The seven-hour, 5-minute excursion went off without a hitch, increasing the station's power by 20 kilowatts in one of the smoothest spacewalks in recent memory.Flight Director Zeb Scoville congratulated the astronauts, saying "this is the kind of day that makes you want to clap your hands."Floating in the Quest airlock compartment, Cassada and Rubio switched their spacesuits to battery power at 7:16 a.m. EST, officially kicking off the 256th spacewalk devoted to station assembly and maintenance and the 11th so far this year."Just thought I'd give you guys the general pulse of the control room, which is a bunch of smiling faces," astronaut Nick Hague radioed from mission control."The first two arrays have been performing outstandingly well," Matt Pickle, development projects senior manager at Boeing, said in a NASA release."