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Minor Technical Issue Aboard Shuttle Discovery
IZ Reloaded writes "Space Shuttle Discovery has a problem with the pipeline for an auxiliary power unit that controls the shuttle's hydraulic steering and braking maneuvers. CNN reports that the pipleline is leaking 'fuel' at about six drops per hour." From the article: "The leak is more likely nitrogen, but there is no way of knowing that, so NASA is treating the problem as if the leak were fuel ... If it is fuel, the current rate is still 100,000 times slower than what would cause a fire ... Just in case, NASA will turn on the power unit with the leak early Sunday as part of its normal testing and then see if the leak rate changes. If it does, NASA may burn off the hydrazine and shut down the power unit before the shuttle returns to Earth to eliminate any fire hazard.'"
Two words: Duct tape.
Hydrazine is nasty stuff but it is just one of the dangerous checmicals aboard the shuttle.
When Columbia broke up, it was the possible presence of Hydrazine from the APUs that make the Texas Dept of Health issue warnings about approaching shuttle debris.
The problem with spaceflight is that everything is so close to the edge. Performance requirements that can still leave a good safety margin mean that simpler and safer methods are often inadequate. Consumers don't have the same risk/reward ratio as people who sit on top of rockets for a living.
-M
# grep slashdot access.log | grep html | sort | uniq | wc -l 2604
Seems off that only APU1 drives the landing gear, with a backup of pyrotechnics...
1 4mplm/
"APU 1 is the only hydraulic system that can deploy the shuttle's landing gear. If APU 1 is out of action, pilot Mark Kelly would have to manually fire pyrotechnic charges to deploy the gear."
http://www.spaceflightnow.com/shuttle/sts121/0607
STS-9 came in with an APU on fire. Here is a video.
Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
Excuse me? The shuttle must be one of the most redundantly-instrumented efforts ever built and they don't know what's leaking?
Obviously not. I guess some rogue foam disabled the giant blinking "HYDRAZINE LEAK" and "NITROGEN LEAK" signs, so they're lost up there. You better call NASA and tell em what's what.
Help me take back Slashdot. When did 'News for Nerds' become 'FUD and Conspiracy Theories for Extremist Nutjobs'?
You can't escape from taxes, and I'd rather see them spent on NASA than on Iraq.
Did you ever watch one of those news conferences held with the astronauts/mission management team representatives? ALL questions somehow related to a concern for safety and NONE are actually asking whatever the crew have done that day. NASA is surely making a big deal on re-entry, but it's the media is making it sound like it's gonna be another Columbia.
The overwhelming concern on safety is exactly what got me excited about these couple of "return-to-flight" missions. NASA is trying to MOVE FORWARD with the construction of the ISS while trying their best to keep the construction workers safe. If they slip and the program stalls it will not only be years and years of your and my tax dollars that go down the drain, but also investments from Russia, Japan, Europe and other international partners. It is ALREADY an international effort. It is a sunken-cost mentality and it is make-or-break for NASA.
Quit acting like you don't care about the lives of those astronauts if they are given in the name of "progress". Everything that NASA does to protect them IS "progress". You protested furiously about the not having any more dead soldiers in Iraq didn't you? What makes you think it is any different in space?
A leak in a "gas tank" is a minor technical issue? :p
"Hey there cowboy, word goes around that there's something wrong with my car."
"Nah sir, just a little scratch."
"Ah if it's just a scratch then I can live with it."
"Yes sir, just a bit of gas leaking through that "scratch", so you might want to cut down on that smoking sir."
They mean it, there really is no way of knowing. They know there's a leak based on pressure readings. They know it's not an instrumentation issue because those pressure readings are redundant (i.e. if one sensor started trending down and it's backup didn't, then the sensor's bad). Based on those same pressure readings they know what the leak rate is (drops per hour was probably the guy's attempt at making it make sense to the layperson by analogy to a dripping faucet. Sadly that analogy seems to have fallen flat.) Since the fuel tank (hydrazine) is connected to the pressurant system (nitrogen), the entire system is at the same pressure, so since there is a leak, every pressure sensor monitoring the system is trending down.
(Time for my own bad analogy) Let's say you've got a Super Soaker with a pressure gauge in the water reservoir. You pump up the Super Soaker and put it in a box so that the only thing you can see is the pressure gauge. Now, somehow a hole forms in the reservoir. Because you can't see the reservoir, you don't know if it's your fuel (the water) or the pressurant (the air you pumped into the thing) that's leaking, but you know from the decreasing pressure reading that there's a leak present. That's essentially what's going on with Discovery. Hence, they're playing it safe and assuming the leak is fuel, when more likely it is the smaller nitrogen molecule that's escaping the system.