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Space Science

NASA Scrubs Launch Due to Faulty Fuel-Tank Sensor 423

Posted by timothy from the safe-than-sorry dept.
VUSE g-EE-k writes "NASA has scrubbed Wednesday's launch of Discovery due to a faulty fuel-tank sensor in the external fuel tank. They are going to begin the troubleshooting process. They have not released details as to how long this delay will last. The crew have begun to get off the shuttle. For more information, see the NASA TV site. Drudge Report has some initial coverage of the scrub." Reader adefa adds a link to NASA's Space Shuttle launch page with more info.
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NASA Scrubs Launch Due to Faulty Fuel-Tank Sensor More

NASA Scrubs Launch Due to Faulty Fuel-Tank Sensor

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  • Begin the countdown! (Score:4, Funny)

    by HyperChicken ( 794660 ) * on Wednesday July 13, 2005 @12:55PM (#13055435)
    Conspiracy in 5, 4, 3, 2...

    • Re:Begin the countdown! (Score:5, Funny)

      by Lumpy ( 12016 ) on Wednesday July 13, 2005 @12:58PM (#13055485) Homepage
      Rumors were that there were Al Quidea terrorist members hiding inside the engines waiting to strike just before the shuttle left the atmosphere.

      Also they found a saddle strapped to the main fuel tank with a note that it was reserved for Lance Bass.

    • Re:Begin the countdown! (Score:5, Insightful)

      by Scoria ( 264473 ) <slashmail@nosPaM.initialized.org> on Wednesday July 13, 2005 @01:02PM (#13055523) Homepage
      If you scrutinize a vehicle that is several decades old, it's likely that you'll find a number of unforeseen defects. Even vehicles that are well-maintained suffer from the aging process.

      Just to play devil's advocate, a conspiracy theorist might argue that this is one method by which to stop space exploration: Emphasize safety in a medium where safety cannot under any circumstance be guaranteed, scrutinize the aging shuttle until a defect is found, and finally decline the funding required to build a replacement. Repeat. ;-)

      • Re:Begin the countdown! (Score:5, Informative)

        by eggoeater ( 704775 ) on Wednesday July 13, 2005 @01:10PM (#13055629) Journal
        The external fuel tank burns up in the atmosphere after launch. They are never reused or AFAIK even recovered. The external fuel tank on the pad now, and every part in it, is brand new.
      • Good point- although I wish to take it a step further. Yes any vehicle a few decades old will show some bumps, even if maintained (My grandmother's 78 Caddy, only 32,000 miles, but a few bumps), but even well maintained vehicles (My Pick Up, Used to plow snow for extra money in winter- beat to heck- well maintained though). The severity of what the shuttle goes through is also a huge factor I imagine. Amazing temps and pressures. I don't pretend to have the knowledge about rocket science others here do, but
        • Forget cotton... how about plain old ordinary Cellophane like you have on the front of an alarm clock to prevent scratches. It could be stuck on prior to leaving the VAB, then peeled off and discarded prior to launch.

          The problem is that the shuttle is a paragon of overdesign. It's a shining example of what happens when defense contractors say "Oh, but if we do it this way, we can bill twice as much for a part costing only a little more, but it will be better because [insert BS excuse here]."

  • Don't worry... (Score:5, Funny)

    by Loonacy ( 459630 ) on Wednesday July 13, 2005 @12:55PM (#13055437)
    I'm still confident they'll launch before DNF or Longhorn are released.

  • Redundant system (Score:5, Informative)

    by Fiz Ocelot ( 642698 ) <baelzharon@NOSPaM.gmail.com> on Wednesday July 13, 2005 @12:56PM (#13055454)
    One of four sensors used to detect a low level of hydrogen propellent. They need 2 to work of the four. After they detank, it can be diagnosed, possibly launching tomarrow.

    • Re:Redundant system (Score:5, Funny)

      by plover ( 150551 ) * on Wednesday July 13, 2005 @01:04PM (#13055561) Homepage Journal
      Thanks for the explanation.

      From the article above, I first read it as "a sensor that detects if the fuel tank is present". That didn't sound too critical, because it's a "look-out-the-window-and-see-if-it's-still-there" kind of problem.

      • Re:Redundant system (Score:5, Interesting)

        by Aglassis ( 10161 ) on Wednesday July 13, 2005 @01:11PM (#13055649)
        They had a fuel low level sensor fail. This was some sort of instrumentation and control equipment or sensor fault. The possible causes could be that the actual sensor failed (which might require replacing the liquid fuel tank) or there was an instrumentation fault. Since they were using a test circuit to simulate a low level (since the tank is actually full), an instrumentation failure could be either a failure in the normal instrumentation circuitry or a failure in the test circuitry. Either of these two cases should be easy to fix.

        As someone who has worked extensively on I&CE operation, maintenance, and repair on nuclear reactors, I fully understand why they scrubbed the launch. Redundancy is for faults in operation, not to compensate for damaged equipment prior to operation. From my experience, it is probably the test circuit that failed. Then the instrumentation circuitry. Then, in the most unlikely case, the sensor itself.

        An astronaut on NASA TV explained that the there is a coincidence circuit if two low level alarms trigger that will cause an automatic engine turnoff. If this did not happen and the tank completely emptied, he said that it could cause major damage to the shuttle's main engines. I'm not sure exactly how, perhaps because either without liquid hydrogen, only the oxygen would flow through the engine and no chemical reaction would occur, cooling parts of the engine below their specifications? Or flow characteristics wouldn't be predictable?

        • Re:Redundant system (Score:5, Interesting)

          by EvilTwinSkippy ( 112490 ) <yoda@NosPAM.etoyoc.com> on Wednesday July 13, 2005 @01:30PM (#13055881) Homepage Journal
          Unlike your car engine, where a loss of fuel simply stops the process, the shuttle actually has to suck in the fuel out of the tank, and then ram the propellent into the nozzel at a pretty high rate of speed.

          If you tried to run the engines without any fuel in them, it would be like putting your foot to the floor when the transmission is in neutral. Without a load the engine spins faster and faster until parts start flying off.

          On the shuttle, the turbines are large enough that a catostrophic failure would probably destroy most of the equipment in the tail end of the craft. This includes the orbital maneuvering system, the hydrolic system, several fuel cells, and the rearmost parts of the cargo bay. You also run an outside risk of damaging the tail and flight surfaces on the wings.

          Not a fun thought at all.

        • Re:Redundant system (Score:4, Informative)

          by Rei ( 128717 ) on Wednesday July 13, 2005 @01:41PM (#13056015) Homepage
          You run the SSMEs fuel-rich for two main reasons.

          * It gives better ISP by reducing the number of atoms in the exhaust stream molecules (H2 vs H2O), thus increasing the amount of directional translational energy compared to rotational and vibrational energy (not because of the lower mass/higher velocity of the output gas, like some sites and even textbooks mistakenly state, because you get less energy output from the reduced reaction rate at the same time and thus over-cancel out the effect)

          * It strongly reduces corrosion (not that a mixture containing incredibly hot hydrogen isn't corrosive; it's just less corrosive than a mixture containing incredibly hot oxygen, as far as the combustion chamber and nozzle linings are concerned)

          The latter issue is undoubtedly the reason for concern of running out of hydrogen.

          • Re:Redundant system (Score:3, Interesting)

            by DerekLyons ( 302214 )
            You run the SSMEs fuel-rich for two main reasons.
            The issue isn't why you run fuel rich - but why you need a low level sensor. The two are not quite the same.

            You need a low level sensor for two reasons;

            1. shortly before running out entirely of fuel, you can start sucking bubbles into the fuel line - this leads to unstable combustion.
            2. if you actually run dry, the turbopumps will overspeed and tear itself apart.
      • haha, but seriously.. if they can see the main tank (orangish red) out their windows, they have some serious problems. Unless they installed a glass-bottom. hmm.. glass-bottom shuttle. Not a bad idea. now we just need spacemermaids.
    • I don't think there's another launch window until September last I checked?
    • Er, no.

      Depending on where the sensors are located, engineers may need to remove the orbiter from the boosters. That requires towing the shuttle back to the Vehicle Assembly Building (VAB).

      On STS-98 the launch was pushed back 2 weeks when they had to roll the shuttle back to the VAB to repair a damaged cable on one of the SRB's.

      Linq [spaceflightnow.com]

  • Another article link (Score:3, Informative)

    by JLSigman ( 699615 ) <jlsigman@hotmail.com> on Wednesday July 13, 2005 @12:57PM (#13055457) Homepage Journal
    In case others get Slashdotted, Here's CNN.com's article [cnn.com].

  • It's a shame (Score:2, Insightful)

    by Glsai ( 840331 )
    Just got back to my desk looking to count down the final hour and find it's been scrubbed. I feel sorry for all the astronauts who had to go through all the buckling up and such, it was fun to watch such an involved process. Oh well, better safe than sorry.
    • Those of us who remember Apollo 1 don't feel sorry for the astronauts.

      I am sure the crew is very happy that they are paying attention to all details again.

  • Launch window? (Score:4, Interesting)

    by captnitro ( 160231 ) * on Wednesday July 13, 2005 @12:57PM (#13055464)
    Anybody know how big their launch window is? I was under the impression they had a very small amount of time to be able to meet the ISS.

  • Better safe than sorry (Score:4, Informative)

    by ravenspear ( 756059 ) on Wednesday July 13, 2005 @12:57PM (#13055470)
    Hopefully they will get the issue fixed soon.

    They have until July 31st in the current launch window if I recall correctly.

  • Fuel sensor (Score:5, Funny)

    by MyLongNickName ( 822545 ) on Wednesday July 13, 2005 @12:58PM (#13055478) Journal
    I have a faulty fuel sensor in my car. My solution: just fill up every few days to make sure I don't run out of gas. Why can't these "genius" rocket scientist just have the crew stop off and get gas half way up, and again when they come back down?

    Dammit, *I* should be in charge of NASA.

    (please note, that this post is as insightful as most of the other Slashdot 'advice' to NASA. please mod accordingly)
    • Why can't these "genius" rocket scientist just have the crew stop off and get gas half way up?

      You only get the free insulated beer can holder with a FULL fillup. *taps right temple while smiling insightfully*
    • That's crazy - think of the risks and possible delays this would introduce:

      1) Getting to the front of the queue only to find that the filler cap is on the other side of the rocket - you'd have to exit and queue again adding to further fuel and time wastage.

      2) The reach from the shuttle's window to the credit card slot on the fuel pump is too far and someone has to suit up and take the card outside.

      3) You get there and the gas station's closed for a delivery.
      Think before you post such stupid remarks e

  • Drudge - WTF?!? (Score:3, Insightful)

    by RealityMogul ( 663835 ) on Wednesday July 13, 2005 @12:58PM (#13055479)
    Why link to Drudge??? WHY!?!?

    Just so you all know - here's the "initial coverage" he has which was just a link to an AP blurb on Yahoo:

    "KENNEDY SPACE CENTER - Today's launch of the space shuttle "Discovery" has been scrubbed. The launch was called off because of a faulty fuel-tank sensor. Discovery was supposed to take off for the first shuttle flight since the "Columbia" disaster of two and a-half years ago."

  • Troubleshooting to begin shortly (Score:4, Informative)

    by Alizarin Erythrosin ( 457981 ) on Wednesday July 13, 2005 @12:58PM (#13055480)
    NASA engineers are waiting for the astronauts to disembark so they can troubleshoot the sensor while the tank is still full. The way they were discussing it on NASA TV, the tank will be defueled at some point, so they wanted to run some tests before that.
  • Just bang it a couple times!

  • Launch to coincide (Score:2, Funny)

    by Anonymous Coward
    .. with the release of Duke Nukem Forever.

    Duke Nukem Forever programmers are staffing NASA Launch Control.

  • Troubleshooting process? (Score:5, Funny)

    by savagedome ( 742194 ) on Wednesday July 13, 2005 @12:59PM (#13055496)
    They are going to begin the troubleshooting process

    Trouleshooting prcocess??? Alright. In words of George Carlin:

    Whole thing starts when you get to the gate. First announcement, "We would like to begin the boarding process." Extra word, "process", not necessary. Boarding is enough, "We'd like to begin the boarding." Simple! Tells the story...

    People add extra words when they want things to sound more important than they really are. "Boarding Process" sounds important.... It isn't! It's just a bunch of people getting on an airplane. People like to sound important. Weather men on television talk about shower activity, sounds more important than showers. I even heard one guy on CNN talk about a rain event. Swear to god. He said, "Louisiana is expecting a rain event." I thought HOLY SHIT I hope I can get tickets to that!

  • Amazing (Score:4, Funny)

    by CompressedAir ( 682597 ) on Wednesday July 13, 2005 @01:00PM (#13055499)
    I've never heard every engineer at JSC say "Doh!" at the same time before.
  • The launch page (cited in the story) shows nothing different. "Today's countdown", however, continues. [nasa.gov]

  • Launch Window (Score:2, Informative)

    by UMhydrogen ( 761047 )
    From Spacelight Now [spaceflightnow.com]:

    "There is no word how long the delay will last and when Discovery's launch could be rescheduled. NASA has through July 31 to launch Discovery or else wait until September 9 due to the need to lift off and separate the external tank in daylight."

  • Comment removed (Score:4, Insightful)

    by account_deleted ( 4530225 ) on Wednesday July 13, 2005 @01:01PM (#13055515)
    Comment removed based on user account deletion
  • As much as I am disappointed in the delayed launch, I am willing to give NASA the benefit of the doubt about the seriousness of this malfunction (some would like to question the necessity of scrubbing the launch over a redundant sensor failing). I've since grown too tall (6'4) to think of any time in space, but when columbia disentigrated, I was not. The accident made me reconsider my dreams, and an accident with Discovery would make the nation do the same thing, which would be a very bad thing.

  • Playing it safe (Score:2, Interesting)

    by dmurray14 ( 899569 )
    At this point I think they're just playing it safe. Even after the whole CAIB regulations and requirements, they're taking a chance with the shuttle launch. I don't think any of the guys in that control room wanted to be responsible for another horrible accident because they declined to call off the launch. It seems like they probably didn't have to call it off, since there was a backup for the backup, but I think I would have done the same. Hopefully it's something they can have fixed in a day or two.

  • over doing it? (Score:3, Insightful)

    by jmcmunn ( 307798 ) on Wednesday July 13, 2005 @01:04PM (#13055552)

    I understand that this is a big deal, since the last time a shuttle flew it did not get to land, and no disrepoect meant for the friends and family of those imvolved...

    But seriously, this kind of thing would barely be news if not for the previous flight. They end up reschduling a good deal of all shuttle flights due to weather or other circumstances. If they were this careful with every airplane flight that took off and landed in the world each day, we would never get where we need to be. It makes you wonder how many times they launched in the past with problems like these and were "lucky" nothing happened.

    Honestly, this trip into space is more of a political statement (or publicity shoot if you prefer) than anything. They are just dropping off some supplies and doing a little work on testing repair methods from what I understand. This shoudn't be as big of a deal as it is, just let them fly the mission when the time is right and things look correct on the ground, then tell us about the success. That's good enough coverage.
  • The problem was that a low-level cut-off fuel sensor seemed to be indicating the hydrogen level of the external fuel tank was low. There are four of these sensors but NASA prefers a high level of "redundancy" for the launch. Small things like this scrub liftoffs quite often. Spirits are low at NASA. Thanks to NASA's live TV coverage, this problem was made public before even the NASA website could report on it. I was going to liveblog the Discovery launch at GlobeLens.com until this happened. Rats.

  • Orlando Sentinel shuttle blog (Score:3, Informative)

    by kingrat ( 25475 ) on Wednesday July 13, 2005 @01:06PM (#13055591) Journal
    Here. [blogs.com]
  • ...maybe it's time to put NASA down. The old dog just can't hunt no more. I still believe that space exploration should be the number one priority of the human race, but it's starting to look like NASA may be hindering that more than helping. The money would probably be better spent sponsoring things like the X-Prize.

  • Risk averse society? (Score:4, Insightful)

    by isotope23 ( 210590 ) on Wednesday July 13, 2005 @01:10PM (#13055630) Homepage Journal
    Are we becoming so risk averse that we will significantly slow or stop the tide of exploration?

    How the heck did NASA put men on the moon in a decade? They did not have a bunch of high tech crap that they have now, it was the ability to take risks.

    Perhaps Nasa should take a lesson from Henry Ford. Forget multi-billion dollar boondoggles (with quadruple backups out the wazzoo) like the shuttle. build a freaking factory to mass produce a SIMPLE, STANDARDIZED rocket.

    Either that or let free enterprise take over...

    • Re:Risk averse society? (Score:4, Insightful)

      by Bemopolis ( 698691 ) on Wednesday July 13, 2005 @02:46PM (#13056740)
      How the heck did NASA put men on the moon in a decade? They did not have a bunch of high tech crap that they have now, it was the ability to take risks.


      Well, they did chicken-fry three astronauts on the ground, which led to significant delay in the Apollo program, including (surprise) Congressional hearings. The accident was largely the result of the cowboy risk-taking you endorse. Do that a few times and public support would evaporate like, well, those very astronauts. Oh wait, we did -- NASA cowboyed the Challenger launch over the heads of the engineers who BUILT the damn SRBs, and the scattering of Columbia over my high school in East Texas was at least in part attributable to the same mindset.
      In short, there's "risk" and then there's "pointless risk". Often hard to tell apart until the inquest.

      As for "free" enterprise, if they could do it they'd do it already -- and have the taxpayers subsidize it AND insure it for them. And then they'd be chicken-frying citiesworth of people at no risk to them. After all, why do you think they call it "free" enterprise?

      Bemopolis

      • Re:Risk averse society? (Score:4, Interesting)

        by isotope23 ( 210590 ) on Wednesday July 13, 2005 @03:38PM (#13057259) Homepage Journal


        Risk-taking is a part of life. If airplanes had been invented under the current regulatory climate noone would get off the ground.

        NASA cowboyed the Challenger launch over the heads of the engineers who BUILT the damn SRBs

        If the engineers who built the things say "its not safe" and you ignore them that is pointless risk.

        However what is acceptable risk? Assume they had 12 fuel sensors, needed 2, but only 11 worked. I bet they'd STILL delay the launch...

        Another thing to think about, how is it that we can have a couple thousand ICBM's ready to launch hot molten death on a few minutes notice,
        but don't have a space program capable of launching humans every few days?

    • How the heck did NASA put men on the moon in a decade? They did not have a bunch of high tech crap that they have now, it was the ability to take risks.

      Simple, they had a single goal: Land a man one moon, get him back to Earth safely. That was it. Everything else was gravy. The hardware for the Apollo missions were built from the ground up around that goal and that goal alone.

      Along the way they did discover a few really cool side-applications for the Saturn V launch system. It was really good at gettin

  • When I was in high school, many years ago, the fuel sensor in my beat up jalopy didn't work, and the fuel gauge always read empty.

    I just kept a few gallons of gas in the trunk of the car in case I ran out.

    There was no problem. In fact, on some Saturday nights with the right herbal accoutrements, the car served as a fine transport vehicle for trips to outer space (and that's when it was parked in the ally behind the Burger King).

    So just put a few gallons of fuel in the trunk of the shuttle, and tell the
  • Sad as it is to say, but 'splosions are about the only thing that get the public to care about the space shuttle.

    At least there's Mars, bitches.
  • ...If you don't screw the gas cap on tight enough it turns on the "Service Engine soon" light. My hypothesis is that this is to encourage less intelligent customers to take the car to the dealer to figure out what is "wrong."

    I, of course, get my diagnostic codes read for free at AutoZone...

  • Drudge "Report" (Score:4, Funny)

    by courtarro ( 786894 ) on Wednesday July 13, 2005 @01:18PM (#13055726) Homepage
    I think it's best not to reference "news sources" that announce "SEN. MCCAIN STARS IN BOOB RAUNCH FEST" in 20-point text concerning his participation in Wedding Crashers, with a tiny link at the top to NASA information.

  • Photo (Score:3, Funny)

    by loconet ( 415875 ) on Wednesday July 13, 2005 @02:04PM (#13056300) Homepage
    So apparently this photo [orlandosentinel.com] was taken after they cancelled the launch. They seem pretty happy about it lol.. "Phewwwf..we dodged that one"

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