October 28, 2007
October 28, 2007
Today Scott Parazynski and Dan Tani performed the mission's second spacewalk. They had a full schedule of required tasks, plus three "add-on" inspections. The big job was detatching the huge P6 truss from the Z1 segment and directing it to a temporary parking position, with the help of the station's robotic arm. During a later spacewalk it will be moved to its final resting place on the port side of the station.
In an effort to possibly see what might have caused cuts to astronaut gloves on previous missions, handrails were inspected. Some pitting, possibly due to micrometioroid impacts was noted, but nothing that looked like it was sharp enough to cut a spacewalker's glove.
The biggest add-on to the schedule had Dan Tani inspecting the starboard Solar Alpha Rotary Joint (SARJ). This is a critical piece of equipment, since it controls the rotation of the starboard solar panels, enabling them to track the sun as the station moves along its orbital track. Proper solar panel orientation is vital to supplying the station with the electricity it needs. For the past 50 days, the starboard SARJ has required an ever increasing amount of power in order to do its job.
Tani did a 360-degree visual inspection of the SARJ and saw nothing unusual. Mission control then directed him to remove the cover from the device and look inside. When he did, he noticed what appeared to be metal shavings scattered around the unit. Rather than floating in space, these anomalous particles were adhering to the surfaces of the SARJ as if they were magnetized. Tani gathered some of the particles with tape and then restored the cover. The particles will be analyzed to the extent possible in the station and then taken back to Houston for a thorough analysis and determination of what they are and what should be done about them. Since the startup current needed to move the SARJ is slowly increasing and may ultimately exceed what is available, some resolution must be found in the long term. Mission management is confident that any rquired repair will be possible, using spare parts that are already on the station.
While performing one of the scheduled maintenance tasks, a spacewalker lost an O-ring to space, thus adding one more element to the cloud of orbital debris that encircles the planet.
All in all, today's spacewalk was a success, with all major objectives met.
Allen G. Taylor
Posted by allen.taylor at October 28, 2007 03:27 PM