Enterprise, the first shuttle, did test flights on Jan 31, 1977, but was never flown into space. It is already on display at a museum outside Washington. Finally, on Nov 18, 1985, it was ferried to Washington, D.C., where it became property of the Smithsonian Institution.

Columbia, built in 1981 at a cost of about $1 billion, made its maiden flight on April 12, 1981. It had been refurbished three times since its first flight. It completed 27 missions before being destroyed during re-entry on February 1, 2003 near the end of its 28th. 

Challenger, NASA's 2nd Space Shuttle orbiter to be put into service. Its maiden flight was on April 4, 1983, and it completed 9 missions before breaking apart 73 seconds after the launch of its tenth mission on Jan 28, 1986, resulting in the death of all seven crew members.

Discovery is one of the three currently operational orbiters in the Space Shuttle fleet of NASA, the space agency of the United States. It has logged 143 million miles (230 million kilometers) since its first flight in 1984. It decommissioned in 2011. 

Atlantis is the fourth operational Space Shuttle to be constructed and was delivered to the John F. Kennedy Space Center in April 1985. After 32 flight, it has orbited the Earth more than 4600 times, traveling over 120 million miles. Its last mission  is scheduled for June 28, 2011. 

Endeavour is the fifth and final spaceworthy NASA space shuttle to be built, constructed as a replacement for Challenger. Endeavour first flew in May 1992 on mission STS-49 and was scheduled for decommissioning in 2011. The final takeoff is set on April 19, 2011. 

The 30-year-old shuttle program is ending due to high operating costs. The Obama administration wants to free NASA to focus on deep space exploration and new technology development. 

NASA plans to give its three shuttles - Discovery, Atlantis and Endeavour - to museums for preservation. 

When the US space shuttle program officially ends later this year, the Russian space program's Soyuz capsule will be the only method for transporting astronauts to and from the ISS. Obama administration want to spur private companies to get into the space taxi business.