Live In Orbit: Spacewalkers Move On To Last Task

Spacewalking astronauts outfitted the Hubble Space Telescope with a newly refurbished Fine Guidance Sensor today and stowed an old unit in a shuttle cargo bay container for a return trip to Earth.

Atlantis mission specialists John Grunsfeld and Drew Feustel now are moving on to the final task on the final mission to service the 19-year-old observatory. The astronauts will be installing thermal blankets that will help protect Hubble from the harsh environment in low Earth orbit.

The old unit had been onboard Hubble since it was installed on a 1999 servicing mission.

You can watch the final action unfold here in The Flame Trench. Simply click the NASA TV box on the righthand side of this page to launch our NASA TV viewer, and be sure to refresh this page for periodic updates.

Now about four hours into a planned 6.5-hour spacewalk, Grunsfeld and Feustel now will try to install a trio of thermal blankets on the observatory.

One of them was supposed to be installed during the fourth spacewalk of the mission on Sunday but Mike Massimino and Mike Good ran into trouble repairing the Space Telescope Imaging Spectrograph. So the blanket installation was put off until today.

NASA astronaut Dan Burbank, working as the "capcom" or capsule communicator in Mission Control, asked Atlantis mission commander Scott Altman whether the spacewalkers could get all three installed.

"Gee, I don't know Scooter," Grunsfeld said.

"I had a feeling," Altman said. "How 'bout you, Drew? You all worn out?"

"No I feel pretty good, actually" Feustel said. "I got a lot more in me."

"And I'm feeling great," Grunsfeld added.

Spacewalking astronauts during a 1999 servicing mission detected damage to come of the telescope's thermal insulation. Nine years exposure to the harsh environment at that point had taken its toll on the observatory, and some areas were torn or broken.

The multi-layer insulation protects the observatory from the severe and rapid temperature changes it experiences as it moves through its 96-minute orbit from very hot sun to very cold night. Temperatures swing between swings 215 degrees Fahrenheit every 45 minutes.

The New Outer Blanket Layer, or NOBL, covers were designed to prevent further degradation of the insulation and maintain normal operating temperatures of electronics housed in equipment bays.

The NOBL covers are designed to protect Hubble from charged particles, X-rays, ultraviolet radiation, and thermal cycling for at least ten years.

Made of specially coated stainless steel foil, the covers all are trimmed to fit over the doors to Hubble equipment bays. Each has a steel picture-frame structure, and expanding plugs, like common kitchen bottle stoppers, fit into door vent holes to allow quick installation."

Three covers were installed in 1999 and a fourth was installed in 2002. The installation of a remaining trio is the final task of NASA's last mission to Hubble.