Space Shuttle Replacement

[aphh]

<p>Ariane 5 is basically same configuration as Energia, only smaller. One of Ariane 5's payload included small Hermes spaceplane. </p><p>Ofcourse they cancelled Hermes but Ariane 5 is available for 25 metric tonnes to LEO.&nbsp;</p>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>... So, I think it is safe to say that the shuttle is probably 99% safe today. We'll see if any stick-capsule design lifting 6 people can reach this level of safety. I know that I would rather fly on STS-134 than Area-1-1. Of course, the fact that the shuttle cannot do heavy-lift duty *combined* with the fact that using a capsule is more efficient is what doomed the shuttle program. If we had used a Buran-like shuttle, the program would not be cut, and we could have a space station and moon base. <br />Posted by wubblie</DIV></p><p>I tend to agree with you in principle, although 99% safe is open to argument.&nbsp; Rockets in gerneral are in the 96%-97% reliable range.&nbsp; The shuttle reliability ought to be&nbsp;higher due to the higher level of scrutiny for manned missions, but on the down side the addition of re-entry and landing adds complexity to the mission and with it risk.&nbsp; In any case the shuttle really is a pretty good system.&nbsp; I am not sure what&nbsp;you mean by saying that the shuttle cannot do heavy lift.&nbsp; By today's standards&nbsp;I think it qualifies for heavy lift.&nbsp; By Saturn V standards is does not.&nbsp; There are concepts for use of an unmanned shuttle with an extremely high payload capability.&nbsp; The propulsion system is up to it.&nbsp; What reduces the shuttle's capability is the extra inert weight for prolonged manned operation.&nbsp; If you were to consider the orbiter itself as the payload, then the shuttle would represent heavy lift indeed.</p><p>I see no reason why the Areies I should not be capable of reliability as good as that of the shuttle.&nbsp; Perhaps greater due to a simpler landing concept.&nbsp; You are also quite correct in that failures result in the identification of new potential modes and those modes are addressed before restart.&nbsp; There is a document produced for each program called a FMECA (Failure Modes and Effects Criticality Analysis).&nbsp; That documente is the result of an analysis of the system, identifying potential failure modes, their likely effect, and suggested corrective action.&nbsp; I have never been involved in a failure analysis in which the ultimate culprit was on that list.&nbsp; The reason is simply that recognized failure modes are mitigated and generally do not actually become realized.&nbsp; It is the stuff that you don't recognize that bites.&nbsp; One possible counter-example is the Columbia disaster, since the incidence of foam breaking off the main tank was known.&nbsp; In that case the uncertainties were not properly evaluated and mitigated.&nbsp; It may be that the failure mode was on the FMECA, I just am not sure about that point.&nbsp; I am of the opinion that the Columbia accident need not have happened.&nbsp; </p><p>But I think the real reason for the demise of the shuttle is rooted in political consideratioins.&nbsp; The shuttle&nbsp;was the subject of &nbsp;terrible public perception after the Columbia accident.&nbsp; All sorts of arm-chair experts came out of the woodwork.&nbsp; And NASA wanted a new project to work and new objectives.&nbsp; A shuttle replacemente fits the bill nicely, particularly when combined with a vaguely-defined mission to return to the Moon and then go to Mars.&nbsp; In any case it appears that this train has started down the track and it will be difficult to stop it.&nbsp; But it may not be so difficult to delay it, and perhaps to put off forever the development of the complete system -- Obama seems to have such a delay in mind to free up money for some of his social goals.<br /></p> <div class="Discussion_UserSignature"> </div>

 

[vulture4]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>there are really no major design shortcuts in the rocket itself that would be available to a commercial launch provider that are consistent with the high reliability that is needed. <br /> Posted by DrRocket</DIV></p><p>Exactly. That's why expendable launch vehicles can never provide practical human spaceflight. It is no more practical to use ELVs (or "salvageable" solids) for human spaceflight than it would be to take a vacation on an airliner that can only be used once. A reusable system must, like an aircraft, be reflown with a minimum of maintenance, inspections, and building of new components. </p><p>The cost of Shuttle went through the roof because we learned the wrong lesson from Apollo; that we could simply draw a radically new launch vehicle on paper and without any flight experience with critical systems of radical design, accurately predict operating cost and reliability. We compounded the error with the Shuttle by cutting development costs while ignoring recurring costs. NASP, like Shuttle, was proposed as a final design, to satisfy presidential ego, without any serous analysis or prototype experience. </p><p>The technology demonstrator program was on the right track; a series of unmanned vehicles (X-33, X-34, DC-X, X-37) to get experience with each technology and flight phase of a reusable launch vehicle. But the technology demonstrators were eliminated by leaderhip that didn't understand its value.&nbsp; Unfortunately the cost of the Constellation program precludes any serious RLV development for the forseable future. </p>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> </p><p>1.&nbsp; However, the vehicle on which it was carried was a modification of the Pegasus launch vehicle which is a space laucher, and one that NASA also uses for other purposes.&nbsp; </p><p>2.&nbsp; They also participate in the decision making of other un-manned missions.&nbsp; They even sometimes are invited to participate with the Air Force.&nbsp; Their participation varies, but it is not a totally hands-off proposition.</p><p>&nbsp;3.&nbsp; I don't know quite what you mean my the "standard procurement for launch services".&nbsp; It certainly was procured in compliance with the FAR.&nbsp; Not sure what makes you so over-confident of your opinion.&nbsp; Do you have some expertise that is not evident ? <br /> Posted by DrRocket</DIV></p><p>1.&nbsp; That version of the Pegasus was nowhere near to being a space launcher (no 2nd & 3rd stage, moved avionics and a whole lot of ballast) and it was not managed the same as NASA's space launchers, contract and engineeringwise.&nbsp; <br /> </p><p>2.&nbsp; It is hands off.&nbsp; NASA doesn't buy hardware, it buys a launch service.&nbsp; NASA only has insight and not oversight.&nbsp;</p><p>&nbsp;3.&nbsp; I meant it wasn't bought through the standard NASA contracts for Pegasus.&nbsp; </p><p>&nbsp;I work in the NASA launch services program. &nbsp; Hyper-X was so much different from a standard Pegasus that the first flight wasn't a strike against the Pegasus.&nbsp; </p><p>&nbsp;</p>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The crew is quite large and not 100% utilized at all times.&nbsp; There is room for significant increase in efficiency.&nbsp; That was one of the reasons for the EELV program.&nbsp; It is also possible to make some of the processes more efficient, and allow more of them to proceed in parallel rather than in series.&nbsp; </p><p>1.&nbsp; Payload preparation is one example where some of that can be accomplished.&nbsp; In some cases the preparation of the propulsion piece is shut down while classified work is carried on the payload which is mounted on the launch vehicle at the time.&nbsp; When that can be done in parallel and off-line efficiencies are obtained.</p><p>&nbsp;2.&nbsp; There is a tremendous amount of reporting and communication between engineering groups, often through rather inefficient contractual channels that can be siimplified.&nbsp; Time is money and speeding up communication and resolution of issues can save a ton of it.&nbsp; </p><p>&nbsp;3.&nbsp; There are also often a myriad of formal reports that are required by specification and many times not used for any constructive purpose.&nbsp; That is one reason that when the EELV RFP went out, the Air Force imposed only one specification.&nbsp; Contractors then had the flexibility to propose alternate means of doing business for consideration by the customer.</p><p>&nbsp;4.&nbsp; Reduction in the size of the launch crew was one of the significant cost reduction steps taken in the EELV program.&nbsp; The benchmark for reduction was the Titan IV program, and a major rationale for EELV was to provide an alternate and less expensive heavy lift capability to replace Titan IV.Small launch vehicle providers have tried, with some success, to reduce costs by simplifying launch site operations.&nbsp; </p><p>5. Pegasus is a case in point.&nbsp; It is relatively inexpensive on a per launch basis, at about $20 million give or take.&nbsp;&nbsp; But it still is expensive on a per pound to orbit basis, and the individual launch costa are nearly double the original goal. Still it has a substantially lower launch site cost, both because of&nbsp;preparation procedures and because of the use of an aircraft as the "zero stage". <br /> Posted by DrRocket</DIV></p><p>&nbsp;</p><p>1.&nbsp; That is nothing new and is/was SOP for most ELV's.&nbsp; Only notable exception was Titan-IV, and that wasn't true for all it's payloads</p><p>2.&nbsp; What&nbsp; "rather inefficient contractual channels"?&nbsp;&nbsp; Idon't see them in my work</p><p>3.&nbsp; " myriad of formal reports that are required by specification"&nbsp; and they are?&nbsp; Nothing new here,&nbsp; that is the way NASA has been buying launch services. &nbsp; Basically, put this spacecraft in this orbit.</p><p>4.&nbsp; Nothing has changed here.&nbsp; Atlas crew size are the same.&nbsp; Delta-IV is huge. &nbsp;</p><p>5.&nbsp; Not really true, the Pegasus VAFB facilities are no different than other solid motor vehicles and are man power intensive.&nbsp; A pad for a solid motor vehicle is cheaper than an aircraft </p>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Why shuttle type winged spacecraft?A small shuttle with good cross-range could land on any runway thus enabling rapid deorbit in case of emergency. <br /> Posted by aphh</DIV></p><p>Not necessarily true.&nbsp; the oceans are larger than the cross range of most designs.&nbsp; A capsule is better for rapid deorbit, it can land anywhere.&nbsp;</p>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I think the next generation shuttle was already produced in the Energia/ Buran system. The main engines would be located on the external tank, not the orbiter. This would allow a corgo-only configuration. If the shuttle had been designed this way, we would not need the Aries IV, so it would have been very easy to go back to the moon by simply producing a stick-capsule medium lift rocket for the crew. There would not be any pause in the manned mission, because we could send modules to the moon using Energia-like rocket while we were waiting for the manned capsule to be produced. Yes, the decision to use the "piggy back" configuration was a mistake, but the much more crucial mistake was the decision to mount the engines on the shuttle. It may even be that we would continue to use the shuttle system to ferry people to the ISS. Even though it is probably more dangerous than using a stick-capsule, we have yet to see if a stick-capsule design is feasible for ferrying 6 people into space (we'll soon find out). Also, one has to wonder if the Ares I will be any safer than the shuttle. The shuttle 1s 118-120 *overall*, but as with any system, after every mistake, it actually becomes more safe, because the things that can break are fixed, reducing the number of failure modes. So, I think it is safe to say that the shuttle is probably 99% safe today. We'll see if any stick-capsule design lifting 6 people can reach this level of safety. I know that I would rather fly on STS-134 than Area-1-1. Of course, the fact that the shuttle cannot do heavy-lift duty *combined* with the fact that using a capsule is more efficient is what doomed the shuttle program. If we had used a Buran-like shuttle, the program would not be cut, and we could have a space station and moon base. <br /> Posted by wubblie</DIV></p><p>&nbsp;</p><p>there is no need for a cargo carrying orbiter if a Energia launcher used.&nbsp; Just put the cargo on the launcher and not in an orbiter.</p>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;1.&nbsp; That is nothing new and is/was SOP for most ELV's.&nbsp;</p><p><font color="#0000ff">Yes it is.&nbsp;&nbsp;And it accounts for a significant cost factor, which was the point.</font>&nbsp;</p><p>&nbsp;Only notable exception was Titan-IV, and that wasn't true for all it's payloads2.&nbsp; What&nbsp; "rather inefficient contractual channels"?&nbsp;&nbsp; Idon't see them in my work3.&nbsp;</p><p><font color="#0000ff">You would see them if you were in a different segment of the industry</font>.&nbsp;<font color="#0000ff">Quite a bit of engineering communication goes through formal contractual channels.&nbsp; Engineer-to-engineer communications when feasible are often much more efficient.</font></p><p>&nbsp;" myriad of formal reports that are required by specification"&nbsp; and they are?&nbsp; Nothing new here,&nbsp; that is the way NASA has been buying launch services.</p><p><font color="#0000ff">That is the point.</font>&nbsp;&nbsp;</p><p>&nbsp;Basically, put this spacecraft in this orbit.4.&nbsp; Nothing has changed here.&nbsp; Atlas crew size are the same.&nbsp; Delta-IV is huge. </p><p><font color="#0000ff">Yes, and the cost savings envisioned have not been realized.&nbsp; Boeing has not been pleased with the business performance of the system.</font></p><p>&nbsp;5.&nbsp; Not really true, the Pegasus VAFB facilities are no different than other solid motor vehicles and are man power intensive.&nbsp; A pad for a solid motor vehicle is cheaper than an aircraft </p><p><font color="#0000ff">I'm not at all sure that this is correct.</font><font color="#000000">&nbsp; <font color="#0000ff">There are savings acrued throgh an ability to launch at a flexible location and away from inhabited areas in terms of range safety concerns and associated costs.&nbsp; Also, there is an alternative to the Pegasus that adds a large solid in place of the airplane.&nbsp; It is called the Taurus.&nbsp; Yet Pegasus launches outsell Taurus launches.&nbsp; I haven't seen the VAFB faclities but I did see the earlier work at Edward AFB and that was quite modest.</font></font></p><p><font color="#000000">Posted by Cygnus_2112</DIV><br /><br /></font></p> <div class="Discussion_UserSignature"> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp; 2.&nbsp; It is hands off.&nbsp; NASA doesn't buy hardware, it buys a launch service.&nbsp; NASA only has insight and not oversight.Posted by Cygnus_2112</DIV></p><p>Would you care to elaborate on this point ?&nbsp; How is this insight achieved ?<br /></p> <div class="Discussion_UserSignature"> </div>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'></p><p>&nbsp;1.&nbsp; That is nothing new and is/was SOP for most ELV's.&nbsp;</p><p><font color="#0000ff">Yes it is.&nbsp;&nbsp;And it accounts for a significant cost factor, which was the point.</font> <br /><br /> Posted by DrRocket</DIV></p><p>&nbsp;The point was that this wasn't new for EELV.&nbsp; This already existed&nbsp; for the legacy systems so there isn't a new cost "benefit" to take advantage of. &nbsp; </p>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'></p><p><font color="#0000ff">You would see them if you were in a different segment of the industry</font>.&nbsp;<font color="#0000ff">Quite a bit of engineering communication goes through formal contractual channels.&nbsp; Engineer-to-engineer communications when feasible are often much more efficient.</font><br /><br /> Posted by DrRocket</DIV></p><p>Not in my work, Engineer to Engineer is SOP&nbsp;</p>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Would you care to elaborate on this point ?&nbsp; How is this insight achieved ? <br /> Posted by DrRocket</DIV></p><p>&nbsp;</p><p>We get&nbsp; copies&nbsp; of&nbsp; the starndard analyses and reports that the contractor produces in the integration processes.</p><p>&nbsp;</p>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;We get&nbsp; copies&nbsp; of&nbsp; the starndard analyses and reports that the contractor produces in the integration processes.&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>What do you do with those reports?<br /></p> <div class="Discussion_UserSignature"> </div>

 

[wubblie]

<p>Here's a thought experiment. Say you needed to design a spacecraft to orbit 12 astronauts into space at a time. Would you go with a capsule or a spaceplane? I imagine a shuttle-like orbiter would have no problem with this. I cannot imagine a capsule doing this though. It would need immense parachutes and retrorockets to slow down, and it would need a lot of structure to absorb the landing, which in turn would increase the weight, which would increase the need for bigger parachutes, which would add more weight, needing more structure... etc. I think there is a sweet spot where capsules work best (maybe from 1 to 4 astronauts), and any more than this, spaceplanes work better. They do not need extra weight to decelerate- they use the atmosphere, which is obviously external to the shuttle. So it gets its deceleration for free. Also, it rolls to a stop, which puts less stress on a heavy frame than a vertical landing would. </p><p>&nbsp;</p><p>Also, when the decision was made to retire the shuttle, I remember people saying that we need something more reliable. I think that this may come back to haunt NASA. A 122-2 record is certainly not that bad for launching spacecraft. The Soyuz is more reliable, but the re-entry module is tiny- like 3000 Kg. The Orion will weigh be at least 3 times larger. I may be wrong, but I don't think any single-occupant capsules has been lost. One 3 person soyuz was lost, and two 7 person shuttles have been lost. The more people you need to return to earth, the more extreme the engineering challenge becomes. It's not just capsule vs spaceplane, the question depends on what you need to do with it, and spaceplanes may be better for some tasks.&nbsp; </p>

 

[Cygnus_2112]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'></p><p>&nbsp;</p><p>1.&nbsp; Here's a thought experiment. Say you needed to design a spacecraft to orbit 12 astronauts into space at a time. Would you go with a capsule or a spaceplane? I imagine a shuttle-like orbiter would have no problem with this. I cannot imagine a capsule doing this though. It would need immense parachutes and retrorockets to slow down, and it would need a lot of structure to absorb the landing, which in turn would increase the weight, which would increase the need for bigger parachutes, which would add more weight, needing more structure... etc. I think there is a sweet spot where capsules work best (maybe from 1 to 4 astronauts), and any more than this, spaceplanes work better. They do not need extra weight to decelerate- they use the atmosphere, which is obviously external to the shuttle. So it gets its deceleration for free. Also, it rolls to a stop, which puts less stress on a heavy frame than a vertical landing would.</p><p>2,&nbsp; Also, when the decision was made to retire the shuttle, I remember people saying that we need something more reliable. I think that this may come back to haunt NASA. </p><p>&nbsp;3.&nbsp; A 122-2 record is certainly not that bad for launching spacecraft. The Soyuz is more reliable, but the re-entry module is tiny- like 3000 Kg. The Orion will weigh be at least 3 times larger. I may be wrong, but I don't think any single-occupant capsules has been lost. One 3 person soyuz was lost, and two 7 person shuttles have been lost. The more people you need to return to earth, the more extreme the engineering challenge becomes.&nbsp; <br /> Posted by wubblie</DIV></p><p>&nbsp;</p><p>1.What about launch aborts?&nbsp; how are you going to protect all the passengers? &nbsp;</p><p>2. &nbsp; How is NASA going to regret it.&nbsp; It doesn't need the all shuttle&nbsp; capabilities. </p><p>3.&nbsp; Incorrect, Soyuz had two accidents and one of them with only one occupant.&nbsp; The shuttle and soyuz are equal WRT reliability.&nbsp;</p>

 

[halman]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If a new generation space shuttle was to be designed, what improvements would be made? <br /> Posted by spacefanagain</DIV></p><p>&nbsp;For starters, it could be built a lot lighter, using composite materials.&nbsp; Extendable wings could be used, so that the vehicle is more stable during landings.&nbsp; An airlock/docking probe could be incorporated into the design.&nbsp; A horizontal launch system could be developed, incorporating a fly-back winged booster which is launched by a catapult.&nbsp; The payload could be reduced to a small enough value that the external tank and Solid Rocket Boosters are not needed.&nbsp; The "one vehicle to do it all" mentality could be scrapped.&nbsp; Kerosene could be used as fuel, instead of liquid hydrogen, which is extremely difficult to work with and to store.&nbsp; The thermal protection system could be designed for standarized replacement, instead of having to make each replacement tile individually.&nbsp; The crew module could be made to seperate from the vehicle in case of catastrophic failure during the ascent phase. </p> <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[qso1]

<p><font color="#800080">I may be wrong, but I don't think any single-occupant capsules has been lost. Posted by wubblie</font></p><p>Technically, one single capsule was lost. Gus Grissom, the second American manned spaceflight of the American Mercury series. Grissom survived as the capsule sank into the ocean. One factor that kept there from being more losses. There were very few single occupant missions flown by the U.S. and Russia.</p><p>6 U.S. Mercury flights and 6 Russian Vostok flights. The flight rate was simply not high enough for there to be more capsule losses.&nbsp;</p> <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>

 

[JonClarke]

<p>Three Soyuz were launched with single occupants, S-1, S-3, and S-4.&nbsp; Soyuz 4 was launched with three crew, two of these transferred to S-4 and S-5 returned with one.&nbsp; S-1 was lost, killing Komarov.</p><p>There have also been 15 single occupant spaceplane flights, 12 X-15 and 3 SS-1.&nbsp; One X-15 was lost, killing Adams.</p><p>Jon</p> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[qso1]

<p>I'd forgotten the Soyuz single occupant missions, thanks for reminding me.</p><p>I didn't mention the X-15 spaceflights or even the Rutan flights because they were not capsule missions.&nbsp;</p> <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>

 

[vt_hokie]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If a new generation space shuttle was to be designed, what improvements would be made? <br />Posted by spacefanagain</DIV><br /><br />I'd like to see something like this!</p><p>&nbsp;http://www.astronautix.com/craft/blakstar.htm</p>

 

[space_dreamer]

I wonder if the SR-3&nbsp;had a rocket engine on the back to boost it's speed to higher than mach 3?

 

[vulture4]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I wonder if the SR-3&nbsp;had a rocket engine on the back to boost it's speed to higher than mach 3? <br /> Posted by space_dreamer</DIV></p><p>Regrettably the S-3 seems apocryphal. The cold war being over, if it existed we should demand the details. However it remains true that ELV cost cannot be substantially reduced, and therefore only a launch vehicle that is reusable with minimal maintenance can provide practical human access to space. The exact technologies that would make such a vehicle sucessful cannot bepredicted solely by analysis, therefore a program of reusable unmanned technology demonstrators remains the next appropriate step. &nbsp;</p>

 

[scottb50]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Regrettably the S-3 seems apocryphal. The cold war being over, if it existed we should demand the details. However it remains true that ELV cost cannot be substantially reduced, and therefore only a launch vehicle that is reusable with minimal maintenance can provide practical human access to space. The exact technologies that would make such a vehicle sucessful cannot bepredicted solely by analysis, therefore a program of reusable unmanned technology demonstrators remains the next appropriate step. &nbsp; <br /> Posted by vulture4</DIV></p><p>TSTO and re-usable Modules makes the most sense.&nbsp;</p> <div class="Discussion_UserSignature"> </div>