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The Business Case for Reusable Launch Vehicles
An anonymous reader writes "Remember the failures of "shuttle replacements" like VentureStar? A Space Review article argues that even if VentureStar succeeded technically, it and other proposed big RLVs would never have made it financially: they cost too much to develop and wouldn't have made it up through increased launches. What's the solution? The author says that suborbital RLVs, like what Carmack, Rutan, and the other X Prize contenders are working on, will create a business cycle that will eventually lead to orbital vehicles."
The problem with incremental development of RLVs is that there's a huge
leap between the size and difficulty of putting something into space
for five minutes (as in the current X-prize contenders) and putting it
into orbit (as in the shuttle). That will make it difficult to evolve our
way into a commercial space program.
I often find myself pointing out that just getting into space isn't
all that hard. Lifting yourself up 100km requires about a megajoule
(that's the energy equivalent of a stick of dynamite, or about 1/12th
of a gallon of gasoline (about 1/4 kg or 1/2 pound of gasoline), or a
jelly doughnut, or running a hairdryer for 2 minutes) per kilogram of
mass.
By contrast, orbital speed is something like 7000 meters per second,
(or 16,000 miles per hour for you provincials). Getting going that fast
requires an additional 24 megajoules per kilogram of mass (for a total of
25).
In short, the difference between the amount of energy you need to
get into orbit and just into space is a factor of 25, for the same
mass. That ratio of 25 is about equal to the difference between the
latent chemical energies of broccoli and gasoline.
Except that, in the case of space travel, you better be burning
something at least as energetic as gasoline to start with, or you'll
never even hoist yourself up 100km.
The way we've traditionally gotten into orbit is to concentrate the
kinetic energy into ever smaller bits of the vehicle: you use a huge
rocket motor and tanks to get everything started moving, then ditch the
empty tankage and rocket motors for the first stage -- that lets you
concentrate on moving a smaller amount of stuff even faster.
Realistic reusable designs are usually not staged designs,
because it's hard to recover and reuse the first stages. The problem is
that you have to have incredibly lightweight tankage and engines to make
everything work. But pushing stuff to lighter weight makes it more
flimsy and less prone to being reusable. Darn.
The VentureStar, IIRC, ran into problems with exactly this technology --
they were using lightweight carbon fiber tanks to hold their propellant,
and they couldn't make the tank light enough to boost itself into orbit.
The shuttle is NOT a reusable vehicle in any but the most technical
sense of the word: it requires constant skilled redesign and intelligent
(rather than scripted) maintenance, and the engines have to be overhauled
after every flight.
The best picture I could find was this one on HowStuffWorks.
Comment forecast: Bits of genius surrounded by a sea of mediocrity.
It's imagination. The aviation industry used to have a handful of folks who could imagine and conceptualize the darndest vehicles - and a slew of brilliant engineers to turn those concepts into reality (or dis-prove the concept based on technical limitations, materiaks, etc.)
Nowadays, money issues and the eternal pursuit of higher profit margins has forced many of the dreamers out of the big aerospace companies and into places where there simply isn't the technical base to turn their ideas into anything at all. That's where the X-Prize will hopefully bear fruit - IF (when) the prize is claimed.
How long did it take for Trans-Atlantic airlines to start showing profits after Lindy made his flight? It's a rhetorical question, but the answer might be interesting, nonetheless.
This sig is a test. If this had been an actual sig, you would be reading something quite a bit wittier than this now.
While the article does make some good points about the high development costs, technological hurdles, and poor ROI on reusable orbital vehicles, I think that there is very little evidence of any solid business case for reusable sub-orbital vehicles. Just because it's not cost-effective to build and fly ROVs doesn't somehow make RSVs any more logical.
As a development step leading to the next ROV, an RSV may make sense. I am the first to admit that *anything* that gets the public to refocus their attention (and money) on the pursuit of space-related technological goals is a good thing, as it will inevitably drive the aerospace industry to push the engineering envelope in many areas, particularly in materials science (things like new composites, high-temperature ceramics, etc.). Technological advancement is a worthy (and, ultimately, profitable) pursuit.
But, in and of itself, as a "working vehicle", I can't see any suborbital spacecraft making money. There just aren't that many rich "space tourists" around to subsidize this as an industry. Suborbital vehicles are completely useless for the two main "space jobs" that countries and/or companies are willing to pay for: satellite launches and trips to the ISS.
Low Earth Orbit (LEO) is a useful destination. If you can get "stuff" into LEO, later trips can bring more "stuff", and, if you bring enough pieces of another space ship to LEO, you can assemble them there, and can go to other places. In terms of energy, LEO is truly "halfway to anywhere". One of the (rejected for complexity and deadline reasons) proposed Apollo moon landing plans involved assembling a Earth-to-Moon ship in LEO from modules launched over a period of time using multiple smaller launchers.
But, suborbital vehicles, by definition, can't reach LEO. Anything launched sub-orbitally *will* return to Earth, usually sooner, rather than later. There's simply no market for delivery vehicles that always bring their cargo back, and never leave it at the destination!
Bottom line: it may make sense to use an RSV as a technology test-bed as a step on the path to developing an ROV. It makes no sense to develop an RSV as an end in itself.
Ed, one of the guys aboard the ISS currently, wrote his take on the future of spaceships, which i thought was a good read.
...then imagine how much they'll pay for the experience of zero-G sex! Screw the mile-high club, I wanna join the 800-mile high club!
Sorry to disagree but your argument is historically invalid. Every new frontier has had entry costs: cost in money, cost in materials, cost in lives. If Columbus had thought the way you do the New World would never have been discovered, and you probably wouldn't be here.
Eventually, every frontier has been commercialized and used for profit, whether it be new continents, the sea, space, the microcosm, you name it. Space already has been successfully exploited for communications, research, military and entertainment purposes, and if we continue to expand our presence there it will become even more valuable. I got news for you: space became commercially viable some time ago.
The higher the technology, the sharper that two-edged sword.
Let's not forget that there are a number of potentially viable alternatives to strapping oneself to a controlled chemical explosion and hoping it gets you where you want to go.
The mass-driver concept pioneered by MIT is one that could provide continuous access to near-Earth orbits with clockwork precision. It would be expensive to build and run, but once running would reliably put anything we want into orbit, continuously, twenty-four hours a day.
Another possibility is the laser-launcher. A rocket fueled simply by tanks of water would be heated by a bank of ground-based lasers: the resulting superheated steam would lift the vehicle into the desired orbit. The energy to propel the spacecraft would come from the source powering the lasers, not from any chemical fuel in the vehicle itself. This system would have the advantage of not requiring massive acceleration: laser power could be modulated to provide a comparatively gentle takeoff.
The irrational focus on self-contained launch vehicles is the problem: there are ways to get the required kinetic energy to the vehicle without an on-board fuel supply. Granted, it might take a nuclear power plant or two to run either of the above options, but that's a lot cheaper than building even a single space shuttle, much less developing and flying the current crop of pie-in-the-sky alternatives. Current estimates put the cost of a single space-shuttle launch at 1.5 billion dollars (I suspect that's conservative.)
And hey, when one of these gound-based launching systems isn't boosting spacecraft into orbit, it can be connected to the local power grid to light homes and businesses. Sales of power to the local utilities could be used to help offset launch costs.
The higher the technology, the sharper that two-edged sword.