Jeff Foust has a report on two speeches at the recent ISDC, from Jeff Greason and Paul Spudis.
[Update a few minutes later]
Grant Bonin explains the economics of rockets, and why the Senate Launch System is a waste of money.
9 thoughts on “How To Settle Space”
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Every step forward for a heavy lift system is a step backwards for sustainable human flight BEO vs. stunts. Because instead of HL, we need fuel storage facilities and high flight rates to force down costs.
I’m sure I could find a useful scenario for an HL beyond 70 MT if I thought about it. But like Ike said about RMN, I’d need some days (or months? or years?) to think about it.
Greason has most of the puzzle figured out, but he’s missing one piece, alluded to at the end of Robert Bigelow’s speech, and it’s something that was learned the hard way by the Jamestown settlers. The US must exercise Article 16 of the Outer Space Treaty (i.e. withdraw from the treaty) so that private claims on extraterrestrial assets can go forward. Without private property you get no investment in BEO activities, with private property investors have an exit strategy.
Can anyone answer this: Is it possible to build H2/O2 Isp 450 rocket engines that have similar re-usability at similar maintenance requirements as the jet engines on airliners?
Well, the original RL-10 was pretty close. No maintenance needed under normal conditions as I understand it. Regeneratively cooled, low pressure engines as a general class are pretty light on maintenance needs.
Even the shuttle SSMEs have virtually no maintenance. The problem is that they only made a limited number and any maintenance is next to impossible – you can’t get parts.
My recollection of something I read years ago was that the SSME’s had a lifetime of 20 launches, but when I was looking this stuff up yesterday I found something saying they were good for 10 consecutive launches without requiring major maintenance. If that’s the case, why does it take NASA so long to turn the shuttle around, what bits are so complex and time consuming?
The engines are still inspected quite frequently and that requires their dismounting in many cases.
The basic problem with the Orbiter maintenance is that it was NOT DESIGNED to be easily maintained. Not that it couldn’t have been, but that it wasn’t. The components were “supposed” to have very long life, and so the design features needed to allow them to be removed and replaced without enormous labor were not included. Imagine that 99% of your car engine parts lasted a long time, but the 1% that failed often were buried in the heart of the engine and you had to diassemble the whole engine to get at it. The 99% that works doesn’t help the average much….
All of this could be corrected in a second generation reusable system, applying lessons learned — as long as it were being designed by an organization which viewed high operating cost as a bug, rather than a feature.
If that’s the case, why does it take NASA so long to turn the shuttle around, what bits are so complex and time consuming?
From what I’ve heard checking and rewaterproofing the tiles is the greatest culprit. The hypergolic OMS doesn’t help, especially as everybody else has to evacuate the facility as it is being safed or loaded with propellant.
It sounds like there really are no technical show stoppers then for developing fully reusable spaceplanes with turnaround times of a day or so?
If you do the maths, working on TSTO HTHL, on the cost to orbit on that assumption you get what are ridiculously low numbers (less than a hundred dollars a kg) compared to todays payload costs. Add in a hypersonic rotovator, which could halve the delta V required of the upper stage the cost/kg gets into the very low double figures.