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  Shuttle launch controls and configurations

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Author Topic:   Shuttle launch controls and configurations
QuiGon Grin
Member

Posts: 42
From: Rutherford, NJ 07070
Registered: Apr 2010

posted 02-06-2011 07:08 PM     Click Here to See the Profile for QuiGon Grin     Edit/Delete Message   Reply w/Quote
I have some questions which may seem simple, but I have never been able to find answers to.

My first question is when a shuttle launches, I'm assuming that the engine firing is handled by computers and not someone "pressing a button" in the firing room. If this is so, when did this begin? On a recent viewing of "The Right Stuff" a technician is seen pressing a button in the firing room (hence its name) for Alan Shepard's Mercury launch.

Also while watching a Soyuz launch, a launch key was mentioned. So how exactly do they launch (a bit off topic)?

My next question regards the external tank piping connections to the orbiter. After the external tank is jettisoned, what happens to the exposed intake areas on the bottom of the shuttle? I have never seen open doors on the bottom of the orbiter which would close. Sliding doors don't make sense to me as I would think the tiles could be damaged, and the "seal" between the "door" and bottom wouldn't be proper atmospheric reentry.

Any answer would be appreciated.

Robert Pearlman
Editor

Posts: 27328
From: Houston, TX
Registered: Nov 1999

posted 02-06-2011 08:20 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
In the lead-up to a shuttle launch, after exiting the final built-in hold at T-9 minutes, control is turned over to the Ground Launch Sequencer inside the Launch Control Center (LCC). At T-31 seconds, control is turned over again to the shuttle's onboard computers ("auto sequence start").

As such, there is no launch button in the LCC.*

From T-8 seconds, the final ignition sequence and liftoff of the Saturn V was computer controlled (T-3 seconds for the Saturn IB).

Gemini-Titan's first stage engine ignition signal was given from the blockhouse.

The Soyuz countdown includes a key being inserted in the launch bunker after the T-5 minute mark, a carryover from the Vostok launch countdown. Control is turned over to an automatic sequencer at one minute to launch.

As for the external tank umbilicals to the orbiter, doors close to cover the attach points after ET jettison.

An electromechanical actuation system on each umbilical door closes the left and right umbilical cavities after the external tank is jettisoned and the umbilical plates retracted inside the orbiter's aft fuselage. Each umbilical door is approximately 50 inches square.
* Astronaut Greg Chamitoff tells a great story about how his wife brought with her one of those round push-button lights (example) to his shuttle launch. She brought it out during the final countdown and presented it to their twin three-year old children. At T-0, the kids pressed the button, it lit up, and then the shuttle launched. Amazement ensued...

FFrench
Member

Posts: 3093
From: San Diego
Registered: Feb 2002

posted 02-06-2011 08:59 PM     Click Here to See the Profile for FFrench     Edit/Delete Message   Reply w/Quote
Here are some photos I took of the umbilical doors of Endeavour (first photo) and Discovery in their respective OPFs.

Ben
Member

Posts: 1843
From: Daytona Beach, FL
Registered: May 2000

posted 02-06-2011 10:15 PM     Click Here to See the Profile for Ben   Click Here to Email Ben     Edit/Delete Message   Reply w/Quote
At launch, those belly ET doors are flush up against the tile (as opposed to hanging in the above photos). But because the feedlines are in place, it is hard to see the doors on tv.

ilbasso
Member

Posts: 1494
From: Greensboro, NC USA
Registered: Feb 2006

posted 02-07-2011 07:26 AM     Click Here to See the Profile for ilbasso   Click Here to Email ilbasso     Edit/Delete Message   Reply w/Quote
Former Shuttle Launch Director Bob Sieck gave an interesting talk at MIT on ground operations and the countdown sequence. Check out his lecture here.

You can also read a little about his work in designing the launch sequencer for shuttle in his two NASA oral history interviews: KSC | JSC

QuiGon Grin
Member

Posts: 42
From: Rutherford, NJ 07070
Registered: Apr 2010

posted 02-07-2011 09:05 PM     Click Here to See the Profile for QuiGon Grin     Edit/Delete Message   Reply w/Quote
Thanks a lot everyone for providing answers to questions which have plagued me for a long time. Especially Ben for commenting that the doors are flush to the bottom tiles, since that is probably why I missed them in every photo that I looked at. If you hadn't stated this information I most likely would have missed the door in the first photo posted by FFrench.

One more follow up question: So what does the Soyuz key actually do then?

Ben
Member

Posts: 1843
From: Daytona Beach, FL
Registered: May 2000

posted 02-07-2011 11:10 PM     Click Here to See the Profile for Ben   Click Here to Email Ben     Edit/Delete Message   Reply w/Quote
Here is an image where you can see the doors, just barely, between the feedlines and flat against the belly.

QuiGon Grin
Member

Posts: 42
From: Rutherford, NJ 07070
Registered: Apr 2010

posted 02-08-2011 08:08 PM     Click Here to See the Profile for QuiGon Grin     Edit/Delete Message   Reply w/Quote
Thanks Ben. When I first looked at the photo I couldn't see the doors, but once I magnified the image and now knew were to look, I was able to spot the doors.

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