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Old August 23 2013, 11:45 PM   #52
gturner
Admiral
 
Location: Kentucky
Re: Mars One - Unethical?

publiusr wrote: View Post
gturner wrote: View Post

That's the low cost estimate - from the NASA guy who's trying to sell the SLS program.
Any new LV is going to cost out the wazoo up front. Imagine if Venture Star or some other RLV were on the table--I guarantee you it would be even more costly--and with less payload to boot. Compared to F-35 and other things this gov't does, it's a bargain.
But we're not getting a reusable launch vehicle, where the insanely high upfront cost gets paid down by a high flight rate. We're getting an expendable rocket with an insanely high upfront cost and an insanely high unit cost, so we won't launch it very often at all.

The Falcon 9 v1.1 can deliver payloads at about $1,800 a pound to LEO, and the Falcon Heavy target is about $1,000 a pound. If they manage to get re-usability working that should drop to about $200 a pound.

The best case scenario for the SLS is about $7,000 a pound, and it's more likely to come in over $10,000 a pound, with a high-end estimate of $50,000 a pound.

gturner wrote: View Post
Even if you advocate for heavy lift, it needs to be cheaper, and it shouldn't be wasting precious payload and stack height on a big crew module.
I don't know why you are concerned so much about stack height. It worked perfectly well for Saturn, and will work perfectly well for SLS.
Here's a Saturn V rollout.



The Saturn V is 363 feet tall, and the launch tower clears the top of the VAB door by about six feet. The SLS Block II crew version is already 385 feet tall, and there's no big payload bay underneath the crew module, either. That's probably why they're not developing any payloads (like a lunar lander) for it. There's no place to put one.

The screw-up was that they picked a fuel that's not dense, and thus doesn't have much impulse per volume, and then picked a narrow tank diameter (8.4 meters) so that the first and second stages necessarily have to be really, really tall. Then they mandated a very, very tall launch escape tower to sit on top of their capsule. And then it's pretty much done, already scraping the paint on the roof of the building. It'll work, as long as you don't mind limiting your missions to joy rides.
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