CAPE CANAVERAL, Fla. (AP) — NASA astronauts are spacewalking again, this time to grease the robot arm's new hand.

The International Space Station's commander, Randy Bresnik, ventured out Tuesday for the second time in less than a week, along with Mark Vande Hei (VAN-duh HI).

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.

These latches, or hands, are located on each end of the Canadian-built robot arm. They're used to grab arriving U.S. cargo ships and also allow the robot arm to move around the orbiting lab.

Launched in 2001, the original latches were showing their age.