 Complete the following phrase:  The museum received COSTAR, the corrective optics instrument installed in the Hubble Space Telescope during its first servicing mission STS-61, when it was removed and returned to Earth after Space Shuttle mission STS-125. The museum also holds the backup mirror for the Hubble which, unlike the one that was launched, was ground to the correct shape. There were once plans for it to be installed to the Hubble itself, but plans to return the satellite to Earth were scrapped after the 