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  Circular opening on shuttle orbiter nose?

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Author Topic:   Circular opening on shuttle orbiter nose?
QuiGon Grin

Posts: 52
From: Rutherford, NJ 07070
Registered: Apr 2010

posted 03-13-2011 04:21 PM     Click Here to See the Profile for QuiGon Grin     Edit/Delete Message   Reply w/Quote
Sorry if this is a pretty basic question, but after all these years I just noticed something on the nose of the space shuttles that I never saw before, and I don't know what it is nor have I been able to find any reference for what it is.

What is the circular opening just fore of the orbiters windows? As can be viewed here:

In my search I've noticed that it is covered with paper or is it plastic on the launch pad, which may be why I never noticed it before.


Posts: 93
From: Seattle, WA, USA
Registered: Sep 2010

posted 03-13-2011 04:25 PM     Click Here to See the Profile for FullThrottle   Click Here to Email FullThrottle     Edit/Delete Message   Reply w/Quote
Are you referring to the oval hole for the RCS thruster? I think that's what it's called... They put covers over them on the pad to keep moisture out so the water doesn't freeze causing a faulty thruster.

Robert Pearlman

Posts: 42988
From: Houston, TX
Registered: Nov 1999

posted 03-13-2011 04:32 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
While it is true that the reaction control system (RCS) thrusters are covered by Tyvek paper (hence they are referred to as "Tyvek covers") before launch, the opening to which the original post refers to is for the orbiter's two star trackers and is protected by a door that can be opened and closed by the crew.
The star tracker system is part of the orbiter's navigation system. Its two units are located just forward and to the left of the commander's plus X window in a well outside the pressurized crew compartment... The star trackers are used to align the IMUs on board the orbiter as well as to track targets and provide line-of-sight vectors for rendezvous calculations.

Each star tracker has a door to protect it during ascent and entry. The doors are opened on orbit to permit use of the star trackers.

QuiGon Grin

Posts: 52
From: Rutherford, NJ 07070
Registered: Apr 2010

posted 03-19-2011 02:24 PM     Click Here to See the Profile for QuiGon Grin     Edit/Delete Message   Reply w/Quote
Thanks Robert. Sorry for the late reply but I didn't turn my computer on until today. The "openings" are indeed the star trackers as I did a web search using that term and all results show the openings in question as star trackers.


Posts: 210
From: australia
Registered: Feb 2008

posted 03-21-2011 01:27 PM     Click Here to See the Profile for golddog     Edit/Delete Message   Reply w/Quote
Every time I see it I think God, that is such a magnificent machine. It makes me weep to think that soon it will no longer be flying


Posts: 1966
From: Atlanta, GA
Registered: Feb 2007

posted 09-30-2011 01:02 PM     Click Here to See the Profile for garymilgrom   Click Here to Email garymilgrom     Edit/Delete Message   Reply w/Quote
I have acquired a tile from this area of the Shuttle. Here's a close up photo of the area around one of the star trackers:

391027 In Situ 400px

And here's a photo of my tile. I believe this is the third tile to the right of the unlabeled tile in the above photo. That tile is number 391027-274, while mine is 391027–268.

391027 GM 400px


Posts: 419
From: Seneca, IL, US
Registered: Jan 2009

posted 09-30-2011 09:40 PM     Click Here to See the Profile for dabolton     Edit/Delete Message   Reply w/Quote
How did the star trackers open? Manually from the crew cabin or automatically?


Posts: 2475
From: Guyton, GA
Registered: Jan 2006

posted 10-01-2011 05:50 AM     Click Here to See the Profile for GACspaceguy   Click Here to Email GACspaceguy     Edit/Delete Message   Reply w/Quote
WOW, cool tile Gary, great addition to your collection!

Jay Chladek

Posts: 2272
From: Bellevue, NE, USA
Registered: Aug 2007

posted 10-01-2011 02:18 PM     Click Here to See the Profile for Jay Chladek   Click Here to Email Jay Chladek     Edit/Delete Message   Reply w/Quote
I am pretty sure the doors could likely open automatically when the star trackers powered up and knowing NASA there was also a manual bypass as well in case an automatic system didn't work. These doors close during launch and reentry, but once on orbit, they stay open nearly the entire time.

New Member


posted 10-07-2011 01:10 PM     Click Here to See the Profile for ARodriguez   Click Here to Email ARodriguez     Edit/Delete Message   Reply w/Quote
Each star tracker door actually has a three position open/close/off switch and a dedicated power switch. However it is also possible to use one door switch to close/open both doors although at 12 sec instead of 6 seconds with its own switch. The crew nominally uses both door control switches. In the event of a power loss to the star tracker electronics assembly the associated door will automatically shut.

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