re: An excellent idea for saving hubble!
Who is 'Wingo' - the idea is flawed beyond comprehension.
You put hubble near ISS, and it's trashed - the ammount of debris and pollution near it will trash the mirror quality very quickly.
Furthermore - the ammount of delta V needed to move from the hubble orbit to the ISS orbit is enormous - and I doubt even Ion propulsion could manage it.
What SHOULD be done, is an active deorbit module that has Gryos of its own that can attach to the base of Hubble - take over the orientation of Hubble for another few years, then de-orbit it safely.
Doug