NASA Space Shuttle Mission March 13, 2009 among other Shuttle mages

The STS-119 flight will deliver the final pair of power-generating solar array wings and truss element to the space station. The delivery and installation of the station’s final, major U.S. truss segment, Starboard 6 (S6), during the STS-119 mission will signal the station’s readiness to house a six-member crew for conducting increased science. With the installation of the 31,127-pound, 45.4-foot-long segment, the station’s completed truss, or backbone, will measure 335 feet – more than the length of a football field. Air Force Col. Lee Archambault (ARSH-um-boh) will lead the STS-119 crew. Navy Cmdr. Tony Antonelli will serve as the pilot. The mission specialists for the flight are Joseph Acaba, John Phillips, Steve Swanson, Richard Arnold and Japan Aerospace Exploration Agency astronaut Koichi Wakata (Ko-EE’-chee Wa-KAH’-tah). Wakata will remain on the station, joining Expedition 18 Commander E. Michael Fincke, an Air Force colonel, and Flight Engineer Yury Lonchakov (LAHN'-chuh-coff), a Russian Air Force colonel. Wakata will replace Expedition 18 Flight Engineer Sandra Magnus, who will return to Earth with the STS-119 crew. Wakata will serve as a flight engineer for Expeditions 18 and 19. Fincke and Lonchakov were launched to the complex in the Soyuz TMA-13 spacecraft on Oct. 12, 2008, from the Baikonur Cosmodrome in Kazakhstan. Wakata will return to Earth on shuttle mission STS-127, while Fincke and Lonchakov will return in the Soyuz in April. The space station’s solar arrays are the largest deployable space assemblies ever built and the most powerful electricity-producing arrays in orbit. Until deployed, each SAW remains folded in a special canister called a Solar Array Assembly (SAA) at the end of the S6 element. In the canister, each wing is equipped with an expandable mast. Two solar array blanket boxes, containing 32,800 solar cells, are connected to the ends of each canister and are restrained to the element frame for launch. The addition of S6 brings the station’s total SAWs to eight. Each wing is 115 by 38 feet wide and, when all eight are fully deployed, will encompass an area of 32,528 square feet, minus the masts. The 310-foot integrated truss structure to which the S6 will be attached forms the backbone of the space station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and the various elements. The 45-foot-long S6 began as an operations test item for its twin sister, the Port 6 truss segment that was launched during Endeavour’s STS-97 mission on Nov. 30, 2000. The starboard element was delivered to Kennedy Space Center in Florida on Dec. 17, 2002. Boeing, NASA’s prime contractor for the station, designed the S6 and worked with major subcontractors Lockheed Martin, Honeywell, Space Systems/Loral, and Hamilton Sundstrand to build it. Pratt and Whitney Rocketdyne provided most of the electrical power system components. The PVMs use large numbers of solar cells assembled onto solar arrays to produce high power levels. NASA and Lockheed Martin developed a method of mounting the solar arrays on a “blanket” that can be folded like an accordion for delivery to space and then deployed to its full size once in orbit. The cells are made from purified crystal ingots of silicon that directly convert light to electricity for immediate use through a process called photovoltaics. Gimbals are used to rotate the arrays so that they face the sun to provide maximum power to the space station. After the conversion process, the PVMs also use the electricity to recharge onboard batteries for continuous sources of electricity while the station is in the Earth’s shadow. Once complete, the station power system, consisting of U.S. and Russian hardware and four photovoltaic modules, will use between 80 – 100 kilowatts of power or about as much as 42 average houses (defined as 2,800 square feet of floor space using 2 kilowatts each). Some of the electricity is needed to operate space station systems, but once that is figured in, the addition of the S6 will nearly double the amount of power available to perform scientific experiments on the station – from 15 kilowatts to 30 kilowatts. Each SAW weighs more than 2,400 pounds and uses 32,800 solar array cells, each measuring 8 centimeters square with 4,100 diodes. The individual cells were made by Boeing’s Spectrolab and Aviation Systems Engineering Co. There are 400 solar array cells to a string and there are 82 strings per wing. Each SAW is capable of generating 32.8 kilowatts, or about 10.5 to 15 kilowatts of usable power. There are two SAWs on the S6 module capable of delivering a combined 21 to 30 kilowatts of usable power per PVM with a total of four PVMs on the station. The solar arrays produce more power than can be made available to the station’s systems and experiments. Because all or part of the solar arrays are eclipsed by the Earth or station structure at times, batteries are used to store electricity for use during those periods. About 60 percent of the electricity generated is used to recharge the batteries.