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Biting Commentary about Infinity, and Beyond!

« Fixed And Variable Costs | Main | Space Prizes Continue To Get Interest »

New Space Blog

Over at The New Scientist. And contrary to commenters who think that few indulge in it, the current top posting repeats the fallacy of high launch costs.

Posted by Rand Simberg at June 09, 2007 10:56 AM
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hmm, that's funny. I read the whole page, I didn't see any words about launch costs. The topmost post was about the difficulty of attaining orbital spaceflight, and mentioned that chemical rockets are inefficient in the sense of low payload fraction. surely you're not arguing that?

Posted by tom at June 10, 2007 07:03 AM

I disagree that a) "inefficiency" defined in such a way is a problem and b) that the solution to that non-problem is a space elevator. The implication is clearly about launch costs, even if the phrase isn't used.

Posted by Rand Simberg at June 10, 2007 08:07 AM

Mass fraction doesn't matter. $/kg is what matters. Spending billions to reduce the mass fraction just increases the capitalized cost if the flight rate stays low.

Posted by Sam Dinkin at June 10, 2007 08:34 AM

A simple formual for lowering launch costs:


That initial investment is the one everyone forgets! If you are a private company, you must pay either interest on a loan or return on investment to investors (or your won't get investors!). If you are public (NASA), it is less obvious but since you are spending Joe publics money, and Joe public's money has a time value of about 10% (just ask Joe public if he'd rather have $100 today or $110 a year from now - it is about a wash at that point), you still need to apply propper discount rates - as in, Joe public (your boss) would prefer to spend less on infrastructure up front and more on per flight costs.

When you examine space elevators using this formula, they are less appealing - though perhaps still doable. (Space elevators appear to have a rather low maximum flight rate - if it takes a week to get there, your maximum flight rate is 54 per year...)

Posted by David Summers at June 10, 2007 10:30 AM

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