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Astronauts Having Trouble With Tranquility Module
Coldeagle writes "Astronauts ran into trouble while trying to connect up the new Tranquility module onto the ISS. A critical insulating cover didn't fit quite right: 'The fabric, multilayered cover is supposed to go between Tranquility and its observation deck, but the metal bars are not locking down properly because of interference from a hand rail or some other structure at the hatch.' One has to wonder if this is another imperial/metric snafu."
The Hubble misfocusing problem wasn't due to English-metric stuff. A contractor was assembling an optical apparatus and was supposed to be adjusting the focal length to a point inside some hollow cylindrical cap with a hole bored in its center. When adjusting their eyepiece they missed the hole, and centered instead on a shiny point near the edge of the cap that was also reflecting laser light, because the paint had been scratched there. They couldn't get the focus knob to rotate far enough as they would need to get this paint scratch into focus, so they drove out to a hardware store, bought some flat washers, inserted them on the threaded rods holding up the laser, and elevated the focusing section out a bit so they could dial the focus length to properly get the length to the scratch right.
Indeed. I'm an American, but I'm familiar with SI units. If I tell a friend that something is about two meters long, he's surprised, but he understands what I mean. That goes for everyone. Even in the US, people intuitively grasp how much a liter is, how heavy a kilogram is, and how long a kilometer is. We seem to have more trouble with temperature and speed though. I'm still a little taken aback when I drive into Canada and see speed limits far higher than what I'm used to.
Unfortunately you are about 50 years too late. In the aerospace industry, virtually ALL the data about most components is already "stored" in conventional units, no Metric. Forcing it to all be converted to Metric just creates the problem you are trying to solve.
BTW, the MRO incident may have *started* with a units conversion error, but the real flaw was with the lack of due dilligence. The trajectory was diverging for months, and the problem could have been detected and solved easily if the normal checks and balances were applied.
Brett
That's because, ironically, the inch now is DEFINED as being 25.4 millimetres, so a clean and exact conversion is no problem since the inch is already based on metric units. Saying "one inch" is just another way of saying "25.4 millimetres". Other units are less clean and exact.