and there's the considerable expense of operating and maintaining the mission control center for the HST. Between the salaries for the support staff, computer equipment, image processing, and other expenses, it costs several million dollars a year to keep the Hubble functioning. Since it was launched in 1990, there have been several dedicated Shuttle missions to repair and upgrade the Hubble. Those missions cost several hundred million dollars each, so it isn't unreasonable to claim that the Hubble has cost over $100 million a year to operate.

If it could be boosted to a higher orbit without damage like Raoul suggested, it wouldn't be possible to send any more Shuttles up to it but you'd still have several million dollars a year for O&M costs. In an era of tight budgets, something else would have to give (opportunity costs). That's asking a lot for a system that will be 20 years old in 2010.