SOmebody mentioned  a re-boost of HST during this mission,  meaning
that Weight is a very tight  margin on this  mission.

How will said re-boost be done?

Grapple, HST,  stow it in Cargo bay,  do OMS burn to high altitude,  

unstow  HST,   repair  gyros,  costar install,  fix solar arrays,

then return to earth?

My guess is  why  bother with  usingthe shuttle to reboost?

why not  grapple,  do all said fixes,   bolt a small  liquid  fueled
thruster module  to  HST,   then let it make the re-boost.  it has to be
cheaper on mass then usingthe shuttle as a tug.   that way, now that
they are going to need at least 5  spacewalks,  then they can carry
an EDO pallet,  and  sit on station and even  maybe do the  solar array
tilt  motor  fix.