Vande Hei performed a similar spacewalk last October, when he replaced the first of two original hands on the Canadian-built arm. This second hand will go on the opposite end of the 58-foot arm. The bulky bundle of latches needs to be replaced because of wear and tear. It's been in orbit, grabbing cargo capsules and performing other chores, since 2001.

Vande Hei performed a similar spacewalk last October, when he replaced the first of two original hands on the Canadian-built arm. This second new hand -- a spare -- will go on the opposite end of the 58-foot arm. The bulky bundle of latches -- more than 3 feet, or a meter, long and weighing more than 440 pounds, or 200 kilograms -- needed to be replaced because of wear and tear. It's been in orbit, grabbing cargo capsules and performing other chores, since 2001.

The pair last week replaced the latching mechanism on one end of the 58-foot robot arm, which malfunctioned in August. Now they need to lubricate the newly installed device. The two-part lube job is expected to spill into next week, in a third spacewalk.