Up, Up, And Away!

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I discussed Chinese preparations to invade Taiwan in this post. Fellow Chicago Boy TMLutas of Flit fame left a comment.

“In other words, conventional invasion has an expiration date attached. I would guess it’s about 5 years after cheap launch becomes a reality.”

This prompted reader David Davenport to ask what was meant by “cheap launch”.

Generally speaking, the biggest expense for a satellite is getting it up there. Rockets are terribly inefficient and costly, but so far no one has built a viable alternative. But there have been some ideas proposed to get around this problem.

One of the easiest is to build a big gun and shoot small payloads into orbit. This would work to get the packages up into Low Earth Orbit (LEO), but the acceleration the payload would be subjected to would mean that it would have to be rather overbuilt. This would increase the cost per, and the size of the gun would mean that it would have to be fixed in place. Your options for the orbital path of the satellite would be limited. Still, this is the cheapest and most practical method for launching orbital weapons, and its well within the technical capability that we have now.

(As an aside, famed weapons designer Gerald Bull was very enthusiastic about this idea. He was so taken with the concept of using a giant cannon to launch satellites that he agreed to work for Saddam Hussein in the 1980’s. In return for helping the Iraqis with their missile and artillery projects, Saddam was going to fund Bull’s space-launch supergun.)

Another idea is to use ground based lasers to boost craft up to the edge of the atmosphere, where conventional rockets could take over. High intensity lasers would be pulsed into the underside of a vehicle and focused by mirrors into an air-filled chamber. The intense heat created would cause the air to heat up and explosively expand. The craft would act like a rocket without having to carry all of that heavy fuel, at least until it travels so high that the atmosphere runs out.

The most popular proposal is for a space elevator, which is a giant cable tens of thousands of miles long that stretches out into space. In simple terms, use an elevator to crawl up the cable and then simply push the satellite out the door when you get high enough.

The non-trivial technical problems that keep the space elevator from being built are legion. First and foremost is developing a material both strong enough to withstand the stress and light enough to make it possible to haul a strand about 65,000 miles straight up. Until I see bulletproof T-shirts for sale, or buy a car that weighs 2 or 3 pounds but can still withstand a 40 MPH collision with a brick wall, I’m afraid that it’s a pipe dream.

So TMLutas is very correct in saying that any large invasion force is impossible a few years after cheap ways of launching space-based defenses are developed. But, since it doesn’t look like they’re going to be developed any time soon, we’ll just have to keep on muddling along the way we have been.

12 thoughts on “Up, Up, And Away!”

  2. [ … But, since it doesn’t look like they’re going to be developed any time soon, we’ll just have to keep on muddling along the way we have been. ]

    Eggs-ackly. Space launch via giant canon is a bad idea, any way.

  3. For a few dollars worth of electricity, a payload can be accelerated using an electromagnetic accelerator, to orbital velocity.

    The length of the track would determine the accelerations necessary, and how hardened the payload would have to be. A long track to the base of Mt. Fuji and up the side might create a prideful monument to Japanese space ingenuity.

    Superconducting materials would be a tremendous boon for such a project, although not absolutely necessary with some of the newer supercapacitors and very precise timing circuits.

    Electricity is rather inexpensive.

  4. Anybody who has been following research into exotic launch methods for the last couple of decades can tell you that there are any number of potential ways to cheaply launch payloads, which are physically practical. So far they’ve all suffered from one basic difficulty: That they require a huge capital investment before you launch the first pound into orbit, and only become economic at launch rates far in excess of current market demand.

    For instance, that mass driver? It requires an evacuated tunnel, ideally hundreds of km in length. And the terminus will be subject to regular sonic booms of incredible amplitude.

    Further, the minimum payload size is quite large, as the payload has to be massive enough to punch it’s way out through the atmosphere, ablating along the way. Such a mass driver would be an engineering project that would dwarf any to date.

    The space elevator is actually the most feasible, from this perspective, once the material problem is solved, (And given progress in manufacturing long carbon nanotubes, that problem seems to be on track to a solution within a decade or so.) as it’s actually possible to build a small working space elevator, and then expand it’s capacity.

  5. First of all, today’s lift costs are between $10k and $40k per kilo. Cheap lift prices would lop off two zeros from current figures. That’s the set of goal posts I was looking at.

    The driving force to lop off those two zeros will be new things to do in space. As the PRC and India drive energy costs through the roof people are going to come to the realization that we’ve got a hard limit on energy that can only be solved by new sources and our best new sources are orbital and lunar. That’ll require cheap lift. There are likely going to be other drivers such as space tourism catching on (see Virgin Galactic) but I see that as a big one.

    I view the elevator as the most likely of the projects. The material is known (Single Wall Carbon NanoTubes, SWCNT) and progress is fairly rapid. Right now, it’s all a debate on the pace of progress and when all the technologies needed will come together. The optimists are with the Liftport group where they’re currently aiming for a 2018 launch, 13 years down the road. The pessimists are more on the lines of 2100. Here’s a recent article on the current state of the art.

    Here’s an abstract from 3/4/2005 on a new technique that may make carbon nanotubes possible in any length. Previous research had already gotten them to 4cm in length, sufficiently long to start weaving.

    There’s an awful lot of work left to do but the recent progress has been breathtakingly fast. The initial capital investment estimate on a space elevator system is about $10B. That’s not chump change but it’s certainly within the possibilities of capital markets to raise. How high does the price of oil have to get before a $10B expenditure looks like chump change?

  6. [ Electricity is rather inexpensive. ]

    Umm-hmmm, and how much for that electromagnetic rail gun up the side of and to the top of Mt. Fuji?

  7. “Anybody who has been following research into exotic launch methods for the last couple of decades can tell you that there are any number of potential ways to cheaply launch payloads, which are physically practical. So far they’ve all suffered from one basic difficulty: That they require a huge capital investment before you launch the first pound into orbit, and only become economic at launch rates far in excess of current market demand.”

    Of course “current market demand” is driven (downward) by current market price, which is (if you’ll pardon the expression) sky-high. The real questions are (a) will current market demand remain low when the capital investment is made and per-launch and per-pound charges plummet? (Not bloody likely) and (b) will current market demand be artificially held low and the required investment amount be artificially held high by the regulatory environment? (much more likely, alas)?

    High fixed cost is a feature of several currently viable industries, including the computer industry (if I recall correctly, the first computer chip to come out of a modern plant costs about a billion dollars). The space industry could become another such, and probably will in the fullness of time – the best way to shorten that time is to improve the regulatory environment.

  9. Space elevators would require incoming loads from out side earth orbit to live up to their promise. You then can have the load from Moon or Mars going down, pulling up the load you want to get into space
    in the process.

  10. Terrorists are already salivating over a target like a space elevator. A sitting duck stretching from below ground level clear out of the atmosphere and beyond, 24/365. Until security gets much better than at present, the risk is too high. Rocket launches last for a short time and either succeed or fail. But the risk is confined in time.

    Don’t be so quick to write off the electromagnetic accelerators. Of course they are more ideal on a planet without an atmosphere, such as Luna. Dealing with atmospheric resistance is a problem to be solved, among others.

    It is not necessary for the electromagnetic portion of the launch to provide the complete orbital boost. It might provide an important first stage, with a second stage provided by high powered laser or even a chemical rocket, which would require much less fuel weight thanks to the EM boost.

  11. Forgive me for my lack of vision, but why does solving this problem require cheap launch? A Chinese amphibious invasion fleet could only be so large, so the number of conventional warheads falling from orbit that would be required to defeat it couldn’t be all that huge. What prevents us from giving Taiwan 50 or 100 retired Peacekeeper boosters to be armed with conventional payloads for use against a PRC assault fleet?

    Now I don’t know some important details, like the maximum impact size and velocity that one could generate from a payload that a Peacekeeper could handle. (It was designed for MIRVs, which aren’t all that big. But it was designed for ten of them. If those ten were replaced with a single conventional payload, it might be pretty sizable — a few hundred kilograms at least, I’d bet.) But I’m betting they’re respectable, in which case the kinetic energy of a single warhead might well be enough to destroy or at least disable a large amphibous ship.

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