NASA STS-121/ULF1.1 FD 13 Execute Package

Status Report From: Johnson Space Center
Posted: Sunday, July 16, 2006


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Good morning, Discovery.

This is the last execute package you're going to get from us. We've had it. We're done with execute packages, finished, over, our cooked indicator has popped, the fat lady is singing (and she's not singing the Aggie War Hymn). No more... O.K., maybe that's a little bit of an exaggeration. Actually, if the truth be told, we really have enjoyed working this mission and if the Ku antenna wasn't going to be stowed tomorrow, we would gladly do another execute package. Thanks for making this a great mission one we're proud to be part of. Take care and see you back in Houston and we'll buy the first adult malted beverage.


MSG 124 (13-0720) - FD12 MMT SUMMARY
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Page 1 of 1, MSG 124 (13-0720)

FD12 MMT Crew Summary

Today's MMT wrapped up the APU 1 pressure decay story.

APU 1 Tank Pressure Decay There is no change in the APU 1 leak decay rate. There is still no way to definitively tell if the leak is N2 or hydrazine. Data presented by the NESC, White Sands, and JSC Engineering today reaffirmed that if this leak was hydrazine, as it dribbled out underneath the insulation it would be ice and would induce increased heater duty cycles which would turn it to vapor. We are not seeing this in our data, and the team is confident that we would be if the leak was hydrazine. The only location that is not covered with insulation is the fuel fill Quick Disconnect (QD), so this may still be a possible leak site. For your information, this QD panel is external to the vehicle but is vented back to the aft compartment in order to maintain delta pressure across the closeout panel. The bottom line is that data and analysis from all the experts strongly suggests that we are not leaking hydrazine.

Even so, the MMT reviewed the impacts if the leak was hydrazine. There was no change in the conclusions reached yesterday that showed that at this slow leak rate, vapor concentrations in the aft compartment would still be well below the flammability limits. Below 95,000 feet, a minimal amount (less than 20 cc's) of liquid hydrazine could drip from the leak site. There are no hot spots, ignition sources or catalyst concerns below the APU fuel tank in the drip zone. We'll also have the standard entry MPS helium purge and airflow from the vent doors to help disperse the hydrazine vapors. Again, our data and analysis is leaning strongly towards this not being a hydrazine leak.

You'll hear the details about the entry plan later today from your Entry team, but the quick look is to use APU 1 for a nominal FCS checkout. For entry, we'll start APU 1 pre-TIG at the nominal time or maybe a little bit earlier. Post-landing shut-down plan will be nominal.

Mission managers continue to analyze images from the post-undocking inspection of Discovery's port wing and nose cone. Initial analysis indicated nothing amiss. A decision on whether to clear Discovery for landing is expected later today.

Discovery's deorbit burn is scheduled for 7:07 a.m. Monday, for an 8:14 a.m. CDT landing at Kennedy Space Center. A second opportunity would see a deorbit engine firing at 8:43 a.m. for a landing at 9:50 a.m.

Aboard the International Space Station, Expedition 13 Commander Pavel Vinogradov and Flight Engineers Jeff Williams and Thomas Reiter are enjoying an off-duty day after the intense activity during Discovery docked operations.

The next STS-121 status report will be issued Sunday evening or earlier if events warrant.

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