> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of hkhenson > Sent: Friday, April 11, 2008 3:43 PM > To: [email protected] > Subject: RE: An interesting response > > At 12:00 PM 4/11/2008, Dan M wrote: > > (Keith wrote) > > >Takes 10 200 ton payload > > > rockets each flying once a day to do it and with a blank check > > > perhaps under 5 years to work up to this production rate and 6-7 > > > years from start to get to a $50 billion a year revenue stream > > > increasing at $25 billion a year. > > > >OK, let's do the math on that. At the present time, the cost of lift to > >geosynchronous orbit is $20,000 per kg or $20M per metric ton. Ten 200 > ton > >payloads would be about 40 billion per day or 14.6 trillion per year. > >That's roughly the GDP of the US. > > And the analogy would be how impossible it is to build a dam sending > all the contents in Fed Ex envelopes. > > >The trick is, as it always has been, to lower launch costs. > Unfortunately, > >even in inflation adjusted dollars, launch costs haven't dropped much > over > >the past 40 years. > > I agree with you. The question is why?
I wrote a blog on that general topic at the Scientific American website http://science-community.sciam.com/blog-entry/Dan-Ms-Blog/Unfortunate-Promin ent-Misconception-Concerning-Tech/300004870 The essence is that when the engineering community starts working on something, it starts working on the obviously solvable problems first. Then, progress slows as the easy problems are solved and harder problems are faced. The point at which this happens, and the manner in which it happens is based on what is found. The speed of sound barrier is rather significant, and we have not found a way to develop efficient planes that go at Mach 1.1 almost 60 years after we first went above Mach 1. >It's not the cost of energy. No, it's the cost of the system. A nearly hundred percent efficient space >elevator lifts about 2400 mt a day > > Of course you have the cost of the elevator and cleaning up the space > junk as capital costs. It can't be done at all now because we don't > have the cable, but just for analysis put a $1000 billion price tag > on it. Sure, if the cost were that low, it would work. But setting a figure like that reminds me of the story of the engineer, the chemist, and the accountant who were all stuck on a desert island with cans of food and no can opener.....I'm sure you've all heard the joke....but the punchline is the accountant, after hearing suggestions from the engineer and the chemist that don't work gives his solution that starts with "first assume we have a can opener." I've invented a few things that are used worldwide and am still engaged in practical science/engineering. I've worked close to guys who's inventions have reduce world costs for producing oil by about 250 million/day. So, I think I'm fairly familiar with processes that are economical and that work. I have not seen anything in what you have written on this subject that gives an indication of an understanding of the nature of practical solutions to problems. > Done with rockets of this sort > http://www.ilr.tu-berlin.de/koelle/Neptun/NEP2015.pdf the energy > input is about 15 times that high, or from $15 /kg down to $1.50 as > you get less and less expensive energy. I went to this website, and it looked like a speculative conference. Vaporware is easy to build. Doing something that works is hard. Most things we wish we could do we do not know how to do. I think that this is the absolutely fundamental difference you have with folks who argue for nuclear reactors vs. space based solar power. We've demonstrated > >>safety mechanisms, > > Can you be specific about what you mean here? Sure, to be effective, power would have to be transmitted down in a fairly dense fashion. One needs mechanisms that provide feedback to turn the power off should the aim stray. > > >Plus, > >it costs money to build the actual arrays. > > That's true, but with just mild concentration you can get at least 10 > times more power out of a solar cell in space. We have an overwhelmingly fundamental difference here. I have looked at the solar arrays for the space station and they are expensive. If concentration were trivial in space, don't you think they would have used it? We know on earth that techniques that use concentration have practical problems that have prevented them from being cost effective. > >If you can find a way to drop > >launch costs a factor of 100 to 500, then space based solar becomes a > >player. There is nothing like that on the horizon. > > There doesn't seem to be any reason a really huge throughput > transport system should not be able to give you that much > reduction. Then, why hasn't it happened with the scores of airline industries? 747s were brought online in the '60s....almost 40 years ago. 747s remain competitive. The airline industry is huge, and we've only seen incremental improvements over the past 40 years. _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
