n INTEGRATED DEFENSE SYSTEMS PHOTO NASA Astronaut Robert Curbeam, STS-116 mis- sion specialist, works with the port over- head solar array wing on the International Space Station’s P6 truss during the Decem- ber mission’s fourth spacewalk. Curbeam and other astronauts worked to guide the array wing neatly inside its blanket box. Creativity in space Fully deployed, the array’s 32 massive ISS Structures and Mechanisms team. Shuttle crew to apply panels extend 120 feet (36.6 meters) along At the end of the first spacewalk, only a system of guide wires. They’re designed 17 panels had been retracted. The retrac- past lessons to fold to fold up like an accordion and retract tion was not complete, but it was enough along the wires into large storage boxes to allow the crew to move forward with arrays on space station at the bottom of the arrays. The process the second and third spacewalks—during may sound simple. But folding an array which they reconfigured part of the sta- BY AMANDA SMOKE that’s been extended for six years is simi- tion’s power system and readied the ISS for lar to folding a well-used road map into future additions of laboratory modules. ho knew the ancient art of paper its original position. A fourth spacewalk was added to the folding would one day come in The first attempt to retract the arrays was mission, giving the astronauts another Whandy assembling the Interna- automated from inside the ISS. But min- chance to unstick the arrays manually. tional Space Station? utes into the process, hinges between the The crew inside the ISS used the station’s Like origami artists, Space Shuttle delicate array panels folded in the wrong robotic arm to position the spacewalking Discovery astronauts carefully wiggled, direction and had to be redeployed slightly, astronaut close to the array. Seven hours nudged and folded the station’s delicate, then retracted again. As the retraction con- later, the job was done, followed by high- gold-colored solar arrays into position dur- tinued, excessive tension caused the guide fives and cheers at Mission Control. ing the STS-116 mission in December. The wires to become snagged, and the arrays This time around, Mission Control will intricate procedure wasn’t an art exhibit: It draped over the blanket box below. begin the process by automatically retract- was meant to retract the station’s P6 port- On the ground, Boeing engineers were ing the set of arrays one panel at a time side solar array, to provide enough clear- troubleshooting the problem and advising while astronauts watch from inside the sta- ance for the P4 solar array to begin track- NASA’s mission control on next steps. tion. They will be prepared to assist with ing the sun’s motion. Boeing Extra Vehicular Activity (EVA) & folding the arrays during the mission’s This month when Space Shuttle Crew Systems Integration team members second spacewalk, using tools that proved Atlantis heads for the ISS, STS-117 mis- were also working to verify the tools the most effective on STS-116. sion objectives will feel familiar, since space-walking astronauts would use were “We learned so much from the last similar maneuvers will be performed. The safe and compatible with the electrically EVA and the crew debriefs that confirmed crew will install the Boeing-built S3 and charged elements of the solar arrays. what we saw,” said Dan Sweeney, Boeing S4 truss segments, unfurl new solar arrays “On-orbit operation is a 24/7 thing, so Solar Array Specialist, ISS Structures and retract another set of old solar arrays. we were constantly working with NASA and Mechanisms. “The opportunity is This time around, astronauts will apply to determine what happened and correct there to be much more efficient.” n learnings from the previous mission. it,” said Carter Reznik, Boeing lead for the [email protected] 26 March 2007 BOEING FRONTIERS.