STS-121 possible leak

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oceans777

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Reports from NASA today that Discovery may be leaking slight amounts of propellant - possibly hydrazine or nitrogen gas, from APU1 of the three APU's.
If nitrogen is leaking NASA says it is "no issue at all" and even if hydrazine the leak appears to be so slight that it would not cause any risk of fire or ignition on re-entry
currently planned for Monday at 9:14 EDT. The shuttle can also land on one APU if required.

During a press briefing today there was some discussion of Edwards being an increased possibility for landing on Monday due to unpredictable wx at Cape - I wasn't clear
if they were also saying Edwards would be the landing site if APU1 were shut down but that seemed to be the idea.
Engineers were looking at options to check the possible leak in more detail during Saturday after the undock from ISS but were not considering it the serious issue
they intially thought it was.

So maybe a long shot but for CA monitors it may be worth keeping up with - if anyone knows, where can those of near Edwards to see a landing there if possible at all?
Any particular freqs other than Edwards ops and UHF\VHF to monitor?
 
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rdale

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They can still land with APU1 shut down at KSC, but the weather requirements are much more strict so that increases the odds of Edwards. There will be a test very early on Sunday so they'll know by around lunchtime tomorrow what the plan will be.
 
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That's not exactly what the flight director said.

With 2 APUs running, they can easily land at KSC. 2 APUs provide full control of all shuttle systems involved in atmospheric maneuvering and landing. If they go down to a single APU, then the weather limitations become very strict and the alternate site comes into play if KSC has a crosswind or other problems.
 

rdale

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You didn't hear everything correct...

It is true that they can land on 2 APUs. However if they are down to 2, they protect for the loss of one more so they act as though there is only one APU left. So the weather requirements (when they are on 2) matches that of being on one only.

Those requirements are more strict, so that's why they WILL have Edwards open up if tomorrow's test has them shut down APU #1.

I'll try to find a link to help explain.

- Rob
 

oceans777

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Ahhh - thanks for the clarifications - I had it on in my office and was trying to follow with multiple interruptions - good to know the correct facts.
 

DPD1

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oceans777 said:
So maybe a long shot but for CA monitors it may be worth keeping up with - if anyone knows, where can those of near Edwards to see a landing there if possible at all?
Any particular freqs other than Edwards ops and UHF\VHF to monitor?
Unless you have a contact to get you on the field, it would pretty much be a non event in the dark. I raced out there on the last day landing, and found out the hard way that watching on the range is not tolerated now. Lets just say it involved an Army H-60... It wasn't pretty. So the days of camping on (or getting anywhere near) the lakebed, are over.

On the last one, I stayed up and got a couple decent transmissions on one of the three main UHF while they came over L.A., and also heard the chase up on one of the Dryden freqs... I forget which.

Dave
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