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Space Forum / Shuttle / August 2007Can the damaged tiles tear off?
Normal tiles provide for smooth airflow over the aerodynamic surface. It would seem damaged tiles would disrupt the airflow, creating turbulence. Could this turbulence dislodge completely several tiles, or even strip off a whole area like peeling an orange? If this is so, could not a seemingly small damage lead to catastrophy? Il mittente di questo messaggio|The sender address of this non corrisponde ad un utente |message is not related to a real reale ma all'indirizzo fittizio|person but to a fake address of an di un sistema anonimizzatore |anonymous system Per maggiori informazioni |For more info https://www.mixmaster.it Well, judging by what has happened before in such circumstances, this will only occur if the underlying aluminium gets hot enough to buckle, and this is no doubt the main worry. The airflow when the heat is worst should cause a kind of buffer of non moving air in the hole to some extent as I understand it, but I think if I were in the hot seat, I'd go with stuffing up the hole with a layer of wash, then goop and maybe another layer of wash, making sure the level was just below the level of the surface. Brian  SignatureBrian Gaff....Note, this account does not accept Bcc: email. graphics are great, but the blind can't hear them Email: briang1@blueyonder.co.uk ______________________________________________________________________________________________________________ > Normal tiles provide for smooth airflow over the aerodynamic surface. It > would seem damaged tiles would disrupt the airflow, creating turbulence. [quoted text clipped - 8 lines] > Per maggiori informazioni |For more info > https://www.mixmaster.it > Well, judging by what has happened before in such circumstances, this will > only occur if the underlying aluminium gets hot enough to buckle, and this [quoted text clipped - 5 lines] > > Brian Talk is they are thinking of not repairing it, but I hope they do, if only to get some good experience if there turns out to be a more serious case in the future. Experience both at executing the repair and how it fares during re-entry. >Talk is they are thinking of not repairing it, but I hope they do, if only >to get some good experience if there turns out to be a more serious case in >the future. Experience both at executing the repair and how it fares during >re-entry. It sure seems like they're afraid to try the repair technique. I agree that this seems like a good time to try it out so they have better data for when they REALLY need it. Maybe they're not expecting it to work all that well so they will only use it in a last-ditch attempt to save the crew. >> Talk is they are thinking of not repairing it, but I hope they do, if only >> to get some good experience if there turns out to be a more serious case in [quoted text clipped - 6 lines] > that well so they will only use it in a last-ditch attempt to save the > crew. No, that is not a correct characterization. The repair task itself carries some risk of making the situation worse. NASA is taking all this time in order to make sure that the risk reduced by doing the repair outweighs the risk taken. >>> Talk is they are thinking of not repairing it, but I hope they do, if >>> only to get some good experience if there turns out to be a more serious [quoted text clipped - 11 lines] > order to make sure that the risk reduced by doing the repair outweighs the > risk taken. And there is some risk to the EVA crew just to go EVA. Danny Deger >No, that is not a correct characterization. The repair task itself >carries some risk of making the situation worse. NASA is taking all this >time in order to make sure that the risk reduced by doing the repair >outweighs the risk taken. Jorge, I truly don't mean to be argumentative. But it seems the risk of doing the repair is minimal. It also seems that the knowledge gained would be immense. Could you explain the risk concerns in a bit of further detail? I am really trying to understand. IIRC They talked quite a bit about risk with the gap filler issue on the first post Columbia flight, and it went splendidly. They now understand that we can go under the orbiter without much worry, and we now know that the gap fillers aren't a big concern. So why not do the repair? Thanks Jim in Houston. Contrary to popular opinion RN does not mean Real Nerd! Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches" SignaturePosted via a free Usenet account from http://www.teranews.com >>No, that is not a correct characterization. The repair task itself >>carries some risk of making the situation worse. NASA is taking all this [quoted text clipped - 6 lines] > >Could you explain the risk concerns in a bit of further detail? There are multiple; There is a risk to damaging other tiles simply gaining acess to the damaged area. (The SRMS/OBSS combo is a lot more stable than orginally thought - but the residual risk is non zero.) There is a risk that the astronauts, highly trained as they are, can cause additional damage. There is the risk that repair itself my cause additional damage. (I.E. by putting unusual strains on the adjacent tiles, or causing an early boundary layer trip.) Etc... Etc... None of these risks are highly likely, but they are nonzero - and the odds are, to some extent, cumulative. D. SignatureTouch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL I have a bad feeling about this. I'm not saying I believe there is a likelihood of catastrophic failure, but I do believe no one at nasa really knows. The carefull and awkward wording of public announcements is a sure sign of confusion. I also believe there is a lot of politics going on behind the scene. An attitude of "we don't want to hear any bad news here gentelmen, make it work!" People not admitting just how uncomfortable they are with the situation. I believe they are sitting with fingers crossed at every launch wondering where the foam will hit next. This is a moderately educated perspective B > I have a bad feeling about this. I'm not saying I believe there is a > likelihood of catastrophic failure, but I do believe no one at nasa really [quoted text clipped - 8 lines] > > This is a moderately educated perspective You are ignoring that they are doing a lot more testing (arcjet tests, for instance) then they've done *during* previous flights. They are not relying just on 1 computer program this time. /dps >I have a bad feeling about this. I'm not saying I believe there is a >likelihood of catastrophic failure, but I do believe no one at nasa really [quoted text clipped - 8 lines] > > This is a moderately educated perspective I have listened to all of the mission briefings. In addition I know John Shannon well and he is very, very smart. If NASA decides to not do the repair it is because they think this is the overall lowest risk option. Ames Center has done computer modelling of the hole, Langley Center has done the same. In addition to this they are doing arc-jet testing. Even if they are wrong in the temp at the bottom of the cavity, it is NOT loss of orbiter. It is some melted aluminum and a repair job when they get home. I also have seen dissenting opinions making the press. I think NASA is doing much better at not quashing the dissenting opinion. Danny Deger > B >>>No, that is not a correct characterization. The repair task itself >>>carries some risk of making the situation worse. NASA is taking all this [quoted text clipped - 24 lines] > None of these risks are highly likely, but they are nonzero - and the > odds are, to some extent, cumulative. And don't forget the risk to the EVA crewmen just to go EVA. I can't believe it, but I think we agree with each other -- once again :-) Danny Deger >And don't forget the risk to the EVA crewmen just to go EVA. I can't >believe it, but I think we agree with each other -- once again :-) Yes, but EVA-4 was on the books anyway if SSPTS worked well, which it has. Brian lets not forget the damage implications on future flights >> None of these risks are highly likely, but they are nonzero - and the >> odds are, to some extent, cumulative. > > And don't forget the risk to the EVA crewmen just to go EVA. I can't > believe it, but I think we agree with each other -- once again :-) And today's shortened EVA due to a torn glove says something on the risk. > Danny Deger SignatureGreg Moore SQL Server DBA Consulting Remote and Onsite available! Email: sql (at) greenms.com http://www.greenms.com/sqlserver.html >> Etc... Etc... >> >> None of these risks are highly likely, but they are nonzero - and the >> odds are, to some extent, cumulative. > >And don't forget the risk to the EVA crewmen just to go EVA. That was covered under the "Etc... Etc..." part. I knew the knowledgeable would know about it, but hoped to leave the unknowledgeable with the impression that my list was far from complete. >I can't believe it, but I think we agree with each other -- once >again :-) It will happen from time to time if we slip up. I'll be more careful in the future. D. SignatureTouch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL > >>No, that is not a correct characterization. The repair task itself > >>carries some risk of making the situation worse. NASA is taking all this > >>time in order to make sure that the risk reduced by doing the repair > >>outweighs the risk taken. What's interesting is that according to a newspaper article, scientists at Johnson Space Center think it should be repaired; it would be "prudent," they said. Better to have and not need... The opposition is coming from NASA. If they turn out to be wrong, there will be hell to pay. It'll be a bloodbath. Ron M. >> >>No, that is not a correct characterization. The repair task itself >> >>carries some risk of making the situation worse. NASA is taking all this [quoted text clipped - 9 lines] > >Ron M. No, the article states that out of all the Centers involved in the discussion, which include Marshall Space Flight Center, Kennedy and others, it was the group at Johnson that dissented. I would add that the group at Johnson have the least knowledge of orbiter construction, and the TPS (as it applies to the vehicle). There were many groups involved in the discussion. The OPF (Orbiter Processing Facility) is at Kennedy and could be the most knowledgeable about the construction of the Orbiter. Remember too that "NASA" is comprised of many different centers. Jim in Houston. Contrary to popular opinion RN does not mean Real Nerd! Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches" SignaturePosted via a free Usenet account from http://www.teranews.com > >> No, that is not a correct characterization. The repair task itself [quoted text clipped - 10 lines] > without much worry, and we now know that the gap fillers aren't a big > concern. So why not do the repair? 1) The gap filler EVA was done by an astronaut on the end of the SSRMS while the proposed tile repair EVA would be done by an astronaut on the end of the OBSS attached to the SRMS. The problem is comm, not dynamics. The SRMS operator is the final line of defense for structural clearance and she depends totally on comm with the EVA crew in this scenario. The EMUs use UHF comm and shuttle UHF comm coverage is expected to be spotty underneath the orbiter. This wasn't an issue with the gap filler EVA since the SSRMS operator was running the show and the ISS UHF comm situation is much better.But for this proposed EVA, the ISS crew will probably need to relay comm between the EVA crewmembers and the SRMS operator. Comm may well turn out to be better than expected and this turn out to be a non-issue. But I'd hate to find out the hard way when the EVA crewmember sees an impending collision and calls "All stop! All stop! All stop!" but the comm gets ratty, the SRMS operator doesn't hear it, and the ISS crew doesn't relay the call in time to avoid a collision. I consider this a small but non-zero risk. 2) Rick has trained STA-54 application exactly once, in a 1-g glove box. Yes, the odds are the repair will go just fine. But there is a small chance something could go wrong and the repair site wind up worse than pre-repair. 3) One of the components of STA-54 is mildly toxic (tox level 1-2, IIRC) so the post-EVA cleanup in the airlock will need to be handled *extremely* carefully to avoid an eye/inhalation hazard. 4) Inherent risks of EVA (MMOD, EMU puncture, etc). Driven home dramatically by Rick having to terminate today's EVA early due to glove damage. Repair *will* cause total EVA hours to go up (EVA 5 will be added for the tasks displaced by EVA 4) and so will the cumulative risk. None of these are big risks but it is rapidly becoming clear that the benefit of the repair is not big either. I take no position on whether the repair should happen or not - I am simply annoyed at people who think this is a no-brainer, slam-dunk decision when they don't know all the complexities involved. Would we learn something valuable by trying anyway? Sure. We'd also learn something from an RTLS DTO and John Young's quote regarding that seems apropos right now. (And yes, I do consider the two comparable - not because this repair is so dangerous, but because RTLS is less dangerous than popularly imagined. It's been a certified intact abort mode since Day 1.) Jorge wrote: > RTLS is less dangerous than popularly imagined. It's been a > certified intact abort mode since Day 1.) Interesting comment Jorge. This is the first time anywhere that I have read that RTLS was not as risky as many seem to think, or at least publish. While I would agree that I may not be being entirely rational about this, the "negative return" call during ascent is my 2nd favorite thing to hear during a launch (right after the SRB jettison call). *S* I seem to recall within the last year, AWS&T publishing an article that left the impression that things would get a little skosh during an RTLS. AWS&T is not perfect by any means but its not the NY Post either *S* Can you share more . . . or offer a cite where I could read more other than what is widely available. The NASA website has a good RTLS discussion in the description of the STS but if you have more, I would appreciate it. Thanks in advance and take care . . . John P.S. Hey Rusty, If you are still lurking out there, do you have a .pdf or two on the subject? > 1) The gap filler EVA was done by an astronaut on the end of the SSRMS > while the proposed tile repair EVA would be done by an astronaut on the [quoted text clipped - 37 lines] > but because RTLS is less dangerous than popularly imagined. It's been a > certified intact abort mode since Day 1.) Jorge, Thank you for a very cogent discussion of the risk factors. John > None of these are big risks but it is rapidly becoming clear that the > benefit of the repair is not big either. I take no position on whether > the repair should happen or not - I am simply annoyed at people who > think this is a no-brainer, slam-dunk decision when they don't know all > the complexities involved. I appreciate your expert opinion and insider vantage point, but this essentially is a no-brainer decision. The downside risk in political terms is so prohibitive that there is no way that NASA senior management will risk reentry with the full flight crew unless some form of repair is attempted. The engineering analysis will be a relatively minor factor in the decision except in defining the extremes of the risk calculation. If NASA sends the bird home with seven souls onboard and they die due to a thermal protection that will seem to the public eye to be a virtual re-run of the Columbia breakup--only time NASA will have known about the tile damage in advance and done nothing to fix it--it's over. It won't just mean grounding all the shuttles permanently, the political fallout would lead to the cancellation of all the manned spaceflight programs, current and future. Our ISS obligations would be met by transferring and subsidizing a handful of astronauts to the EU and Russian programs, but basically we'd renege. NASA would be slashed back to a few relatively unambitious unmanned space exploration programs. >> None of these are big risks but it is rapidly becoming clear that the >> benefit of the repair is not big either. I take no position on whether [quoted text clipped - 19 lines] > basically we'd renege. NASA would be slashed back to a few relatively > unambitious unmanned space exploration programs. I'm one one of those who would like to see a repair, but I know it is partly because I'm interested in seeing how it's done and how it stands up. You're right that a failure of the TPS in re-entry leading to vehicle loss would surely doom the program, but what Jorge was saying is that there is a measurable risk that an attempted repair could make things worse. Shuttle loss after a botched repair would be just as bad politically as shuttle loss with no repair so can't agree that it's a no-brainer, it has to be a rational decision based on the risk analysis. > From: "MichaelJP" <m...@nospam.com> > You're right that a failure of the TPS in re-entry leading to [quoted text clipped - 5 lines] > a no-brainer, it has to be a rational decision based on the risk > analysis. I disagree. If they don't try to fix it, and it burns up on entry, it's yet another case of not even trying to fix anything. But if they try to fix it, and something goes wrong, at least they tried their best. Also, a lot of the suggested failure modes with the repair-attempt are things that can be detected before de-orbit. If the repair goes well, they improve their chance of safe re-entry. If the repair goes badly, they know it went badly in many cases, and can decide to send a rescue mission instead of ever landing Endeavor. But the kinds of things that may go wrong in absense of repair are all things they won't learn until it's too late to change plans. Also even if putting goo into the gouge has no effect at all on safety, still they'll obtain a live test of how it really performs during an actual entry, not just a simulated test on Earth. That test really needs to be performed, and now seems like an optimal time to run that test. (In addition to putting some goo into this worrisome gouge, they ought to also put some in other places, such as in cracks between tiles, any place the goo would experience a different kind of heat/pressure combination during re-entry, but where it won't disturb airflow enough to cause downstream damage.) As for minimizing chance of collision of the remote arm with the underside of the orbiter, I suggest they go very slowly. Instead of the person on-site relaying a command to start moving and later relaying a commad to STOP, whereby loss of the STOP command will cause collision, they should have an auto-stop mode, whereby the arm operator turns the arm on for a pre-determined length of time to move a pre-determined distance, which is only halfway from starting position to desired position, and repeat several more times getting halfway from second position to goal equals third position, halfway from third position to goal equals fourth position, etc. until they are "close enough" and need no further motion. It may take a little longer to get "close enough" compared to a single START......STOP sequence, but given possible intermittant loss of communication it seems the prudent way to operate the arm. If they actually try the repair, even if they accomplish no increase in safety, still they will have acquired practical knowledge in a wide variety of areas (communication and arm control, astronaut performance, how the goo really works in space when being applied, how the goo reacts to intense heat of re-entry, how their simulations of the repaired situation agree with reality). If they do nothing they learn only one thing (how their simulations of the not-repaired situation compare with reality). I.e. they learn a lot more if they try the repair. And like I said, if they screw up and damage the underside really badly, they can simply change plans and not bring Endeavor down at all. Of course they might have all the flight crew onboard ISS during the repair, except those which absolutely must be either in Endeavor or on the spacewalk, which I think means two in danger (one EVA and one arm-operator) and five safely in ISS just in case the underside of Endeaver is completely punctured. And of course one of those two would be already in spacesuit and the other ready to grab a spacesuit on a moment's notice, before air has seriously leaked out. >> From: "MichaelJP" <m...@nospam.com> >> You're right that a failure of the TPS in re-entry leading to [quoted text clipped - 65 lines] > to grab a spacesuit on a moment's notice, before air has seriously > leaked out. And of course, if nothing else, the weight that NASA has assigned to the risk of the repair going wrong raises concerns that they do not have a proper TPS repair plan and training in place and ready to go. Anyway moot points now - hope this one goes well and the concerns can be remedied post-flight. >>> From: "MichaelJP" <m...@nospam.com> >>> You're right that a failure of the TPS in re-entry leading to [quoted text clipped - 72 lines] > Anyway moot points now - hope this one goes well and the concerns can be > remedied post-flight. It's not a moot point until the deorbit burn. People talk about how with any accident there is always some chain of event, all contributing in some way as they go down the path to disaster. Changing any one along the way would have broken the chain. And, the twenty-twenty vision looking back at the chain of events. What about foresight, before the event, the decisions along the path, was it simply an acceptable decision or the best decision. Acceptable ones, the ones with no strong objections, no proof of impending disaster seems to be NASA's mode of operation. Comport and warm feeling for those making the decisions, on the ground, from the safety of their desk. Worried about themselves, the implications of a hurricane on them, not the others who have different implications. Most of the time, never fully completing the chain of events, having a successful mission and looking at that as proof that the right choices were made. A recipe for disaster that is averted most of the time, random, proof of their competence. Who feels a warm fuzzy flying entry with an unrepaired heat sheild? Who feels a warm fuzzy about coming home a day early to ensure good "control" and communications, worried about a hurricane? Who feels a warm about flying thru the top of a hurricane? > It's not a moot point until the deorbit burn. > [quoted text clipped - 19 lines] > > Who feels a warm about flying thru the top of a hurricane? I don't think anybody feels warm and fuzzy about any of those, and I'd question their sanity if they did. But I think this is coming down to landing with the beast you know (some tile damage), versus the beast you don't (the TPS repair). Ya know, being just a pack of nerds on a web-board, at this point I'd save the beating around the bush for post-flight. All we can do now is hope MCC has made the right call and tomorrow a couple of twin sonic booms will be heard over KSC or Edwards. We're about to find out if NASA knows what "acceptable" damage to the TPS is, post-Columbia. For better or worse. -A.L. > We're about to find out if NASA knows what "acceptable" damage to the > TPS is, post-Columbia. For better or worse. > > -A.l the price of a mistake, end of shuttle, end of manned space, basic end of nasa as we know it, which may not be a bad thing, nasa currently stands in the way of privatazition. but i dont want any mre deaths >> None of these are big risks but it is rapidly becoming clear that the >> benefit of the repair is not big either. I take no position on whether [quoted text clipped - 8 lines] > attempted. The engineering analysis will be a relatively minor factor in > the decision except in defining the extremes of the risk calculation. If this were really true, then NASA's manned space program should be completely shut down now. I don't believe this is true. The exact opposite is happening. Deliberate analysis and testing is happening on the ground as we speak. NASA does not appear to be in a hurry to rush a decison, let alone rush to a predetermined conclusion based on politics. In other words, you're full of it. > If NASA sends the bird home with seven souls onboard and they die due to a > thermal protection that will seem to the public eye to be a virtual re-run > of the Columbia breakup--only time NASA will have known about the tile > damage in advance and done nothing to fix it--it's over. That might be a possibility, but I think it's unlikely given that the decision to end the program by 2010 has already been made. The shuttle's days are numbered and some risk will be taken to keep the program flying until it ends. > It won't just mean grounding all the shuttles permanently, the political > fallout would lead to the cancellation of all the manned spaceflight > programs, current and future. You're full of it. There have been many deaths on the ground and on actual spaceflights, but that hasn't stopped the US or Russian space program yet. There are many deaths on big construction projects, yet there are still huge structures going up every day around the planet. > Our ISS obligations would be met by transferring and subsidizing a handful > of astronauts to the EU and Russian programs, but basically we'd renege. > NASA would be slashed back to a few relatively unambitious unmanned space > exploration programs. Doubtful. This wouldn't fulfill the political goal of continuing to spend manned space program money in the same districts that we're currently spending money for the shuttle program. This program is driven as much by the politics of spending money as it is anything else. Jeff Signature"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety" - B. Franklin, Bartlett's Familiar Quotations (1919) >3) One of the components of STA-54 is mildly toxic (tox level 1-2, IIRC) >so the post-EVA cleanup in the airlock will need to be handled >*extremely* carefully to avoid an eye/inhalation hazard. Just out of curiosity, do you have a link to the descriptions of the levels? (I.E. is level 1 actually dangerous or merely slightly paranoid.) D. SignatureTouch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL >> 3) One of the components of STA-54 is mildly toxic (tox level 1-2, IIRC) >> so the post-EVA cleanup in the airlock will need to be handled [quoted text clipped - 3 lines] > levels? (I.E. is level 1 actually dangerous or merely slightly > paranoid.) I think it's the same 1-4 scale used by the NFPA (1=irritant, 2=temporary incapacitation, etc). Three things disappoint me on NASA being prepared to do the repair. One is the comm situation. NASA has been planning for an under the belly repair for quite some time. Why not have antennas put in place (on the arm itself?) to insure good comm. Good comm between the crew on the boom and the arm operator is essential for this operation. Second, apparently NASA has not done an inspace test of the "goo". They have tested the wash in space, but not the goo. Third, apparently none of the onboard crew has ever worked with the goo before. Why not, for each flight, have the dedicated repair crewmen practice applying goo to a test sample. Danny Deger www.dannydeger.net >>> No, that is not a correct characterization. The repair task itself >>> carries some risk of making the situation worse. NASA is taking all this [quoted text clipped - 51 lines] > less dangerous than popularly imagined. It's been a certified intact abort > mode since Day 1.) >> >>> No, that is not a correct characterization. The repair task itself [quoted text clipped - 27 lines] > it, and the ISS crew doesn't relay the call in time to avoid a > collision. I consider this a small but non-zero risk. Easily worked around with one space walking astronaut in good communications with both the station and the other space walking astronaut. "Stop" says one spacewalker, "Stop" says the other spacewalking astronaut, "Stop, Stop" hears the arm operator. Or, was it just "Stop", either way the arm operator stops. > 2) Rick has trained STA-54 application exactly once, in a 1-g glove box. > Yes, the odds are the repair will go just fine. But there is a small > chance something could go wrong and the repair site wind up worse than > pre-repair. Wow, sounds like NASA is unprepared to do repairs, everyone knows NASA likes to choreograph all the space walks to the Nth degree. This really tells me that there was zero training for the crew, NASA isn't seriously considering repairing the heat shield. It was just lip service, to satisfy the CAIB, to place a check in the right box, nothing else. > 3) One of the components of STA-54 is mildly toxic (tox level 1-2, IIRC) > so the post-EVA cleanup in the airlock will need to be handled > *extremely* carefully to avoid an eye/inhalation hazard. So, tell the astronaut to use gloves, eye and breathing protection. Oh yeah, don't wipe your hands on your pants. > 4) Inherent risks of EVA (MMOD, EMU puncture, etc). Driven home > dramatically by Rick having to terminate today's EVA early due to glove > damage. Repair *will* cause total EVA hours to go up (EVA 5 will be > added for the tasks displaced by EVA 4) and so will the cumulative risk. The current risk during an EVA is in the category of "has not happened yet", it's a risk to only one crew member, not seven. That makes it around 1 (6hrX2) in "how many hours of EVA time has been"? > None of these are big risks but it is rapidly becoming clear that the > benefit of the repair is not big either. I take no position on whether > the repair should happen or not - I am simply annoyed at people who > think this is a no-brainer, slam-dunk decision when they don't know all > the complexities involved. Would we learn something valuable by trying > anyway? Sure. Sure, NASA would be flying the Shuttle within the original specifications if they repaired it. Flying it outside specifications, not repairing it. I doubt the original specification contained anything about it being acceptable to fly with hole all the way down to the felt pad in the bottom of the Orbiter. To me, it's pretty much a no-brainer to fly within specifications when it is so simple to do so. Let see, Challenger flying outside specification, the O-rings were not designed to have any erosion, but erosion to the O-rings became acceptable as they had made it safely to orbit with erosion. Columbia, flying outside specification, the heat shield wasn't designed to fly through a debris field. Here a little more, Challenger, increased test pressure to ensure the O-rings are working properly, seats the inner O-Ring in the wrong direction. This increases frequency and magnitude of the O-ring erosion problems. Endeavour, increased hold time with the External Tank full of fuel, to allow more time to inspect for ice on the tank. Creating a higher probability of ice build up and increase frequency (probability) of shedding large pieces of foam. SignatureCraig Fink Courtesy E-Mail Welcome @ WeBeGood@GMail.Com >>> >>>> No, that is not a correct characterization. The repair task itself [quoted text clipped - 91 lines] >ice build up and increase frequency (probability) of shedding large pieces >of foam. This entire post was incorrectly attributed to me. In fact it contains posts from both Jorge and me. Jim in Houston. Contrary to popular opinion RN does not mean Real Nerd! Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches" SignaturePosted via a free Usenet account from http://www.teranews.com > Talk is they are thinking of not repairing it, but I hope they do, if only > to get some good experience if there turns out to be a more serious case > in the future. Experience both at executing the repair and how it fares > during re-entry. Repairing the damaged area introduces risks as well, so if the ground tests show that the shuttle can land safely, they likely won't risk a repair. Sometimes the cure can be worse for the patient than the illness. Jeff Signature"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety" - B. Franklin, Bartlett's Familiar Quotations (1919) > From: "MichaelJP" <m...@nospam.com> > Talk is they are thinking of not repairing it, but I hope they > do, if only to get some good experience if there turns out to be a > more serious case in the future. Experience both at executing the > repair and how it fares during re-entry. I agree completely. The whole point of the ISS+STS is to learn how to do new things in space (and also learn some new science, but that has become a very minor part of the project). This seems to me an excellent opportunity to try to learn how to do something new, even if it isn't *necessary* to do now. Virtually none of the things being done in space are necessary *now*, they are merely necessary in the future, if and when we go back to Luna or we go to Mars. This falls into that same category. In particular we need to get experience dealing with emergencies that might occur without warning. We got lucky with Apollo 13, that with no prior practice we just happened to be able to figure out a way to use readily available materials to accomplish a fix good enough to avoid loss of life. Getting that lucky is a rare event. Compare for example the current crisis in the mine where none of the trapped miners have been located yet and three rescue workers have already died in a later collapse, or the WTC collapse that killed so many rescue workers. Believing you'll always get lucky, succeeding in a dangerous situation where you've never practiced, is stupid. Practice doesn't make perfect, but it still improves the odds. IMO, if there's suitable repair materials on board, they should be tried, just to see what effect it really has, and to get experience with the repair itself. Just my opinion. Nobody cares what I think. > Just my opinion. Nobody cares what I think. I care Robert. Now go take a Valium and rest. Jim in Houston. Contrary to popular opinion RN does not mean Real Nerd! Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches" SignaturePosted via a free Usenet account from http://www.teranews.com |
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