Live in orbit: Spacewalkers spot more damage

Spacewalking astronauts Dan Tani and Peggy Whitson now are inspecting a fouled-up solar wing rotary joint after finding no apparent damage with another component key to keeping outpost arrays pointed at the sun.

Using pistol-grip power tools, the astronauts removed one of 22 multilayer insulation covers that ring the Solar Alpha Rotary Joint, or SARJ -- a mechanism designed to turn the station's starboard solar wing like a paddlewheel so it remains pointed at the sun as the outpost circles Earth.

Tani and Whitson both are reporting that they see fine dust as well as metal shavings within the joint -- an indication that gears or other internal components are grinding.

NASA engineers in Mission Control are getting an up-close look at the contamination through the astronauts' helmet-cams. A faint 16 in the bottom righthand corner of downlinked video indicates the view is coming from Whitson's Wireless Video System. A faint 18 shows the view is coming from Tani's helmet-cam.














The station is equipped with two of the 10-foot diameter joints -- one on the port side of the outpost's central truss, the other on the starboard end.

Each solar wing also has two so-called Beta Gimbal Assemblies that tilt, or pivot, the wing along its long axis to maximize electrical output.

The port-side equipment is working without problems. But the starboard rotary joint and one of the gimbal assemblies on that end of the truss are now locked.

Tani and Whitson spotted no obvious problems with the faulty gimbal assembly, which was turned off after associated circuit breakers tripped Dec. 8.

The internal damage on the solar wing rotary joint was spotted as soon as Whitson and Tani removed the thermal cover. Engineers suspect the problem must be coming from one or more of 12 trundle bearing assemblies that press against the joint's circumferential race ring.

Whitson and Tani aim to remove as many of the 22 thermal covers around the wheel-like joint as possible. They also might remove of of the bearings so it can be brought back to Earth for analysis.

NASA needs to fix both problems so the station can generate enough electricity to proceed with plans to deliver European and Japanese science laboratories to the outpost between January and April.