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Author
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Topic: What does the "T" in T-minus mean?
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flight_plan
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posted 07-31-2009 01:44 PM
   
Have just been out for a sit in the park and a read of Buzz Aldrin's latest book. Trouble is I was suprised when the wife took it first. She is not normally interested in space stuff but suprised me even more when she asked:"When doing the countdown and they say T minus 10 minutes, what does the T mean?" I had no answer but am sure I know deep inside my head but need refreshing. Any takers? |
Mr Meek
Member Posts: 348
From: Chattanooga, TN
Registered: Dec 2007
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posted 07-31-2009 01:54 PM
I've always understood it as "Time". However, that's my armchair understanding. It's possible that it could stand for something much more esoteric. |
ColinBurgess
Member Posts: 1539
From: Sydney, Australia
Registered: Sep 2003
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posted 07-31-2009 04:51 PM
I always thought it was short for Takeoff, but I'm happy to be proven wrong. |
David Stephenson
Member Posts: 290
From: England
Registered: Mar 2003
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posted 07-31-2009 05:26 PM
I would be happy to know also, that's the sort of question I dread been asked by a group of school children. |
mikej
Member Posts: 359
From: Germantown, WI USA
Registered: Jan 2004
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posted 07-31-2009 06:26 PM
I have always assumed that it means "takeoff," but according to Shuttle Launch Director Mike Leinbach, it stands for "test": Abigail from Pembroke Pines: I've heard that during a launch countdown the "T" in T minus does not stand for "Time." If so, what does the "T" really mean?You hear us talk in the Launch Control Center about T-9 minutes, T-20 minutes, etcetera. And so the assumption is that T stands for time. I joined the space program about 20 years ago and I asked this question of my elders in the program when I did join, and it turns out that T stands for test. Because it's not always related to time. And so, in the early days of the space program, back in the Mercury and Gemini days and, indeed, Apollo, T stood for test. Because again, not all tests are based on time. It could be the start of a particular test in our Orbiter Processing Facility that is independent of the time of day. And so, the T actually stands for test. Good question. It took me awhile to figure that out myself, but it's a good question. |
Rizz
Member Posts: 1208
From: Upcountry, Maui, Hawaii
Registered: Mar 2002
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posted 07-31-2009 11:18 PM
And TALO stands for Time After Lift Off. |
Sy Liebergot
Member Posts: 457
From: Pearland, Texas USA
Registered: May 2003
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posted 08-01-2009 12:32 PM
Time. |
AstroAutos
Member Posts: 722
From: Monaghan Town, Co. Monaghan, Ireland
Registered: Mar 2009
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posted 08-01-2009 12:48 PM
We can't argue with Sy - if he says it's time, then it's time because he's been there...Case closed! |
flight_plan
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posted 08-01-2009 04:19 PM
Well my flabber is ghasted. I am so glad it was not an easy one to answer. As the wifey is sitting nearby I have just read all these replies to her and she is a tad smug at finding a question that stumped some of us.As she is now converted to Space history, I have just explained who Sy is as well! Thank you all. |
David Bryant
Member Posts: 891
From: Norfolk UK
Registered: Feb 2005
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posted 08-02-2009 12:53 AM
In the blue corner: EECOM Sy LiebergotIn the red corner: Flight Director Mike Leinbach They can't both be right! |
Rizz
Member Posts: 1208
From: Upcountry, Maui, Hawaii
Registered: Mar 2002
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posted 08-02-2009 01:39 AM
They're not, Sy wins.T-X minutes and 'counting' certainly does relate to 'time'. Most launches are not tests. |
flight_plan
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posted 08-02-2009 01:45 AM
Do we have a problem Houston?As Sy was a member of the pioneers, using the "T" word long before the shuttle guys, I will go with him. We could always ask "John" Jack King. Is he a member on here? |
Robert Pearlman
Editor Posts: 26581
From: Houston, TX
Registered: Nov 1999
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posted 08-02-2009 09:21 AM
The person that manages the countdown (among other preparations) for any launch is called the "Test Director". S/he in turn, then reports to the Launch Director. All launches are tests, but not all tests are launches. Colloquially, I think "T" became known as time, even amongst the mission control ranks, but if you think about it, it really is not a measure of time. During a shuttle countdown, the clock begins at T-43 hours (and counting). If 'T' was strictly 'Time' then one should expect the shuttle to launch 43 hours later, but it does not. The actual length of the countdown is longer than 43 hours as a result of seven built-in holds. |
lm5eagle
Member Posts: 382
From:
Registered: Jul 2007
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posted 08-02-2009 10:18 AM
Time to edit Wikipedia. wherein the question is posed: Was T definitely Time or might it have been Takeoff, Terminus, Termination, Triumph, Teatime, or some foreign word or esoteric term? |
Sy Liebergot
Member Posts: 457
From: Pearland, Texas USA
Registered: May 2003
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posted 08-02-2009 10:41 AM
Again, it's Time (to go).Sy |
Lunar_module_5
Member Posts: 173
From: Wales, UK
Registered: Dec 2004
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posted 08-02-2009 11:09 AM
I remember hearing Hugh Harris on the PAO for one of the early Shuttle flights. He said "....we will pick up the count at the Time minus, T minus 9 minute point...."So for me "T" is time....always will be! |
Rick Boos
Member Posts: 828
From: Celina,Ohio U.S.A.
Registered: Feb 2000
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posted 08-02-2009 07:31 PM
I agree "T" is for time, but does anyone recall X-minus? I've read books and saw movies where they say X minus, but what I thought was interesting, I once owned Guenter Wendt's MR-4 whiteroom notebook (black in color) and on the cover he wrote "X-4 days" in yellow crayon. Just a side note. |
Rizz
Member Posts: 1208
From: Upcountry, Maui, Hawaii
Registered: Mar 2002
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posted 08-02-2009 10:40 PM
quote:
Originally posted by Robert Pearlman:
All launches are tests.
Really? I don't think so. They've worked the bugs out for the most part. When astronauts and payloads are being prepared for launch, they are not being 'tested', are they? Granted, accidents do occur, but I'd have to respectfully disagree with your statement above. When you start up your car in the morning, is that considered a test also. Its sort of a given that it will 'go'. Just my opinion. quote:
Originally posted by Sy Liebergot:
Again, it's Time (to go).
LOL |
mdmyer
Member Posts: 893
From: Humboldt KS USA
Registered: Dec 2003
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posted 08-03-2009 08:01 AM
quote:
Originally posted by Sy Liebergot:
Again, it's Time (to go).
How about It's Time (to go) to the Moon (again). |
blue_eyes
Member Posts: 161
From: North Carolina, USA
Registered: Jul 2005
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posted 08-03-2009 11:46 AM
quote:
Originally posted by Rizz:
When you start up your car in the morning, is that considered a test also.
With my car, definitely yes.  |
robsouth
Member Posts: 598
From: West Midlands, UK
Registered: Jun 2005
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posted 08-03-2009 03:57 PM
I had always assumed it meant takeoff. Takeoff minus 10 seconds and counting... minus 8 seconds... we have a go for main engine start... 3... 2... 1... liftoff, maybe it should have been L-10... 9... 8!!!!! |
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