Re: The "Real Spacecraft" Thread
Posted: Fri Apr 19, 2013 12:35 am
There is a cost associated with everything. With SLS, that cost is $40B development, plus $5B per year for running LC-39. And the political impossibility of replacing it with anything else any time soon due to the sunk cost fallicy. And that's just for the 70 ton version, which isn't lunar capable, and only 20 tons more capable than Falcon 9H.Nemo wrote:Well, technically, the component bolts and nuts and pannels only weigh in at ounces to pounds each, why use nine tons! Thats too big! There is a cost associated with building in situ versus doing it prefab under controlled conditions.
Stop right there. Salyut, Mir, and the russian, european, japanese and spaceX cargo capsules all feature automatic docking. You can build en entire spacestation this way without a single space walk. Mir was in fact built that way. The reason ISS wasn't was because NASA required a large amount of it had to be launched as dump-payloads via the shuttle, as opposed to russian style self assembally modules, which can be launched from medium-heavy rocket. They needed the station to justify the shuttle, otherwise the shuttle would have served no purpose.Every time you have to launch a new piece, every time you have to put those pieces together in space wearing a suit,
Not true. Larger constructs CAN have greater redundancy, but almost certainly will not, because useful redundancy tend to be too heavy.Larger / more massive constructions will have capability and redundancy smaller units do not.
Begging the question. Apollo failures have as much bearing on modern spaceflight as the BAC comet failures have on modern airliners. Quite frankly, if any group of engineers can't do better than 50/50 chance of survival, then either they are massively incompetent, or the mission should be scrubbed until the odds significantly improve.Assume for a minute the same failure rate held true today.
Because the whole purpose of ISS' existance was to justify the space shuttle (which meant the space shuttle had to be essential to its construction) which is a problem because the shuttle is made from arse and failure. NASA was also never quite sure, and still isn't quite sure, what the ISS is for; which is reflected in a very long string of redesigns and its jack-of-all-trades-master-of-none nature.Skylab was built on the ground and launched as one piece, with SL-2 performing some repairs to make it functional. How much time and how many cost over runs were involved in building the iss again?
Well I can guess from that question that you didn't follow the development of the station that took a hell of a lot longer than that, during which time the russians built a sx module station with out encountering any of the assembally problems the americans did. The vast majority of the problem experienced during ISS construction were home-goals, though in fairness some of them were deliberate and quasi-justified. "We do these things not because they are easy, but because they are hard," so on and so forth.They wanted to spend a lot of time outside practising orking in space, so they designed construction so they'd need to.Arioch wrote:I don't know if you followed the assembly of the ISS, which was built ~20 tonnes at a time, but it took 13 years and was a bit of a mess.
I'm not talking about nut and bolt work in freefall. I'm talking about automated docking, fuel transfer, and robotics, backed up by a proper support framework.Assembling things in orbit is difficult and expensive and fraught with problems.