cybergibbonsOn Mark Rober's new satellite video, they use torque rods before reaction wheels to stabilise the satellite's attitude.
Why did they need to wait?
YouTube
Jos Dingjan@cybergibbons Not watched the full vid, but a reaction wheel can only take up so much angular momentum before needing to unload it with your thrusters or otherwise. Magnetorquers don’t have that limitation.
@cybergibbons (but magnetorquers give you a lot smaller torques, so you get much smaller angular accelerations compared to wheels)
FishermansEnemy 「漁師の敵」 
@happydisciple @cybergibbons that is my understanding as well. The magnetorquers are there for small attitudes alterations and to desaturate the reaction wheels. If you saturate the reaction wheels before becoming stable you’ll end up with only the MTs available anyway, and then you’ll have to spend time desaturating the wheels.
I suppose the could have done that, but it was simpler to bring the rotation down with MTs to a level you can tune out the rest with wheels without saturating them, leaving you with 2 functional attitude control systems when you’re finally stable. Then desaturate the wheels over time.
I suppose the could have done that, but it was simpler to bring the rotation down with MTs to a level you can tune out the rest with wheels without saturating them, leaving you with 2 functional attitude control systems when you’re finally stable. Then desaturate the wheels over time.