What am I seeing? Take a look at the video link below.

http://www.metacafe.com/watch/758304/shuttle_launch/

Look at 1:49 on the video. To the upper right of the OMS engine are three circles.
These seem to blow out at T-3 seconds. What are they?

All I see are the usual plumes/vapors

Three circles stacked vertically.

These are covers on the nozzles of maneuvering engines. They're there to stop rain etc. getting in - and are designed to either fall apart with the acoustic shock of launch, or rip off early in the flight.

Doug

Any idea what they are made of? They seem to act like paper. I've watched them on several launches.

They're Tyvek, a waterproof material often used in homebuilding. All the RCS nozzles are covered, and the covers are removed by pressure (as with these) or aerodynamics (for the front ones).

All the covers on the thrusters are just "butcher wax paper", $200 a cover, but that all they are. I used to work on the OMS/RCS engines and that cost always amazed me

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Joe Bartoszek

Rocket Scientist for the win.

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http://www.hq.nasa.gov/pao/FOIA/FRRdocs/15_spr2.pdf

Check page 7 in the processing...it appears the forward RCS covers were changed to Tyvek as part of the post Columbia RTF process. Not sure about the aft ones (Google search for Tyvek, RCS Shuttle has a lot of different forum discussions on the subject).

Dave

You are both correct. The upper RCS covers are Tykvek and the rears are still the old butcher paper. The ones you see here are the paper ones. Tyveks can be seen falling off in some video angles (not here) and appear as silvery foil.

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