Except for its external fuel tank, shuttles are reusable launch vehicles. Capable of maintaining a consistent orbit, the supersonic transports provide up to seventeen days of high-quality micro-gravity conditions. Decades in the making, they offer a tremendous environment for conducting many types of experiments, and from a shuttle astronauts see breathtaking views:
America’s shuttles have flown hundreds of missions since the first launch of Columbia in the spring of 1981. A normal mission sequence includes liftoff from Pad 39A or 39B, at the Kennedy Space Center, with re-entry and landing at either Edwards Air Force Base or Cape Canaveral. More than 20,000 small tiles, part of its Thermal Protection System, safeguard the shuttle when it forces its way back into the earth’s atmosphere.
Although NASA never lost a mission to re-entry problems until Columbia exploded on February 1, 2003, it came close once before. On his 1962 Project Mercury return, John Glenn had a broken heat shield which almost cost him his life.