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Nuclear Booster Rockets
Logic Bomb writes: "According to the New Scientist, NASA would like to explore replacing its chemical-based booster rockets with nuclear versions. Engineers think it could be the first step towards major reductions in launch costs that would eventually lead to widespread public access to space. NASA is aware that such a project faces massive PR difficulties. As a non-expert member of the public, I can verify that. :-)"
(Disclaimer: this comes from an advocate of nuclear power. Add the appropriate block of salt.)
I've often wondered if your average anti-nuclear activist actually understands the physics involved. I'm not flaming, I'm genuinely curious. Through the media, I've seen many protests over the most trivial and safe use of nuclear technology (the Cassini launch comes to mind) but in all those news reports I've never seen an activist give a solid technical reason why they oppose nuclear power. Is that subtle filtering on the part of the media, or are these people genuinely clueless?
That's absurd! Thousands of people die every year from toxic coal waste (a good amount of which is released into the air, despite a complex filtering system).
Very, very true, and I thank you for bringing it up. In fact, less than a thousand kilometers from where I live, there's one of the world's worst coal-related toxin sites. Do a search for "Cape Breton tar ponds" in any search engine and you'll find tons of news reports on this problem.
The Sierra Club has put together a horrifying report on this site. By an astonishing coincedence, this place also has the highest cancer rate in Canada. Hmm.
And this is Canada, supposedly a bastion of environmental friendliness. Can any of you imagine what the situation might be like in countries where the local government doesn't care at all about the environment and doesn't have to be accountable to citizen's health concerns?
I'll be the first to admit that nuclear isn't a perfect solution, but stories like the Sydney tar ponds are what make me realize just how much more horrible fossil fuels can be. Nuclear waste may be more dangerous per mass unit, but at least there's a lot less of it.
It's sad that even the term nuclear had been so villified in the United States. Environmentalist groups did their best to kill American nuclear power in the 70's and 80's - unwittingly allowing for more and more pollution from smog-emitting coal plants and inefficient natural gas plants. Good luck on NASA pushing nuclear rockets through - look at the trouble they had with the Cassini probe.
Considering that in 1993 then Vice President Al Gore killed both the lithium breeder and fuel pellet nuclear designs after tests showed them to be excellent energy producers and perfectly safe against radiation release, it's clear that the American attitude to anything with "nuclear" in the title is based off irrational fears and half-truths.
Breaking through this ignorance barrier is going to harder for NASA than sending a man to the Moon...
Let's look at some of the claims in the article:
"Nuclear systems give you a chance to reduce your mass and so your overall costs to orbit," Adams says.
This is a missile-builder talking. He's clearly obsessed with one particular engineering measure of "goodness", which is called "ISP". There has been any amount of research in the last twenty to thirty years that shows that maximizing ISP does not necessarily reduce costs. If NASA's current rockets were operating at the lower end of what you can do with chemical engines then he might be correct, but they are in fact several orders of magnitude off.
Nuclear propulsion could allow single-stage rockets to reach orbit - cutting the need for expendable boosters and allowing what he calls "airline-like" access to space.
Chemical propulsion allows single-stage to orbit, if you do it correctly. In fact, NASA has already built several rockets capable of single-stage to orbit operation, but they just haven't used them that way. The second stage of the Saturn V was one of them. Launched by itself, it would have been capable of making orbit with a small payload. It had the necessary ratio of fuel to total mass.
It would also be lighter and be able to lift a bigger fraction of its starting mass into orbit - perhaps as much as 45 per cent. "With existing systems, it's more like 10 per cent," he says.
This is true, but it DOES NOT MATTER. The 90% of the mass that doesn't make it to orbit is fuel. Fuel is very cheap. The current Space Shuttle uses something like $20 million dollars of fuel to get to orbit (and the vast majority of that is the solid rockets, not the hydrogen). The total cost of a Shuttle mission is more like $1000 million. Even if you could make the fuel free it wouldn't make the shuttle any cheaper.
What is important to cheap access to space is to make the vehicles *totally* reusable, like an airliner, not throw-away like a missile. The Shuttle is partially reusable, but it still throws away a huge amount of itself each flight, and has to be totally refurbished -- a process that takes months. Space flight won't be cheap until you can fly, come back down, fill-her-up, and fly again the next day.
Even if that means that 98% of what you leave the ground with is fuel it doesn't matter until you've got total costs down to well under a tenth of what they are today, and maybe closer to a hundredth.
If you're interested in this then I highly recommend that you go and read what the Space Access Society has been writing about this stuff for more than five years now.
Based on the limited and informal associations I have with nuclear engineers, most US citizens became afraid of Nuclear power right around the time of the Three Mile Island accident. The feeling I generally get is that the majority of Slashdot doesn't remember three mile island.
Back in the 70's and 80's, Nuclear power was considered the clean solution to all of our energy problems. And they were considered increadibly safe. Until one melted down. Most Americans seem to remember Murphy's Law ("Everything that can go wrong, will go wrong"), and as such, prefer to err on the side of safety. Furthermore, there _is_ a problem with disposing of Nuclear waste. That stuff doesn't just disappear.
In response to a comment I saw earlier about how the first use for nuclear power being a weapon. That really doesn't apply. We detonated the first atomic weapons back in the 1940's. Our Nuclear Power industry was booming in the 60's and 70's. It died in the 80's. People didn't just wake up and realize that this same technology had intentionally killed thousands. No, they were more afraid that it might _unintentionally_ kill thousands more.
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