The astronauts of STS-115 spent a second day outside the International Space Station working to connect up the new P3/P4 truss element. During the 7-hour spacewalk Dan Burbank and Steve MacLean had to remove insulation covers and hundreds of bolts from the truss. The final test will come on Thursday, when the new electricity-generating solar panels are unfurled to their full 13.7-metre (45-foot) length. Once operating, the new panels will double the amount electricity available to the station. The third and final spacewalk will occur on Friday.
The STS-115 astronauts wrapped up a busy Wednesday that featured the mission’s second spacewalk to prepare the International Space Station’s P3/P4 truss for operation. The 17.5-ton, 45-foot truss was attached to the station Tuesday. The P3/P4 will provide power, data and communication services for the station.
During the 7-hour, 11-minute spacewalk, Mission Specialists Dan Burbank and Steve MacLean removed launch locks and launch restraints on the Solar Alpha Rotary Joint (SARJ), which will allow the arrays to track the sun. During the remainder of the spacewalk, the astronauts were instructed to perform get-ahead tasks. They prepared the P3 truss for use by the Mobile Transporter – a platform that allows the station’s robotic arm, Canadarm2, to move along the Integrated Truss Structure.
Following the conclusion of the spacewalk, controllers sent up commands to engage the second drive lock assembly of the SARJ but did not receive an indication it had been properly engaged. More commands were sent, still no indication had been received that the drive assembly had engaged. Engineers are looking at the issue and have decided to temporarily delay unfurling the solar arrays. The arrays may be unfurled to a full length of 240 feet Thursday.
Original Source: NASA Shuttle Update