Ares I: Thrust Occiliation (TO)

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windnwar

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I am surprised to hear you think that springs are not simple and rugged. Initially, I was suprised to hear that they would work, in the first place. Now that some ? whether they do work it is going to be an interesting first flgith of the Ares 1. I am thinking that the first flight will be for the first stage only. That will resolve the major ? to date anyway.&nbsp;Let's just&nbsp; shoot one off and see what happens.&nbsp; &nbsp; <br />Posted by job1207</DIV><br /><br />The reality of it is, they really won't have good data at all until they actually test fire a five segment srb and then actually launch one. The Ares 1-X test is a standard four segment SRB and won't reflect the burn characteristics of the 5 segment vehicle. Everything I've seen so far though indicates that it'll be worse in the 5 segment SRB. The fact that we have better liquid boosters that have greater payload and none of the oscillation issues though is what I find disturbing. This whole thing is just a kludge design, and every fix is reducing the payload to orbit even more and there simply isn't enough performance in the upper stage to make up for the failures in the first stage. Not to mention that every fix is degrading the LOC/LOM numbers. This isn't pessimistic, this is a realistic view. </p> <div class="Discussion_UserSignature"> <p> </p><p><font size="2" color="#0000ff">""Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein"</font></p> </div>
 
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job1207

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The reality of it is, they really won't have good data at all until they actually test fire a five segment srb and then actually launch one. The Ares 1-X test is a standard four segment SRB and won't reflect the burn characteristics of the 5 segment vehicle. Everything I've seen so far though indicates that it'll be worse in the 5 segment SRB. The fact that we have better liquid boosters that have greater payload and none of the oscillation issues though is what I find disturbing. This whole thing is just a kludge design, and every fix is reducing the payload to orbit even more and there simply isn't enough performance in the upper stage to make up for the failures in the first stage. Not to mention that every fix is degrading the LOC/LOM numbers. This isn't pessimistic, this is a realistic view. <br /> Posted by windnwar</DIV></p><p>Ok, well let's send up the 5 segment SRB. And what are LOC/LOM numbers?&nbsp; </p>
 
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Swampcat

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ok, well let's send up the 5 segment SRB. And what are LOC/LOM numbers?&nbsp; <br /> Posted by job1207</DIV></p><p>&nbsp;</p> <p>Probabilities for <strong>L</strong>oss <strong>O</strong>f <strong>C</strong>rew and <strong>L</strong>oss <strong>O</strong>f <strong>M</strong>ission.</p> <div class="Discussion_UserSignature"> <font size="3" color="#ff9900"><p><font size="1" color="#993300"><strong><em>------------------------------------------------------------------- </em></strong></font></p><p><font size="1" color="#993300"><strong><em>"I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."</em></strong></font></p><p><font size="1" color="#993300"><strong>Thomas Jefferson</strong></font></p></font> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>A safe, analytical, and logical response.&nbsp; Thank you. <br />Posted by kyle_baron</DIV></p><p>Yes, that is how professionals procede when engaged in engineering and science.&nbsp; First you clearly define the problem, then you figure out what the contributing factors are, identify a root cause if possible and only then determine appropriate corrective action.&nbsp; Fixing non-existent or ill-defined problems can be anything from a waste of time to a counter-productive disaster.<br /></p> <div class="Discussion_UserSignature"> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Yes, that is how professionals procede when engaged in engineering and science.&nbsp; First you clearly define the problem, then you figure out what the contributing factors are, identify a root cause if possible and only then determine appropriate corrective action.&nbsp; Fixing non-existent or ill-defined problems can be anything from a waste of time to a counter-productive disaster. <br />Posted by DrRocket</DIV></p><p><strong>I'll agree, that at this time, TO&nbsp;is ill-defined.&nbsp; It is hardly non-existant.&nbsp; Even the astronauts say that the ride in the shuttle smooths out considerably after SRB seperation.&nbsp; And I guess, that's where us arm chair amatures, will tackle an ill-defined problem (even out of ignorance) where a professional "will wait and see".&nbsp; Tackling an ill-defined problem IMO, is not a waste of time.&nbsp; It presents alternative solutions.</strong><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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MeteorWayne

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'll agree, that at this time, TO&nbsp;is ill-defined.&nbsp; It is hardly non-existant.&nbsp; Even the astronauts say that the ride in the shuttle smooths out considerably after SRB seperation.&nbsp; And I guess, that's where us arm chair amatures, will tackle an ill-defined problem (even out of ignorance) where a professional "will wait and see".&nbsp; Tackling an ill-defined problem IMO, is not a waste of time.&nbsp; It presents alternative solutions. <br />Posted by kyle_baron</DIV><br /><br />Which is exactly what has been done so far. Even though the problem may not exist, a plan is inplace to alleviate th treat to the passengers that will keep them safe even if it does occur. It's rather heavy preventative medicine, but if it does turn out to be a problem, the solution is already planned. Perhaps further down the road it will not turn out to be an issue and the weight can be saved instead. It would be nice to get some weight back, instead of always adding more :) <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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shuttle_guy

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'll agree, that at this time, TO&nbsp;is ill-defined.&nbsp; It is hardly non-existant.&nbsp; Even the astronauts say that the ride in the shuttle smooths out considerably after SRB seperation.&nbsp; And I guess, that's where us arm chair amatures, will tackle an ill-defined problem (even out of ignorance) where a professional "will wait and see".&nbsp; Tackling an ill-defined problem IMO, is not a waste of time.&nbsp; It presents alternative solutions. <br />Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>It is ill defined. The 5 segment SRB has never been test fired. The problem, if it exists, will only be fully defined when the 5 seqment booster with a fully simulated upper stage and Orion&nbsp;is &nbsp;flown with it. The vehicle must be free flyingso that any vibration is not dampened out by attachment to the ground. The upper stage and Orion must be structurally and dynamically the same as the actual flight hardware. the ground firing of the 5 segment SRB in the spring will <strong>help </strong>define the problem by measuring the chamber pressure changes during the burn.</p><p>&nbsp;</p><p>On the Shuttle the ride smooths out after SRB sep. because the vibration come from the SRBs.....</p> <div class="Discussion_UserSignature"> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Which is exactly what has been done so far. Even though the problem may not exist, a plan is inplace to alleviate th treat to the passengers that will keep them safe even if it does occur. It's rather heavy preventative medicine, but if it does turn out to be a problem, the solution is already planned. Perhaps further down the road it will not turn out to be an issue and the weight can be saved instead. It would be nice to get some weight back, instead of always adding more :) <br />Posted by MeteorWayne</DIV></p><p><strong>First, Con-Grats on your new Moderator status. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" />&nbsp; But, that doesn't mean that I won't throw a tongue your way, once in a while. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-tongue-out.gif" border="0" alt="Tongue out" title="Tongue out" />&nbsp; You are correct, it is just a plan or idea, nothing official.&nbsp; T.O. has not gone through a PDR (Preliminary Design Review) by a panel of experts.&nbsp; That has been conviently postponed&nbsp;until next year (I think).</strong></p><p><strong>As far as weight is concerned, I wouldn't be surprised if the whole 2nd stage ends up being a composite (some day).&nbsp; This should save 10-15% off the existing Lithium-Aluminum&nbsp; alloy.</strong><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'll agree, that at this time, TO&nbsp;is ill-defined.&nbsp; It is hardly non-existant.&nbsp; Even the astronauts say that the ride in the shuttle smooths out considerably after SRB seperation.&nbsp; And I guess, that's where us arm chair amatures, will tackle an ill-defined problem (even out of ignorance) where a professional "will wait and see".&nbsp; Tackling an ill-defined problem IMO, is not a waste of time.&nbsp; It presents alternative solutions. <br />Posted by kyle_baron</DIV></p><p>You have a point.&nbsp; The tackling of an ill-defined problem by inept amateurs does not waste any valuable time.&nbsp;&nbsp;To talk of meaningful solutions without a problem definition is a bit difficult.&nbsp;</p><p>It is true that the ride smooths out aftet the solids have burned out, but low level random vibration is a different animal from an oscillation that excites a resonant mode and creates a real problem.&nbsp; </p> <div class="Discussion_UserSignature"> </div>
 
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job1207

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gee whiz, when this story first broke, they talked to the cogniscenti in the universities. Each considered this a huge problem. loc/lom type problem.
 
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shuttle_guy

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>gee whiz, when this story first broke, they talked to the cogniscenti in the universities. Each considered this a huge problem. loc/lom type problem. <br />Posted by job1207</DIV></p><p>&nbsp;</p><p>They were addressing the worse case which is almost certainly not the T/O that the vehicle will actually have. We will not know if there is a problem until the first flight type vehicle flies (Ares 1X does not count ! )<br /></p> <div class="Discussion_UserSignature"> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You have a point.&nbsp; The tackling of an ill-defined problem by inept amateurs does not waste any valuable time.</DIV></p><p><strong>The only difference between amateurs and&nbsp;professionals&nbsp; is "getting paid".&nbsp; You&nbsp;DON'T think professionals make bad decisions, simply because they're in management or supervisory positions, and have more education?&nbsp; I'd trust a working stiff who puts in 8-10 hrs a day, with his hands on the object, over a geek (in management) isolated in&nbsp;his Ivory Tower.&nbsp; This is exactly the reason the Japanese kicked our buts in building higher quality cars in the '80s and '90s.</strong>&nbsp;</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;To talk of meaningful solutions without a problem definition is a bit difficult.&nbsp;&nbsp; <br />Posted by DrRocket</DIV></p><p><strong>Hmmmmm.....Hey Dr. Rocket, have you ever taken an educated guess?&nbsp; Or, is guessing not in your nature?&nbsp; Like Spock in Star Trek.</strong></p><p><br /><br />&nbsp;</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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MeteorWayne

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>First, Con-Grats on your new Moderator status. &nbsp; But, that doesn't mean that I won't throw a tongue your way, once in a while.&nbsp;&nbsp; Posted by kyle_baron</DIV><br /><br />Thanx. I would expect nothing more than that!! :) <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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vulture4

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Since there were published discussions of the TO problem even before STS-1, would one of the professional authors of the Exploration Systems Architecture Study care to join the group and explain why the document that defines the course of human spaceflight for the next generation doesn't even mention it?
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The only difference between amateurs and&nbsp;professionals&nbsp; is "getting paid".&nbsp; You&nbsp;DON'T think professionals make bad decisions, simply because they're in management or supervisory positions, and have more education?&nbsp; I'd trust a working stiff who puts in 8-10 hrs a day, with his hands on the object, over a geek (in management) isolated in&nbsp;his Ivory Tower.&nbsp; This is exactly the reason the Japanese kicked our buts in building higher quality cars in the '80s and '90s.</DIV></p><p>No the difference between amateurs and professioinals is knowing what they are talking about and applying appropriate knowledge and tools to the solutoin of a problem.&nbsp; Not all professionals are in suspervisory and management positions.&nbsp; In fact most working engineers are not.&nbsp; I know you would trust a working stiff who works hard over a working stiff who works smart, and that is why you in particular are completely unqualified to make any such decisions.&nbsp; Sometimes professionals do make bad decisions, but amateurs almost often make bad and irrational decisions.&nbsp; The likelihood of a good decision coming from someone with an appropriate education, applicable experience, and the basic smart to get that education and experience in the first place is vastly greater than the likelihood of getting it from someone with zero technical smarts, confidence born solely from ignorance and a complete lack of understanding of the basic problem.</p><p>The biggest problem with car companies in the 80's and 90's was decision-making by bean counters (BBA's) instead of folks who would be concerned with engineering and quality.</p><p>&nbsp;</p><p>&nbsp;
Hmmmmm.....Hey Dr. Rocket, have you ever taken an educated guess?&nbsp; Or, is guessing not in your nature?&nbsp; Like Spock in Star Trek&nbsp; Posted by kyle_baron</DIV></p><p>Certainly.&nbsp; And they are EDUCATED guesses.&nbsp; A critical distinction.&nbsp; My guesses are just that guesses.&nbsp; They are not wild-ass speculations with no understanding of what is going on.&nbsp; </p><p>When you do make a guess it is important that;</p><p>1.&nbsp; You know that you are making a guess, and you know the basis for that guess.</p><p>2.&nbsp; You know the ramifications of being right and of being wrong.</p><p>3.&nbsp; You have a good sense of the likelihood that you are right and that you are wrong.</p><p>4.&nbsp; You take action based on the guess only if the likelihood of being right is high and the ramifications of being wrong are acceptably low.</p><p>In most cases the purpose of guess is not to take final action, but rather to focus analytical and experimental work on determining if the guess is really right or wrong.&nbsp; That it because, with rockets, the ramifications of being wrong, are almost always very expensive, often castrophic and not uncommonly tragic.&nbsp; One must guess responsibly.</p><p>Good guessers are not locke up in an ivory tower.&nbsp; On the contrary they tend to have a broad education,&nbsp; a lot of applicable experience, and some basic smarts.&nbsp; On the other hand loud-mouth amateurs tend to have little technical education, zero appreciation for how physics really works, no experience of practical use, lots of confidence that substitutes for lack of real intelligence, and a general swashbuckling demeanor --&nbsp; Sound familiar ?<br /></p> <div class="Discussion_UserSignature"> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;&nbsp;
Hmmmmm.....Hey Dr. Rocket, have you ever taken an educated guess?&nbsp; Or, is guessing not in your nature?&nbsp; Like Spock in Star Trek&nbsp; Posted by kyle_baron</DIV>Certainly.&nbsp; And they are EDUCATED guesses.&nbsp; A critical distinction.&nbsp; My guesses are just that guesses.&nbsp; They are not wild-ass speculations with no understanding of what is going on.&nbsp; When you do make a guess it is important that;1.&nbsp; You know that you are making a guess, and you know the basis for that guess.2.&nbsp; You know the ramifications of being right and of being wrong.3.&nbsp; You have a good sense of the likelihood that you are right and that you are wrong.4.&nbsp; You take action based on the guess only if the likelihood of being right is high and the ramifications of being wrong are acceptably low.In most cases the purpose of guess is not to take final action, but rather to focus analytical and experimental work on determining if the guess is really right or wrong.&nbsp; That it because, with rockets, the ramifications of being wrong, are almost always very expensive, often castrophic and not uncommonly tragic.&nbsp; One must guess responsibly.</DIV></p><p><strong>You just put into words, what everyone else knows intuitively.&nbsp; Good job.&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" /></strong></p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Good guessers are not locke up in an ivory tower.&nbsp; On the contrary they tend to have a broad education,&nbsp; a lot of applicable experience, and some basic smarts.&nbsp; On the other hand loud-mouth amateurs tend to have little technical education, zero appreciation for how physics really works, no experience of practical use, lots of confidence that substitutes for lack of real intelligence, and a general swashbuckling demeanor --&nbsp; Sound familiar ? <br />Posted by DrRocket</DIV></p><p><strong>LOL!&nbsp; Ok, I'm Captain Kirk, and your Spock.&nbsp; Sound familiar?&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-tongue-out.gif" border="0" alt="Tongue out" title="Tongue out" /></strong><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp; I know you would trust a working stiff who works hard over a working stiff who works smart, and that is why you in particular are completely unqualified to make any such decisions.</DIV></p><p><strong>Wrong.&nbsp; The one thing I know for sure, is that you have no clue as to what I'm thinking.</strong>&nbsp;</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The biggest problem with car companies in the 80's and 90's was decision-making by bean counters (BBA's) instead of folks who would be concerned with engineering and quality.&nbsp; <br />Posted by DrRocket</DIV></p><p><strong>I'm guessing, that you never saw the Ron Howard movie "Gung Ho".&nbsp; Ron Howard makes movies that are a representation of real life (Apollo 13).</strong><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>American cars, do they make them anymore? <br />Posted by job1207</DIV></p><p><strong>It would appear, that American cars and American rockets, have a lot of parts in common.&nbsp;&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-tongue-out.gif" border="0" alt="Tongue out" title="Tongue out" /></strong></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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kyle_baron

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<p>http://www.nasaspaceflight.com/2008/11/sts-126-srb-modification-thrust-oscillation-data/</p><p><span>STS-126 will see the flight debut of two new sets of instrumentation, aimed at gathering more detailed data on RSRM (Reusable Solid Rocket Motor) behaviour during the first stage of launch. The resulting data will benefit the efforts to understand and mitigate Thrust Oscillation on Ares I.</span></p><p>&nbsp;</p><p>The main objective is to record pressure variations inside the boosters at higher fidelity than has been achieved in any previous shuttle flight.</p><p><span>These initiatives are in support of the Ares I program and will provide valuable input to the ongoing efforts to overcome problems the design teams have encountered with Thrust Oscillation (TO).</span></p><p><span>Modelling carried out on the Ares I vehicle predicts two major structural resonances at about 10 Hz and 12 Hz. Natural oscillations and variations in thrust - which the RSRMs generate - are predicted to produce significant excitation of these resonances. Higher frequency vibrations are also of interest for their potential impact on sub-components.</span></p><p><span>Analysis so far has relied heavily on data gathered from extensive static ground firing tests of SRMs and there is a need to validate results against real flight data. This requirement for comparative flight data will be addressed in STS-126 and several following missions.</span></p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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