STS-115 Status - Part II

[MeteorWayne]

That sound like a project for Sunday or Monday <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>

 

[spacester]

Well I'm not SG but he's prolly a tad busy right now . . .<br /><br />LOX and LH2 in, water and electricity out. <br /><br />It's a start? <div class="Discussion_UserSignature"> </div>

 

[AbsolutSpaceGirl]

Here is a good site on orbiter fuel cells:<br /><br />http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts-eps.html#sts-fuel-cell<br /><br />

 

[georgeniebling]

Thanks SG ... that was perfect ... (and thanks to others for the other links and such) ...<br /><br />I must learn that secret handshake!

 

[SpaceKiwi]

<blockquote><font class="small">In reply to:</font><hr /><p>The exact inner workings of these Fuel Cells is a Corp. secret.<p><hr /></p></p></blockquote><br />Wayne Hale made a joke yesterday about this point. They bought the items from the vendor without really knowing how they work, due to the information being proprietry. The observation got a good chuckle from the room. Hale has great comedic timing. <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>

 

[paul_bacon]

When will tanking start again?

 

[SpaceKiwi]

Have the ECO sensors ever caused a slightly premature MECO in the history of Shuttle? <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]

One more question. What amount of prop is typically left in the ET at MECO, percentage-wise? <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>

 

[paul_bacon]

Cheers<br /><br />From cbs "Engine cutoff - ECO - sensor No. 3, the one that "failed wet" earlier today and derailed an attempt to launch the shuttle Atlantis, continued indicating it was immersed in liquid hydrogen after the ship's external tank was drained this afternoon, officials said. The other three ECO sensors in the hydrogen tank correctly indicated they were dry as one would expect.<br /><br />The readings lend some credence to the belief that three of the four sensors are operating normally. If they continue to behave properly when the tank is re-loaded with liquid hydrogen early Saturday - and if no other sensor issues develop - NASA managers may be able to approve a flight rule waiver allowing a launch with three of four operational ECO sensors"<br />

 

[lysol]

JonClarke,<br /><br />No i dont have any evidence. Im not an engineer...but im also not a blind fool either. There are those i bet who would want to see money used on manned flight be put elsewhere. And if it is true wouldn't using every avenue to embarass and discredit the NASA manned flight program be concieveable?<br /><br />They used to stop shuttle launches for birds for gods sake. And here they want to try and short cut thier way around an obvious problem which past STS missions that had experianced grounded the mission.<br /><br />With the heat those fuel cells produce while in ATMO, my wild guess is it wouldnt last more than 6 to 12 minutes before they would cut out. And to have a major system fail while during the insertion phase wouldnt be a bad thing?<br /><br />I know that it would probally run fine in the ambiant temp while in orbit. But that specific part is 30 years old, if there is a fault. Then there could be a larger underlying issue.<br /><br />But i do think there is an element that wants to see man flight be scrubbed for several years because of politics and money. And as far as the NASA engineers, i dont trust them because my nieghbor is a former snipe for nasa and he has yet to stop raving about how "Medocrity and laziness" that lead to Columbia going down.<br /><br />They are trying to short cut. Short cutting kills people. Im glad the ECS sensor went bad becuase it gives them time. <br />I want to see the mission happen as much as the crew does. Not by being irresponsible...and you may disagree, but should Alantis go up and should a problem happen that causes the loss of the vechile or cargo, more importantly the crew. You will be eating your woulds and our space program will trip backwards 40 years. <br /><br />But as far as evidence...I have none. Its called common sense...you dont gallope your only horse with your wife and baby riding through a catus patch on three good legs.

 

[askold]

That's how the argument always goes - if you launch in anything other than perfect conditions, you're putting crews at risk. You can always make things more perfect - put 5 ECOs in the tank, 4 fuels cells in the orbiter, 6 computers in the cockpit.<br /><br />That's why we should shut down the manned program and only launch robots. We've never had a state funeral for a crashed probe.

 

[tronchaser]

The reason for the 24hr scrub is that the launch window now is about 7 minutes. There is no way to have the test rationale written, looked over with more than one set of eyes, execute the test procedure.

 

[JonClarke]

"That's why we should shut down the manned program and only launch robots. We've never had a state funeral for a crashed probe."<br /><br />By this logic let's not travel the world because we might be killed in a plane crash, let's just watch vidoes that people send to us from other countries. Nobody held a funeral for a file corrupted in transmission or for a parcel lost in the post.<br /><br />Let's got send robot probes at all - ground based telescopes are cheaper, more flexible, more reliable and have longer operating lives.<br /><br />Don't hijack this discussion of this mission with your absurd prejudices. Start a thread if you wish.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[halman]

SpaceKiwi,<br /><br />I seem to remember that they swapped out the External Tank on the Discovery because of a bad Engine Cut Off sensor, and took the sensor apart, and could not isolate the fault. In further testing, it was intermittent, which was never pinned down. The whole batch was declared bad, and supposedly all the tanks in the pipeline had the ECO's switched out. So, is this an old ECO, or one of the newer ones? <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[farmerman]

All I know that if the sensor is faulty tomorrow, which I guess it will be, and Nasa decides to launch tomorrow it will be eight minutes of hell praying that another sensor doesn't go bad. The astronauts will have "balls of steel" riding the rocket tomorrow if they launch. All I've got to say is "God's speed sts-115". Your in my prayers. I have never been so nervous about a mission as this one. Nasa seems to be getting "go" fever with the failures going on. They seem to me that they are trying to talk themselves into launching with the troubles they are having. Just my opinion from the little bit of news I get in this part of the world.

 

[colchadisatlend]

Anyone know when tanking is scheduled to begin?<br /><br />I heard that there were concerns regarding later afternoon thunderstorms effecting turn around work, so I was check to see if everything was still was on time and going as planned.<br /><br />

 

[bobw]

Tanking started about 15 minutes before you posted the question <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[colchadisatlend]

ALRIGHT! <img src="/images/icons/cool.gif" /><br /><br />I have a feeling it's going to launch for real this time....

 

[SpaceKiwi]

I'll need to go back and look at the discussion on that mission, but it sounds about right, halman. I don't know that the batch of unused sensors was thrown out, but I think they did/have been re-checking each one as it goes into a new ET. I'm assuming that's additional to the acceptance testing and certification that took place when Michoud accepted them into their parts inventory.<br /><br />I seem to remember reading somewhere that they have all been 'graded' as well. I'll assume it's been a fairly rigorous process with these sensors, so it's completely baffling that the problems just keep coming. IIRC there was also some discussion about a 'mesh diffuser' which was changed in the ET, and its downstream impact on prop flow across the sensors. I think they went back to the old design as part of the troubleshooting on '114. <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]

<blockquote><font class="small">In reply to:</font><hr /><p>All I know that if the sensor is faulty tomorrow, which I guess it will be, and Nasa decides to launch tomorrow it will be eight minutes of hell praying that another sensor doesn't go bad. The astronauts will have "balls of steel" riding the rocket tomorrow if they launch.<p><hr /></p></p></blockquote><br />Well, it has to be said that any astronaut strapping himself/herself to the side of the Shuttle stack has a pretty strong constitution as factory standard. However, I think you might be slightly overstating the danger from this particular problem though.<br /><br />As SG and others have noted, the ECO sensors only come into play a handful of seconds before the Shuttle reaches MECO. Should a worst case scenario develop, and you get 'drys' across multiple sensors, they will initiate an emergency MECO relatively close to the desired delta-V. Not enough to enable a stable orbit with OMS burns, but enough for mission managers to have time to plan the Orbiter's return.<br /><br />Assuming the other sensors read correctly, with the faulty also reading 'wet', they will not come into play to impact the mission as the Flight Computers will initiate MECO first per the programmed ascent profile. That's why you get the series of OMS burns ... to finalise the orbit correctly after the SSME's and SRB's place the Orbiter in approximately the right attitude.<br /><br />The SSME's (and ET) could probably take the Orbiter all the way to a stable orbit but they stop just shy so that, when the ET is jettisoned, it falls back into the Pacific. <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]

7hrs:45mins till lift-off <img src="/images/icons/smile.gif" /> <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>

 

[halman]

It strikes me that testing the Engine Cut Off sensors would entail putting them in liquid hydrogen at the same pressure as they experience in the External Tank, which uses tanks that are at least 30 feet high. Then, cycling the tank a few times, with a long period of no hydrogen followed by a period of high pressure liquid hydgrogen. There seems to be a regieme which can lead to failure that we haven't detected yet.<br /><br />The ECO sensors are in place to prevent the Space Shuttle Main Engines from trying to run without fuel, which could lead to an explosion. They are part of the original design, a safety feature in case of a failure of the ET which would allow the fuel to leak, or in case the engines consume more fuel than predicted. Years of experience with this vehicle have led to knowing how it behaves quite well, as long as certain things are avoided, like launching in really cold weather, or letting large chunks of foam from the ET strke the orbiter. So, when it is decided that the failure pattern on the ECO sensors is within a regieme with little risk, that is not a blind decision, but a rational assesment of risk. <br /><br />I am a bit more surprised at the decision regarding the Auxillary Power Unit, but this mission is considered essential to the International Space Station program, and a great deal of money has been on hold while waiting for construction to continue. With the daylight constraints, and weather factors in launches later in the year, making this window is apparently critical. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[colchadisatlend]

Are anymore of those damn ECO sensors acting up, or is it just the same one? I am really beginning to hate those things....

 

[earth_bound_misfit]

Good question, tanking has been in progess for a few hours now, so we should hear something soon. <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>

 

[earth_bound_misfit]

<b>Atlantis Set for Launch Today, Tanking Begins</b><br />nasa.gov<br /><br />Sept. 8, 4:45 a.m. EDT<br />At Launch Pad 39B, the loading of Space Shuttle Atlantis' orange external tank with about 528,000 gallons of liquid oxygen and hydrogen began on time at 1:15 a.m. EDT today. The "topping off" of propellants into the tank will continue until liftoff. All systems onboard the space shuttle, including the four engine cut-off (ECO) sensors, are functioning normally and are ready for launch at 11:15 a.m. EDT. <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>