Is the space shuttle too risky to use?

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qso1

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Ultimately thats true. But management failure in cases like Challenger and Columbia are much easier to refer to as management failure. Hardware failures I regard as that involving the failure of a perfectly good piece of hardware.<br /><br />In Challengers case, the hardware was good (Rubber O rings) until they sat in almost sub zero weather in Florida and cold soaked, then failed at launch. This is traceable by a management decision to launch despite seeing evidence of problems with "O" rings in cold weather in previous launches in temps below about 45 degrees F.<br /><br />Same with Columbia, an accident caused ultimately by management and engineering decisions to fly hardware that posed a threat to the vehicle, foam coming off the ET in this case.<br /><br />A scenario that could be the closest thing to hardware failure is one in which a catastrophe occurs when a piece of critical hardware fails for no apparent reason, but as you point out, it all can be traced back to some human decision. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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scottb50

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To think something so complex as a Spacecraft could be designed to be fool proof is rediculous. I remember, back in the 80's the FAA decided that everything on an aircraft was absolutely needed to allow safe flight. Then they finally saw some failures could be dismissed and came up with the overly cumbersome minimum equipment lists. This allowed flight with nonworking items, but entailed lengthy and often confusing procedures and paper work to defer an item. <br /><br />Stuff breaks and the more complex it is the more likely it is to break. A good example is a four engine aircraft. The odds are four times greater there will be a certain failure. Each engine, generator, fuel control unit, turbine wheel or whatever, has a statistical number for failure, add three more and the odds of any one of them failing is much higher because each has it's own statistical number. The odds of a similar failure on a twin engine aircraft are a lot less. The odds of two identical units failing at the same time is also higher than either failing in the first place.<br /><br />Shuttle offers one scenerio that has no backup, an SRB failure at or just after lift off. If Challenger could have seperated before the Hydrogen tank exploded, when a problem was first indicated, there may have been a chance to return or at least ditch. If it happens too soon there are no options available, the major defect in Shuttle. <br /><br />A commercial launcher could not allow this. <div class="Discussion_UserSignature"> </div>
 
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vulture2

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>>>The biggest reason why the shuttle had no where to go for 20 years? The STS system itself cost to much. That can be blamed on design changes down the road to accommodate the Air Force....<br /><br />In my opinion the Shuttle failed to meet specs for both cost and reliability by orders of magnitude primarily because critical design decisions were irrevocably made at a time when we had absolutely no flight experience with many of the critical systems. Analysis is not equivalent to experience.<br /><br />NASA was on the way to correcting this problem with the technology demonstrators, including the X-33, x-34, X-37, and DCX, unmanned suborbital craft that would have tested in flight the technologies for a new generation of resuable spacecraft.<br /><br />But Sean O'Keefe cancelled the technology demonstrators to eliminate a $4B overrun in the outyears of the ISS program, only to have Griffin cancel the STS and ISS to pay for the VSE, which is guaranteed to keep the cost of human spaceflight far to high to be practical.<br /><br />We learned the wrong lesson from Shuttle. It failed not becase reusable spacecraft are impractical, but because we had never done anything like it, and we made mistakes. Obviously if we did it again we would use more reliable systems tested in flight before being used in a manned spacecraft. We would start with a suborbital two-stage fully reusable unmanned vehicle and slowly evolve to a practical reusable shuttle, probably a TSTO with all-composite tanks and at least the first stage winged.<br /><br />But we've concluded instead that reusable spacecraft are impractical and we have to go back to '60s technology. Earlier really - in the 60's we at least had liquid fuel. The downside is that expendables will always be far to expensive to make human spaceflight practical. <br /><br />We could have advanced the technology of flight and opened the sky. Instead we've settled for expensive stunts using obsolete rockets.<br />
 
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qso1

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Scottb50:<br />I remember, back in the 80's the FAA decided that everything on an aircraft was absolutely needed to allow safe flight. Then they finally saw some failures could be dismissed and came up with the overly cumbersome minimum equipment lists.<br /><br />Me:<br />It all boils down to money. Commercial airlines have had their share of failures but as the vast majority of air travel is safe, these failures can be absorbed over time.<br /><br />Hundreds of commercial aircraft fly daily and aircraft production per model number can be measured in the hundreds. That is, there may be over a hundred 767s flying. In 1979 the 1,500th 727 was produced. Don't see many now.<br /><br />Shuttle, only 5 space worthy vehicles have ever been built and their flight rates are far below that of commercial aircraft. Between that and the cost of maintaining the shuttle fleet, loose a shuttle, you have to ground the fleet for extended time periods to ensure to the maximum extent possible that you don't loose another. In part because of the expense. We lost 2 now and if a 3rd vehicle is lost, it would shut the program down.<br /><br />Even with commercial aircraft, when an aircraft type is involved in several accidents over a short period of time, groundings are typical and in extreme cases, an aircraft may be withdrawn from service until defects are corrected.<br /><br />Scottb50:<br />A commercial launcher could not allow this.<br /><br />Me:<br />No commercial launcher flies at the very edge of technology either. The one that did was the Concorde. Government subsidized because the technology was expensive and only 16 Concordes were ever in service IIRC. <br /><br />Commercial aircraft do have a few items not possible to back up. Wings. Though it rarely happens, a wing could fail or suffer structural damage in flight. If the damage is severe enough, the craft will crash as there are no backup set of wings. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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bdewoody

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As the originator of this thread I'll make one last comment. Even though I posed the question I do not believe that the shuttle is too flawed and therefore too risky to use.<br /><br />Sure we need something better, easier and cheaper to get into space but until then I believe in it's continued use and hope and pray they have no more incidents that end up taking more lives.<br /><br />I still think the two part ship with half being an air breathing launch platform carrying the orbiter to the edge of space should be the focus of the next generation instead of a capsule sitting on top of a rocket stack. <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>
 
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scottb50

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I agree with everything except an air breathing platform. I don't think that could be done with adequate payload capacity.<br /><br />A Shuttle engine and SRB launcher that takes an upperstage to the edge of Space and returns for re-use makes a lot more sense. <div class="Discussion_UserSignature"> </div>
 
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j05h

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> I still think the two part ship with half being an air breathing launch platform carrying the orbiter to the edge of space should be the focus of the next generation instead of a capsule sitting on top of a rocket stack.<br /><br />One is mature, working technology, the other has never been shown to work. The only use I can see in a hypersonic-airbreather/orbiter is for a very small crew ferry, essentially an uprated x15 or SS1. Even that pushes the technology. Quickreach's airdropped rocket (from a c17) makes more sense, if you insist on air launch. People have been talking about hypersonic carrier craft for 40+ years, there is a reason that they haven't been developed. The tech just isn't available. <br /><br />I think a mass-produced LEO booster (Soyuz class) for passengers and a larger module-launcher (DeltaIV-H class) make more sense, mostly because they already exist. If you want truly affordable, reusable, heavy lift, put your development money into a Sea Dragon. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
 
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willpittenger

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There is danger with some types of airborne separation. Think of the Lockheed M-21 and D-21. The M-21 (might be correct to call it M-12, but I am going with WikiPedia) was designed to carry a D-21 drone on its back. The drone would be launched at Mach3+. The program died after a drone crashed into the mother ship shortly after release. One pilot died. It was the only crash of an A-12/SR-71 variant.<br /><br />Even worse would be how you reconnect them. Unless you have a STS-like Mate-Demate device at every airport you service it, you must dock them in flight. That is an accident waiting to happen. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>
 
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j05h

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> There is danger with some types of airborne separation. <br /><br />I'm a capsule+rocket fanboy - hypersonic airbreathing 15-stage RBCCCCC rocketplanes need not apply. I mentioned Airlaunch as an interesting variant- they are dropping rockets out the back of military cargo planes. Much more benign environment than supersonic staging. There are 2 similar efforts I'm aware of: Quickreach and Airlaunch. At least one of them has stated a desire to fly capsules out the back of C-17s.<br /><br />josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
 
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qso1

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My estimate was lowballed to be sure. I'd lost track of 747 hulls and didn't account for military aircraft. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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vulture2

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>>There is danger with some types of airborne separation. Think of the Lockheed M-21 and D-21. The M-21<br />------------------------------------------------<br />Plans for TSTO have called for minimizing dynamic pressures by separation at either subsonic speed in level flight or supersonic but at very high altitude where the air is thin (peak of zoom climb by carrier aircraft, perhaps 30km or more). In either case the aerodynamic forces at separation should be modest. Shuttle has acomplished the very demanding lateral separation of the SRBs at Mach 4 many times. Perhaps the M-21/D-21 was just ahead of its time.
 
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