Mission Control Center, Houston, Texas

HOUSTON - Two down, two to go.

Building on Tuesday's spacewalk experience, Heide Stefanyshyn-Piper and Shane Kimbrough headed out of the International Space Station's Quest Airlock at 11:58 a.m. CST to continue the process of removing debris around the starboard Solar Alpha Rotary Joint (SARJ) and applying lubrication in an effort to eventually restore it to full functionality. The EVA ended at 6:43 p.m. for a total time of six hours and 45 minutes. As the spacewalkers were finishing up their activities, ground controllers noticed that Kimbrough's carbon dioxide levels were increasing, so he made his way back to the airlock a few minutes ahead of Piper.

Piper and Kimbrough began the second spacewalk by relocating two equipment carts in preparation for February's installation of the final pair of solar arrays. Once that task was completed, the two applied lubrication to a balky snare on the end of the station's robotic arm before concentrating on repair of the rotary joint designed to automatically track the sun as the station circles the Earth. The balance of the spacewalk was focused on replacing four more of the 12 trundle bearing assemblies (TBA). One of them was over-torqued during installation, so Piper installed one of the two back-up TBAs instead.

The 116th spacewalk dedicated to station assembly and maintenance was the second of the four planned during space shuttle Endeavour's STS-126 mission. It set the stage for Saturday's third excursion to complete the cleaning and lubricating process. Station flight controllers plan to briefly test the repair early Sunday morning by commanding the solar array into “auto track” mode to evaluate its performance.

On the 10th anniversary since station construction began with launch of the Zarya Control Module atop a Proton rocket from the Baikonur Cosmodrome in Kazakhstan, astronauts and cosmonauts aboard the station worked inside and outside to increase the capability and performance of systems to eventually support doubling the crew size from three to six.

Friday at 11:10 a.m., shuttle Commander Chris Ferguson, Pilot Eric Boe and Flight Engineer Steve Bowen will oversee a small reboost of the station's altitude using spare propellant aboard Endeavour.

At 2:05 p.m., both the crews will hold their traditional news conference before reviewing procedures for the third spacewalk scheduled for Saturday afternoon.

Mission Control will wake both crews up at 7:55 a.m. Friday to begin Flight Day 8, and the next mission status report will be issued Friday morning or sooner if events warrant.

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