National Geographic : 1981 Mar
Incredible machine PIGGYBACK on its externalfuel tank and two solid-rocket boosters, an orbiter will shed them in flight priorto achieving orbit. Then the vehicle's cargo bay doors will swing open and space tasks will begin. By the end of this decade, four orbiters could be making a total of about 50 flights a year. Complex mechanicalarm deploys and retrieves such payloads as satellites and telescopes. Payloadbay doors of graphiteepoxy withstand temperaturesfrom minus 170° to plus 1350F. \ Gulpingfuel and oxidizer ' from the external tank, each ofthe orbiter'sthree main engines generates375,000 pounds of thrust at sea level, and 470,000 pounds in the near vacuum of space. Smaller engines fire to insert the craft into orbit. Tiny thrusters jockey the vehicle to various orbitalattitudes. More than two million pounds of aluminum powder in the two solid-rocket boosters will provide 5.8 million pounds of thrust. Spent after a two-minute burn, the boosterswill separateandbe parachutedto earthfor reuse. Reentering the earth's atmosphere, the orbiter will use elevons on the aft edges of its wings for pitch and roll control. Its rudder will split open to function as a speed brake. 322 The wing's forward edge is layered with carbonto withstand the heat of reentry. Silica-fiber tiles cover other high temperature areas.
1981 Feb 28