STS-114 Mission Update Thread (Part 3)

[ozspace]

Thanks Kiwi, I'll try another time, any plans to make the pilgrimage yourself?

 

[emerrill]

"It hot a flight rule, it is a LCc (Launch Commit Criteria). The waiver has been written and agreed to however it will only be used if the failure hits again."<br /><br />Just to clarify for ppl. They have made it clear that they will only sign the exception to the LCC if the error shows up on sensor 4 (physically sensor 2 in the ET).<br /><br /><br />Well. Im on my way back to FL. No scrubbing allowed <img src="/images/icons/smile.gif" /><br /><br />-eric <div class="Discussion_UserSignature"> </div>

 

[alokmohan]

I hope tuesday will give us good news.

 

[haywood]

I do wish the media in general and CNN in particular would refrain from editorializing...<br /><br />Today's news item about the launch includes this statement...<br /><br />"Any rule change at the last minute, to allow less than four good gauges, would almost certainly raise eyebrows."<br /><br />This would not be a "last minute change", as the rationale has already been written and would simply be "put into effect" should the need arise, as I understand it.<br /><br />Maybe they said that for brevity but isn't accuracy more important? <br />Just another case of sensationalizing the news...an attempt to get headlines out of fear something might happen.<br /><br />The point is, with that one statement, they trivialize the entire two-week effort to trouble-shoot the problem.<br />In other words they are saying "wow, if they switch to 3/4 they must be taking a big chance".<br />Sounds like garbage reporting to me.<br /><br />Or am I picking nits?<br />

 

[bushuser]

I was a reporter long ago. The quote from CNN is bull&%$#@!e. [sighs and rubs his brow] Whether it is bias or ignorance is hard to say. I can't believe the reporter was too busy to get this story correct.

 

[najab]

><i>Or am I picking nits?</i><p>No, you're not nit picking. "News" agencies are all about rating these days.</p>

 

[halman]

Most of us spacehounds have some knowledge of what is going on at the Cape right now, what is involved in getting the Shuttle ready to fly, the steps that are involved in making it to orbit, and that sort of thing. I have gotten the impression over the years that reporters, and even the so-called 'science reporters', often lack even a rudimentary knowledge of spaceflight.<br /><br />In the aftermath of the Columbia loss, many people are expecting that there will be no launch unless there is no risk. To have a 'last-minute' change, (well, to the public, it IS,) in a safety guideline is very questionable.<br /><br />Unfortunately, a lot of the public puts launching the shuttle in the same catagory as Star Trek. It is all super science, that everyday people cannot understand, (What does a rocket push against?) or so they think, because every answer seems to include a lecture about physics, or electronics, or computer science. The principals of rocketry are not taught in most science classes, or demonstrated by television programs, or even written up in the newspapers, it seems. You have to be interested in space flight enough to dig into it on your own, which sets us apart from the mainstream right there. We have devoted our own time, in varying amounts, to learning about this esoteric subject, with no anticipation of reward or participation, just for the excitement of watching the greatest adventure anyone can take.<br /><br />I feel that we should be happy that the shuttle launch is in the news, even if the facts are mis-represented, because exposure to this launch will probably capture the imagination of some child, and give them something beyond the horizons of going to the mall, or watching South Park, or playing ball. Shuttle launches become routine as far as the media is concerned, very quickly, it seems like. It probably will not be long until a launch is only good for a ten-second story on the evening news, and a few column-inches in the local paper.<br /> <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[haywood]

Excellent post halman!<br />

 

[shuttle_rtf]

It's certainly not an easy subject to cover. But it pays to ask questions and be open to people correcting you on ensuring a story reads right on the facts. <br /><br />The minute you publish something incorrect (when it could have been corrected by simply asking Engineers etc.) is the minute you'll get a bad reputation...and that's deadly in the world of journalism.<br /><br />The key is to always keep asking the questions by way of a learning curve.

 

[dougbaker]

Don't forget, the people reading this forum are intelligent and literate. <br /><br />I don't think I would use these descriptors for the general public. It is a world of stories spun, sound bites, and headlines that only last a day or two. <br /><br />I would guess you could take a poll and a very large percentage of the public would have completely forgotten about the space shuttle hype of just a few days ago. (less than two weeks). I don’t think this has anything to do with the space program or NASA, I would guess you could do the same poll about any large new story and it would be the same.<br /><br />Anyway back to the topic. Waiting for the tanking to start 11pm (mst) or I think 5:00 GMT? <br />

 

[lunatio_gordin]

I agree. an Educate the public campaign, maybe.

 

[sabby223]

I wasn't able to see tonight's press conference... <br /><br />Anyone able to report the highlights?

 

[shuttle_rtf]

Just that they are not tracking any issues. That they expect all four ECO sensors to be fine, as per test results.<br /><br />That was followed by the usual rubbish questions from the media present, such as "Your hair is so cool, why is that?" etc <img src="/images/icons/wink.gif" />

 

[shuttle_rtf]

Just wait till you see me at a press conference on NASA TV. Bill Parsons will be holding me down, while Wayne Hale slaps me over the head with a LOX Feedline whilst saying: "See, look how the only debris coming off this bad boy are parts of your head!!"<br /><br /><img src="/images/icons/wink.gif" />

 

[SpaceKiwi]

Haha, I'd subscribe to a pay-per-view to see that, SRTF!<br /><br /><br />j/k <img src="/images/icons/wink.gif" /><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>

 

[redgryphon]

A question for the shuttle experts here. What is the strict definition of T-0? Is it when:<br /><ul type="square"><li>The command is sent to ignite the SRBs<li>The ignition command is received by the SRBs<li>The SRBs reach 100% thrust<li>The command to fire the hold down bolts is sent<li>The hold-down bolts are actually fired<br />or when<li>The SRBS physically separate from the MLP?<br /></li></li></li></li></li></li></ul>

 

[SpaceKiwi]

Just read the article on SDC, suggesting they could give a launch-commit with 3 of 4 ECO sensors under certain conditions. I think there has been some re-routing of the circuit on the troublesome sensor, hasn't there?<br /><br />Would a further failure of this same sensor give increased 'confidence' to fly, or less, with the next launch? I can see arguments both ways. <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>

 

[shuttle_rtf]

I believe the release/fire command to the hold down bolts is sent just (and I mean just) before the command to fire the SRBs is given.

 

[shuttle_rtf]

Yeah.<br /><br />Sensor curcuits 2 and 4 have been swapped.<br /><br />Should Sensor 4 fail, fault will be shown as the Sensor 2 circuit path, and that's a certain condition that I believe allows for the launch to proceed.<br /><br />If it's Sensor 2 again, then the problem's still there despite the swap and that's a potential issue with the Point Sensor Box, and may lead to scrub.<br /><br />3:30am, so I may have that a bit wrong. SG will slap me into place if so, so it's all good <img src="/images/icons/smile.gif" />

 

[SpaceKiwi]

red, courtesy of NASA TV, I now know the bolts are fired before the SRB ignition command is sent. So, I don't think that's your answer.<br /><br />I would say it is on the SRB ignition command if I had to guess. The thrust they produce is pretty instantaneous and, even if not at 100%, they surely produce enough in the first few milliseconds to suppliment the SSME's and physically lift the stack off the MLP.<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>

 

[redgryphon]

Thanks for your answers guys. I also have seen the JSC guy talk about the hold down bolts and SRB ignition more than a few times! I recall that following launch NASA gives the time of t-0 to 0.001 seconds, so I was wondering what defines that point. I also would guess it is the SRB ignition command, but perhaps someone can confirm.

 

[strandedonearth]

I am/was under the impression that the "T" in "T minus..." (or "T plus...") stands for "Tmax," which is the (first?) moment that maximum thrust is reached. For the STS, I assume that would be when the SRBs ignite. IIRC, the SRB hold-down bolts are fired 0.001 seconds before SRB ignition. <br /><br />I believe Tmax is a holdover from older, all-liquid-fueled rockets that took a few moments to build up to full thrust. The same holds true for the SSME's (which ignite at about T-6, IIRC), but I'm not sure if they're just reaching max thrust at T-0, or if they've been holding max thrust for a second or two while the computers make sure everything is nominal. <br /><br />disclaimer: I am not an expert.

 

[bobw]

It is an interesting question. I thought they start the SRB's and blow the bolts at the same time. I get that from the Space Shuttle Reference Manual in the section about the SRB's but that could be wrong. The ISS one was wrong about using US suits in the Pirs module. Same time makes sense to me, but it isn't hard to imagine that it just works better with some timing thrown in.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>The GPC launch sequence also controls certain critical main propulsion system valves and monitors the engine- ready indications from the SSMEs. The MPS start commands are issued by the onboard computers at T minus 6.6 seconds (staggered start- engine three, engine two, engine one- all approximately within 0.25 of a second), and the sequence monitors the thrust buildup of each engine. All three SSMEs must reach the required 90-percent thrust within three seconds; otherwise, an orderly shutdown is commanded and safing functions are initiated.<br /><br />Normal thrust buildup to the required 90-percent thrust level will result in the SSMEs being commanded to the lift- off position at T minus three seconds as well as the fire 1 command being issued to arm the SRBs. At T minus three seconds, the vehicle base bending load modes are allowed to initialize (movement of approximately 25.5 inches measured at the tip of the external tank, with movement towards the external tank).<br /><br />At T minus zero, the two SRBs are ignited, under command of the four onboard computers; separation of the four explosive bolts on each SRB is initiated (each bolt is 28 inches long and 3.5 inches in diameter); the two T-0 umbilicals (one on each side of the spacecraft) are retracted; the onboard master timing unit, event timer and mission event timers are started; the three SSMEs are at 100 percent; and the ground launch sequence is terminated.<</safety_wrapper></p></blockquote> <div class="Discussion_UserSignature"> </div>

 

[haywood]

Where is the Mission Status Briefing?<br />I thought it was at 10:00 am this morning according to the NASA TV Schedule.<br />

 

[najab]

><i> I thought they start the SRB's and blow the bolts at the same time. </i><p>on human scales, they are at the same time. The hold-down bolt command is issued just 0.001 seconds before the ignition command.</p>