Making the rounds over the past several days has been the BBC Future article Should we give up on the dream of space elevators?
The author, Nic Fleming, quotes both Elon Musk (of Tesla, SpaceX , SolarCity, Paypal and who knows what else) and Dr. Peter Swan, the President of the International Space Elevator Consortium (ISEC). Mr. Musk states that “This is extremely complicated. I don’t think it’s really realistic to have a space elevator” and, that it would be easier to “have a bridge from LA to Tokyo” than it would be to build a space elevator. Dr. Swan, on the other hand, thinks building a space elevator is a “slam dunk” once the materials problem has been solved.
I must respectfully take issue with statements from both parties.
Musk’s statements regarding the space elevator’s complexity and building a bridge from LA to Tokyo are almost certainly true, but I fail to see the relevance. Just because something is hard to do doesn’t mean it isn’t worthwhile attempting. And, building a bridge from LA to Tokyo is not going to open up the solar system to colonization and mineral mining and all of the other truly spectacular opportunities that await.
And I can’t agree with Dr. Swan’s statement about the non-materials issues / problems being “slam dunks” either. There are so many unknowns about building and operating a space elevator that using the term “slam dunk” to describe them is really premature. Yes, humans have decades of experience in space, but not with constructing and operating anything remotely like a space elevator. And yes, the unknowns are being addressed – it’s a major focus of ISEC (an organization of which I was proud to be the President for four years). I liked to say that one of the things we did/do at ISEC was to “take away reasons that people can say ‘no’ to a space elevator”. But we’re still in the early stages of that effort. It is quite possible that technical issues will ultimately make a space elevator impossible. But we don’t see any now and, unless and until we do, the idea is so compelling that it would be foolish not to pursue it.
At this point, it might be useful to review what the advantages of a hypothetical space elevator are over conventional rockets (IMHO of course):
- The space elevator is massively scalable. If/when a space elevator becomes possible, there is absolutely no reason why you can’t build one (or more than one) that can send hundreds of tons of payload from earth to space every day. It’s a transportation infrastructure, like the trans-continental railroad.
- Riding on a space elevator is akin to riding on a high-speed train. You do not have to worry about cushioning cargo against high-g forces and the “shake, rattle and roll” that always accompanies rocket launches.
- The space elevator will pollute less. I don’t know the numbers here and don’t know how much pollution (however you want to define that term) a rocket generates, but the space elevator’s “pollution” should be essentially zero.
- The space elevator should be safer. Rockets still have a 1-3% failure rate and it’s difficult to see how that can be significantly improved. A space elevator should have a failure rate close to 0%.
- It should be cheaper to send cargo to space via a space elevator rather than via rockets. This alleged advantage is, IMHO, more difficult to prove. It’s always a great talking point; “Space Elevators will be able to send payload into space much cheaper than rockets can“, but I’ve yet to see the numbers on this (despite my best efforts). It’s hoped that this is true, but it’s not a “slam dunk”…
I don’t see any obvious disadvantages of a space elevator vs. conventional rockets. Yes, it’s true that a ride to space in a space elevator is much slower, but so what? As you can have multiple cargo loads on a space elevator at the same time, you can set up a pipeline – getting cargo to LEO or GEO or points in between/beyond on a daily or near-daily basis. And yes, it’s also true that human cargo will traverse the Van Allen belts (and other places of radiation) for a much longer period of time on a space elevator than they would be in rockets. But, if you assume that this problem is going to be solved for longer space voyages (to Mars and beyond), then whatever technology is used to solve this problem will apply equally to both modes of transport.
One possible game-changer is if SpaceX can really prove the concept of reusable rockets. If they can do this significantly better than NASA could with the Space Shuttle, then they may largely negate two of the potential advantages of the space elevator (scalability and cost). It remains to be seen how many times a SpaceX rocket can be re-used and what the turnaround time/costs/issues are. Let’s remember that the cost of a 747 is much more than a rocket, but the 747 can be “reused” thousands of times and thus the cost per trip / per pound is significantly amortized.
Fun times ahead…