Mir orbital control

Willie Koorts (wpk@saao.ac.za)
Thu, 21 Aug 1997 09:45:43 +0200 (GMT+0200)

Part of a (news) message kindly passed on to me by Jay Respler read :

     The outbursts came after the latest in the long sequence of Mir's
     recent near disasters. On Monday, just as Mir docked with a supply
     ship, the station's computer failed, sending the spacecraft
     spinning into space without light, heat, oxygen or the ability to
     generate power of any kind.
     
     Tuesday the crew members overcame many of those problems. Using
     thruster rockets on the Soyuz space capsule that took the two
     Russian members of the crew to the ship, they nudged Mir back into
     orbit and aligned the vessel so that its batteries could start
     absorbing energy from the sun.
     
This and the similar problem they had recently when the power cable was
accidently unplugged made me wonder just how much efford is required to keep
the station under control? I know same media "blow-up" is envolved here, but
it seems like the station requires a lot of power and/or computing power to
keep it from spinning out of control. Why is this? Why are thrusters needed
to get it under control again? What is the main source of "orbital control"
for a spacecraft of this size? 

Regards
Willie

         Willie Koorts   wpk@saao.ac.za   http://www.saao.ac.za/~wpk/

       Cape Town,  Observatory   33d 56' 03"S   18d 28' 36"E   GMT + 2h
       Wellington, South Africa  33d 38' 56"S   19d 00' 52"E   GMT + 2h