STS-121: Launch target May, 2006 - Griffin

[jschaef5]

I don't get it how for 20 years we don't have any issues with foam falling off in big chunks and now its a huge problem... what has changed to cause foam to break off more now? Are we using different materials? Can we go back to the old foam? <div class="Discussion_UserSignature"> </div>

 

[askold]

"for 20 years we don't have any issues with foam falling off in big chunks and now its a huge problem"<br /><br />I think they always had the problem, but were lucky.<br /><br />The other day I watched an old video on NASA channel with the guys from the first launch talking about the ascent - they said something like, "We noticed something falling from above and hitting the window - we're not sure what it was ..."<br /><br />Probably foam.

 

[radarredux]

> <i><font color="yellow">does that mean that the foam problem is unsolvable?</font>/i><br /><br />That is certainly a possibility. As SG has said, foam has always been an issue (he had to repair the foam on the Saturn 5s), and the STS's fatal flaw was to put a delicate orbiter in the path of the shedding foam.<br /><br />Since Columbia, STS engineers made heroic strides to solve the foam problem, but it obviously wasn't enough. I believe the foam problem cannot be completely solved. So the question is now: <font color="yellow"><i>Will the efforts over the past year solve enough of the problem so that there is high confidence that ~18 more flights can be flown without a foam event?</i></font><br /><br />If the next flight has another foam incident, it may well be the last Shuttle flight. That is why (I believe) getting the next launch right (or as right as possible) is critical to the STS and ISS programs. Thus, while the launch delays are frustrating for us observers, a premature launch could be fatal to both STS and ISS.</i>

 

[radarredux]

> <i><font color="yellow">what has changed to cause foam to break off more now? Are we using different materials? Can we go back to the old foam?</font>/i><br /><br />Foam has always been a problem; NASA has detailed statistics of how frequently and where foam has hit the orbiter before. In fact, that history of strikes was a contributing factor to why NASA chose <b><i>not</i></b> to perform additional analysis of the of Columbia before she re-entered -- NASA was fully aware of the foam strike on Columbia, but strikes had happened so many times before they didn't think it was a big problem.<br /><br />In other words, because foam shedding and strikes were such a ubiquitous problem, NASA no longer considered it a problem.<br /><br />Now the problem NASA faces is that there are lots of sensors watching for foam (cameras, radar, vibrational sensors, etc.), that some foam shedding will be observed -- then NASA will have to proclaim the problem is "solved enough" to a skeptical audience.</i>

 

[baktothemoon]

I wonder if Russia's Buran shuttle had foam falling off of it too. I would be interesting to see if they noticed any falling off, or what they did about it. Frankly, the whole foam problem is really starting to tick me off now. It seems like there are a million causes for foam loss and a million solutions that won't work. But we have done absolutely everything we can. We have three good spacecraft here, they may not be perfect, but it is a dishonor to the shuttle and NASA to do all that we can to improve them and then get cold feet because of foam and gap fillers. THEY WORK! Fly em! Columbia was a freak accident that was never considered a possibility before. Now we have taken it into consideration, we have either done or studied everything to eliminate foam loss. What is practical has been done. The bipod foam is gone, the PAL foam is gone. What more is needed? Micromanaging every gap filler and scratch won't get us anywhere. Discovery was virtually clean and now it's only major flaw is gone. We have to stop being so timid. It's time to move on from the Columbia fear, lets honor the astronauts and launch in July. We shouldn't let anything stop us, not foam, not fear. Exploration is risk, enough "return to flight" mindset.<br /><br /> Light this Candle! <br /><br />"Ask not what your country can do for you, ask what you can do for your country." John F. Kennedy

 

[llivinglarge]

There has to be an acceptable amount of foam loss...

 

[SpaceKiwi]

<blockquote><font class="small">In reply to:</font><hr /><p>I don't get it how for 20 years we don't have any issues with foam falling off in big chunks and now its a huge problem... what has changed to cause foam to break off more now? Are we using different materials? Can we go back to the old foam?<p><hr /></p></p></blockquote><br />The composition of the foam has changed since the start of the Program due to environmental concerns over the original formulation. I believe the stuff used latterly is CFC-free, or at least reduced.<br /><br />SG will confirm, but the new composition is not nearly as good from an ET-shedding standpoint. However, even were they to go back to the original formulation, there still would be foam loss. <div class="Discussion_UserSignature"> <p><em><font size="2" color="#ff0000">Who is this superhero?  Henry, the mild-mannered janitor ... could be!</font></em></p><p><em><font size="2">-------------------------------------------------------------------------------------------</font></em></p><p><font size="5">Bring Back The Black!</font></p> </div>

 

[SpaceKiwi]

<blockquote><font class="small">In reply to:</font><hr /><p>Does the new design create more problems than the old design? If we get even more foam loss on the next launch does that mean that the foam problem is unsolvable?<p><hr /></p></p></blockquote><br />The "foam problem" is unquestionably unsolvable. All NASA can really do is manage the problem to an acceptable level. Although, it is worth emphasising that the "problem" only becomes one <b>IF</b> foam sheds from the ET in an unacceptably large size from a potentially dangerous (to the Orbiter) area, <b>AND</b> it strikes the Orbiter in a re-entry-critical area.<br /><br />The chances of this happening are statistically remote.<br /><br />Those statistics are further improved by the work being done to reduce foam from the ET where possible. And also by the development of patching systems for the TPS in the unlikely event of a critical strike on the Orbiter.<br /><br />NASA have also instituted a raft of improvements designed to monitor debris-strike to the Orbiter. It will "appear" that the Orbiter is being hit more than ever, or that more foam is being shed from the ET than ever. However, this will only be a by-product of the steps implemented to more fully understand Orbiter TPS health.<br /><br />Given all the work NASA has done in this area, should there be another critical Shuttle incident (and touch-wood there won't be), it is unlikely in the extreme that it will be foam-related. I believe they have more than addressed this issue with the STS on a number of different fronts. <div class="Discussion_UserSignature"> <p><em><font size="2" color="#ff0000">Who is this superhero?  Henry, the mild-mannered janitor ... could be!</font></em></p><p><em><font size="2">-------------------------------------------------------------------------------------------</font></em></p><p><font size="5">Bring Back The Black!</font></p> </div>

 

[radarredux]

> <i><font color="yellow">the "problem" only becomes one IF foam sheds from the ET in an unacceptably large size from a potentially dangerous (to the Orbiter) area, AND it strikes the Orbiter in a re-entry-critical area.</font>/i><br /><br />The foam also needs to be travelling at a fairly high speed relative to the orbiter, which only happens during part of the ascent.<br /><br />However... a piece of foam falling off and missing the orbiter <b><i>IS NOT</i></b> a problem to the orbiter for that mission, but it <b><i>IS</i></b> a problem to the entire program.<br /><br />My guess: If a large piece of foam falls off during the next launch, STS will be retired immediately. However, if a number of flights succeed without any major foam problems (say 8-10 good launches) and then a piece of foam falls off during a launch, STS will be allowed to continue.</i>

 

[jschaef5]

Alright i got a solution...<br /><br />Lets move to Alaska and ditch the foam <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[baktothemoon]

Ok, then we can open up ANWR. LOL!

 

[askold]

"The test in question was of a potential modification to the ET which has not been performed."<br /><br />Not yet performed? Not according to SpaceFlight Now:<br /><br />"During wind tunnel tests earlier this week, NASA subjected a full-scale mockup of a shuttle external tank section to aerodynamic forces greater than a real tank would experience during launch. In one series of tests, unmodified foam insulation used to prevent ice buildups around external fittings suffered only minor damage while a redesigned "ice/frost ramp" suffered major foam loss."<br /><br />http://spaceflightnow.com/shuttle/sts121/060413update/<br />

 

[baktothemoon]

<br />"NASA subjected a full-scale mockup of a shuttle external tank section to aerodynamic forces greater than a real tank would experience during launch." <br /><br />How is it a valid test if they subjected it to far greater forces than what would really happen? You can torture test almost everything until it breaks, that just means it is safe up to that point. Since that point is past what the real tank would experience than how is it a danger?<br /><br />"Ask not what your country can do for you, ask what you can do for your country." John F. Kennedy

 

[askold]

I think the key finding in this test is that the "old configuration" - which was considered suspect - is better than the "new configuration" which was supposed to fix the problems that were causing the engineers concern.<br /><br />From a testing standpoint, if the hypothetical solution does not improve the situation, that is a problem.

 

[drwayne]

Test to failure can serve several purposes:<br /><br />(1) It serves as a check of what your models are telling you about the way components perform.<br /><br />(2) It gives you some idea of margins of your design/implimentation.<br /><br />(3) It has a way of exposing failure modes that you might not have anticipated. This last one has happened to me once or twice, and has led to at least some "back to the drawing board" type of analysis.<br /><br />I know hardware is not software, but there is a saying in the software world - "A successful software test is one that breaks the software".<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[baktothemoon]

So it's nothing to worry about?<br /><br />"Ask not what your country can do for you, ask what you can do for your country." John F. Kennedy

 

[frodo1008]

Another thing that should be realized is that with the exception of a possible Hubble repair mission all remaining flights of the shuttle are going to the ISS. Further at the ISS the entire shuttle will be examined very closely, and if there is damage that would stop the shuttle from flying back throught the atmosphere either another shuttle or additional Soyuz flights will bring the crew back. <br /><br />This makes the ISS basically a safe haven, so NASA should indeed do all possible to see that there is no damage, but I feel VERY strongely that they MUST fly this year, or just shut the program down and find other ways to get the ISS completed.<br /><br />I think that this would be both expensive and difficult, but not impossible. If there was going to be any savings left over from shutting the shuttle down, that should go into the CEV program to get a craft capable of taking six people at least up to the ISS as soon as is possible! Then on to the moon and beyond. <br /><br />For once I have to agree with askold and others, if NASA can't overcome its no-go fever, and take at least one flight (and hopefully more) up to the safe haven of the ISS (with another rescue shuttle ready to go), then there really is NO hope for continuing the use of the shuttle to finish the ISS!

 

[radarredux]

> <i><font color="yellow"> I feel VERY strongely that they MUST fly this year, or just shut the program down and find other ways to get the ISS completed. ... if NASA can't overcome its no-go fever, and take at least one flight (and hopefully more) up to the safe haven of the ISS (with another rescue shuttle ready to go), then there really is NO hope for continuing the use of the shuttle to finish the ISS!</font>/i><br /><br /><img src="/images/icons/shocked.gif" /><br />Moderators, please check to see if frodo's account has been hijacked by askold.<br /><br /><img src="/images/icons/wink.gif" /></i>

 

[frodo1008]

Please note that I didn't say that human space flight should be cancelled. That was askold's original position, but if circumstances can modify my own direction then perhaps they can modify his also!

 

[askold]

Stand by - I'm in the process of composing a detailed post that will make my position clear and the conditions under which I'll modify my position.

 

[jschaef5]

Can we leave the STS-121 status thread as an update thread and not turn it into a discussion about our opinions on NASA and manned space flight...? <br /><br />And there are enough posts already about it and many of your opinions obviously aren't going to change. <div class="Discussion_UserSignature"> </div>

 

[earth_bound_misfit]

<i>"During wind tunnel tests earlier this week, NASA subjected a full-scale mockup of a shuttle external tank section to aerodynamic forces greater than a real tank would experience during launch."</i><br /><br />Wow, that must be one hell of a wind tunnel! What's the wind velocity it tests up too? Whats the max velocity of the STS while still in the atmosphere (that is thick enough to cause trouble)? I'm guessing at least Mach 8. <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>

 

[barrykirk]

Maybe they compensate for a lower velocity with a higher air density. Would this give similar results?

 

[jschaef5]

A Soyuz can seat 3 max?<br /><br />That means that 3 can come home on the one parked at the ISS, the next soyuz could be sent up with tons of supplies (can soyuz go up unmanned?) and then 3 more can come down. That only leaves 1 extra person up there after the soyuz leaves. It seems somewhat possible though? <div class="Discussion_UserSignature"> </div>

 

[radarredux]

> <i><font color="yellow">that must be one hell of a wind tunnel! What's the wind velocity it tests up too?</font>/i><br /><br />I've recently read somewhere that the speed when the SRBs separate is still pretty low (I want to say on the order Mach 3 - whatever it was, I was surprised). As the orbiter continues to accelerate, the atmosphere get thinner, so the net "aerodynamic forces" might not be that great. But that is just speculation.</i>