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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.
There are pipelines in space now? Cool.
The leak is more likely nitrogen, but there is no way of knowing that.
Excuse me? The shuttle must be one of the most redundantly-instrumented efforts ever built and they don't know what's leaking?
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.
I wonder if those on board would call a fuel leak a minor technical fault?
It may be slow now, but in my experience leaks tend to get worse...
Because you can - or because you should?
I know its alreay too late for the space shuttle, but i wonder how much it would have cost them just to modernize all of the shuttle parts. Or at least make all the tubing and pipes out of duct tape. If they sell the space shuttles in fifty years or so anybody want to try?
NASA is crippled. Rather than cover the achievements of each mission, they cover the lack of failures. It's a no-win situation. If they screw up ANYWHERE, they look terrible. If they make it back ok, they wasted a ton of money on... what again?
In the media, I've heard all about how they made sure the stupid thing can land, on at least 3 media sources. But WTF is the reason they launched? What are they up there for, other than to make it back alive? I could do that on a Mooney for alot less money and with alot less stress!
This is being handled all wrong. They shoulda spun this as "making real forward progress sometimes hurts - there's risk in growth - DEAL WITH IT" - but instead they're trying to make it seem like it's a big deal to launch into low-earth orbit and make it back alive.
How stupid!?!?!? We've been able to do THAT since the 1960s.
This is a PR ball that's being dropped, and NASA is now neutered. It's a worthless waste of time. Send everybody home, take the (piddling, thanks to terrible PR management) amount of money that was being spent there, and give it to an organization that can LOOK FORWARD again...
Give me a reason to get excited, or stop spending my damned tax dollars. (Oh, and don't mention Iraq, I marched in the streets with signs over that one!)
I have no problem with your religion until you decide it's reason to deprive others of the truth.
It's ok.
I think with the talk of shroom-like trips before, a Truffle fragment was stuck in your brain & just happened to come loose at that time.
Wanna fight ? Bend over, stick your head up your ass, and fight for air.
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."
It's nice to know they can detect leaks so small they're "100,000 times slower than what would cause a fire." What is that, about a few molecules a second?
The write-up missed the important angle that if they decide to power down the possibly leaky APU, they'll have to use explosive bolts to lower the undercarriage. That's never been used in flight before. That doesn't mean it won't work, of course, but it will make the re-entry and landing a little more interesting than usual.
Everything I needed to know about life, I learnt from Blake's Seven
I wonder if the astronauts can taste or smell it to see what it is.
Better use X-Treme tape. Have you seen this stuff? Silicone compound based tape, 600 psi tensile strength, self-fusing forming air-tight and water-tight seal, sticks to anything, withstands temperatures up to 500 F. Shuttle crew shouldn't leave home without it.
Didn't see which stores carry it, but still again, I haven't had but one bottle of Mt. Dew to wake up
I had an undetected small leak in a Diesel system for some time because it only leaked under feed pump pressure, which meant the engine was running, and the heat volatilised the fuel which was then sucked into the air inlet above the leak. It may have been there for several years undetected.
Despite all the fuss about it being hydrazine, it may be safer and easier to ignore it because any attempt to fix the leak may simply make it worse.
Pining for the fjords
If they really are leaking Hydrazine, they have worse problems than a possible fire. That stuff is pretty damn deadly. In fact it is the only (AFAIK) compressed explosive gas that isn't required to have a pressure release valve. Why? Because out-gassing would pretty much kill anything within a very small radius. It would actually be safer for the whole tank to explode than for the tank to be emptied. Luckily, the ship is airtight and they all have space suits if that really were the problem. I'm not sure how dangerous the other RCS fuel (nitrogen-tetroxide) is, but I'm guessing it's not that great for you, either.
The shuttle has 3 auxillary power units. One is necessary to land. They are routinely tested while in space. If one fails they land as soon as possible. The APUs are not small, they are powered by a 100 horsepower turbine which is turned by decomposing hydrazine over a catalyst. Sometimes on good movies of the shuttle after it has landed you can see the heat waves from the hot gases (nitrogen, hydrogen, and a little ammonia) from the decomposing hydrazine coming straight up from the shuttle.
The larger thrusters and the rocket engine used by the shuttle in space are powered by methyl hydrazine reacting with nitrogen dioxide. These are hypergolic (burn on contact with each other) so no possiblity of them failing to ignite for a second or two then going boom which is possible with other fuels like hydrogen and oxygen. They are liquids at ambient temperatures so don't require cryogenic storage.
Hydrazine, N2H4, is a great rocket fuel. It is a liquid with similar boiling and freezing points to water -- but can explosively decompose (it is dangerous to measure its boiling point), is toxic at ppm levels, is carcinogenic (ie all the rats that breathed it got nasal cancer), causes skin burns. Like most amines it smells like rotten fish. Believe it or not there are people who believe that low levels in the blood is an anti cancer agent.
I'm tired of this crap. Lets just get all the people out of these death traps and blow them the fuck up on earth and save everybody a lot of time.
Minor Technical Issues is no eye catcher :)
You take it, I don't want it...
Hydrazine reacts in the precense of a catalyst such as silver or iridium, which is why combustion chambers of many reaction control rockets are lined with such. Hydrazine is semi-stable. It will breakdown in the precense of the catalyst or if it warms up to the proper point. If neither happens, you're fine. The engineers who actually know how the system is designed (ie, not you), and know where stuff can get into, where it might come into contact with a catalyst, or where it might warm up are the ones qualified to analyze the risk.
As for the risk of explosion, well that's poorly written, but if you don't have enough to cause a pressure increase of damaging magnitude, well then there's nothing to worry about. In this case they have a lot less. That suggests to me they looked it over and decided it must be leaking in a way that there's no place for it to accumulate.
Furthermore, according to NASA, they don't actually use pure hydrazine in the shuttle RCS jets. They use nitrogen tetraxide and monomethyl hydrazine (add on a carbon atom), which are hypergolics. They're more stable but they react spontaneously in each others presence.
Of course, the shuttle engineers don't have a clue about any of this. They like playing dice with their co-workers lives.
Believe it or not there are people who believe that low levels in the blood is an anti cancer agent.
Are these the same ones that believe low levels of fluoride is an anti-cavity agent?
Hydrazine wasn't chosen for performance. It actually has a rather low ISP. It was chosen for reliability. The reaction control jets have to fire repeatably far more times than other types, and usually while cold. In this case, NASA uses a hypergolic form; one which spontaneously combusts in the precense of another chemical. The two are released simultaneously into the reaction control jet and voila, fire.
NASA would love to develop a methane based version with a much higher ISP and less handling risk, but it got cut out of their CEV budget. I think now they're sponsoring a private company to develop one via the COTS program. It would have to be actively ignited, which raises reliability concerns. I'm not sure what other design problems are holding it up.
The nitrogen is used to pressurize the hydrazine tanks to feed the reaction control system. It's pretty simple. Rather than have pumps that would be corroded by the hydrazine, they just warm up the nitrogen a little bit and the pressure increases. They know the pressure is dropping, but they're not sure if it's because they're losing nitrogen or losing hydrazine. I suppose they decided it wasn't worth the extra effort, cost, complexity, and weight to be able to isolate the tanks soley for the purpose of determining where a leak was, should one occur, so they just assume the worst case and prepare for that, if necessary.
Just another sign of the past catching up with us. The things that have become the norm, which ought to be the exception, that we all deal with are going to have consequences somewhere down the line, whether it's NASA, or nursing. Unfortunately, 'tis human nature to do nothing (legitimate reasons or otherwise) until catastrophe strikes, and when it does, to have a flurry of cleanup, follwed by a similar flurry of fingerpointing, denials, litigation, apathy, and then...a band-aid solution until the next disaster. Usually the causes boil down to greed at the executive, stress/ poor information/ resource management at the ministerial, and subsequent exhaustion/ understaffing/ inadequate resources at the production levels. I've seen this in nearly all aspects of society, and generally, few exceptions aside, the ones who get the bulk of the blame and the lion's share of the punishment for these disasters are those either least able to shoulder the burden or least responsible for the causes of the problem, while the ones who truly deserve ire walk away free of responsibility. In our allegedly classless society, we have the "golden rule" -Them that's got the gold makes the rules. Shame on us all, the haves for fostering this attitude, and the have-nots for tolerating it. A civillised people ought to know better.
Offtopic, certainly. But not as much as you might think. Who pays ?
How many beans make five, anyhow ?