The link to the Space Shuttle launch video. At 1:30 mark, three circular disks get torn away. It happens immediately after the engine ignition begins.

Here is a cropped image of the Discovery after take off. Image source: Wikipedia page for Space Shuttle Discovery. These disks seems universal of all launches.

STS124 Launch

What are they and why does this happen? What function do they serve?

Adding images from the video for reference: Shuttle disk tear away

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    $\begingroup$ I suggest you watch the Space Shuttle Ultra Slow Motion Launch video to better see that the covers are torn by the intense 'sound'. $\endgroup$ – amI Jan 25 at 7:44

Those are covers on the RCS thrusters. They're on all the other thrusters too, to prevent rain etc. from getting into the thrusters.

For most of the program, the covers were butcher paper. Towards the end, we switched to using Tyvek.

The covers are designed to get blown off during launch. On the OMS pods, it's mostly done by the shockwave of the igniting engines. The RCS covers on the nose of the Shuttle get blown off by the air rushing over the shuttle after liftoff.

Here is a cutaway drawing of the OMS pod. The shaded areas are part of the RCS.

OMS cutaway drawing

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    $\begingroup$ Woah! I didnt expect such a comprehensive question in quora! Thanks for the link. And I did not know they were covering the RCS thrusters! $\endgroup$ – karthikeyan Jan 24 at 12:38
  • $\begingroup$ @rainer Does each circular hole indicate a single RCS or there are 3 holes in total for the one RCS? Also, thanks for the picture. $\endgroup$ – karthikeyan Jan 24 at 13:31
  • $\begingroup$ Do these protective membranes tear themselves or is there a mechanism to tear them? $\endgroup$ – karthikeyan Jan 24 at 13:32
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    $\begingroup$ ask @RainerP. , he added the image. $\endgroup$ – Hobbes Jan 24 at 15:10
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    $\begingroup$ Image taken from another answer (@OrganicMarble) $\endgroup$ – Rainer P. Jan 24 at 15:29

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