CAPE CANAVERAL, Fla., Oct. 12 (UPI) -- Space shuttle astronauts David Wolf and Piers Sellers worked on the space station's cooling system on Saturday during a successful six-hour spacewalk.
The outing was the second of three planned during Atlantis's weeklong servicing mission at the International Space Station.
"Thanks a lot everybody in Houston," Wolf radioed from the station's Quest airlock at the end of spacewalk. "It was a good day."
"You guys were hot," replied astronaut Stan Love from the Mission Control Center in Houston.
The astronauts spent most of their time attaching about two dozen clamps in fittings to prevent ammonia from leaking out of the station's cooling system. They also installed television equipment and set up a rail cart that will be used during future construction and maintenance tasks to haul equipment to various work sites.
"Everything ... that needed to get done got done, we're on track for finishing the mission and finishing it on time," said flight director Bob Castle.
Wolf and Sellers are scheduled for their third and final spacewalk on Monday.
Meanwhile at the Kennedy Space Center, shuttle Endeavour was moved to its launch pad in preparation for a mid-November mission to install a matching truss segment on the station's port or left side. The shuttle also will be delivering a new crew to the station, replacing the Expedition Five team which has been aboard since June.
The current crew -- NASA astronaut Peggy Whitson and cosmonauts Valery Korzun and Sergei Treschev -- will have one more group of visitors in orbit. A Russian Soyuz rocket is scheduled to blast off at the end of October with commander Sergei Zaletin, Belgium astronaut Frank De Winne and a newly named crew member -- cosmonaut Yuri Lonchakov.
The Russian Space Agency had planned to sell the third seat to pop singer Lance Bass, but canceled the trip because payments were not received. Officials had planned to fly a cargo container weighing the same as Bass to keep the loads aboard the vehicle the same, but announced on Saturday that Lonchakov, who flew to the space station with a shuttle crew last year, would fly instead.