Stuck Knob Causes Serious Window Damage To Atlantis 291
FTL writes "While in orbit a metal knob floated between a window and the dashboard of Atlantis. Once back on Earth, the shuttle contracted, wedging the knob firmly in place and damaging the window. Initial attempts to free the knob have failed and engineers may need six months to disassemble that section of the orbiter. Given that the shuttle program will probably end next year anyway, such a delay might mean scrapping Atlantis early rather than repairing it. Efforts to remove the knob using less invasive techniques continue."
Re:physics (Score:5, Informative)
why not just put it in a vacuum chamber, warm it up, and slide it on out?
What, you mean like they discussed in the article? They even came up with a better idea: instead of heating up the whole vessel, just freeze the knob with dry ice!
The options relating to the application of dry ice to shrink the knob have already been attempted, and failed. However, the same method, along with a pressurization of the Crew Module, may be enough to free the knob from its lodged position.
The only problem is the amount of pressurization that can be conducted in the OPF is far less than the pressure that played a part in allowing the knob to become embedded in the first place.
Pressurize crew module and dry ice on knob to TBD (To Be Determined) pressure. Pro's: Could allow for uniform structural deflection to increase gap between pressure pane and dashboard; enough to free up the knob non-destructively. Less potential for inducing further damage to the pane.
**UPDATE: The above option was selected on Thursday as the opening process for an attempt to remove the knob. The cabin will be pressurized to 3 psid, before an engineer will apply dry ice to the knob. This option is not deemed to be a likely solution, but more so the opening option that avoids additional damage to the window.**
Although it's lengthy, you should try reading the article next time. The guys at NASA are pretty clever.
Re:physics (Score:5, Informative)
FAO any other Monday morning quarterbacks, armchair rocket scientists, and other self-appointed experts and "why don't they just" merchants out there who never seem to consider that the people working on the thing might actually have thought about what they are doing, quoth TFA:
"Induced damage of the knob being wedged between the glass and the dashboard closeout panel structure, or from removal of the knob could result in unacceptable damage.
"Consequences of unacceptable damage to the glass pane: Replacing the pressure pane would result in a significant impact to ground schedule (potential 6+ month impact). Requires de-configuring dashboard structure and instrumentation to remove window assembly for refurbishment. Windshield pressure pane removal has never been performed at KSC.
"Knob removal must be performed carefully; exhausting all risk free options first, then attempting more intrusive (higher risk) options, if others fail."
Re:Aren't the windshields replaced all the time? (Score:5, Informative)
Or is that only an outer protective layer? I know I've seen pictures of the pitting that micrometeors and paint flecks have caused on the Shuttles while in orbit, I just assumed they were made to be easily replaced.
The article isn't wholly clear, but implies that there are three layers of glass, only the outer one gets replaced. The inner ones have never been replaced on any shuttle. The innermost one is the most important for retaining the internal pressure, and is the one that has sustained damage.
And to be clear, if you read the article, it's obvious that the engineers working on this are SERIOUS and have thought of just about anything that slashdot readers have come up with. Drill/cut? Too high risk because of (a) vibrations transmitted to the window and microgrinding of the knob against the window and (b) metallic dust it will generate. Pressurize orbiter? Yep. For some reason, they think they can only get it to +3 PSI. Might help. Apply cold to the knob to shrink it? Yep. They tried dry ice. Didn't work. (My guess is that they'll try liquid nitrogen, too at some point.) They're planning on trying dry ice and pressurization at the same time. Apply downward pressure to the dash with a crobar? Probably very risky because of unknown damage it might cause to dash.
Once the knob is out, they'll make visual inspection of the remaining surface, including taking microscopic moldings to assess the damage. The pane is tempered, so scratches are a big problem, as they can lead to spontaneous, catastrophic failure.
Re:physics (Score:4, Informative)
Yeah this was my thought too as soon as I read "dry ice". Just freeze it and smack it. I'm sure the reason why not is because the fragments will only cause more damage once in space.
Try this, for educational purposes:
Drop a piece of aluminum or steel into a bucket of liquid nitrogen. Now take it out and drop it on the ground from a height of 6 feet, or hit it with a hammer. Notice it not shattering.
The first time I dropped a 10 pound block of aluminum while taking it out of a nitrogen bucket I expected it to shatter, too. Then I realized I thought that because of hollywood.
Re:Scrap it! (Score:4, Informative)
pencils contain graphite. graphite conducts electricity. graphite powder is generated when you rub it up against paper to write stuff. graphite powder gets everywhere in microgravity, including behind control panels, into switches, and sensitive electrical components.
i'm glad you're not in charge of so much of a paperclip at NASA.
Re:Scrap it! (Score:5, Informative)
Re:Scrap it! (Score:5, Informative)
Nope sorry p51d007
Fisher developed the pen at their own expense NASA only had to buy the pens, at the same price the general public could I might add.
You know, just a little research would keep you from looking quite so stupid.
As a personal note you might try not being an ass, just for fun.
re: http://en.wikipedia.org/wiki/Space_Pen [wikipedia.org]
NASA never approached Paul Fisher to develop a pen, nor did Fisher receive any government funding for the pen's development. Fisher invented it independently, and then asked NASA to try it. After the introduction of the AG7 Space Pen, both the American and Soviet (later Russian) space agencies adopted it. Previously both the Russian and American astronauts used grease pencils and plastic slates
Re:physics (Score:4, Informative)
The "Hollywood style" liquid nitrogen brittleness is best seen with some plastics and rubbers - there is a glass transition temperature below which the material is very brittle. You can do the rick of smashing a rubber dog toy into fragments with a hammer after soaking it in liquid nitrogen for a few minutes. Polyethylene as in cling wrap doesn't do this (which is dissappointing. Anything with a lot of water (eg. a banana) will of course freeze and smash just like ice. An important safety tip is to wait some time before placing the frozen banana in your mouth or it will burn your tongue (my classmate that did that now works in an explosives factory but is still intact last I heard).
Re:physics (Score:4, Informative)
We've used a similar technique in one of our workshops, but there's no need to brush and collect - you use an inert sponge and/or capillary tube to circulate the etchant. Likewise, you don't need to use acids which produce potentially corrosive fumes and aerosols. A solution of copper sulphate and sodium chloride will do the job nicely with less risk.