[amsat-bb] Re: Discovery

John Magliacane kd2bd at yahoo.com
Wed Dec 13 11:25:21 PST 2006

--- Nate, WY0X, wrote:

> I'm no expert, just some casual layman's notes below, but did you watch 
> the replays on NASA TV, John?  Some of what you saw could probably be 
> described from the video from the External Tank (ET) centerline camera 
> video.  (Which is absolutely phenomenal by the way... if you haven't 
> seen it and you're reading this, find an outlet for the Flight Day 1 
> video and watch the launch videos.  The lame press here in the States 
> doesn't ever play the good stuff.)

I've seen some external tank videos from previous missions, but didn't get a
chance to see any for STS-116.

> Just after MECO, there's a bunch of thruster, and (I think) OMS engine 
> firing to pull away (+Z) from the dropped ET.  Plus I would assume the 
> main engine bells are probably still quite hot, possibly producing 
> visible light?  That last part is just a guess.

I did see some smaller flashes some time after the main engines extinguished
(as I was walking back to my car, to be exact), so my guess is that they were
due to OMS firings.  I saw some "after glow" for a while as well.

--- Joe Leikhim, K4SAT wrote:

> I would expect the main engines might continue run on for a while because of
> the fuel remaining in the lines and turbo pumps being under tremendous
> pressure and expansion. Also I think the engine bells are cooled by cryo fuel
> so some may remain inside as well and some flow desirable to cool down.

Could be.

> Perhaps someone more familiar with the engines can describe the shutdown
> process. It is probably more complex than closing one set of valves so that
> unburned fuel doesn't burn/explode when the tank separates.

Sounds like a good question to pose to an astronaut the next time they show up
on 2-meters.  :-)

73, de John, KD2BD 

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