ISS SARJ

What's the latest on the SARJ damage/repair?

"Sir Frederick" wrote in message
...
What's the latest on the SARJ damage/repair?

There is some pretty good info on NASA SpaceFlight.com and I think Florida
Today's website as well.

Jeff
--
A clever person solves a problem.
A wise person avoids it. -- Einstein

On Thu, 29 Nov 2007 01:32:46 -0800, Sir Frederick
wrote:

What's the latest on the SARJ damage/repair?

They had Tani and Whitson spacewalk over and open a cover last
weekend. They found more of the debris and indicated the race ring is
pockmarked, or something. NASA is trying to squeeze in an extra
spacewalk on 122 to give a more thorough inspection so that what
caused the pockmarks can be determined and repair plans can be
formulated. They'll probably need several EVAs early next year to
repair the offending pockmarker or move the whole joint over to the
backup race ring.

Brian

I listened to the last inspection, and it sounded to me like there had been,
or was a foreign body in there, which was being ground into the bearing
surface. One would have thought this would have been noticed long ago, as
something that could cause that amount of damage in under six months or so,
must be fairly substantial. Of course, there could be a rogue roller bearing
which was damaged in some way, but I do hope its not a use of the wrong
material or wrong surface hardening or similar as this might be affecting
both rings.

Exactly what is it in the system which holds the bearing surfaces together
in a 0 g environment?


Brian

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Brian Gaff....Note, this account does not accept Bcc: email.
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"Brian Thorn" wrote in message
...
On Thu, 29 Nov 2007 01:32:46 -0800, Sir Frederick
wrote:

What's the latest on the SARJ damage/repair?

They had Tani and Whitson spacewalk over and open a cover last
weekend. They found more of the debris and indicated the race ring is
pockmarked, or something. NASA is trying to squeeze in an extra
spacewalk on 122 to give a more thorough inspection so that what
caused the pockmarks can be determined and repair plans can be
formulated. They'll probably need several EVAs early next year to
repair the offending pockmarker or move the whole joint over to the
backup race ring.

Brian

Brian Gaff wrote:

I listened to the last inspection, and it sounded to me like there had
been, or was a foreign body in there, which was being ground into the
bearing surface. One would have thought this would have been noticed long
ago, as something that could cause that amount of damage in under six
months or so, must be fairly substantial. Of course, there could be a
rogue roller bearing which was damaged in some way, but I do hope its not
a use of the wrong
material or wrong surface hardening or similar as this might be affecting
both rings.

Exactly what is it in the system which holds the bearing surfaces together
in a 0 g environment?


Brian


The SARJ has two large parallel race rings, one is just used to hold the 12
trundle bearing assemblies while the other race rotates. Each race is
triangular in cross section, and the TBAs each have three rollers that fold
around the non-fixed race and roll around it. If the race is ruined, the
TBAs can all be flopped around during an EVA to grip the bad race and roll
on the spare. If a TBA is bad, they have a spare on orbit. Biggest
problem is wedging the work into an already filled schedule.

Mike Ross