Two astronauts went out on a spacewalk Tuesday to wire up the international space station's newest room and keep the next shuttle visit on track for early December.
Commander Peggy Whitson and Daniel Tani needed to hook up power and heater cables and fluid lines between the space station and the Harmony compartment that was delivered by the shuttle last month.
The fluid lines — for carrying ammonia, a coolant — were in an 18 1/2-foot, 300-pound tray. The spacewalkers removed the tray from its storage location on the space station, then lugged it over to Harmony.
"Don't get it going too fast," Whitson warned Tani. The two took turns carrying the tray, which was awkward to handle, and crawling forward.
While venting some of the hookups, frozen ammonia crystals floated out and bounced off Whitson. Mission Control told her not to worry about it for now; decontamination procedures include brushing off the toxic substance and letting the sun bake it off.
NASA cannot launch another space shuttle until the school bus-size Harmony is all hooked up, inside and out. Atlantis is supposed to blast off Dec. 6 with a European laboratory that will dock to Harmony. One of Harmony's other parking spaces is reserved for a Japanese lab.
The space station's three residents have been working almost nonstop since Discovery's departure two weeks ago, and just last week moved Harmony to its permanent location. This was their second spacewalk; a third and final outing is set for Saturday to attach another fluid tray to Harmony.
They've already volunteered to work on Thanksgiving.
"With this particular crew on board, I don't know if holidays mean anything to them. They are just a hard-charging, get-it-done crew," Kenny Todd, a space station manager, said late last week. "We'll have to make sure they understand that it's Thanksgiving, and take some time and take a breath."
NASA is still trying to figure out how to fix a jammed joint that is needed to turn one of the space station's two sets of huge solar wings. Even though Discovery's crew returned samples of steel shavings clogging the joint, engineers were unable to ascertain which parts are grinding against each other.
The joint will probably need to be cleaned and fixed, a formidable task requiring as many as four spacewalks, before Japan's lab can fly next year. Astronauts on the next shuttle flight may squeeze in a joint inspection.
Early in the spacewalk, Tani reported some minor abrasion on the outermost layer of his right glove. He said it occurred while he was working with fluid line hookups. "Maybe not the big smoking gun we're hoping for, but something," he said.
Spacewalking astronauts have ripped their gloves three times over the past year on sharp station edges. NASA is hunting for those jagged areas.