On my flight to Paris last night, I finished a detailed reading of The Space Elevator by Bradley Edwards and Eric Westling (I praised the book in an earlier post based on skimming it and reading a few sections). This 2003 book is a real tour de force that describes and analyzes the coming technology of space elevators with great clarity and detail. The amazing thing is that the space elevator (SE) is now not so much a problem of waiting for scientific breakthroughs as it is solving a lot of challenging but not unprecedented engineering problems (and getting the funding). The main technical breakthrough took place in 1991, with the discovery of carbon nanotubes (CNT). This material has many useful properties and a growing list of applications, but for SE applications, its main strength is its... strength! It's incredibly strong and light.
Within the last few months, I read of a technical breakthrough in the rapid fabrication of CNT ribbons and sheets of the type needed by the SE at a prototype rate of 7 meters per minute (published in Science magazine, August 19). These prototypes are very strong but not yet strong enough, and this is not fast enough for the thousands of kilometers of CNT ribbon that will be needed for the SE -- but it's a huge advance over previous methods of making CNT composites.
I also learned about the LiftPort Group a few weeks back -- a commercial venture that is developing SE technology now. They have begun to test early versions of the robotic "climbers" that will pull themselves up the ribbons and eventually to space. Their small test lifters recently climbed 1000 feet (305 meters) up a balloon-suspended test ribbon.
Here's the thing. Rockets are cool and have gotten us where we are today in space, but chemical rockets can never be an efficient and cost-effective way to get large cargos and people to space on a routine basis. The Earth's gravity well is just too deep, and a huge fraction of any rocket has to be fuel. The space elevator is the solution. It will eventually make access to low Earth orbit and beyond as routine and cost-effective as international airline flight is today. The astounding thing is that "eventually" is not centuries or even decades. We could have these things in 10-15 years. The benefits will be enormous. This is not science fiction, boys and girls.
7 comments:
A space elevator is a solution - and we may yet find that for some reason or another it can't be made to work.
It is possible to make an efficient inexpensive chemical rocket system but the details of getting it done make that program as tricky to pull off as a space elevator. And possibly more expensive for less throughput.
Thanks for the reality check Brian. It's hard not to be optimistic after finishing that book, though the authors are clear that there are many problems to be solved, some of them possibly show-stoppers.
It's good that people are actually working to make the SE happen, and that private enterprise is also going after cheaper launch vehicles and other space projects too (not to mention the government agencies that are still in the game). I'm optimistic -- or maybe hopeful.
I agree that a space elevator is a solution, but I don't think that chemical rockets will ever provide anywhere near the capabilities that an elevator would. If for some unfortunate accident of materials sicence, we are unable to make the elevator work, we will be much poorer for it.
The economics of chemical rockets will never allow for mass migration off of the planet, or at least not anytime soon. The primary reason why the space elevator is so vastly more efficient is that you needn't build a vehicle capable of withstanding enormous dynamic loading during acceleration to orbit. You need only to withstand the gentle acceleration of the elevator, so the elevator "climbers" will be far lighter/ton of orbited material. That means less fuel, which means less fuel to lift the additional fuel.
The turnaround times of an elevator climber will always be higher than those of chemical rockets, again for the dynamical loading reason. Thus costs are amortized over many more "launches", and service lives will inevitably be longer, further increasing the argument for the elevator.
Others far more dedicated than I to the elevator cause have no doubt investigated these issues already, so I mainly point out these things to support my contention that chemical rockets will not allow for cheap spaceflight in my lifetime. Space will be a playground of the rich and of large corporations and governments. The vast majority of the world will look to the sky and see only further segregation, not opportunity and optimism. I firmly believe in the transformative power of a spacefaring civilization, but to make it happen this century, we need the elevator.
How was your flight to Paris, Bruce? How long are you staying there? I'm flying to Paris in 7 days myself :)
Thanks for the reality check Brian.
I figure 'skeptic' is not a bad stance for someone working where I do. At the very least it's a mental reset for people who expect someone from Liftport to be a an uncritical cheerleader.
It's good that people are actually working to make the SE happen,
Others far more dedicated than I to the elevator cause have no doubt investigated these issues already, so I mainly point out these things to support my contention that chemical rockets will not allow for cheap spaceflight in my lifetime.
John London wrote a really good book on the subject - it's worth reading if you're interested.
His contention is that chemical rockets CAN bring costs down. But in my humble somewhat informed layman's opinion the number of factors that have to conspire to allow it just won't happen. Perhaps if we could go back to the 60s and change come things .. but no do-overs in life.
John London, Lt Col USAF -
"LEO on the Cheap, Methods for Achieving Drastic Reductions in Space Launch Costs"
Available at Amazon. There used to be a place to download it free (and with the author's permission). I have - or should have - a copy if you ask.
Brian,
I would be interested in the copy if you could find it. My email is kendal30 AT yahoo DOT com. Thanks!
Anthony
Colonel London's book is donwloadable at http://www.dunnspace.com/leo_on_the_cheap.htm
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