The plan of the day was to set a cleanroom over BSC2 so that we could pull the dome at that chamber and de-populate both BSC2 and BSC3, including SEI stacks prior to cleaning either chamber. Unfortunately, reality got in the way: turns out it is impossible to set two regular BSC cleanrooms side by side and have both cleanrooms center over the domes. If the short-sided BSC cleanroom was available, the plan would work but "the special" cleanroom is tied up at BSC8! In addition, there is a limited soft roof supply soooo.... We went with de-install lite: pull the beamsplitter from BSC2 and then de-install at BSC3. 

After lunch, Cheryl and I went in to document the condition of the optics and chambers. Cheryl took lots of pictures. The highlight (or low light) of the initial inspection was the elliptical baffles in BSC3 and BSC1. The side of the black glass facing away from the optic has both a very fine layer of particulate and then an overlying of larger particulate. There seem to be features associated with gloved fingertips touching the glass: it looks like the oxide from the chamber interior may be differentially attracted to these spots. (I'm sure Cheryl will attach pix when she gets a chance.) On a brighter note, the side of the glass that faces the optic looked quite clean. We found the usual metal fines, a few fibers, etc. on the suspensions. Of the three chambers, BSC2 appeared to be the dirtiest. I took a wipe sample from the chamber bottom and collected two clumps of fibrous material there. We looked at bellows convolutions: BSC1 was atrocious as it contained a couple areas that looked like chunky mucus and some small shards of what looked like black glass. We saw the usual mess at gate valves with particulate accumulated onto rollers, large particulate gathered up in all the low spots and lots of smaller particulate on all flat surfaces. There is even a very long fiber (~2 inches) down in BSC1's gate valve. (I'll try and collect it when we chamber clean there.)

Once we were finished, Michael L, Chris S, and Kiwamu went in and retrieved the OSEMS and beamsplitter from BSC2.