This is an excerpt from EERE Network News, a weekly electronic newsletter.

March 18, 2009

Space Shuttle Delivers Final Set of Solar Wings to the ISS

Photo of the space shuttle launching on twin pillars of flame against a dark sky, with fire-lit clouds of smoke billowing around the launch pad.

The space shuttle Discovery launched on Sunday to deliver the final set of solar "wings" to the International Space Station. Enlarge this photo.
Credit: Scott Andrews, NASA

The space shuttle Discovery blasted off from Earth on Sunday, March 15, to deliver the fourth and final set of solar "wings" to power the International Space Station (ISS). The mission will involve adding a final truss, called S6, to the starboard side of the ISS and then unfurling the solar arrays, which are folded and packed into the truss like an accordion. The four new solar arrays will extend in pairs from each side of the truss, forming solar "wings," each 115 feet long. The new solar wings will increase the solar capacity of the ISS to 264 kilowatts, allowing it to produce 84-120 kilowatts of usable power, or about enough power for more than 40 average U.S. homes. But since most of that power goes toward day-to-day operational needs and life support aboard the ISS, the new set of solar wings will actually double the amount of power available for scientific research. The 31,000-pound truss segment, solar wings, and accompanying batteries were built by Boeing and delivered to Kennedy Space Center back in 2002, but problems with the space shuttle program repeatedly delayed its launch. See the Mission Overview, press release, and press kit (PDF 5.2 MB) from the National Aeronautics and Space Administration (NASA), as well as the Boeing press release. Download Adobe Reader.

The latest schedule from NASA TV shows the ISS crew and shuttle crews spending most of Wednesday, March 18, removing the S6 truss from its berth in the shuttle and repositioning the station's robotic arm. The first spacewalk begins at 1:13 p.m. EDT (15:18 GMT) on Thursday, March 19, for the installation of the truss and its electrical wiring connections. A heat radiator will be deployed at 6:43 p.m. EDT (22:43 GMT), with the spacewalk ending about an hour later. The actual solar array deployment starts early in the morning on Sunday, March 22, beginning at 3:33 a.m. EDT (7:33 GMT), and deploying each array about halfway over the course of two hours. After a rest to let the arrays warm up in the sunlight, the deployment will resume at 10:18 a.m. EDT (14:18 GMT), continuing until the arrays are fully deployed. However, the schedule might be moved up by two days, so be sure to check the Shuttle Mission TV Schedule for updates. Past missions have had some trouble with binding of the solar arrays as they unfurl, but NASA believes that it has learned how to avoid the problems. For details about the mission timeline, see the mission fact sheet (PDF 784 KB).