The International Space Station is scheduled to receive a second set of giant solar energy panels later Tuesday. They were carried up by the U.S. space shuttle Atlantis, which docked with the outpost Monday. Two shuttle astronauts plan to connect it to the station's power supply during a spacewalk.
The new solar panels are currently folded up on a 17-ton truss, one of the heaviest loads ever carried into space. When the array is unfurled later this week, it will stretch 80 meters, doubling the amount of power available to the research complex. It is the second set of four planned solar arrays that will provide electricity for three science laboratories, two living chambers, and other systems to come.
The truss barely fit into Atlantis' cargo hold. There were just 11.5 centimeters clearance when the shuttle robot arm lifted the truss to transfer it to the station's arm shortly after Atlantis docked Monday.
It will take three spacewalks by four shuttle astronauts this week to make the new solar wing fully operational.
The first takes place later Tuesday after the station's robot arm operator installs the truss. Astronauts Joe Tanner and Heidiemarie Stefanyshyn-Piper will leave the shuttle airlock to connect it to the outpost's power supply.
Shuttle flight director Paul Dye says this will activate heaters that protect the unit in the frigid space climate. "This truss has a lot of electronic components that we don't want to get cold, so we have a clock that is running and we want to get the umbilicals [cables] hooked up in order to make sure we can keep alive and in good shape. We've got margin to that, of course. It's not a disaster if we don't make it there, but it will be a long day and we want to get those umbilicals on to get the heaters up and operating," he said.
The solar array is the first new component on the half built outpost in nearly four years. The loss of the shuttle Columbia in early 2003 halted shuttle missions for several years. The U.S. space agency NASA plans to send a shuttle to the station 14 more times to complete it before the shuttle fleet is retired in 2010.