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 changes before it could be completed, the retirement of the Space Shuttle was delayed several times until 2011, serving at least 15 years longer than originally planned. "Discovery" was the first of NASA's three remaining operational Space Shuttles to be retired. The final Space Shuttle mission was originally scheduled for late 2010, but the program was later extended to July 2011 when Michael Suffredini of the ISS program said that one additional trip was needed in 2011 to deliver parts to the International Space Station. The Shuttle's final mission consisted of just four astronauts—Christopher Ferguson (Commander), Douglas Hurley (Pilot), Sandra