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NASA Scrubs Launch Due to Faulty Fuel-Tank Sensor
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.
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.
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.
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.
They WONT cancel becuase a freaking window FELL OFF of the shuttle (because it was TAPED on incorrectly...), but they WILL cancel becuase one the sensors that tells them HOW MUCH GAS THEY HAVE IN THE TANK isn't working?
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Because:
A) They don't have the budget they used to, which is a dang shame.
and
B) You can only glue something back together so many times before it totally breaks down. This is the state the shuttles are finding themselves entering now.
You are who you are, let no one tell you different. But, never close your mind to a new point of view.
I'm old enough to remember the Apollo days, and even back then they were regularly delaying launches at the last minute.
The problem isn't that they don't do things like they used to. The problem is that they're still doing things they way they used to. They've never put any priority into actually simplifying their launch systems. They just keep dragging along with this bloated overpriced Rube Goldberg contraption.
...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.
It's a plot to distract us from Rovegate!
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?
Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
In short: Space guys were hanging around drinking a slurpee (I swear one had a 7-11 cup!), got into the giant silver toaster-mobile, drove down the huge road to the vehicle building, and that's it. Waiting for press conference at 4PM (Eastern time, I am assuming).
Free of Flash! Free of Flash!
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.
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
About this time someone says "get on the shuttle, get on the shuttle"
I say "FUCK YOU I'm getting IN the Shuttle! Let Lance Bass ride ON the shuttle."
He who knows himself to be profound endeavors to be clear; he who would like to appear profound to the crowd endeavors to be obscure. Nietzsche
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 I do know the shuttle goes through some majorly extreme stress and conditions...
It isn't "funny," as nothing that has to do with lefe and death of the crew members is funny, however, I feel like NASA keeps having these setbacks in an almost tragicomic way. I mean, a cover falling off a window and damaging heat tiles? I read that the cover is to prevent dust- so why does it need to be made of something hard that can damage the shuttle? Wouldn't cotton have done as nicely? If someone knows, I really am curious, I am not being a jack-a##
And All I Ask is a Tall Ship And a Star to Steer Her By
You need a low level sensor for two reasons;
Before they slid the shuttle on, NASA had an oppertunity to fill the tank and test the sensors. They chose not to, figuring that the problem wouldn't show up on the new tank. So the assembled the orbiter and wheeled it out, and the first all-up test on this new tank was when they filled it for launch.
Since NASA has not track record with this system, they can't rule out anything. They will have to take the shuttle back to the VAB, dismount it, open up the tank, yank out the sensors, and test them on a bench.
The best case scenario is actually that the sensors themselves are wonky. Otherwise they are going to have to trace back all of the electrical connections, the diagnostic equipment, and re-evaluate the testing procedure.
All of this should have been done already.
In the private sector, somebody's head would be on a stick in the lobby for a costly goof like this one.
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
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 getting big things into orbit, ala that Skylab. Other than that, the system was useless. It was too big and too costly for day-to-day satellite launches. It was also too big and too costly to support a manned presence in orbit. (Which is why skylab was allowed to de-orbit.)
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...
A rocket is neighter simple, nor subject to much standardizing. You need one design for a low Earth orbit. You need another design for Geo-Sync orbit. Still another to carry things out of Earth's orbit. What works for one application doesn't really work too well for another.
The size and type of payload also dictates the performance requirements of your launch system. A heavy payload requires a large launch system. Payloads that require a specific trajectory require a launch system with a good deal of control and precision. Depending on your mission, perhaps a very great deal of control and precision, to the point of needing additional fuel and bulkier control systems.
As such, you would need a plethora of "off the shelf" designs, or one design with so many modules and modes of operations as to make it the burdonsome monster we call "The Space Shuttle."
I favor a component-based approach. Instead of designing a compete system, design and mass-produce the components. When it comes to to plan a mission, each "rocket" would be a custom job, but built on well known and well-tested parts.
The Auto Industry has forgotten this lesson. Every model year is a complete re-design from the ground up, that tends to create as many problems as the fix from last year's model.
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
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?
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