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Spacewalk #2

Spacewalk #2 is in progress.

Highest priority is to replace three Rate Sensor Units, which contain spinning gyroscopes that are used to point Hubble and keep it stable. Because the gyros constantly spin at 1,000s of revs per minute, they wear out (these have been in Hubble since 1999).

On this mission, they have brought a new improved design. Two of three went in okay--problem on the third. It does not seat properly.

They've tried it in two different locations without success. Next they abandoned the improved version, and went to a spare unit they have (one of the original design, removed from Hubble in 1999 and reconditioned).

It, too, has been unable to go in properly, but on the final attempt it just worked.

So they have now successfully replaced all Hubble's gyros, but because of the problems they are at least one hour behind on their spacewalk. Yesterday went long as well, but management allowed them to stay outside late. Today they'll probably have to get that permission again.

Their next task is to replace batteries, which should be easier.
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