The last time astronauts floated out, Dextre got arms. This time, the robot was getting a tool belt and two cameras that will serve as eyes - interestingly, at waist level.
"Happy St. Patrick's Day, guys," astronaut Michael Foreman called out to his spacewalking colleagues.
"I forgot it was St. Paddy's Day," replied Richard Linnehan.
"Should have worn the green EMUs." That's NASA talk for extravehicular mobility units, otherwise known as spacesuits.
The robotic work by Linnehan and Robert Behnken should complete Dextre's assembly outside the international space station. So far, the 12-foot robot and both of its 11-foot arms have checked out fine. Each arm has seven joints, and the crew wanted to make sure the brakes worked.
Dextre, a Canadian Space Agency contribution that cost more than $200 million, is designed to assist spacewalking astronauts and, eventually, to take over some of their chores. Its designers envision the robot one day replacing batteries and other space station parts - it can lift as much as 1,300 pounds - and also performing some fine precision tasks like handling bolts.
It has a sense of touch and is capable of sensing force and movement.
That's how Dextre got its name, in fact. It's short for dexterous.
By the end of Monday night's spacewalk, expected to last into the wee hours of Tuesday, Dextre should have three types of tools, four in all, as well as a platform for holding big items like batteries.
Linnehan, who also took part in the mission's first two spacewalks, said it has been surreal to work around the gigantic white robot. It reminds him of a prop from a "Star Wars" movie.
"But it isn't sci-fi, it's reality, and it's happening up here right now," he said.
Five spacewalks are planned for Endeavour's 16-day flight, which is nearing the halfway mark. While shuttle astronauts have performed five spacewalks before on a single flight - on trips to the Hubble Space Telescope - it will be a record for a shuttle-station mission.
Besides delivering Dextre to the space station, Endeavour's crew dropped off a storage compartment for the Japanese lab that will fly up in May. The astronauts not involved with the spacewalks - including Japanese Takao Doi - continued setting up the storage compartment in preparation for the arrival of the lab, named Kibo, Japanese for hope.
