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  STS-93 first launch attempt: abort or scrub?

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Author Topic:   STS-93 first launch attempt: abort or scrub?
Rick
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Posts: 264
From: Yadkinville, NC
Registered: Jun 2000

posted 08-09-2011 03:29 PM     Click Here to See the Profile for Rick   Click Here to Email Rick     Edit/Delete Message   Reply w/Quote
Would the first launch attempt of STS-93 be considered a launch pad abort or simply a scrub? There was a manual cutoff split seconds before the start of main engines, but after the igniters — the sparkler thingies — lit.

If it's not an abort, what's the textbook definition?

Ben
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From: Daytona Beach, FL
Registered: May 2000

posted 08-09-2011 03:54 PM     Click Here to See the Profile for Ben   Click Here to Email Ben     Edit/Delete Message   Reply w/Quote
A Redundant Set Launch Sequencer (RSLS) abort does not have to mean after the engines ignite. STS-93 was indeed an RSLS abort, and you can hear Leinbach discuss it with the team here (first asking and then getting confirmation) at 1:45 in.

STS-56 also had an RSLS abort around T-11 seconds.

Rick
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Posts: 264
From: Yadkinville, NC
Registered: Jun 2000

posted 08-11-2011 07:47 PM     Click Here to See the Profile for Rick   Click Here to Email Rick     Edit/Delete Message   Reply w/Quote
I received an e-mail from Eileen Collins this afternoon, and she had checked with the booster flight controller for STS-93 and copied me on his reply. According to him, the early shutdown was NOT considered a pad abort because the SSMEs did not start. Also, he continued, it was not an RSLS abort since it was a manual ground launch sequencer cutoff. Therefore, it evidently must be considered a scrub.

I'm just sayin' ...

Jay Chladek
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Posts: 2211
From: Bellevue, NE, USA
Registered: Aug 2007

posted 08-12-2011 03:50 AM     Click Here to See the Profile for Jay Chladek   Click Here to Email Jay Chladek     Edit/Delete Message   Reply w/Quote
And if it was an abort, they would have spent a longer period of time turning it around before a launch. As I recall, it was a 24 hour turnaround before launching the next night.

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

posted 08-12-2011 10:02 PM     Click Here to See the Profile for Ben   Click Here to Email Ben     Edit/Delete Message   Reply w/Quote
No, the abort occurred July 20, and it was an automatic 48 hour scrub. It was then scrubbed a second time due to lightning, launching three days after the first attempt on July 23.

psloss
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Registered: Jun 2011

posted 08-18-2011 08:17 PM     Click Here to See the Profile for psloss   Click Here to Email psloss     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Ben:
STS-93 was indeed an RSLS abort, and you can hear Leinbach discuss it with the team here (first asking and then getting confirmation) at 1:45 in.
Actually, you can hear the GLS console operator say this was a RSLS hold, not an abort. The difference is when cutoff is given -- before the first engine start command, it's a RSLS hold; after, it's a RSLS abort.

Ken Havekotte
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Posts: 1823
From: Merritt Island, Florida, Brevard
Registered: Mar 2001

posted 08-18-2011 10:38 PM     Click Here to See the Profile for Ken Havekotte   Click Here to Email Ken Havekotte     Edit/Delete Message   Reply w/Quote
While STS-93 in July 1999 was not a RSLS abort, there were five times it did occur.

First with Discovery's maiden launch on Mission 41-D, Challenger on 51-F,
Discovery again on STS-51, Columbia/STS-55, and with a first launch attempt halted at T-1.9 seconds with Endeavour on STS-68 on Aug. 18, 1994.

Only Atlantis was spared from a pad abort like this in the shuttle program history.

Heck, I was there and covered all these missions first-hand here at Kennedy.

SpaceAholic
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From: Sierra Vista, Arizona
Registered: Nov 1999

posted 02-27-2012 12:09 PM     Click Here to See the Profile for SpaceAholic   Click Here to Email SpaceAholic     Edit/Delete Message   Reply w/Quote
During the "successful" launch of STS-93, a near catastrophic event occurred in one of the shuttle's SSME's. In a practice which in retrospect is surprising and symptomatic of the culture which precipitated STS-107, SSME's with faulty injector components (Liquid Oxygen (LOX) Posts) were routinely plugged up with pins and disabled (effectively deactivating a portion of the engine's injector) rather then removing and replacing the post. As briefed within this NASA Ames presentation, one of the pins was ejected during flight and resulted in additional engine damage.

• 600+ LOX Main Engine Injectors are CRIT 1 components that are manufacturing or fatigue life limited (cracking results)
– Cracked LOX Post could allow combustion within injector head and cause main engine failure
– Repair consists of pin ( 1 inch long, 0.1 inch dia.) friction-fitted into post to deactivate injector by blocking LOX flow
– After pin insertion, vacuum leak checks and engine firing (green run) verify repair

• Pin Ejection IFA on STS-93
– 2 LOX posts deactivated with standard pin repair
– 1 deactivation pin ejected upon engine start
– 3 of 1080 SSME nozzle coolant tubes ruptured
– 4.5 lbs/sec leak of H2 (visible on take-off)
– Premature MECO (0.15 seconds early) and 16 ft/sec underspeed

music_space
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Posts: 1050
From: Canada
Registered: Jul 2001

posted 02-29-2012 12:54 PM     Click Here to See the Profile for music_space   Click Here to Email music_space     Edit/Delete Message   Reply w/Quote
And keep in mind that the "sparkies" are not from SSME ignitor systems but rather "hydrogen burn-off igniters", meant to burn spilled hydrogen from the vicinity of the engines, as previously discussed here.

All times are CT (US)

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