Hubble Repairs

When most of us think of outer space, we think of a place that is quiet and still, like floating through a vacuum. I suppose that some of that is true, but while things do float around in space, they can also crash into other things floating in space. I don’t know if collisions in space make a sound, but I suspect they do. I don’t know how two objects can collide quietly, but maybe the sound does occur, and then doesn’t carry. Whether there is a sound or not, those space collisions are not soft hits, and damage can occur.

After NASA first put the Hubble telescope in orbit in 1990, scientists realized that the telescope’s primary mirror had a flaw called spherical aberration. Basically, the outer edge of the mirror was ground too flat by a depth of 2.2 microns. That is about as thick as one-fiftieth the thickness of a human hair. I don’t know how that could make much difference, but this aberration resulted in images that were fuzzy because some of the light from the objects being studied was being scattered. While this was not caused by other objects in space, it had to be repaired anyway. The Corrective Optics Space Telescope Axial Replacement, or COSTAR, was developed as an effective means of countering the effects of the flawed shape of the mirror. COSTAR was a telephone booth sized instrument which placed 5 pairs of corrective mirrors, some as small as a nickel coin, in front of the Faint Object Camera, the Faint Object Spectrograph and the Goddard High Resolution Spectrograph. The fix worked, and while this was not the only repair job done on the Hubble Telescope, it was the first.

NASA arranged a repair mission SM1, or Shuttle Mission: STS-61 to make the repair. The mission took place on December 2-13, 1993 in the Shuttle Endeavor. The mission, however, was not just to fix a flaw in the original design, which would have been logical when we think of how much we depend on the Hubble Telescope, but the crew also installed and replaced other components including: Solar Arrays, Solar Array Drive Electronics (SADE), Magnetometers, Coprocessors for the flight computer, Two Rate Sensor Units, Two Gyroscope Electronic Control Units, and a GHRS Redundancy Kit. The crew included Commander Richard O. Covey, Pilot Kenneth D. Bowersox, Payload Commander F. Story Musgrave and Mission Specialists Kathryn C. Thornton, Claude Nicollier, Jeffrey A. Hoffman and Tom Akers. The mission successfully made the repairs to Hubble.