The Confidence Run

On Wednesday with did OV103's (Discovery) confidence run. This is where we actually turn on and run the APU to make sure there won't be any issues for the launch. I went in to do the walk down in the morning to make sure that the exhaust plugs on Discovery were taken out. The job is run and monitored from the firing room and it is all a matter of pushing a few buttons. Each APU was run for about 5 minutes at regular speed and then for about 15 seconds on high speed. The exhaust from the APU is mostly ammonia. You can kind of see the vapors being ejected when the APU first starts but after a few bursts, you do not see it after about half a minute. So to monitor it there is also a thermal camera pointed at the Orbiter. And since the exhaust is about 900 degrees, you can see it pretty well on the thermal camera.

After the walk down was complete the Rotating Service Structure had to be rolled open to so that the exhaust did no pollute the platforms where the ports were. The RSS moves pretty slow so it does not damage any flight hardware but when its fully open, it is a beautiful sight.





Very rarely is the RSS open. Really the only time it is open for any extended period is a day or two before launch. So this was an occasion I wanted to be around for. I got a couple pictures in the morning before my battery died and then used my lunch break to take my good camera up and get some more, better shots.