Space Shuttle Columbia facility beginning in January 1984, undergoing modifications that removed the Orbiter Flight Test hardware and bringing it up to similar specifications as those of its sister orbiters. At that time the shuttle fleet was expanded to include "Discovery" and "Atlantis". "Columbia" returned to space on January 12, 1986, with the launch of STS-61-C. The mission's crew included Dr. Franklin Chang-Diaz, as well as the first sitting member of the House of Representatives to venture into space, Bill Nelson. The next shuttle mission, STS-51-L, was undertaken by "Challenger". It was launched on January 28, 1986, ten days after STS-61-C had landed,
Space Shuttle main engine Space Shuttle main engine The Aerojet Rocketdyne RS-25, otherwise known as the Space Shuttle main engine (SSME), is a liquid-fuel cryogenic rocket engine that was used on NASA's Space Shuttle and is planned to be used on its successor, the Space Launch System. Designed and manufactured in the United States by Rocketdyne (later known as Pratt & Whitney Rocketdyne and Aerojet Rocketdyne), the RS-25 burns cryogenic liquid hydrogen and liquid oxygen propellants, with each engine producing of thrust at liftoff. Although the RS-25 can trace its heritage back to the 1960s, concerted development of the engine began in the 1970s,