times more thrust than a ion engine. It has some oomph to it. For cheap launches, you really need somthing like the x-42 scramjet spaceplane. That would cut costs of launching by a factor of 10 with no giant lasers.
VASIMR will get a specific impulse of 30,000 seconds compared to 500 seconds for the shuttle's engines. A specific impulse is the number of seconds 1 kg. of fuel could produce 1 kg. of thrust. The specific impulse of the VASIMR is 60 times better than the shuttle. That is many times better than the ~1500 seconds you'd get with the nuclear rockets.
That would allow cheap interplanetary voyages anywhere in the solar system, using very little fuel. Using these engines, you could get to Saturn in less than a year. It would also allow slow intersteller trips of around 1% the speed of light.
Also, VASIMRs could be easily, cheaply, and quickly refueled for more missions.Interplanetary travel could become cheap. I bet each ship would cost around 5 billion dollars initialy. After that, it's cheap. After each trip, an X-42 could come and restock the ship with fuel and supplies. That would only cost around 50 million. We could send tens of thousands to colonize Mars.
BTW: On this article, it says the VASIMR gets 10,000 seconds. It can reach 30,000 with further development.
Read about the VASIMR here
--
If you don't understand any of my sayings, come to me in private and I shall take you in my German mouth.
You're missing a couple of critical points:
In short, there are huge advantages to a nuclear rocket over a chemical rocket. Check out NERVA and NIMF, the two best treatments of the subject.
-- Jeff Paulsen
Oh, you mean like Chernobyl? Not to make light of 100 or so deaths, but there are worse things in the world. It's hard to get worse than Chernobyl: Big core with high burn-up (that's lots of fision products from running), Zero containment, chemical explosions and fire at ground level.
Or perhaps you were thinking of all of the thousands of above ground nuclear bomb tests that the people have performed?
- Other countries fears that fission powererd rockets are actually orbiting nuclear weapons, able to be dropped on them at will. And again, even if they weren't bombs, orbiting fission rockets would be nuclear weapons: all you have to do is build the containment vessel so it can be blown apart on impact via conventional explosives, leaving a cloud of contamination.
Holy Armagedon, Batman! Do you think that this is a more practical means of nuking your friends than the tens of thousands of purpose built warheads lying around?! What shall we do?
I suggest we quit fooling around with bullshit fears and get some good use out of Nuclear technology. Projects Kiwi and NERVA were technical sucesses killed by ludite nonsense. We can go to Mars, we can exploit the solar system and we should do so. The sooner the beter, population expands geometricaly. We can use nukes to solve our problems peacefully, or we will use them the other way as we run out of exploitable resourses here. Chose your children's future.
DMCA, Hollings, Palladium. What might have sounded like paranoia is now common sense.
Yes. Slow intersteller trips. The ship would probably be passed en route by faster ships. However, it is an easy way to send huge quatities of materials to other stars.
.1 C would be nicer for fast manned missions or probes. That would mean 40 years to Alpha Centauri. That is doable, but would require an enormous amount of fuel. .1 C, you can use several different methods.
.2 C by a 10 gigawatt beam of microwaves from an orbital power station. Very easy to do, especialy if we have nanotech. .9999 C. The gold-foil sail would be only a couple atoms thick, and supported by a scaffolding of nanotubes. The sail would weigh only a few thousand tons. The payload could be a million tons. That sounds fantastic, but an extremely advanced civilization with nanotech and AI could easily do it.
.01 C like you can reach with the VASIMR would be excellent for intersteller resupply, or sending huge numbers of people for colonization.
To reach
1. Fission fragment sail or reactor.
Uses thin films of highly fissionable Americium as fuel.
The fission fragments from the nuclear reaction escape at very high velocities, propelling the ship very fast. You can't use plutonium in this setup because it cannot fission when formed into thin films. You need thin films for fission fragment propulsion so the fragments can escape.
This setup can reach a specific impulse of 1,000,000,000. 2,000 times more efficient than chemical rockets. However, this gets too expensive when you scale it up beyond a small probe. Americium is fscking expensive, millions of dollars per ounce.
2. Fusion
Fusion's great. Once power fusion reactors come on line, the fuel will be cheap.
There are several different fusion concepts. The closest to being realized is the ant-matter catalyzed fusion type. It blows up little fusion pellets at it's rear. This uses fusionable pellets of Deuterium and Tritium that are surrounded by uranium. A very small quatity of antimatter is fired at it. This starts the fission which then starts the fusion and causes the whole thing to explode.
This could be built in 20 years. Everything is here except the antimatter. You only need a few micrograms of antimatter. We could be producing that pretty soon. It could theoretically reach 200,000 seconds.
There are other types of fusion rockets that could reach 1 million seconds. These use magnets to confine the fusion plasma. Some is leaked out the back for propulsion. However, it's hard to build a self-sustaining fusion reactor. Plus the magnet weight (1,000 tons) would have to be reduced dramatically to be practical at all. That's about 50 to 70 years away.
3. Antimatter-matter
Efficiencies of 10 million seconds
A helluva long ways away. We don't know how to begin producing enough anti-matter.
4. Beamed energy
In the distant future, the best thing for fast intersteller flight.
Just a couple decades down the road, we could build Robert Forward's starwisp probe. It would be 6 kilometers wide and be made of a fine mesh. It would weigh 42 grams, if you can believe that. It would be easily propelled to
For manned flights, you need gigantic solar arrays around the sun. Here, I'll talk about a project for a Class 2 civilization. That means one able to harness the power of an entire sun. Say, 100 years down the road, we decide to have thin-film photovoltaics constructed around the sun. That would capture around 1 octillion watts. Anyway, autonomous self-constructing robots and nanobots would get the materails off a large asteroid and begin constructing this. Being very thin solar cells, you'd only need maybe 1,000 square miles of materials. After a few years, we would have a working Dyson sphere.
Some of the power, maybe a quintilion watts could be funneled into lasers and broadcasted to a giant gold-foil sail the size of texas or the US or even much larger. The laser would be able to propel it to
Anyway,
If you don't understand any of my sayings, come to me in private and I shall take you in my German mouth.
It is really annoying when some one arguing from authority (i am a rocket scientist, listen to me) gives you misleading information.
Nuclear engines are much more dangerous than chemical ones.
If a chemical rocket develops problems on ascent ground control push a button and blow it up.
What if that rocket has a shitload of uranium or plutonium on board?
We have sent nuclear material up in rockets withsome nuclear powered stelites but they have a really negligable ammount of radiactive stuff in them, compared with what is needed for a mission to mars.
And if you think that rockets do not blow up on ascent any more you have not seen NASA's record recently.
So there you have it - thats a risk that he did not mention although it is a very relevant factor. Now you may say - the risk is not that great, or it is worth it, but it should have been mentioned in an honest article.
And also the thing he said about getting energy from space is such BS. If he knows as much about nuclear power as he pretends to he should know that we have enough uranium to give us energy for a loooong time and nuclear powerplants are much safer than nuclear rockets.