Astronauts Prepare Arm For HTV Arrival

Nov 20, 2008

AviationWeek.com's On Space blog will provide further coverage of STS-126 as the mission continues. Frank Morring, Jr.'s recap of today's events follows below.

Astronauts Heidemarie Stefanyshyn-Piper and Shane Kimbrough took time out from cleaning and lubricating a damaged rotary joint on the International Space Station Thursday to grease up the station arm for a better chance at grappling an automated Japanese cargo carrier next year.

Cables inside the arm's end effecter that are designed to snare and tighten over the grapple pin of its target have lost their tension over time, reducing the area where the pin can be captured. Normally it doesn't matter, because the arm is grappling stationary objects with precisely known positions.

However, when Japan's H-IIA Transfer Vehicle (HTV) arrives on its first flight next year, the arm will be needed to snatch it directly from orbit and plug it into a berthing mechanism. Unlike Europe's Automated Transfer Vehicle, the Japanese cargo carrier is not equipped for autonomous docking.

In the second extravehicular activity (EVA) of the STS-126 station-logistics and repair mission, Kimbrough used a grease gun to spread vacuum-stable Braycoat lubricant onto the bearings that allow the cable snares to rotate while crewmates inside commanded the snares to open and close. He also used needle-nose pliers to turn the bearings for better coating.

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