Space Station Spacewalkers Stymied By Stubborn Bolt 290
Hugh Pickens writes "Reuters reports that astronauts at the International Space Station ran into problems after removing the station's 100-kg power-switching unit, one of four used in a system that distributes electrical power generated by the station's solar array wings, and were stymied after repeated attempts to attach the new device failed when a bolt jammed, preventing astronauts from hooking it up into the station's power grid. Japanese Astronaut Akihiko Hoshide got the bolt to turn nine times but engineers need 15 turns to secure the power-switching unit. 'We're kind of at a loss of what else we can try,' said astronaut Jack Fischer at NASA's Mission Control Center in Houston after more than an hour of trouble-shooting. 'If you guys have any thoughts or ideas or brilliant schemes on what we can do, let us know.' Hoshide suggested using a tool that provides more force on bolts, but NASA engineers are reluctant to try anything that could make the situation worse and as the spacewalk slipped past seven hours, flight controllers told the astronauts to tether the unit in place, clean up their tools and head back into the station's airlock. NASA officials says the failure to secure the new unit won't disrupt station operations but it will force engineers to carefully distribute electrical power from three operating units to various station systems and says another attempt to install the power distributor could come as early as next week if engineers can figure out what to do with the stubborn bolt. 'We're going to figure it out another day,' says Fischer."
Re:Come on, this is 2012 (Score:4, Interesting)
you're obviously not an engineer. the big things are made up out of tiny things. its always* a tiny things that gets you
Not a mechanical engineer, no. I'm a network engineer. And when I build a network, I make sure to catch the "low hanging fruit" when I test things.
And when it comes to testing bolts, even with my non-mechanical engineering background, I can see that this is low hanging fruit. Will this bolt be able to turn 15 times in this configuration? I'm sure NASA would have been able to test that in their fish tank, and they probably did; with a different bolt...
Are you seriously saying that you've never tested a network device in your test lab that was supposed to be a drop-in replacement for older technology already installed in the office (which is a unique environment that's not repeated anywhere else in your organization), then had the new device fail to work when it was plugged in without having someone tweak the configuration?
And it's often the "low hanging fruit" that causes the problem when it's something out of the ordinary...like that someone had to force the port from autonegotiate to 100mbit because there's a flaky connection somewhere between the device and the core network so the autonegotiated 1000mbit connection wouldn't stay up, and building management refuses to replace the network cable.
In this case, they discovered metal filings when they unbolted the old unit, and though they sprayed them out with compressed nitrogen, there was apparently significant enough thread damage that the new bolt wouldn't go in.
A test lab tries to approximate reality, but it's hard to do a complete simulation of a component exposed to the vacuum of space with repeated and severe heat/cool cycles as it's exposed to and shaded from the sun.
I don't doubt that they tested everything right down to the exact same bolts (probably machined by the same vendor, and possibly even made from the same ingot of raw metal), but no test lab is a perfect representation of the real-world. Most spacewalk maintenance is rehearsed dozens or hundreds of times on earth before attempted in space.
Re:Come on, this is 2012 (Score:4, Interesting)
Re:Red Green solution (Score:5, Interesting)
But, since I do have an armchair and since I am an engineer I figure they will ultimately have to try some sort of lubricant or thread treatment, the risk of snapping off the bolt is too high.
If anybody bothers to read the article it mentions "metal shavings on one of its bolts and around the housing" when they removed the bolt and now it won't go back in again.
Looking at a few random posts it doesn't seem like anybody bothered - none of them are remotely related to the problem (ie. the thread needs cleaning).
Applying more force to a damaged thread will probably make it much, much worse. NASA is right to not force it.
Anecdote: This happened to my bike pedal. The pedal has a steel thread and the crank is aluminum. After a couple of months the aluminum gave up the ghost and the pedal fell out. I put some Araldite on the bolt and what was left of the crank thread and screwed it together. It's been fine ever since, maybe they could do that. :-)
Re:Tap and die (Score:4, Interesting)
There is spontaneous vacuum cold welding of materials, because there's no natural air lubricant is absent and atomic bonds tend to migrate across the interfaces. Capillary action works differently. In microgravity, without an anchor the tool operator is more likely to turn around the bolt than turn the bolt.