Space Shuttle Launch

[kkeenan 13]

We're all ready for a launch today. The weather is beautiful. There are more visitors at KSC than I've seen in a while. This mission is launching the European Laboratory Module, Columbus, to the Int'l. Space Station, so there are a lot of Europeans here to watch. But, there is a problem with fuel sensors, which is being evaluated. We're keeping out fingers crossed. Here's an explanation from Space.com:
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CAPE CANAVERAL, Fla. – NASA engineers are troubleshooting a fuel tank sensor glitch for the space shuttle Atlantis, a potential threat to today’s planned 4:31 p.m. EST (2131 GMT).

Two of four fuel tank sensors at the bottom of the liquid hydrogen portion of Atlantis’ 15-story external tank appear to be malfunctioning. NASA flight rules allow one sensor to fail without affecting a planned launch, but engineers are now studying the impact of two faulty readings aboard Atlantis’ tank.

Known as Engine Cut-Off (ECO) sensors, the intruments serve as liquid hydrogen fuel gauges to ensure that a shuttle’s three main engines shut down before its supply of hydrogen runs out. NASA shuttles use liquid hydrogen and liquid oxygen as propellant during launch.

While fueling Atlantis’ tank, engineers found that two of the four hydrogen sensors failed to report that they were covered in liquid hydrogen. A decision on whether to scrub today’s attempted launch is pending.

Fueling has begun for today’s planned launch of NASA’s space shuttle Atlantis as the orbiter and its seven-astronaut crew prepare for a 4:31 p.m. EST (2131 GMT) launch to the International Space Station (ISS). Weather conditions remain positive, with a 90 percent chance of favorable launch conditions.

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Dude, you are so awesome...
Can I be on your ash jump ?

[2fat2fly 0]

I saw the NOTAM this morning-I really want to get there for one.

I am not the man. But the man knows my name...and he's worried

[cocheese 0]

Thanks for doing what you do. Thanks for this post too. We're with ya, man.

[2fat2fly 0]

http://www.cnn.com/2007/TECH/space/12/06/space.shuttle.ap/index.html

I am not the man. But the man knows my name...and he's worried

[skymama 35]

I just heard it was scrubbed.

She is Da Man, and you better not mess with Da Man,
because she will lay some keepdown on you faster than, well, really fast. ~Billvon

[TypicalFish 0]

Quote

We're all ready for a launch today. The weather is beautiful. There are more visitors at KSC than I've seen in a while. This mission is launching the European Laboratory Module, Columbus, to the Int'l. Space Station, so there are a lot of Europeans here to watch. But, there is a problem with fuel sensors, which is being evaluated. We're keeping out fingers crossed. Here's an explanation from Space.com:
----------------------
CAPE CANAVERAL, Fla. – NASA engineers are troubleshooting a fuel tank sensor glitch for the space shuttle Atlantis, a potential threat to today’s planned 4:31 p.m. EST (2131 GMT).

Two of four fuel tank sensors at the bottom of the liquid hydrogen portion of Atlantis’ 15-story external tank appear to be malfunctioning. NASA flight rules allow one sensor to fail without affecting a planned launch, but engineers are now studying the impact of two faulty readings aboard Atlantis’ tank.

Known as Engine Cut-Off (ECO) sensors, the intruments serve as liquid hydrogen fuel gauges to ensure that a shuttle’s three main engines shut down before its supply of hydrogen runs out. NASA shuttles use liquid hydrogen and liquid oxygen as propellant during launch.

While fueling Atlantis’ tank, engineers found that two of the four hydrogen sensors failed to report that they were covered in liquid hydrogen. A decision on whether to scrub today’s attempted launch is pending.

Fueling has begun for today’s planned launch of NASA’s space shuttle Atlantis as the orbiter and its seven-astronaut crew prepare for a 4:31 p.m. EST (2131 GMT) launch to the International Space Station (ISS). Weather conditions remain positive, with a 90 percent chance of favorable launch conditions.

Hasn't the launch been repeatedly delayed on previous flights because of the same sensors?

"I gargle no man's balls..." ussfpa on SOCNET

[2fat2fly 0]

Quote

I just heard it was scrubbed.

That's the problem with our relationship-you never pay me any attention
Look above you one post

I am not the man. But the man knows my name...and he's worried

[skymama 35]

That's because you made a clicky instead of just sayin' it. Clicking on a clicky takes up too much time. I'm busy, every second counts.

She is Da Man, and you better not mess with Da Man,
because she will lay some keepdown on you faster than, well, really fast. ~Billvon

[kkeenan 13]

It looks like we are not launching today. The launch has been postponed until tomorrow. Too bad, since the wx is awesome. Hopefully, it will be just as good tomorrow.

By way of explanation, the Engine Cutoff (ECO)Sensors are sort of a binary fuel gauge for the big External Tank, which holds all of the fuel for the Shuttle main engines. They sit at the bottom of the tank and tell if they are "wet" or "dry". As the fuel quantity decreases during the 8 minutes of main engine run time, it is important that the system knows when the fuel is about to run out. The fuel shouldn't be depleted before the required time, but if it is, the engines need to know this before it actually stops flowing. The fuel goes to the three main engines through a 17-inch diameter fuel line at a tremendous rate. If it stops flowing without notice, the high speed pumps will literally come apart, possibly destroying the vehicle. These ECO sensors allow the engine computers to shut down the engines in the proper sequence if the fuel runs low. It's sort of like shutting down your computer properly vs. just pulling the plug.

These ECO sensors have been the source of a lot of problems in the past, and it was thought that they were all fixed, but I guess not. Being submerged in liquid hydrogen at a temp. of -423 degrees F is a rough environment, and making flight equipment that functions in that environment is tricky.

Anyway, the External Tank may be drained and refilled as this problem is worked. Hopefully, it will not require rolling the Shuttle back to the Vehicle Assembly Building. That would make for a much longer delay.

Kevin

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Dude, you are so awesome...
Can I be on your ash jump ?

[Shepp 0]

I'm a HUGE NASA nerd, and I go for pretty much every launch. I've got it down to a science. It's an experience not to be missed. But go soon!! After today's (fingers crossed) launch, there are only 11 remaining flights!

I also recommend getting tickets to watch the launch on KSC. The $60 price tag for a Launch Transportation package will get you out to the causeway for an unobstructed view from about 5.5 miles away (the closest that non-NASA personnel are allowed). www.ksctickets.com is the source. Be aware that tickets often sell out in less than 1 minute. If you sign up for the Armchair Astronaut newsletter they'll notify you ahead of time when they go on sale.


edited to add: C license jumpers can drive over to Titusville after the launch and jump at Skydive Space Center too!

Experience is a hard teacher because she gives the test first, the lesson afterward.

Accidents don't just happen. They must be carelessly planned.