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Telecoms and the market for satellites has only recently boomed. You cannot compare the two programs in such a way.
by pothibo 12y ago
Telecoms and the market for satellites has only recently boomed. You cannot compare the two programs in such a way.
- ceejayoz 12y agoThe limiting factor of the Shuttle wasn't low demand for its services, I don't think.
- Retric 12y agoDemand was ~1/10 of projected demand which dramatically increased costs not only by increasing overhead by also by extending vehicle lifespans well beyond what they where designed for. Put another way, scrapping a shuttle mission saved less than 90 million. PS: It was also horribly compromised based on Airforce requirements yet never flew a single Airforce mission.
- nickff 12y agoI am not sure what the rated vehicle lifespans were at the time of building, but the design life was 100 missions per shuttle, and the most-flown shuttle (Discovery) only flew 39.
- Retric 12y agoThe initial assumption was 40 missions a year. Based on the estimated risks you might get 100 missions from a shuttle on average. So 5 orbitors * 100 / 40 = 12.5 years or ~ 10 years with an early loss. They where in service for 30 years and averaged 4.5 missions per year. For comparison compare the matence cycle a low mileage 0 to 10 year old car vs a low mileage 15 to 30 year old car.
- nickff 12y agoI've heard this reasoning before (from NASA personnel), but I have never seen the reasoning behind it. Many of the design life requirements were impossible to meet to begin with, such as the 50-launch design life of the Space Shuttle main engines (because of the high chamber pressures, and problems with bearings). If you have some evidence of the veracity of this claim, I would be very interested to read it.
- deleted 12y ago[deleted]
- deleted 12y ago[deleted]
- Crito 12y agoI wonder if that was "We believe they are capable of 100 missions, because we require 100 missions" or "We believe they are capable of 100 missions, because that is what our test data actually suggests". See: Feynman's Appendix F. Specifically his criticism of the Shuttle reliability numbers quoted by NASA management and how they differed from the reliability numbers quoted by NASA engineers.
- nickff 12y agoDesign life and rated life (as built) are two completely different things. The Space Shuttle requirements stated that it should be capable of 100 missions, but I have never seen any document describing what they were rated for, after they were constructed, and the flight tests were completed.
- Crito 12y ago> PS: It was also horribly compromised based on Airforce requirements yet never flew a single Airforce mission. The shuttles flew a few DoD missions, including I believe at least one for the Air Force (a DSCS satellite during STS-51-J I believe? Maybe others, which DoD mission was for who isn't nicely broken down anywhere that I can find. It looks like most were for the NRO). However none of the Shuttles ever flew a polar orbit mission; an ability that the Air Force demanded but never used. The large cross-range capabilities of the shuttle (necessitating such large wings) was for polar orbit missions, so those massive wings were dead weight caused by the Air Force.
- sitkack 12y agoFunny because wasn't the shuttle-c used for military missions and it has almost no wings.
- Retric 12y agoI should have been more clear. The airforce had two mission profiles outside NASA's goals. Polar orbits AND capturing Russian satilites. Neither of those missions types where ever flown. The Airforce ended up having a huge impact on the design including much larger cargo bay etc but it was those two mission profiles that really fucked up the design. If NASA had gotten it's way the shuttle would have been more reliable and cost less than 1/3 as much per mission at the cost of significantly lowered cargo capasity. Intact both shuttle disasters can be traced back to these compromises.
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- rspeed 12y agoNor is it for Falcon 9. They're launching them as fast as they can build them, and have a significant payload backlog.