Within hours of awakening Grunsfeld and Linnehan, with the assistance of crewmates Jim Newman and Mike Massimino, will begin donning their spacesuits. Grunsfeld, performing his third spacewalk, will wear a spacesuit with red stripes. Linnehan, who is conducting his first spacewalk, will be wearing a spacesuit without any stripes. The pair may work ahead of schedule and leave the airlock as much as an hour earlier than planned.

They will begin the spacewalk with about an hour of setup activities in the payload bay to prepare for the total of five spacewalks for this mission. The next scheduled task is to install the new solar array's electrical support components, called a Diode Box Assembly, on the Hubble Space Telescope.

Space shuttle robot arm operator, Nancy Currie, will move the spacewalking duo by providing transportation to and from the worksite at the starboard array of the telescope. Grunsfeld, anchored to the telescope, will prepare the array for removal. Linnehan, on the end of the robotic arm, will then hold onto the array as Currie guides the arm into the payload bay where Linnehan will stow the old array for its return to Earth. Linnehan will then return to the worksite to help install the new solar array.

The third-generation solar arrays are two-thirds the size of the current arrays but will provide 20 percent more power to the telescope. Because of their smaller size, the new arrays will impart less atmospheric drag, slowing the rate at which Hubble's orbit decays.

Columbia Commander Scott Altman and Pilot Duane Carey will document their crewmates' work during the spacewalk with television and still-photo cameras, while also monitoring systems onboard Columbia. Today's spacewalk is scheduled to last 6 1/2 hours.

The crew is to begin its sleep period at 11:52 a.m. CST. The next STS-109 mission status report will be issued Monday morning or as events warrant.

News from Commercial Space Watch