General Question ISS Attitude Control

[fcn]

Hi,

I've had my fair share of ISS dockings now but I would like to know something. I know ISS has attitude control to keep station facing desired direction. In real missions, is attitude control being used to keep station stable during docking? Also, is this attitude control implemented in the ISS on Orbiter? Or should I use something like Attitude MFD to keep station more stable? I can dock without it, but I can't be sure if this is the right way or not.

 

[Donamy]

Get my ISS AtoZ from OH. It comes with CMG.2 by Poscik, and will keep the ISS rock steady in any attitude.

 

[PhantomCruiser]

:ninja:

The "stock" ISS is in a free-drift state. If you want more fun, use Thorton's ISS (add Donamy's A-Z mod) it's got a CMG that will mimic the ISS station keeping ability.

Of course you may want to consider disabling the CMG during docking, then re-enable afterward (user pref I'd suppose).

 

[ADSWNJ]

Regarding real missions: http://www.draper.com/emailedAnnouncements.html#ISSManeuvers
Have a read of this. It shows that the ISS is indeed pulled into a specific attitude for docking maneuvers - at least for this unmanned docking. Looks like that they have some smart rocket scientists up at that Draper Lab too.

 

[Cras]

the ISS is pretty much always under attitude control. Every space craft is kept in some sort of attitude control nearly all the time.]

Yeah, after contact with the docking ring the Shuttle and the ISS were put into free drift to let the movement null out on its own and the rings get aligned before the ring was retracted on the Shuttle.

the CMG 2.0 addon mentioned in this thread is a must have in my books. It holds the station steady, no jitters. Have it hold the ISS in the standard LVLH attitude, that is with Harmony and PMA-2 pointing forward. That is where the Shuttle docked. Pull up and in front of the station, then slow down a bit and close in on it.

 

[johan]

Or you could do what I do, switch your ship focus to the ISS, you'll see it has a glass cockpit - then hit the shortcut for the Killrot autopilot (numpad 5?)

I only do this when I'm trying to dock, and I detect that the ISS is rotating - it's extremely annoying to try to line up a 20-ton XR2 with a target the size of a pinhead on a 100(?)-ton space station that is rotating however slowly... So when I notice it's harder than usual, I hop into the ISS, use killrot, hop back and usually, that fixes it.