But the study team concluded the obstacles are surmountable and that the project is feasible. Shuttle experts found the spacewalk scenarios acceptable. Three 8.2-meter mirror blanks left over from the VLT project are available. The use of one of these could reduce the time, cost, and risk of the enhancement. The additional mass and a 1.25-meter shift in the telescope's moment of inertia are within the capabilities of the observatory's current control system.
Structural dynamics are acceptable.
Thermal effects are minimal, although Hubble's two solar arrays would operate about 20 degrees warmer. Hubble's fine guidance sensors, the devices that allow the telescope to lock on and track its targets, will still work, although their fields of view will be much smaller. Increased atmospheric drag would necessitate periodic shuttle reboosts or the addition of a small propulsion package. The cost will be of order less than half that of an entirely new spacecraft and observatory. Next Generation Space Telescope - Information on NASA's planned successor to the Hubble Space Telescope.