The first STS-126 spacewalk ended successfully at 8:01 p.m. EST. Astronauts Heidemarie Stefanyshyn-Piper and Steve Bowen spent six hours and 52 minutes outside the station working on several tasks, including removing a depleted nitrogen tank from a stowage platform on the outside of the complex and moving it into Endeavour’s cargo bay.

They also moved a flex hose rotary coupler from the shuttle to the station stowage platform, as well as removing some insulation blankets from the common berthing mechanism on the Kibo laboratory.

During the spacewalk, at approx. 3:33 p.m. EST, Piper reported that one of the Braycote lubrication guns had released grease into her toolbag. As she was cleaning the bag and wiping the tools and equipment inside, the bag floated away. Another bag carrying identical equipment was shared by Piper and Bowen to complete the mission.

"Despite my little hiccup, or major hiccup, I think we did a good job out there," Stefanyshyn-Piper said after returning to the space station.

According to NASA officials, the lost tool bag won’t represent a threat for the security of spacecraft. 

Flight director Ginger Kerrick said that the bag is already 2 1/2 miles in front of the shuttle-station complex. "It's well on its way away from us," she noted. NASA will investigate why the grease gun discharged.

However, AP reported that after the incident the flight controllers were revamping plans for the remaining spacewalks planned during space shuttle Endeavour's visit to the ISS.

Meanwhile the astronauts are preparing the second spacewalk that will take place on the seventh flight day. During this spacewalk, Piper and Kimbrough will relocate the two Crew and Equipment Translation Aid (CETA) carts from the starboard side of the Mobile Transporter to the port side, lubricate the station robotic arm’s latching end effector A snare bearings and will continue cleaning and lubrication for the starboard SARJ and replacement of its 12 trundle bearing assemblies.

The first task of the second spacewalk will give Kimbrough a chance to ride the station’s robotic arm. He and Piper will move the station’s two Crew and Equipment and Translation Aid, or CETA, carts, the rail carts that allow astronauts to move equipment along the station’s truss, from their current homes on the starboard side of the station’s Mobile Transporter (MT) to the port side.

Piper will get the carts ready for transfer by moving them into position and unlocking their wheel bogies. Kimbrough first will carry CETA 1 and then CETA 2 as he is flown on the robotic arm from one side of the MT to the other. Piper will meet him there each time, to install the carts in their new locations. When that task is done, Kimbrough will climb off of the robotic arm and remove the foot restraint Piper installed on the first spacewalk.

This will give him access to the arm’s latching end effector, or LEE, the snares that allow it to grasp equipment. Inside the station, Pettit and Magnus will command the LEE, which has been experiencing some sticky spots, to open and close its snares. Kimbrough will apply lubricant to the LEE’s snare bearings and rotate the bearings using needlenose pliers to ensure the lubricant covers the bearings. Meanwhile, Piper will return to the starboard SARJ to continue its cleaning and lubrication.