STS-115 Status - Part II

[nyarlathotep]

You'd think that with the massive costs of these scrubs, they'd redesign it to be freaking pressure fed.

 

[vt_hokie]

Damn! Seems this flight just wasn't meant to be...<br /><br />

 

[earth_bound_misfit]

Atlantis is not getting any lucky breaks (except the weather ATM). What's the bet this sucker doesn't fly this year unless they lift the light limit. <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>

 

[paul_bacon]

"The plan calls for the external tank to be drained and another countdown performed tomorrow to evaluate how the hydrogen fuel level gauge acts. If it behaves in the same manner, officials could allow Atlantis to launch with only three of the four sensors working. Tomorrow's launch time is 11:15 a.m. EDT. "<br />

 

[MeteorWayne]

I think the only other vehicle that uses them is a '72 Caddy <img src="/images/icons/smile.gif" /> <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>

 

[nyarlathotep]

The way their luck is going, the October tank is going to have a failed ECO sensor too.

 

[SpaceKiwi]

It's going to be very interesting to hear what SG has to say about all this.<br /><br />I can't see the ECO problem miraculously going away. And, even if it does co-operate during polling tomorrow, what real degree of confidence are you going to have that it will be reading right in a crunch situation? <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>

 

[earth_bound_misfit]

I'm disappointed but MMT made the right decision. Better safe than sorry. <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>

 

[SpaceKiwi]

Complete ECO sensor re-design, six month program stand-down, end of program.<br /><br />I can't wait to hear what Wayne Hale has to say about them, given they supposedly went over all their ECO sensor stock with a fine tooth comb to make sure only 100% guaranteed-to-work units were fitted to ET's.<br /><br />How many of the ones in Discovery's next ET are dicky? And, the one after that? It's an absolute nightmare. <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>

 

[SpaceKiwi]

I'm going to bed. Can someone please wake me when they come out of the T-9 minute hold with greens across the board.<br /><br />If you could also inform me which year it is when you do, that would be great too. <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>

 

[earth_bound_misfit]

Maybe the answer lies in installing more of them, connect them up in parallel or something. <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>

 

[bobw]

I agree wholeheartedly, it sure is a nightmare. New ship, new tank, same problem. They must be pulling their hair out at the cape. <div class="Discussion_UserSignature"> </div>

 

[foochar]

"I can't see the ECO problem miraculously going away. And, even if it does co-operate during polling tomorrow, what real degree of confidence are you going to have that it will be reading right in a crunch situation?"<br /><br />From what I have heard of the Launch commit criteria, at this point the "desired" outcome is for it to fail wet again with the same "electrical signature". In that case according to what I have read elsewhere it is permissible according the LCC to proceed with launch. Failing wet and failing dry present two different levels of risk, with failing wet being the less risky situation in my opinion.<br /><br />The purpose of these sensors is to prevent the tanks from going empty with the engines still running, which can cause an explosion. There are four sensors, two of which (three early in the flight) have to read dry for the empty tank criteria to be met. If the sensor were failing dry then only one more sensor would have to fail to cause a problem, since then two sensors would be reading dry and the engines would be cut off. Since it is failing wet two of the remaining three sensors would have to fail wet, and the tank would have to be empty for this to cause a failure. Even if all four sensors would get stuck on wet, you would not have a failure unless the tank also ran empty (Granted from what I have read this failure would be catastrophic if it did happen.)

 

[flynn]

<font color="yellow">flynn's beer money is suddenly looking much safer</font><br /><br />I take no pleasure from that.<br /><br />I'd glady buy Shuttle_guy a beer any day of the week. (Flying days prohibited obviously) <div class="Discussion_UserSignature"> <font color="#800080">"All God does is watch us and kill us when we get boring. We must never, ever be boring" - <strong>Chuck Palahniuk</strong>.</font> </div>

 

[spayss]

I'm confused. They won't launch because of a failed sensor. But they will launch tomorrow if they have the same problem?<br /><br /> Am I missing part of the equation? If there is a failed sensor why wouldn't they lauch today if they may launch tomorrow?

 

[spacester]

Well explained, foochar. I would add that my understanding is that the ECO sensor system itself is redundant, as the flight computers are the primary means of deciding when to quit burning.<br /><br />Combined with the fact that the actual problem is likely not the sensors themselves, but orbiter wiring that is not used post-MECO, to launch tomorrow would not be a case of go-fever but of getting the job done with adequate but not excessive margins of safety. IMO.<br /><br />Not only that, but a launch tomorrow would make even more sense when you consider that it's my birthday. <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>

 

[spacester]

They will launch tomorrow if their review of the decision to modify the LCC indicates that the level of redundancy remains adequate for mission success. <br /><br />If the prob is in orbiter wiring, and the other orbiter wiring checks out, then there is no reason to suspect that the other ECO sensors and their associated circuits would give false readings. My understanding is that they are looking to verify that the prob is where they think it is.<br /><br />I have been very impressed by the decision making process going on at Dr. Griffin's NASA. This has been quite a drama yet I applaud every decision made so far. <div class="Discussion_UserSignature"> </div>

 

[rybanis]

Man what in the hell?<br /><br />I'm sure USA is probably wanting to shoot some enginners at Michoud. SG and the crew probably wants nothing more now than to get this launch done and moving on! <div class="Discussion_UserSignature"> </div>

 

[colchadisatlend]

DAMN IT!!!!!!!!!!!!!!!!!!!! <img src="/images/icons/frown.gif" /> <img src="/images/icons/rolleyes.gif" /><br /><br />I am officially starting the "I hate ECO sensors" Club <img src="/images/icons/mad.gif" />

 

[foochar]

"Am I missing part of the equation? If there is a failed sensor why wouldn't they lauch [sic] today if they may launch tomorrow? "<br /><br />By waiting a day and going through another tanking cycle they will be able to see if the failure appears to be consistent. If the same sensor fails in the same way then they are more confident that the problem is with only that sensor. The sensor has to fail with the same "electrical signature" in order to allow for a launch.<br /><br />" I would add that my understanding is that the ECO sensor system itself is redundant, as the flight computers are the primary means of deciding when to quit burning"<br /><br />Based on my understanding this is true. The only time that the ECO sensors come into play is if the shuttle is running out of LOX or LH2 before it reaches the intended orbit. The flight computer is controlling the engines to allow the shuttle to reach the intended orbit. The shuttle tank is always loaded with more propellants then needed to reach the intended orbit, however if something goes wrong and the engines are going to run of propellant before reaching the intended orbit the ECO sensors trigger a shutdown before the propellant runs out. According to what I have read not shutting the engines down before they run out of propellant can cause an explosion.

 

[montmein69]

> I'm going to bed. Can someone please wake me when<br /> /> they come out of the T-9 minute hold with greens across<br /> /> the board.<br /> />If you could also inform me which year it is when you do, <br /> />that would be great too. <br /><br />I'm sure you can awake around the 14 th, these old bad russians will pull out the Semiorka with their old bad loco, they will put it vertically with their old bad crane, they will fill it with their old bad pump ... and they will shoot this old bad rocket whatever the weather ... and nothing more to say except the price is lower .... <div class="Discussion_UserSignature"> </div>

 

[AbsolutSpaceGirl]

"According to what I have heard here the pump is only on for about the first 30 minutes after launch, and presumably during landing, at times other than that the ambient cold of space takes care of the fuel cell cooling needs. There is basically only a 30 minute window where this problem can affect the mission."<br /><br />This isn't true - the fuel cell coolant pumps run constantly. In fact, a fuel cell can only survive a matter of minutes without its cooling pump. If the cool pump dies, the fuel cell will have to be shut down.

 

[MeteorWayne]

That is not what they said in yesterdays press conference. That's where I got that information from. <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>

 

[AbsolutSpaceGirl]

I saw the conference and don't recall them saying that, but I know with 100% confidence that if a fuel cell does not have its pump, it is considered lost. It absolutely cannot run for more than about 10 minutes without a coolant pump during all phases of flight. That is why they would have to shut the fuel cell down and possibly shorten the mission if the pump dies.

 

[georgeniebling]

SG, could you write a brief (yes, I know, it could be a book) bit about fuel cells; what they are, how they work, etc .... a refresher for those of us that haven't heard that lovely term lately.