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Thread: Preliminary verdict: Shuttle had a hole in the wing.

  1. #1
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    I just found this on the NYT. Strangely, it's not anywhere near being a major headline. It's buried away on the National (and linked to the science) page. It also seems to be a day old, but it's the first I've heard of it. Did I just miss the big announcement?

    http://nytimes.com/2003/02/14/nation...al/14SHUT.html (requires registration)

    Anyway, the initial findings say that missing tiles would not have been enough to cause the sensor readings, there had to be an actual hole in Columbia's wing to let hot plasma in. It also says that the first indications came much earlier than originally thought. They still aren't exactly sure where the hole was on the wing either.

    So now speculation seems to be on what caused the hole. Was it the insulation during liftoff? Or a micrometeor puncture? At least it's eliminated some theories.

    Edit: Here's a CNN link g99 just posted in another thread. I guess this is just coming out after all.

    http://www.cnn.com/2003/TECH/space/0...ire/index.html

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    <font size=-1>[ This Message was edited by: David Hall on 2003-02-14 16:22 ]</font>

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    I heard this on NPR yesterday. Besides the possible causes you mentioned, one they seem to be looking at very seriously is whether the chamber that contained the landing gear opened for some reason, and that the plasma originally entered at this point.

    <font size=-1>[ This Message was edited by: Zathras on 2003-02-14 16:45 ]</font>

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    Stupid Question of the Day.

    By John Witts.

    From the CNN article posted above...

    "I am admittedly erring way on the side of absolute worst-case scenarios and I don't really believe things are as bad as I'm getting ready to make them out," Daugherty wrote in his January 30 e-mail. "But I certainly believe that to not be ready for a gut-wrenching decision after seeing instrumentation in the wheel well not be there after entry is irresponsible."

    This engineer considered the possibility of a breach in the wheel well. He seems to be more concerned with the instrumentation that tells the ground and the crew that the wheels are lowered and locked. The Shuttle does this very late in it's approach. What happens if the wheels fail to deploy?

    This seems to be his major concern, his 'worst-case scenario', as confirmed but the next part of his memo. He doesn't consider that the wing may fail.

    In his e-mail, Daugherty theorized that the shuttle's landing gear may not deploy if there was "a substantial breach of the wheel well."

    "It seems to me that with that much carnage in the wheel well, something could get screwed up enough to prevent deployment and then you are in a world of hurt," his missive said.


    So he was worried about the landing gear deploying. Is there a contingency for this? It seems to me that if the gear fails there's not a lot of time to do anything. How about visual confirmation before the crew runs out of time to bail out? There's no second chance on landing the Shuttle, no circle around to try again. Is it sensible to deploy the gear so late in the landing?

    *Even this warning days before the disaster was an under-estimation of the real dangers posed by the foam hit. I cannot believe that that many engineers could be that wrong about the consequences. I can only conclude that there must be some 'wild card' element, perhaps initiated by the foam hit, perhaps unrelated.

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    On 2003-02-14 19:14, johnwitts wrote:
    This engineer considered the possibility of a breach in the wheel well. He seems to be more concerned with the instrumentation that tells the ground and the crew that the wheels are lowered and locked. The Shuttle does this very late in it's approach. What happens if the wheels fail to deploy?
    You crash?

    This seems to be his major concern, his 'worst-case scenario', as confirmed but the next part of his memo. He doesn't consider that the wing may fail.
    This is just a guess, but he probably wasn't asked to evaluate the wing, but only the effect on the landing gear. There might be another email floating around speculating about the wing.

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    Is it sensible to deploy the gear so late in the landing?
    On any aircraft with retractable gear, the gear can only be lowered after slowing to a "safe" airspeed. Too soon and the gear could rip off or the turbulence could cause the craft to spin unpredictably. As the shuttle is slowing down throughout the entire landing sequence, they probably lower the gear as soon as they can. They would help to slow the shuttle anyway.

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    Placement and timing of failed sensors in the left wing: http://spaceflight.nasa.gov/shuttle/...s/Slide025.jpg
    In much more detail: http://spaceflight.nasa.gov/shuttle/...ors/index.html
    If the wheel well had opened, why would the first sign of a problem show up on only one side of the well, and near the hinge, rather than near the gap between the supposedly open doors ?

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    So he was worried about the landing gear deploying. Is there a contingency for this? It seems to me that if the gear fails there's not a lot of time to do anything. How about visual confirmation before the crew runs out of time to bail out?...Is it sensible to deploy the gear so late in the landing?
    The shuttle landing gear is different from most retractable gear aircraft. Most aircraft positively power down the gear, electrically or hydraulically. By contrast the shuttle gear is designed to simply free fall via gravity into position and lock. It requires no power. It cannot be retracted once dropped.

    As a contingency there are pyrotechnic devices in the wheel wells to blow down the gear if gravity doesn't work.

    Re waiting until very low to drop gear, this is typical of high speed vehicles with a low lift-to-drag ratio. If you drop the gear much earlier it couldn't reach the runway. If you recalculated the glide ratio with gear down in theory you could drop gear higher, but the shuttle comes down so fast it wouldn't make that much difference. You might have an extra 15 sec, that's about all. Plus you'd be bumping into the max gear extension air speed, since you're earlier in the approach sequence (hence flying faster).

    So the problem is you can't do a "practice" gear extension at higher altitude like planes do which suspect gear problems. The shuttle doesn't know until the last few seconds whether the gear will work, and at that point there's little time for alternative action.

    -- Joe D.

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    I just found this on the NYT. Strangely, it's not anywhere near being a major headline. It's buried away on the National (and linked to the science) page. It also seems to be a day old, but it's the first I've heard of it. Did I just miss the big announcement?
    -------

    That is because the media are acting responsibly for once. Speculation is ok if...

    1. You save it for forums like this bulletin board - where misunderstandings can be corrected and where people do not expect professional journalism or fact checking.

    2. You don't use such speculation to blame or judge people.

    In this one case, the media is acting properly. They have a responsibility to avoid speculation because people depend on them to do the fact checking, etc. and because people will make major judgements about people and institutions based on what they say. So they are being a bit more careful in what they say then, say, most of us would be when posting to this board. That is the way its supposed to be.

    This is not the way the popular media usualy operates, however. TV news and radio talk shows, in particular, often go out of their way to make the biggest judgements on the basis of the shakiest of speculation.

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    Well, i suppose if the wheel did come down prematurely then that would explain the increased drag on that side of the shuttle as well as the catastrophic wing failure.

    As for possible landing without undercarriage, was there there ever a scenario devised that the shuttle could belly land somewhere?

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    On 2003-02-14 16:16, David Hall wrote:
    Anyway, the initial findings say that missing tiles would not have been enough to cause the sensor readings, there had to be an actual hole in Columbia's wing to let hot plasma in.
    Since the shuttle has tiles covering the whole surface of the wing, if a hole existed the "hole" must at one time have had tiles where it was before it was a hole. Do you think the hole appeared at the same time the tiles went missing? (Likely) Do you think maybe the hole burned through the thin soft aluminium skin where the missing tiles were during reentry? (more likely) Or do you think the "hole" had tiles covering it and there were no styrofoam soft tiles lost when the hole formed? (Seriously?)

    Regarding the softness of the tiles. Ron Dittermore said that the tiles are so soft that an EVA is likely to do more damage by an astronaut bumping into them during the EVA. If he knows that an astronaut moving carefully at a snails pace in zero g might break them, then why did he not think that a (as he, finally, after 3 days of arm twisting, estimated) 2 pound piece of insulation moving at 500 mph with the force of a cannonball couldn't have done any damage serious enough to warrant an inspection (by any of the many means available)?

    I still think that Dittermore is still trying to dodge his moral responsibility for not managing the program budget and politics to allow for the expense of post launch inspection EVA permanant maintanance of a rescue/recovery launch mission, planning, training and equipment. He just wants to say "Nothing can be done." Which is like an HBer who says space missions can't be done.

    I like the idea of a rescue/recovery mission. Although a single crew of astronauts can't be trained to repair all systems aboard the shuttle, anyone who ordinarily works on a shuttle system can be put through astonaut training as in a real working version of space camp against the event that his skills are needed in space. In the space camp training the person should have some input in his own traning and equipment to allow for his knowledge of some particular difficulty in the execution of his job in the space environment. This also gives everyone who works on the shuttle refurbishing, who wants to, a chance to go into space as a recovery mission specialist. At least he gets a vacation (two or three weeks?) and training at space camp.


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    How much does the orbiter heat up during ascent? Did the left wing senors read any temp changes then? IOW, if a hole existed during some part of the ascent, would there have been any instrumentation to indicate such a breach had occured?

    Doug.

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    On 2003-02-15 06:12, Mainframes wrote:
    Well, i suppose if the wheel did come down prematurely then that would explain the increased drag on that side of the shuttle as well as the catastrophic wing failure.
    While a premature wheel deployment would epxlain a lot of things, I assume there is a big, fat sensor for that. That is, we would already know if the gear had deployed prematurely.

    Aporetic

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    http://www.dailycamera.com/bdc/natio...747487,00.html
    This article says:
    "The wings have only a few sensors, not enough to confirm in real time whether the landing gear hatch had come open or had been breached to allow the superheated gases to penetrate the wing, he added."
    My theory posted elsewhe on this subject is that the Shuttle was hit by a red sprite lightning well over the pacific. There were storms west of Hawaii that the shuttle passed directly over. This lighning ignited the NASA Standard Initiator (NSI) that initiates the explosives that blow the wheel well door off in case it gets stuck.
    There were no meteors or insulation causes unless the roughness (from an insulation hit) of the tiles near the wheel well allowed the lightning to penetrate easier. I believe this theory is still a possible cause.

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    johnwitts said:
    This seems to be his major concern, his 'worst-case scenario', as confirmed but the next part of his memo. He doesn't consider that the wing may fail.
    The article lists his name, but not his office of affiliation and job responsiblities. It does vaguely say he worked on mechanical systems.

    As for the contingency, since the opportunity for early drop of gear to verify operation doesn't exist, his warning is that the normal information they have would not be working - the sensors all out. That leaves the gut-wrenching choice he mentions. If the sensors are all out early in the process and you think it's from a wheel well breach, and that causes you to suspect the landing gear won't function (maybe the tires are gone, for instance), then you have to make the decision early enough in the landing to try a bail out, which would be in that 16 minute window between Texas and Florida. I suppose a second option is to try the foam the runway technique, and land on the foam. Either of these is not a good situation. The third option is since the mechanism is so simple, you hold your breath and trust it all works. That's why he is pointing out to be prepared to make the call.

    Cloudy, any idea why the media is treating this situation so properly but were ready to pounce on every tidbit previously?

    SAMU, the possibility of damage or burnthrough of the skin where the tile damage existed is a likely candidate. NASA is evalutating that. However, the possibility also exists that micrometeoroid or orbital debris caused a hole in the wing. This would not require the strike to be in the already tile damaged area. How likely is it? Obviously a strike is pretty low probability - just look how many flights have gone and not seen this problem. However, the probability is definitely above zero and in the above negligible region. Strikes have occurred on the orbiters before - even on the windows.

    Regarding the softness of the tiles. Ron Dittermore said that the tiles are so soft that an EVA is likely to do more damage by an astronaut bumping into them during the EVA. If he knows that an astronaut moving carefully at a snails pace in zero g might break them, then why did he not think that a (as he, finally, after 3 days of arm twisting, estimated) 2 pound piece of insulation moving at 500 mph with the force of a cannonball couldn't have done any damage serious enough to warrant an inspection (by any of the many means available)?
    Once again, your ignorance is showing. You do not seem to have an appreciation of the actual working conditions of an EVA astronaut. You characterize the situation as "a snail's pace", as if it's as simple as creeping through a china shop on your tiptoes. And you completely overlook one of the most serious aspects from the EVA standpoint, there are no handrails along the underside or wings of the orbiter. In fact, there's not enough safety tethers to reach below, either, nor enough rope to try to rig something to climb down. In short, you're talking about a totally free-float situation. Now that is a safety hazard.

    Repeat: there is absolutely nothing for the astronaut to hold onto on the underside of the orbiter. He can't even grip at the tiles because they are pressed tight together. And if he tried to grip them he'd just break them.

    Also, when astronauts are EVA, they are very likely to induce forces on objects without meaning to. All objects in the Payload bay have to be rated to withstand a 200 lb accidental kick load, or else special operational constraints are put in place to make sure the astronaut never goes near that position. An astronaut can give a 40 to 50 lb kick force without even realizing it (well, at least until that bump gives them a push in the wrong direction). And they cannot see their feet or their backpacks, so it is exceedingly difficult to judge how close you are to objects you are trying not to hit.

    As to the foam, it is even more fragile than the tiles. Notice how the piece busted into dust, creating the large flash of light everyone can see in the video (light reflected of the cloud of dust, not an inherent luminous property). That absorbed kinetic energy.

    I still think that Dittermore [sic] is still trying to dodge his moral responsibility for not managing the program budget and politics to allow for the expense of post launch inspection EVA permanant maintanance of a rescue/recovery launch mission, planning, training and equipment. He just wants to say "Nothing can be done." Which is like an HBer who says space missions can't be done.
    Oh please. As if those decisions are Ron Dittemore's to make. The philosophy of Shuttle operations predates Dittemore's tenure as Shuttle Program Manager. The idea of a rescue/recovery launch mission is as much controlled Congress and the President as by Dittemore. The resources for performing a mandatory EVA inspection would be an impact to time, space, and consumables on every flight. Not to mention requiring the development of a whole lot of new hardware to allow that inspection to occur - a way for the astronauts to get underneath the orbiter safely and without touching the underside of the orbiter. What, are you expecting them to fly the MMUs every flight?

    John, I keep the lightning/sprite theory as a possibility, but I'm not so sure about the detonation of the NSI and opening of the wheel well. I would think gear deployment would provide a far more substantial drag than the one encountered. I don't know that the shuttle could maintain attitude with that much drag. Plus, other sensors contradict the one that indicates landing gear deployment. I think this is a case of the sensor being all fouled up by the same problem affecting all the other sensors.

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    Lyons, the red sprite specialist from Ft. Collins said that they had previously evaluated the chances of the shuttle being hit by a red sprite was 1 in a hundred. This was STS 107.

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    Good points, all. I guess I was trying to compare this incident with Challenger. Then, the engineers were pretty sure there was a big problem. They were convinced that Challenger would blow up on the Pad when the O-rings failed. It took a bit longer... With Columbia, no one considered the loss of the craft during re-entry. This E-mail I posted above is the worst 'scary tale' that has so far surfaced, and it involves loss of landing gear rather than loss of a wing. That's all I'm trying to say.

    While we're discounting the foam, has anyone ever fooled about with those styrofoam floats we have at swimming pools? They are pretty light and make good 'frizzbees' if thrown just right. If they hit you edge on they can leave a nasty bruise. What's tougher, your skin or a Shuttle thermal tile?

    In the vids we see the foam smashed to smitherines. Why would it do this if it merely glanced off the underside of the wing? Surely it needed to hit something substantial to be so destroyed? Or maybe it dug into the tiles as it slipped past? All speculation, but I wouldn't expect a glancing blow to destroy stuff that was designed to be out in the airstream all the way to space. That foam is pretty tough stuff.

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    It's pretty sure the aluminum was penetrsted, either pierced or the wheel well door was opened or blown off. While the foam may have damaged the tile, it seems unlikely it pierced the structure below the tiles. It's more likely that the piercing was due to a meteorite/space junk or the door was blown off.
    I think the door was blown off from a lightning strike that sent a current through the NSI and ignited the door ejection explosive system that is there for backup in case the door sticks when trying to open.

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    On 2003-02-15 21:42, John Kierein wrote:
    It's pretty sure the aluminum was penetrsted, either pierced or the wheel well door was opened or blown off. While the foam may have damaged the tile, it seems unlikely it pierced the structure below the tiles. It's more likely that the piercing was due to a meteorite/space junk or the door was blown off.
    I think the door was blown off from a lightning strike that sent a current through the NSI and ignited the door ejection explosive system that is there for backup in case the door sticks when trying to open.
    If the landing gear door was blown off, wouldn't the temperature have went up more than 60 degrees in 5 minutes as it was 3000 degrees or so on the forward wing? Wouldn't the door sticking down into the slipstream have directed at least some of this super hot plasma up into the wheel well?

    A small hole, from either space debris or from burning through an area with damaged or missing tiles, seems more likely to me, but I'm not an engineer. Anyone want to chime in on how much/if any plasma would be deflected into the wheel well if the landing gear door was open?

    Kizarvexis


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    Who is this George Gleghorn who said "The wings have only a few sensors, not enough to confirm in real time whether the landing gear hatch had come open or had been breached to allow the superheated gases to penetrate the wing, he added.", and what is his current relation to the investigation ? He’s not on the Columbia Accident Investigation Board (http://bbsnews.net/bw2003-02-11.html ) and he doesn’t show up in the “People and Organizations” document on the STS-107 Investigation Reference page ( http://spaceflight.nasa.gov/shuttle/...ion/index.html ). It’s apparent that he’s had an axe to grind:
    "I'm disappointed. It appeared for a while that they were going to cut the program to zero," said George Gleghorn, a former chief engineer at TRW who served on both the safety and research center panels. And he said he was not happy that funding was only returned to half its original amount.
    http://www.centredaily.com/mld/centr...ws/5185371.htm
    But that hardly counts as a bona fide for this statement.
    A simple peek at NASA’s graphic reveals 14 pressure and temperature sensors in or near the wheel well, including the first three to go off nominal. ( http://spaceflight.nasa.gov/shuttle/...s/Slide025.jpg )

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    On 2003-02-15 19:21, Irishman wrote:

    ...the possibility also exists that micrometeoroid or orbital debris caused a hole in the wing.
    If orbital debris impacted the shuttle with enough force to damage the shuttle fatally (Greater than had occurred on prior missions)then there must have been a flurry of thruster activity at that time to compensate for the mometum imparted through the thrust of the impact (no it wouldn't have been only as much as normally occurs during orbit) and the astronauts might have heard the impact through the structure of the ship (as the Apollo 13 astronauts did when they had their problem) or at least the accelerometer and RCS thruster telemetry would have picked up the impact thrust.

    As to the objection to the possibility of an EVA inspection (just look, not fix or touch.)because there no hand holds or enough teathers or because the astronaut might damage tiles. Well they should bring enough tethers to do the job and I'm certain they can work out a technique to do it safely (do you really think this is such a biggie?).



    The resources for performing a mandatory EVA inspection would be an impact to time, space, and consumables on every flight. Not to mention requiring the development of a whole lot of new hardware to allow that inspection to occur.
    Don't you think the astronauts, not to mention the shuttle vehicles are worth it? to whit:

    Rescue launch $100,000,000, the cost of any shuttle mission the last time I checked.

    20% of current NASA budget for Maintance of capability , training, equipment etc. Again don't you think they are worth it.

    If a rescue mission is launched every year for 30 years the cost would still be less than the cost to replace a single shuttle. If a rescue launch is done when fatal damage is detected during a post launch inspection at the rate that the shuttles have had fatal post launch damage (once in 23 years) then 600 years would have to pass before you spent as much as the replacement cost of a single shuttle.

    I not only think that it's worth it to give the best support to the finest, bravest, and most dedicated men and women our nation has to offer, but also that it's a good deal too.


    As to one sensor detecting (and having enough time to transmit) "landing gear door opening" during the reentry and/or breakup.

    I'm sure even without sensor telemetry that every door on the shuttle opened at some time during the breakup, wheel well doors, cargo bay doors and passenger doors. In fact everything on the shuttle opened up during the breakup even some places that didn't even have doors.





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    On 2003-02-16 07:07, SAMU wrote:
    If orbital debris impacted the shuttle with enough force to damage the shuttle fatally (Greater than had occurred on prior missions)then there must have been a flurry of thruster activity at that time to compensate for the mometum imparted through the thrust of the impact (no it wouldn't have been only as much as normally occurs during orbit) and the astronauts might have heard the impact through the structure of the ship (as the Apollo 13 astronauts did when they had their problem) or at least the accelerometer and RCS thruster telemetry would have picked up the impact thrust.
    This is my opinion but - not necessarily - if a micro-meteor struck the leading edge of the wing and put a very small hole in the carbon/carbon section, the impact might of not been large enough to alter the attitude of the orbiter or even felt by the crew but the hole could have been big enough to get superheated plasma into the wing structure.

    As to the objection to the possibility of an EVA inspection (just look, not fix or touch.)because there no hand holds or enough teathers or because the astronaut might damage tiles. Well they should bring enough tethers to do the job and I'm certain they can work out a technique to do it safely (do you really think this is such a biggie?).
    This is definitely a show stopper. In order for an EVA to be successful the astronaut must be able to either hold on to something or to use some sort of maneuvering unit. (BTW is the SAFER unit suitable for this purpose?) Going outside of the payload bay except attached to the arm just isn't possible. Do this experiment for yourself. Stand on a chair that swivels and then try to rearrange some heavy boxes on some shelves without holding onto to anything except the box you are trying to move. Now imagine attempting the same thing in free-fall in a space suit that restricts your movements.


    If a rescue mission is launched every year for 30 years the cost would still be less than the cost to replace a single shuttle. If a rescue launch is done when fatal damage is detected during a post launch inspection at the rate that the shuttles have had fatal post launch damage (once in 23 years) then 600 years would have to pass before you spent as much as the replacement cost of a single shuttle.

    I not only think that it's worth it to give the best support to the finest, bravest, and most dedicated men and women our nation has to offer, but also that it's a good deal too.
    There are two problems with simply saying that we should have the capability of attempting a rescue mission because it is just not a matter of money. First, we simply don't have the technology available to do a detailed inspection of the shuttle during every flight. And you are wrongly assuming that a simple visual inspection would find a "fatal" flaw. Second, in odrer to attempt a rescue mission you would need to have a second vehicle "mission ready" all the time with a special crew trained for such a rescue - the current shuttle fleet cannot be maintained that way. Please don't get me wrong, I honestly believe that these are great goals to aspire to, but given our current technology and shuttle fleet, it simply isn't feesable. Sometimes you simply have no choice but to work without a net.

    As to one sensor detecting (and having enough time to transmit) "landing gear door opening" during the reentry and/or breakup.

    I'm sure even without sensor telemetry that every door on the shuttle opened at some time during the breakup, wheel well doors, cargo bay doors and passenger doors. In fact everything on the shuttle opened up during the breakup even some places that didn't even have doors.
    Again you've missed the point with your sarcasm. There is no telemetry data that indicates that the gear door had opened prematurely, and all data seems to argue against it, the sensors on the landing gear just don't show an increase in temperature you'd expect if the door was missing.

    [fix bbcode]

    <font size=-1>[ This Message was edited by: SpacedOut on 2003-02-16 08:54 ]</font>

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    I didn't hear there existed an indicator that showed the door open. There was a late indication that the gear was deployed. I suspect that when the explosives go, it doesn't just open the door; it blows it off?? They don't want it hanging up halfway.

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    John Kierein said:
    Lyons, the red sprite specialist from Ft. Collins said that they had previously evaluated the chances of the shuttle being hit by a red sprite was 1 in a hundred. This was STS 107.
    Nitpick: STS-107 was the 113th flight.

    SAMU said:
    As to the objection to the possibility of an EVA inspection (just look, not fix or touch.)because there no hand holds or enough teathers or because the astronaut might damage tiles. Well they should bring enough tethers to do the job and I'm certain they can work out a technique to do it safely (do you really think this is such a biggie?).
    Yes.

    johnwitts, thanks for the clarification on your intent.

    SpacedOut said:
    (BTW is the SAFER unit suitable for this purpose?)
    Theoretically, the SAFER has the capabilities for attitude control and fine thruster firing to allow the astronaut to maneuver in such a way to inspect the underside using it.

    Practically, there is a limited amount of fuel in the package. It is not intended as a primary means of locomotion, but rather a safety device. Therefore, the supply is limited. It would be a long, time consuming, painstaking process to comb the underside and leading edges of the shuttle to visually look for damage. It would almost definitely exceed the fuel supply. (I don't recall offhand what fuel it uses, or the amount.)

    A far better approach would be a remote camera, such as the SPRINT. SPRINT was tested on STS-87 (IIRC). It is a spherical package ~ 1.5 ft diameter with a camera in it, using compressed nitrogen as the fuel. The outer shell is cushioned to prevent damage to objects it bumps into. The problem with SPRINT is it was stowed in the cabin, and would require opening the airlock to deploy. A better system would be a remote-deployable camera on a sidewall that could be activated and used, then returned.

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    On 2003-02-15 20:05, John Kierein wrote:

    Lyons, the red sprite specialist from Ft. Collins said that they had previously evaluated the chances of the shuttle being hit by a red sprite was 1 in a hundred. This was STS 107.
    If I remember reading correctly, the chance was 1 in 100 if the shuttle flew over a thunderstorm during reentry. This doesn't happen on every flight, so the real chances should be much lower. This is also assuming that the estimation is correct, of course.

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    Regarding premature main gear deploy....

    I've spoken extensively with a gentleman who works with the Shuttle's themselves at KSC (he does preflight testing of the orbiters; if I recall correctly, his main area of concern has been the APUs, but I believe he got a promotion not too long ago and I'm not exactly sure which part he works with now) and he assures me the gear cannot have deployed prematurely, and the door cannot have opened. This is because they have a sensor on the gear to tell them if it is down and locked. It was not, therefore it had to have been up. Since the gear and the door are mechanically linked, one cannot move without the other moving as well.

    That said....

    This still does not say that the door was sealed. There is a seal around the door which could have failed, letting in hot plasma even if the tiles were intact and the door was closed. But he doesn't think it's likely -- the sensors indicating problems in the left main gear didn't start showing problems until *after* the sensors a bit further forward in the left wing started to show problems.

    Personally, I'd say this is indeed pointing away from tile problems and more towards an actual hole. That makes me think the foam hit was indeed a red herring; there's no way the foam is going to make a hole in the actual skin of the vehicle. It's too tough for that. A micrometeorite is seeming a bit more likely now, as scary as that theory sounds. (Micrometeorites are, after all, the one thing which NASA has absolutely no control over and can do little to avoid.)

  26. #26
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    A few points: SAFER has a total delta V of about 10 ft/sec, hardly enough for any significant work. It's intended to get an untethered astronaut back to the ship, that's all. The earlier MMU had about 80 ft/sec delta V (don't remember exact number). http://quest.arc.nasa.gov/space/teac...ted/6work.html The astronaut maneuvering unit (AMU) taken on Gemini IX used hydrogen peroxide thrusters and had a total delta V of 275 ft/sec (Wow!).

    Even if they find a specific problem cause for Columbia (which is not certain), I can't see them flying again without developing procedures to inspect and patch the exterior.

    There are various ways to inspect it: EVA/MMU, EVA on remote manipulator (RMS), RMS camera, or free flying ROV. The RMS doesn't have sufficient reach or articulation, so it would need enhancements.

    A tile repair kit was developed in the early 80s, but supposedly tests indicated it wouldn't work properly in a vacuum. It also was designed for silica tile repair, not the RCC tiles on the wing leading edges.

    My guess is NASA will develop a new patch kit that works for both silica and RCC tiles, and they'll have to develop EVA procedures for using it. No matter how powerful the MMU, you can't do tile repair from one -- physical restraint is the only way. Options are enhanced RMS, long tethers under the orbiter, or adhesive pads of some kind (like sticky show shoes). None very pretty. It will take lots of EVA practice in the water tank and "vomit comet" aircraft to get the procedures worked out.

    From a materials standpoint, to be certain it works they'll have to do reentry tests of a repaired sample on a missile. No wind tunnel can maintain high mach flows long enough.

    All this will take time, I'd estimate 1-2 years minimum.

    In the unlikely event they isolate the problem to a different area (say lightning, flight control problem, etc) my guess is they'll still develop the patch kit and EVA.

    Here's a new theory about possible wing roughness causing the problem:

    http://www.upi.com/view.cfm?StoryID=...4-040233-2507r

    -- Joe

    <font size=-1>[ This Message was edited by: joema on 2003-02-18 01:18 ]</font>

  27. #27
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    On 2003-02-16 12:09, John Kierein wrote:
    I didn't hear there existed an indicator that showed the door open. There was a late indication that the gear was deployed. I suspect that when the explosives go, it doesn't just open the door; it blows it off?? They don't want it hanging up halfway.
    The NASA thinking is that the sensor reading showing the gear down was a sensor failure as two other sensors showed the gear up.

    Columbia Landing Gear Sensor Added to List of Failures

    Kizarvexis

  28. #28
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    Oct 2001
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    I closely follow the world of civil aviation, and I'm almost certain that despite the dire predictions, a landing with raised undercarrige wouldn't be a really big deal. Landing gear up is something that happens quite a lot, mostly from forgetting to lower it in the first place. I don't know how soon the gear is lowered, but it would probably be enough to prepare. (Like you have another choice). I might prefer sand or the like for this... perhaps they could just overshoot the runway or something. :-/

    Landing with only one gear down might be worse however... in jets the engine/pylon assembly can take it on the opposite side, but since the bottom of the shuttle is flat, the opposite wingtip might dig in. Can't find any info on this, since rampant speculation has turned my searches into haystacks with few needles.
    Does anyone know for _sure_, or know where one might find out?

  29. #29
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    Nov 2001
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    An interesting recent speculation that I like is:

    Some ice built up around a wastewater exit on the left side of the Columbia; as that water boils as its left, what's left becomes cold enough to freeze. So when the Columbia re-entered, that ice block broke off and smashed into the wing's leading edge, making a hole in it.

    Such ice blocks have formed in previous missions, and a fix intended to prevent them is some heaters at the exit. But it may not have worked this time around.

  30. #30
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    Nov 2001
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    Irishman & joema – Thanks for the information on the SAFER unit. I have read that the earlier MMU was discarded for safety reasons – anyone know what the issues were.

    If they are going to come up with a repair capability, the MMU or something very similar will be needed. That said, I still don’t see how they can come up with a procedure for repairing tiles on the belly – any method of firmly attaching the astronaut to the shuttle is likely to damage more tiles. In the case of catastrophic tile damage, minor damage to surrounding tiles to repair the major damage might be a worthwhile trade off, but then again it might not.

    As JayUtah has said in other threads, there is a major risk of the knee jerk reaction by the public and congress forcing NASA to implement “something”, even if that “something” is in reality worthless or worse.

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