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## How NASA Steers the Int'l Space Station Around Asteroids & Other Debris44

willith writes "I got to sit down with ISS TOPO Flight Controller Josh Parris at the Houston Mission Control Center and talk about how NASA steers all 400 tons of the International Space Station around potential collisions, or 'conjunctions,' in NASA-parlance. The TOPO controller, with assistance from USSTRATCOM's big radars, keeps track of every object that will pass within a 'pizza-box'-shaped 50km x 50km x 4km perimeter around the ISS. Actually moving the station is done with a combination of large control moment gyros and thrusters on both the Zvezda module and visiting vehicles. It's a surprisingly complex operation!"
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## How NASA Steers the Int'l Space Station Around Asteroids & Other Debris

• #### surprisingly complex (Score:1)

by Anonymous Coward

surprisingly complex? im not in the slightest bit surprised - i cant imagine how difficult operations like this would be. the calculations must be staggering...

• #### Re: (Score:2)

I might actually be trivial with practice, which is also (as you pointed out) not surprising. None of this is very surprising.

I'm guessing if you wanted to add a visiting vehicle's thrust, you'd first have to re-calculate the center of mass given the attached vehicle, and then calculate how much thrust -- and in what direction -- from that vehicle will produce what angles of rotation around which axes.

Not that I could do it all, but I think I might be close, and I can imagine the calculations that go into i

• #### Re: (Score:2)

* "I might" / "It might"

• #### Re:surprisingly complex (Score:5, Funny)

on Friday July 05, 2013 @10:22AM (#44194369) Journal

Yeah, I mean it's not not rocket science is it?

• #### "conjunctions" ? (Score:1)

by Anonymous Coward

Is that because when something gets smashed up there, they say, "BUT it's not our fault!"

• #### Re: (Score:2)

http://www.merriam-webster.com/dictionary/conjunction [merriam-webster.com]

1. the act or an instance of conjoining
2. occurrence together in time or space
3. b : a configuration in which two celestial bodies have their least apparent separation

So.... you could say that the paths of an object like the ISS and one of these fist sized bits of junk meeting is.... them occuring at together in time and space; which would make them have the "least apparent separation" (none at all)....and would likely at least partially "conjoin" them (

• #### Surprisingly complex (Score:5, Insightful)

on Friday July 05, 2013 @09:11AM (#44193883) Homepage Journal
I would have been surprised if it wasn't complex, its a space station
• #### Re: (Score:2, Offtopic)

Well, it's no moon...

• #### Re: (Score:2, Funny)

"I would have been surprised if it wasn't complex, its a space station"

Exactly, it's not rocket science.

• #### Re: (Score:2)

That was my first reaction too. After reading the article, I came away with a different opinion. Apparently there are lots of cats involved, you must be able to read palms, and counting rings in whale teeth is also involved. I won't get into all of the complexity, but I had no idea we were still thatching heat-shields.
• #### So obvious (Score:1)

They use GPS!
• #### Asteroids (Score:2)

How NASA Steers the Int'l Space Station Around Asteroids & Other Debris

If the ISS is anywhere near an asteroid, [wikipedia.org] then Houston, we have a serious problem. (Likewise, if an asteroid is anywhere near LEO, we also have a serious problem.)

• #### Collision probability threshold levels (Score:4, Funny)

on Friday July 05, 2013 @09:44AM (#44194091)

One thing the article talks about is the various alert levels assigned to objects in that "pizza box" possessing a non-zero probability of collision with the ISS.

Yellow: greater than 1 in 100,000
Red: greater than 1 in 10,000
Brown: greater than 1 in 2

• #### Re:Collision probability threshold levels (Score:4, Funny)

on Friday July 05, 2013 @09:59AM (#44194219) Homepage

Brown: greater than 1 in 2

Brown? Seems a strange colour to choose for impending... oh, got it.

• #### Hopefully (Score:2)

no asteroids are going to come as close to the earth as the ISS orbit.

• #### Re: (Score:2)

It's space junk, not asteroids that present the threat....
• #### Not hard at all (Score:2)

Sulu: "Z minus 1000m"
• #### asteroids? (Score:2)

What would an asteroid be doing in a near-Earth orbit?

• #### Re: (Score:1)

Maybe NASA put it there and it was a classic case of the governments left hand not knowing what the right hand was doing?
• #### Pysicists surprized (Score:2)

Afterall, the ISS can be assumed to be a frictionless point masss, as can any objects up there. The odds of two point masses colliding is so infinitesmially small as it must never happen, and if it was looking likely, you just model all the thrusters as a single force vector on the sphereical evenly distributed point mass.... simple.

Sheesh, engineers always make things so complicated.

• #### hmmm (Score:2)

Alright, a stupid question, but what kind of thrusters does the ISS use? Excuse my limited imagination, but when I think of thrusters, I think of an engine burning something to move. Do the ISS's thrusters need constant refueling, in this case?
• #### A blocker perhaps? (Score:2)

Can we bring up and roll out a kevlar fabric style large mesh device that will orbit in front of the station at a far enough away distance so as not to obscure the field of view and act as an absorber of some of these floating objects?

The idea is that it could be unfurled, catch items and when it is degraded enough, it is deorbited and crashes down into an ocean.

• #### Int'l ... (Score:1)

because writing "International" or simply ISS was too mainstream

• #### Re: (Score:2)

Nah, this is a new space station created by Intel!

• #### they dont have the money ... (Score:1)

... but lets ask google (GSS) ... or Apple (ASS ... how fitting), after all their new HQ will already look like an UFO, maybe it can also fly (who really read all the specs of that thing?)

• #### KSP Trainer (Score:2)

Complex, meh, I've got hours orbiting Kerbals successfully....lets just not talk about the staggering number of dead ones.....pretty amazing when you think about what we're doing up there...and folks wonder why maintaining ISS is so pricey, just think about how many people it takes to edge ISS around something.
• #### It's not that complex... (Score:1)

Just time accelerate, and things will fly right through each other without damage. ;)
• #### Need a tug. (Score:2)

Seriously, NASA needs to get a COTS out there for multiple tug/fuel depot. Considering the number of chemical and electric engines, they should be able to get 4 different ones produced. Perhaps allocate 100M or 250M per winner.
However, to make this useful, they need to use LIDs for the interface. With this approach, it allows docking and berthing. Berthing is a strong connection, which is good for moving things around. Docking is ideal for short term connections, such as to a fuel depot, or a satellite.

I

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