Wednesday, February 8, 2012

ISS Mission Control (Or, what I did all night)


Ok, couldn't help it with the memes. Unimpressed Astronaut and Modest Von Braun source crack me up! Since I'm here in MCC for another night shift, I thought I would tell you a little something about what I'm doing here.

While in mission control, I am solely responsible for two space station systems: Electrical power (that's one) and External thermal control (that's two, and a mouthful at that!). I won't get overly technical, but if you don't want to know how we keep the lights on at 250 miles up, you can skip this post now.



There's the space station. See those 8 shiny looking things, those are solar arrays. "But there's 16 things," you might say, and you're not wrong. Each of the 16 things is called a solar array blanket. Two blankets makes up a solar array wing. Each wing supports its own unique power channel. (Excuse the crappy paint edit to demonstrate.) Anything on the space station can get its power from one or more of those 8 channels. This is how we manage redundancy in the power system... not keeping all our eggs in one (power channel) basket.  Imagine if everything were on one channel and it failed. This is how your house is built, but if that fails then the power company sends a truck out and fixes you right up.  Our truck is a little different, and a little harder to make house calls with.
Russian Soyuz launch.
Repairman (actually that's a repair-lady!)


















Station orbits the earth every 90 minutes, and spends about 30 minutes of that in shade, the other hour in sun. When the sun is out we have lots of power produced by these solar arrays to turn everything on. While we are in the sun, we are also charging 6 batteries per solar array.
The batteries are limited in how much power they can hold, so that limits how many things we can turn on while it's dark out (30 of those 90 minutes when the sun is on the other side of the Earth). Batteries also are rather finicky- they need to be kept in a close temperature range, with tightly controlled input voltage, in order to function properly. And like your cell phone battery, or any other rechargeable battery, they develop memory.

In your computer (and your brain) memory is a good thing. In your batteries its a bad thing. Memory keeps them from charging as much as they can, or causes them to empty faster. Of course you get a new cell phone every couple years when the battery goes bad (or you drop it in the toilet). Space station batteries have been up there for many years, and have to last many more!  We do what's called a battery reconditioning to clear out the battery memory and get some of our battery life back. Don't try this at home, our batteries are special. The best way to keep your cell phone battery from going bad is to never fully empty it. Charge that baby every chance you get!

These batteries are NOT special!
What we are doing tonight is draining them down, then charging them back up. This allows us to analyze their current capacity. If the analysis comes back that they need a reconditioning, then we'll do that at a later time. A reconditioning is like a capacity test, but longer. We drain it wayyy down. And then drain it down some more. And then we overcharge it. Then we repeat that a second time. This clears out some of that memory and enables us to get more power from these batteries.  Without them, we couldn't keep the lights on!
And then these guys (they're in space right now!) would be living in the dark.  Actually they'd be living on the ground, not only do we power the lights but also all the life support equipment that keeps them from freezing or running out of oxygen or... well, space is hard.
Expedition 30 Crew
Hope you enjoyed a peek at space station operations. Is this something you would like to hear more about, or should I just stick to pictures of food?
Oh, here's a picture of food, too:
A delicious PB Banana muffin enjoyed at MCC.

2 comments:

  1. LOVE this! You did a great job of explaining it for those that may not have the scientific background :) I was a teacher (math/physics) and would always do an astronomy and space history mini-class. It was seriously the highlight of my year!

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    1. I try my best to be understandable. I know plenty of people have looked at me like I am speaking a foreign language (which I am, pretty much!) when I really get going on space station stuff. I'm glad folks like you are out there inspiring kids to be nerds too. We need all we can get!

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