Author Topic: NASA plan to alter STS-120 launch countdown (Read 9363 times)

Chris Bergin · « **on:** 09/09/2007 10:39 pm »

http://www.nasaspaceflight.com/content/?cid=5224

TJL · « **Reply #1 on:** 09/09/2007 10:53 pm »

This may be a silly question but, what is the difference between reducing the 3 hour hold to 2 hours and 30 minutes or just begin the tanking process 1/2 hour later in the count?

Chandonn · « **Reply #2 on:** 09/09/2007 11:13 pm »

Another good article!

Actually, I think shaving the hold time reduces the tendency to begin tanking early. I believe there have sometimes been issues with ground equipment at the start of tanking so they tend to go for an early start.

ChrisGebhardt · « **Reply #3 on:** 09/09/2007 11:14 pm »

Isn't ET-120 flying with STS-120?

psloss · « **Reply #4 on:** 09/09/2007 11:21 pm »

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Trekkie07 - 9/9/2007 7:14 PM

Isn't ET-120 flying with STS-120?

Yes.

nathan.moeller · « **Reply #5 on:** 09/09/2007 11:50 pm »

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TJL - 9/9/2007 5:53 PM

This may be a silly question but, what is the difference between reducing the 3 hour hold to 2 hours and 30 minutes or just begin the tanking process 1/2 hour later in the count?

I could be wrong, but I believe the tanking process takes place in the T-3 hour hold. Someone correct me if that's incorrect.

psloss · « **Reply #6 on:** 09/10/2007 12:02 am »

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nathan.moeller - 9/9/2007 7:50 PM

I could be wrong, but I believe the tanking process takes place in the T-3 hour hold. Someone correct me if that's incorrect.

It roughly starts when the clock resumes at T-6 hours, or at least that's the plan. The hold at T-3 hours allows for some catch up (like STS-97 or the second STS-116 tanking, although those are extreme cases), but usually the tank is full around the time the count gets there.

« **Reply #7 on:** 09/10/2007 12:23 am »

Is the launch time still going to be the same or is it going to be moved forward if this plan is taken into effect?

Jim · « **Reply #8 on:** 09/10/2007 12:29 am »

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TJL - 9/9/2007 6:53 PM

This may be a silly question but, what is the difference between reducing the 3 hour hold to 2 hours and 30 minutes or just begin the tanking process 1/2 hour later in the count?

Changing holds is easier wrt to documents. The countdown procedure is written per T minus time

mkirk · « **Reply #9 on:** 09/10/2007 12:31 am »

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Jim - 9/9/2007 7:29 PM

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TJL - 9/9/2007 6:53 PM

This may be a silly question but, what is the difference between reducing the 3 hour hold to 2 hours and 30 minutes or just begin the tanking process 1/2 hour later in the count?

Changing holds is easier wrt to documents. The countdown procedure is written per T minus time

This also preserves trouble shooting time for anomalies that arise during the loading process and Final Inspection Team activities.

Mark Kirkman

mkirk · « **Reply #10 on:** 09/10/2007 12:33 am »

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Justin Wheat - 9/9/2007 7:23 PM

Is the launch time still going to be the same or is it going to be moved forward if this plan is taken into effect?

No this will not effect (affect ?) the T-0 time.

Mark Kirkman

mkirk · « **Reply #11 on:** 09/10/2007 12:36 am »

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nathan.moeller - 9/9/2007 6:50 PM

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TJL - 9/9/2007 5:53 PM

This may be a silly question but, what is the difference between reducing the 3 hour hold to 2 hours and 30 minutes or just begin the tanking process 1/2 hour later in the count?

I could be wrong, but I believe the tanking process takes place in the T-3 hour hold. Someone correct me if that's incorrect.

Under normal circumstances the Tank should be in stable replenish by the T-3 hour hold. As you may or may not know "stable replenish" is the continuos topping off of the LO2 and LH2 as they boil off.

Mark Kirkman

ChrisGebhardt · « **Reply #12 on:** 09/10/2007 12:54 am »

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Justin Wheat - 9/9/2007 8:23 PM

Is the launch time still going to be the same or is it going to be moved forward if this plan is taken into effect?

The launch time will still be the same. It's only a 10minute launch window because of rendezvous capabilities with the ISS so the launch time can't change.

EDIT: Sorry.... missed the previous post answering this question.

nathan.moeller · « **Reply #13 on:** 09/10/2007 02:25 pm »

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mkirk - 9/9/2007 7:36 PM

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nathan.moeller - 9/9/2007 6:50 PM

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TJL - 9/9/2007 5:53 PM

This may be a silly question but, what is the difference between reducing the 3 hour hold to 2 hours and 30 minutes or just begin the tanking process 1/2 hour later in the count?

I could be wrong, but I believe the tanking process takes place in the T-3 hour hold. Someone correct me if that's incorrect.

Under normal circumstances the Tank should be in stable replenish by the T-3 hour hold. As you may or may not know "stable replenish" is the continuos topping off of the LO2 and LH2 as they boil off.

Mark Kirkman

Thanks Mark. I know what stable replenish is but I didn't know the timelines.

nathan.moeller · « **Reply #14 on:** 09/10/2007 02:26 pm »

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Justin Wheat - 9/9/2007 7:23 PM

Is the launch time still going to be the same or is it going to be moved forward if this plan is taken into effect?

No change to T-0. They'll start the count a half-hour later than they have for past launches.

Seattle Dave · « **Reply #15 on:** 09/10/2007 06:56 pm »

That's a very good article, especially on explaining the tank, ice and foam relation.

George CA · « **Reply #16 on:** 09/10/2007 10:25 pm »

Can more ice form at more humid times of year?

STS Tony · « **Reply #17 on:** 09/10/2007 10:47 pm »

Good move by Mike!

mkirk · « **Reply #18 on:** 09/10/2007 11:44 pm »

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George CA - 10/9/2007 5:25 PM

Can more ice form at more humid times of year?

Yes.

There are other factor that influence the ice/frost build up as well such as winds (direction & magnitude).

Mark Kirkman

DaveS · « **Reply #19 on:** 09/10/2007 11:46 pm »

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mkirk - 10/9/2007 2:33 AM

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Justin Wheat - 9/9/2007 7:23 PM

Is the launch time still going to be the same or is it going to be moved forward if this plan is taken into effect?

No this will not effect (affect ?) the T-0 time.

Mark Kirkman

It's affect.

GLS · « **Reply #20 on:** 09/11/2007 01:25 pm »

Where are they inserting those 30 minutes? At T-11 Hours? T-6 Hours? I'm asking because the CDC usually starts at the top of the hour, and if you take 30 mins out, then T-43 Hours (and all the other BIHs until T-11) would be at the bottom of the hour....

Stowbridge · « **Reply #21 on:** 09/11/2007 06:02 pm »

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GLS - 11/9/2007 8:25 AM

Where are they inserting those 30 minutes? At T-11 Hours? T-6 Hours? I'm asking because the CDC usually starts at the top of the hour, and if you take 30 mins out, then T-43 Hours (and all the other BIHs until T-11) would be at the bottom of the hour....

Start the count 30 minutes later.

GLS · « **Reply #22 on:** 10/12/2007 05:13 pm »

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Stowbridge - 11/9/2007 7:02 PM

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GLS - 11/9/2007 8:25 AM

Where are they inserting those 30 minutes? At T-11 Hours? T-6 Hours? I'm asking because the CDC usually starts at the top of the hour, and if you take 30 mins out, then T-43 Hours (and all the other BIHs until T-11) would be at the bottom of the hour....

Start the count 30 minutes later.

Not according to Bill Harwood. The CDC still starts at the top of the hour. Looks like those 30 minutes went to the BIH T-11 Hours...

mkirk · « **Reply #23 on:** 10/12/2007 06:06 pm »

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GLS - 12/10/2007 12:13 PM

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Stowbridge - 11/9/2007 7:02 PM

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GLS - 11/9/2007 8:25 AM

Where are they inserting those 30 minutes? At T-11 Hours? T-6 Hours? I'm asking because the CDC usually starts at the top of the hour, and if you take 30 mins out, then T-43 Hours (and all the other BIHs until T-11) would be at the bottom of the hour....

Start the count 30 minutes later.

Not according to Bill Harwood. The CDC still starts at the top of the hour. Looks like those 30 minutes went to the BIH T-11 Hours...

S0007 Call to Stations is currently planned for Saturday Oct 20 at 1:30 PM with the clock starting at 2:00 pm at the T-43 hour mark. The T-3 hour hold has been changed to 2 hours 30 minutes in duration to accommodate the new fueling philosophy.

There is a 4 hour hold at T-27 hours and another at T-19 and a 13 hour 13 min hold at T-11. At T-6 there will be a 2 hour hold. T-20 minutes and T-9 will be standard.

Mark Kirkman