To attempt to fix the malfunctioning solar array, NASA mission specialists Christer Fuglesang (Swedish astronaut with the European Space Agency), and Robert Curbeam (Baltimore, Maryland native with an advanced degree in aeronautical and astronautical engineering), performed a spacewalk (Monday, December 18, 2006) to reposition the solar array, which may include turning protective rings (grommets), pushing hinges, pulling guide wires, and shaking supports and equipment.
The photovoltaic arrays (commonly called solar arrays) provide the primary source of energy for the space station—thus, are essential for the daily operations of the manned station. The arrays (also called Solar Array Wings [SAW]) provide energy to the space station by converting sunlight, which impinges on the arrays from the Sun, to electricity. Each of the flexible pair of Solar Array Wings is about 112 feet (34 meters) in length and approximately 39 feet (12 meters) in width, with about 93% of this total area (or about 4,065 square feet [378 square meters]) being actively used to collect sunlight.
The two arrays (which make up one SAW) are positioned at opposite ends of a truss segment. Each array contains a photovoltaic (solar array) blanket with a deployment mast in between. One array can generate almost 32.8 kilowatts of direct current (DC) power. Each blanket contains 16,400 silicon photovoltaic (solar) cells that convert photons from the Sun (solar light) into electricity. Specifically, 82 panels each contain 200 cells, which are each about 1.25 square inch (8 square centimeters) in area. Each cell area contains 4,100 diodes, which allow the electrical current to flow in one direction.
When completed, the station will contain four Solar Array Wings; that is, eight arrays positioned as four pairs, with two pairs on the port end of the space station and the other two pairs on the starboard end. The solar arrays will be exposed to the harshness of space that exists about 200 miles (320 kilometers) above the Earth’s surface—the orbital altitude of the space station. Although the spacewalks to fix the solar array by the NASA astronauts are dangerous, it is essential that these arrays function normally in order to provide needed electricity for the men and women working onboard the International Space Station.