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Let's hear your cheap launch strategies

But, seriously until “Big business” finds something profitable in micro gravity production, unfortunately, space tourism will be the only driving factor for American businesses.
 
My other favorites have already been mentioned, so here's an interesting but rather unlikely one:
http://en.wikipedia.org/wiki/Nuclear_lightbulb

It's a nuclear rocket with no waste products in the exhaust. Instead, it runs the reactor at a very high temperature and transfers energy to a working gas (hydrogen is one of the better choices) via UV radiation. The reactor is contained with fused quartz.

Beyond that, it's just an ordinary rocket. The hot gas shoots out the rear and the rocket goes up. But there's so much energy in the fuel that you can built in a lot of redundancy, and therefore safety. And of course it's also reusable, since there's more than enough fuel to use powered landings, DC-X style.

- Dr. Trintignant
 
Why stop at a space elevator? Once you have the engineering problems solved, you can go on to build an equatorial rotor (using the earth as the stator) tethered to the moon for power generation.

Be aware of the downsides, though: if the rotor jams and the tether snaps, you have a problem of at least the magnitude of a major natural disaster; and the side effect of slowing the earth's rotation would make it imperative to move on to other space-based power technologies within a few centuries.

Respectfully,
Myriad
 
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Myriad said:
and the side effect of slowing the earth's rotation would make it imperative to move on to other space-based power technologies within a few centuries.
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That seems unlikely. According to this calculation, the kinetic energy in Earth's rotation is ~2.5x10^29 joules:
http://en.wikipedia.org/wiki/Rotational_energy

And according to this page, annual world energy use is ~5x10^17 btus, or ~5x10^20 joules:
http://www.eia.doe.gov/oiaf/ieo/highlights.html

That is 500,000,000 years worth of energy at current rates. Even assuming massive growth in energy use, a couple of centuries would have an absolutely minuscule effect on Earth's rotation (especially since the velocity term in rotational energy is squared).

I suspect that the problem with your scheme is not in the amount of energy to be tapped :).

- Dr. Trintignant
 
I would develop the cheapest possible solid rocket fuel, wrap it up in cardboard composite, and make standardized solid fuel boosters in volume so as to bring down production costs. I would then cluster these together into various launch configurations, put the guidance mechanisms at the top, and kick the whole thing to 3km/s @ 40,000ft (or thereabout) using a reusable jet-engine booster. I would then run like hell.
 
As a materials engineer I'm obviously interested in the possibility of using carbon nanotubes to produce a space elevator which would be the best solution but I think a mass driver/railgun is more feasible given current developments. But you never know, we might come on leaps and bounds within the next few years.
 
dahduh,

Absolutely. Big Dumb Boosters is the way to space. Look at the Sea Dragon link I posted above; Truax was going to have the first booster stage built in a shipyard using shipbuilding techniques. It had no pumps; Just pressurize the tanks to a prescribed pressure before launch and as the pressure in the tank decays the thrust drops off, which is just what you typically want to have happen as fuel is burnt.

And I really do believe that it would be much, much cheaper than this Orion vehicle we are now committed to.
 
dahduh said:
I would develop the cheapest possible solid rocket fuel, wrap it up in cardboard composite, and make standardized solid fuel boosters in volume so as to bring down production costs. I would then cluster these together into various launch configurations, put the guidance mechanisms at the top, and kick the whole thing to 3km/s @ 40,000ft (or thereabout) using a reusable jet-engine booster. I would then run like hell.
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There's quite a bit more validity to this position than you may realize...

There are several vehicles at or near deployment that push launch costs down into the $10M range for moderately sized payloads -- total cost is often more important that "dollar per kilogram." To wit, I could design an Orion for you that launched 1,000,000 tons at 100 dollars per kilogram, but you couldn't afford it. But I digress.

Most of the new wave of low-cost launch systems are dumb, constructed simply, and use (at least some) solid propulsion. Solids are preferred for low-cost launches primarily because of the ease of handling. You don't need a tank farm, you don't deal with so many cryogenic fluids, and your operations are much simpler. The tradeoff is that solid rockets are generally less powerful in terms of specific impulse.

The Rutan spaceplane uses an interesting "hybrid" fuel, basically a bed of rubber that is solid and relatively inert which reacts with liquid nitrous oxide. Because the combustion components are safe and inert, relatively speaking, the rocket's design is straightforward and hence inexpensive. This approach is not quite ready for prime time, but it's a good example of newer thinking.

Totally reuseable vehicles are not practical at the moment, though. Materials technology simply hasn't caught up. Simpler propulsion will lead to lower demands on materials, however, although there is still the problem of re-entry.

In the extremely long-term, it seems most feasible to me that we will develop power transmission methods of launch -- targeting extremely high-energy lasers or masers on ablative targets covering the underside of our "launch vehicles," perhaps a highly inert ceramic that generates thrust as it is melted away. The advantage here is that the main lift engine remains on the ground, and safety is nearly 100%. Such a technique is also scalable to virtually any size, provided the key challenges can be overcome. (The main challenge is how to get that much power through the plume, once the burn begins, followed by creating beams with that kind of efficiency.) It would, however, require an enormous capital investment, one that would only pay dividends after a fantastic number of launches.

At some point it isn't worth making the launch vehicle cheaper. The cargo itself has to come down in price as well. Rad-hard computing, precision instruments, maneuvering, tracking stations, software, testing and certification costs -- to say nothing of environmental control for crewed birds -- are still comparable to the cost of the launch vehicle. All this has to get cheaper too, or else we're already approaching the point of diminishing returns in launch costs (for uncrewed systems only). Of course, economy of scale will help here as well.

I don't believe space elevators will ever be practical. Orion doesn't strike me as practical unless we're faced with a one-time desperate need, though I know other professionals who disagree with me on this point. Railgun launch is a maybe, but I've never heard a good way to deal with the atmosphere -- you kind of have to launch from a vacuum.

NASA scientist, by the way, though opinions here are mine alone, as always.
 
R. Mackey,

Can you say much about the old Truax boilerplate booster idea? Yes, its a cryogenic oxidizer, but you don't have to build a launch pad for it, and you use a tanker ship to fuel it rather than a tank farm. In fact you would really only need to load the oxidizer out at sea as the RP-1 is stable.

And I suppose you could go to a H2O2 and RP-1 combination, lower your Isp, and dispense with cryo entirely, but 100% H2O2 fills me with dread as I had nearly killed myself with it in my teenage rocket building phase...

-Ben
 
I only know a little bit about Captain Truax and the Sea Dragon concept, so take my commentary with a grain of salt...

You actually need more than a tanker ship. Liquid oxygen takes quite a lot of refrigeration. You will need a substantial tank farm somewhere, be it at port or wherever. The purpose of sea launching is to get the most favorable trajectory and assistance from the Earth's rotation, not to eliminate the ground processing problems. Those are actually made more difficult because now you have to unload a gajillion tons of liquid oxygen onto the ship, and then fuel the rocket from there, adding a new and somewhat hazardous step.

In terms of using pressurization instead of boost pumps to power the rocket, this concept has been used elsewhere, in some places with considerable success -- the Atlas being the best-known example. Atlas is so thin-skinned that most of its structural integrity comes from being pressurized, and it cannot even support its own weight without positive pressure. Atlas also used LOX and RP-1, and is among the more successful launchers ever made.

We use pressurization in smaller systems, such as interplanetary stages on robotic probes, all the time -- typically using gaseous helium (GHe) as a driver gas. Safe and simple. Problem is that you lose efficiency, partly because now you have to lug around another tank, and partly because you don't dare lean out your engine. This is minor for an upper stage, where the relative size of the proplulsion system is small and precision is important, but it's hard to fathom a Saturn V-sized launcher without a positive flow system. The amount of propellant flow for a big launcher is almost unbelieveable.

The cost-to-lift claimed for the Sea Dragon is suspicious, but it's important to note that such figures naturally drop as one builds a bigger launcher. While Sea Dragon is out of family, so was Saturn V, and for largely the same reason.

Hydrazine and hydrogen peroxide are pretty dangerous, and we'd like to get rid of them completely. Probably won't happen for a long time. However, you have to keep this in perspective... the early Wehrner von Braun Mars concept called for hydrazine and pure nitric acid as its bipropellant!
 
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Atom bombs.

And if you're not nice, guess where we'll build the launch site?
 
BenBurch said:
Even inhibited Nitric Acid in a pre-passivated tank scares me to death.

But less so than 100% H2O2. (BTW I made my own in a freezer. I figure I had 98% concentration... Yes, I was immortal owing to youth.)
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As well it should...

I sympathize, by the way. A friend and I made an "engine" loosely based on the Me-163 propulsion system -- water-alcohol and hydrogen peroxide, using samarium as a catalyst. Ours was probably no higher than 85%, to be honest, but more than enough to be hazardous.

He entered it in a science fair project. The judges didn't believe him. He sent a nice, foot-long tongue of flame over the exhibit tables, and that was the end of that argument. Good times.
 
Here is a little story for you R. Mackey;

We used to own an old roadhouse out here in what used to be rural western Cook County, IL. We are Germans and so the place was known as a German place and we'd get many visitors from Germany into the place.

One evening my brother was tending bar and an old fellow ordered a beer and a hamburger and they started talking. My brother is a pilot and was reading "Flying" and he and the old fellow started talking about aircraft. And he revealed that he had been training to operate the Me-163 when the project ended and that he had flown the aircraft.

My brother asked him what it was like and he said "It was a kick in the pants."
 
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