Spacewalk ends with cool, bright Tranquility

The second of the Endeavour crew's three spacewalks is complete, and the International Space Station's newest room has flickered to life.

Bob Behnken and Nick Patrick successfully hooked up the Tranquility module to the outpost's cooling system, clearing the way for it to be powered up.

Upon retuning to the Quest airlock, the spacewalkers conducted tests to see if a spray of ammonia had contaminated Patrick's spacesuit. The tests showed nothing above dangerous levels and no risk of poisoning the station's air.

The small leak occured as Patrick connected an ammonia coolant hose. NASA officials said such leaks have been experienced before and were expected.

The spacewalk began at 9:20 p.m. Saturday and ended at 3:14 this morning, lasting five hours and 54 minutes and bringing the mission's total to 12 hours and 26 minutes.

A third and final spacewalk is scheduled to begin Tuesday night to complete the outfitting of Tranquility and its windowed observation deck, called the cupola.

The overnight spacewalk was Behnken's fifth, Patrick's second. Behnken's career spacewalking time now totals 31 hours, 45 minutes.

It was the 139th spacewalk supporting space station assembly and maintenance since construction began in 1998. Total time: 867 hours, 28 minutes.

The spacewalkers completed all their assigned tasks despite planning to finish early to have more time to clean up their spacesuits because of the leak Patrick reported. Behnken inspected his suit during the spacewalk and could see no obvious sign of contamination.

To recap the main accomplishments overnight:
-- Behnken and Patrick teamed to route four ammonia coolant lines between Tranquility and the Destiny lab and covered them with insulation. They later opened valves to allow ammonia to flow through one of two independent loops. With a functioning cooling system, station managers began to turn on the module's electronic systems.

-- Patrick attached five handrails outside Tranquility and a vent that will help depressurize its cupola before a planned move later today. Behnken outfitted a series of gap spanners that bridge areas between handrails.

-- Behnken put covers over five metal trunnions that attached Tranquility to Endeavour's payload bay, helping it to withstand launch vibrations.

-- Inside the station, crew members finished moving a resistive weight training device into Tranquility. Station commander Jeff Williams also removed a set of eight bolts, hopefully clearing the way for a protective cover to fit over the Tranquility hatch that will be exposed when the cupola is moved.