Spacewalkers Jim Newman and Mike Massimino are ready to begin the first science instrument upgrade of the servicing mission when they step outside about 2:30 a.m. CST Thursday. The fourth of five spacewalks to rejuvenate Hubble will feature installation of the Advanced Camera for Surveys, which will see far beyond the reach of current instruments. The final original science instrument remaining on the telescope, the Faint Object Camera, will be removed to make room for the advanced system.

Columbia's crew - Commander Scott Altman, Pilot Duane Carey and mission specialists Nancy Currie, John Grunsfeld, Rick Linnehan, Newman and Massimino - was awakened at 9:52 p.m. CST. The original song "Sittin on Top of the World," played for the wakeup, was recorded and dedicated to the STS-109 crew by Les Paul, a music pioneer and space enthusiast.

Currie will operate the shuttle robot arm to provide transportation to and from the telescope worksites during the spacewalk. Newman will be lifted to Hubble's aft shroud doors where he will meet Massimino, remove the Faint Object Camera and temporarily stow it on the aft fixture of the enclosure holding the new instrument in Columbia's cargo bay. Together they will then unlatch the new camera from its carrier in the shuttle payload bay and install it in the aft shroud of the telescope. Once that is completed, they will stow the old camera in the payload bay carrier for return to Earth.

Massimino will then take a turn on the robotic arm, and the duo will install an Electronic Support Module for a new experimental cooling device to be installed on the fifth spacewalk for the telescope's Near-Infrared Camera and Multi-Object Spectrometer. They also will perform a few remaining cleanup tasks from Wednesday's power control unit installation.

Fellow spacewalkers Grunsfeld and Linnehan will be working inside the shuttle to choreograph the excursion as Altman and Carey provide photo and video documentation of the spacewalk.

Functionality tests continue and already have been fully successful on all of Hubble's major systems that were powered down for the third spacewalk. Functional tests of the telescope's scientific instruments will not be completed until after the telescope is released from Columbia and its aperture door is opened, allowing it to again view the heavens.

The crew is to begin its sleep period at 1:52 p.m. CST Thursday. The next STS-109 mission status report will be issued Thursday morning, or as events warrant.

News from Commercial Space Watch