Four space walks to Hubble completed

Four completed space walks to repair and refurbish the Hubble Space Telescope, four success stories.

On May 16, shuttle astronauts John Grunsfeld and Andrew Feustel completed the third spacewalk to service the aging orbiting observatory. During their venture, which took just over 6½ hours, the astronauts removed the Corrective Optics Space Telescope Axial Replacement, which for several years had acted as a pair of corrective eyeglasses compensating for the Hubble’s infamously flawed primary mirror. The device is no longer needed because corrective optics are now built into each new Hubble instrument.

The team then installed the Cosmic Origins Spectrograph, a new device that will break ultraviolet light into its component wavelengths and allow Hubble to see farther into the cosmos in this part of the electromagnetic spectrum.

Grunsfeld and Feustel then repaired the Advanced Camera for Surveys, a workhorse, high-resolution camera that had stopped working in early 2007 due to a short circuit in its backup power supply. The astronauts removed 32 screws from an access panel to replace the camera’s four circuit boards and install a new power supply. On the ground, engineers at NASA’s Goddard Space Flight Center in Greenbelt, Md., verified that both the spectrograph and camera have electrical power.

On May 17, two other astronauts, Mike Massimino and Mike Good, went on the fourth of five planned space walks to repair the Space Telescope Imaging Spectrograph, which was installed on Hubble in 1997 and stopped working in 2004.

Massimino and Good attached a “capture plate” over the spectrograph’s electronics access panel and then used a power tool to remove 111 screws that attach the panel to the spectrograph. The capture plate ensures that the astronauts don’t have to grab the loosened screws with gloved hands. After removing the panel plus capture plate, the astronauts removed a failed power supply card and insert a new one. The team then finished up by latching in place a new, much simpler panel to cover the open electronics cavity.