STS-120/(10A) Update

[thereiwas]

My point was that they are not to the point when they know that driving on bald tires <i>is</i> dangerous. It is all too new. These cracks may be important, they may not. Until people had been driving cars for a while and gotten into a few accidents that clearly <i>were</i> caused by bad tires, they didn't know that it was a bad idea.<br /><br />Better in the long run to have a re-entry system that is not operating at the hairy edge of its capabilities, where the simple erosion of a coating can result in loss of the vehicle and its crew.

 

[thereiwas]

"As I said a few days ago, the RCC issue was never really a problem for launch."<br /><br />Unless one is concerned about how they land. There is this song about Werner von Braun that I will not quote here... <img src="/images/icons/smile.gif" />

 

[bobblebob]

Assuming the worst case scenario and they lose the protective coating on these tiles, have Nasa done thermal tests (similar to the ones last mission) to see how the tiles would react on reentry?

 

[MeteorWayne]

Yes they have. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[bobblebob]

And did the results show a catosrophic failure of the RCC panels?

 

[bobblebob]

Thanks. Just been reading an article about the conference last night. Seems they could attempt a repair if the inspections show more damage to the tiles. Im guessing that was a factor in them deciding to launch

 

[SpaceKiwi]

I've got to start writing stuff down but, IIRC, these panels have flown twice previously without additional degradation of the surface?<br /><br />This being, if fact, true, I would think that factored into the positive column regards the decision to go fly.<br /><br /> <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>

 

[bobblebob]

Yeah they have flown before without any further degradation to the panels. However, up until recently Nasa thought they knew why the panels were degrading, but it seems from tests their theories were incorrect . That seems to be the main talking point.<br /><br />Flying with a problem that you understand vs flying with a problem you dont understand

 

[scottb50]

From what I have been able to find it sounds like the problem is with a coating applied to the panel not the panel itself. Maybe someone could answer if the coating provides protection to the panel or is more like a sealer to reduce wear to the composite materials underneath? Is it more similar to paint wearing off or a critical part of the panel deteriorating? <div class="Discussion_UserSignature"> </div>

 

[SpaceKiwi]

I believe you are right on both counts. As I understand it, the 'deeper levels' of the RCC are more porous and they apply this outer coating to both protect and seal the interior.<br /><br />The problem seems to exist in the bond between this outer coating and the main 'guts' of the RCC itself. They initially believed it was an oxidation problem between the two surfaces, and could characterise the rate of degradation by this (relatively-speaking) understood process.<br /><br />However, now the thinking is that some other process is at work. As they haven't nailed down what that process (or combination of) is, it is difficult for them to quantify the expected rate of degradation.<br /><br />As I said above, I think they've flown the panels at least twice with no observed degradation in them, so the thinking probably is that atmospheric re-entry is not part of the problem. (for the GO-LAUNCH engineers anyway)<br /><br /> <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>

 

[scottb50]

Have they seen similar problems on the other vehicles? <div class="Discussion_UserSignature"> </div>

 

[SpaceKiwi]

Well, as I understand it, they moved away from the 'simple' oxidation theory to where we are now after STS-114. There was a RCC panel on Discovery (8R, I think) that showed abnormalities, specifically that they could 'chip' the outer coating off like paint flecks.<br /><br />It was at that time that they decided something more than oxidation has been in play. I believe they sliced that panel up to look at the interface between the coating and the main RCC composite. As you know, the jury is still out on what's going on exactly. Wayne Hale said they will work this problem until they establish the root-cause, but couldn't indicate when it might finally be resolved.<br /><br /> <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>

 

[usn_skwerl]

when were the panels in question last replaced?<br /><br />25 year old aircraft - and cars - (or parts "only 5 years old") aren't perfect <div class="Discussion_UserSignature"> </div>

 

[SpaceKiwi]

I'm not sure. I'd suggest they're probably tight for RCC panels, especially after the destructive testing they did following the Columbia tragedy. I'd guess they would only change an RCC panel out if they are sure it's a flight risk.<br /><br />Remember, they have been carefully monitoring the health of each panel since RTF using a number of techniques, including this newer thermography method. The panels in question were identified after '114, then flew on '121 and '116 without any additional degradation in their observed condition.<br /><br />I think that gives the engineers some confidence that they can fly on '120 and will return in an unchanged condition a third time. (since the problem was identified)<br /><br /> <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>

 

[bobblebob]

Is it possible something struck the RCC panels that chipped away at the coating on the tiles? Obviously something that wasnt large enough to do more serious damage, but just damage the coating?<br /><br />Would possible be an explanation as to why other flights havent shown signs of further degradation

 

[bpcooper]

Can see the full forecast here:<br /><br />http://www.patrick.af.mil/shared/media/document/AFD-070517-025.pdf <div class="Discussion_UserSignature"> <p>-Ben</p> </div>

 

[halman]

bobblebob,<br /><br />It is highly unlikely that the condition of the panels is the result of impact damage. This appears to be more of a chemical process, which is resulting in a change in the characteristics of the coating, possibly resulting in physical changes to the underlying material. Apparently, every panel is being subjected to a nearly microscopic examination, and it was this close scrutiny which has detected the changes.<br /><br />What appears to be unknown by many people is that the flow of hot gases during re-entry tends to be at such high velocity that it seems to take a considerable change in the shape of a surface before that surface is susceptible to gas breaching. The degradation of the panels is in the nature of tiny, shallow cracks, which would have no significant impact on the gas flow over the panel surface.<br /><br />Because the safety panel suddenly realized that it did not understand the nature of the process affecting the surfaces of several panels, the safest recommendation is to pull the panels and replace them with new or refurbished ones. I think that this situation is analogous to deciding whether to drive to the movie theater in a snowstorm. The safest course is to stay home, but snowstorms happen at inconvenient times, and we must deal with them. If it was a full blown blizzard, then things would be different. If a driver is experienced in driving in snow and limited visibility, then they are highly likely to make the journey without incident. The shuttle management team has experience with this vehicle, and it is understood that the risks are not significantly worse than they have been before.<br /><br />I think that this is a totally different type of situation than that which preceded the loss of Columbia, where at least one shuttle had returned with potentially catastrophic damage, and several other disturbing foam strikes had occurred. Management at that time decided that the problem was not significant enough to ground the f <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[bobblebob]

Thanks for that, great post <img src="/images/icons/smile.gif" />

 

[bobblebob]

The Launch of STS-120 will be available in High Definition. The HD feed will be DVB compliant MPEG-2, 720 P @ 59.94 fps.**** <br /><br /><br />Uplink provider = Americom<br />Satellite = AMC 6<br />Transponder = 17C<br />72 Degrees West<br />Downlink Frequency: 4040 Mhz<br />Polarity: Vertical<br />FEC = 3/4<br />Data Rate r= 36.860 MHz<br />Symbol = 26.665 Ms<br />Transmission = DVB<br /><br />"HD" Programming Program = 105 (HQ5), Video PID = 1051, Audio PID = 1054 , AC-3 PID = 1055<br /><br /><br />For all you lucky Americans who can get the service

 

[chode]

The launch is also scheduled to be carried in HD by HDNet. <br /><br />From their website:<br />HDNet and HDNet Movies are available in the US on AT&T, Bright House Networks, Charter Communications, DIRECTV, DISH Network, Insight, Mediacom, Time Warner Cable, Verizon and more than 40 NCTC cable affiliate companies. The networks are available in Canada via Bell Express VU, Cogego, Shaw Cable, Star Choice and more. <br /><br />Regards

 

[haywood]

NASA TV is carried now by Bell ExpressVu?<br />When did that happen?<br />

 

[bobblebob]

Just been trying to find out who writes the software for the onboard computers but ont having any look. Anyone know?

 

[SpaceKiwi]

Just if someone saw, but did they carry the Countdown Clock start on NASA TV today? I thought that was normally a live event though, when I looked in this morning, they were showing '120 crew interviews.<br /><br /> <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>

 

[bobblebob]

As far as i remember, they never show it. Got this in the KSC email aswell:<br /><br />2 p.m. - Launch countdown officially begins (not on NASA TV)

 

[MeteorWayne]

Countdown clock is running...<br />T-38:35:00 and counting.<br /><br />~ 2 Days, 17 hours <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>