Hey! Two For One! Over the weekend...

This passed weekend was fuel loading for the APU and HPU. The HPU (Solid Rocket Boosters) was done on Saturday and is, from what I understand, a pretty quick job. I wouldn't know because I was not there. I only got approved for extra time for Sunday which was the APU (Orbiter) loading. Which is fine and dandy with me because on Sundays, I make double...but this job is soooo not about the money. It is a plus though. The APUs take a bit longer. It is said that it can take 12+ hours for the loading. On Sunday it took about 11 if you include the time we had to wait before we actually began flowing fuel. I only stayed for 10.

The process is fairly simple. It just takes a long time. First we have to get whatever fuel is left in the tank from the last flight out. The APUs use Hydrazine. In another post, I'll explain how it works. When all of the fuel is out we fill it back up. It is the easiest way to keep track of how much is loaded. In this case, we had to load 356 lbs. Typically is lower but in this case we had to load 26 lbs more to do a confidence run (a test run where on the ground where the APUs are fired up and operate for a given time to make sure they will be a-ok for flight). Next we pressurize the GN2 (gaseous nitrogen) bladder which applies pressure on the hydrazine to force it out since gravity is of little use in space. Once those parts are complete you have to do leave checks to make sure you won't lose anything. Then there is some clean up and then disconnection of the QDs (quick disconnects (fuel lines)).

The GN2 is fed from the facility. Another project of mine for the semester is to process a new piece of equipment which would allow us to pressurize GN2 on the go. At the moment the GN2 is still connected because we will have to re-pressurize after the confidence run. It is connected to the RSS (rotating service structure) which pivots around on the pad to allow access to the Orbiter and installation of the payload into the payload bay.

All around a good day. It started off where we might have had to put off the operation because of inclimate weather but 5 minutes before the drop dead time of 12pm it cleared up and we were good to go. There was some radio problems later on but that was the extent of the bad juju.