STS-114 Mission Update Thread (Part 4)

[blacknebula]

"I think there is a lot of paranoid fear right now"<br /><br />I'd agree with you, considering that the object in question didn't even hit the orbiter. However, I'd put most of the drama on the shoulders of the media. Problems arise every once in a awhile in the space shuttle program and the fleet is grounded. Yet, the media portrays that NASA will be working on this problem for another two years (let's hope not <img src="/images/icons/wink.gif" /> ).<br /><br />

 

[najab]

Let me expand on that point. There is a difference between a hard grounding and a launch embargo. They saw some foam come off the PAL ramp, they don't know exactly why it did. What they said is that the next launch is delayed until they figure out why it happened. The mission is still scheduled and they are continuing to process Atlantis for flight.<p>If they find a simple reason for the foam failure (eg a manufacturing defect) then STS-121 can still launch as scheduled. Only if they can't figure out why it happened, or it turns out to be a generic fault (highly unlikely since it never happened before) can we start talking about "grounding the fleet."</p>

 

[tap_sa]

Anyone know if they are able to attempt 'real' patching of orbiter tiles if they want to, or just do the tests inside payload bay? There appears to be minor dent somewhere near the edge of front undercarriage hatch. Probably a non-issue but the press will make it look like a gaping hole <img src="/images/icons/wink.gif" />

 

[blacknebula]

"...or it turns out to be a generic fault (highly unlikely since it never happened before) can we start talking about "grounding the fleet.""<br /><br />Well I wouldn't go so far as to say that it hasn't happened before. This is just the first time that we've put a camera on the ET and had it survive that long. This may have happened on every single shuttle mission previous, but this is the first time we're aware of it.<br /><br />Honestly, I don't expect a huge launch delay for STS-121.

 

[spacefire]

could the tank be coated with some kind of paint to improve the covering's resistance to vibration?<br />Early shuttle tanks were painted white and then they got rid of the paint. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[najab]

><i>This may have happened on every single shuttle mission previous, but this is the first time we're aware of it.</i><p>Well, they've done ET sep imagery on almost all the flights and it's never been seen before (though admittedly, some of the ET seps were done in the dark.)</p>

 

[blacknebula]

"Early shuttle tanks were painted white and then they got rid of the paint."<br /><br />For good reason. The paint did nothing except chip and create a bunch of unnecessary, perhaps dangerous, debris.

 

[najab]

The paint added nearly 300 pounds to the ET. Since the ET is carried (almost) all the way to orbit that means a 300 pound reduction in payload.

 

[spacefire]

<font color="yellow">The paint did nothing except chip and create a bunch of unnecessary, perhaps dangerous, debris.</font><br /><br />the tank is doing the very same thing without paint.<br /><br />what if they got rid of the foam? <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[tap_sa]

<font color="yellow">"what if they got rid of the foam?"</font><br /><br />LH2 would boil off faster than they can keep filling.

 

[Astrosag]

CNN's head title "shuttle fleet grounded" sent chills down my spine. I'm at work so I haven't been able to catch up on the news...but according to that title, there seems to be something serious going on? Any updates shuttle_guy?

 

[llivinglarge]

Tungsten.

 

[tap_sa]

S_G said 'insulated', not 'horribly expensive'

 

[spacefire]

polymer based paint, no foam+thick rubber...whatever. or make a carbon nanotubes mesh through the foam to keep it stuck to the tank.<br />if NASA has so many smart people on its payroll, why couldn't they figure something out? <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[redgryphon]

Since I think PAL ramps are going to be a topic of discussion for a while, I thought I would post NASA's latest work on this. The following is an extract from the Return to Flight Implementation Plan, i.e. NASA's published master plan for RTF and subsequent improvement. As you can see, the PAL ramps were pretty much top of NASA's to-do list, following RTF. That is not meant to be a backhand criticism of NASA. In fact, it gives me hope that a solution may be closer. But, right now, I think a September launch of STS-121 is a long shot.<br /><br /><font color="yellow"><br /><b>Protuberance Airload (PAL) Ramps Background.</b> <br />The ET PAL ramps are designed to reduce adverse aerodynamic loading on the ET cable trays and pressurization lines (figure 3.2-1-4). PAL ramp foam loss has been observed on two prior flights, STS-4/ET-4 and STS-7/ET-6. The most likely cause of the losses was repairs and cryo-pumping (airingestion) into the Super-Light Ablator panels under and adjacent to the PAL ramps. Configuration changes and repair criteria were revised early in the Program, thereby precluding the recurrence of these failures. However, the PAL ramps are large, thick, manually sprayed foam applications (using a less complex manual spray process than that used on the bipod) that could, if liberated, become the source of large debris. For this reason, NASA placed them at the top of the priority list for TPS verification reassessment and NDI.<br />...<br />NASA has initiated a three-phase approach to eliminate the potential for debris loss from the ET. Phase 1 includes those activities to be implemented prior to RTF that would control critical debris on tanks already constructed. Phase 2 activities are not required for RTF, but rather focus on continuous improvement. Phase 2 includes debris elimination enhancements that could be incorporated into the ET production line as they become available, but are not</font>

 

[drwayne]

When you ask that question, you have to realize that any proposal must<br /><br />(0) Perform as expected<br />(1) Be really available (you would be suprised how much stuff the manfacturer says they have on the shelf that they just have a vague idea of how to make)<br />(2) Be consistently reproducible<br />(3) Be cost effective<br /><br />A surprising number of solutions to technical problems that occur to us as outsiders fail one of the tests above. Even some that I have been an insider on.<br /><br /> Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[silylene old]

There are polymers (at least in the lab) which could replace polyurethane foam which have quite impressive adhesive capabilities, mechanical strength, flexibility and can be processed to produce closed cell foams. Maybe alternatives to polyurethane should be explored. <br /><br />Has NASA funded any research projects on PUR replacement polymers? <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[kurros]

<blockquote><font class="small">In reply to:</font><hr /><p><br />Additionally, NASA has approved the use of flight instrumentation to obtain data to validate the flight environments used in the test and analysis. The instrumentation package, containing accelerometers, is planned to fly on the second ET planned for RTF mission STS-121. These data, in addition to the tests and analysis, will provide the basis to continue pursuing elimination of the LO2 and LH2 PAL ramps.<p><hr /></p></p></blockquote><br /><br />Didn't Atlantis' ET get moved to Discovery when it was rolled back in May? Did this instrumentation make it into STS-114?

 

[lycan359]

<br />And so the NASA RTF budgetary sink hole continues.

 

[erioladastra]

"Let me expand on that point. There is a difference between a hard grounding and a launch embargo. They saw some foam come off the PAL ramp, they don't know exactly why it did. What they said is that the next launch is delayed until they figure out why it happened. The mission is still scheduled and they are continuing to process Atlantis for flight.<br /><br />If they find a simple reason for the foam failure (eg a manufacturing defect) then STS-121 can still launch as scheduled. Only if they can't figure out why it happened, or it turns out to be a generic fault (highly unlikely since it never happened before) can we start talking about "grounding the fleet." <br /><br />S_G and najaB are correct. We need to analyze the history of the tank (ET-121) and compare it to the one planned for STS-121. The foam on the PAL ramp was changed from BX-250 to BX-265 and part of the PAL ramp appears to have been repaired on ET-121. Some of this was in work prior to STS-107. NASA analyzed and debated what to do with the PAL ramps. More homework is required. It likely will require a standown since I doubt the story can be put together in time for Sept (most people are focused on STS-114 right now) but it is theoretically possible a non systemic flaw might be identified and cleared. But with the daylight requirements and Beta angle constraints if we miss Sept it might be 2006. Sigh.

 

[redgryphon]

enrioladastra, thanks for the info on the foam change. They may still try for the short window in November. I think it could be stretched to be about a week long.

 

[najab]

I stand corrected. It did happen before, back in 1982 and 1983.

 

[ozspace]

"NASA grounds shuttle fleet"<br /><br />This is a tabliod way of stating what, I expect, would have been the plan all along. 114 is a test flight and 121 was never going to fly before a solid understanding of the results from 114 were in.<br /><br />In other words, we won't fly untill we have checked how well we did in the RTF effort and feed that back into the second test flight.

 

[redgryphon]

<font color="yellow">It did happen before, back in 1982 and 1983. </font><br /><br />True, but it has not been observed since the procedures were changed early in the program.<br /><br />Looking at the video of the event again, the piece looks to be quite thin. It's almost like a sheet of the stuff peeled off. Maybe it was just an application fault, although NASA did put in place more oversight and testing of foam application. I bet the videotape record of the application is getting plenty of scrutiny.

 

[ehs40]

i hate how the media makes everything look or sound like disaster but when nasa solves this problem and when discovery comes home without a problem it will make nasa look like heros. yay!! but im glad i found this fourm so that i can find out what is relly going on form people that know what is really going on instead of from those idiots at the news stations