Question 4 - Reading Practice Test for the PERT

In 1981 the first space shuttle, Columbia, was launched from the Kennedy Space Center in Florida. Initially, there were five orbiters built for space flight; Enterprise, Columbia, Challenger, Discovery and Atlantis. In 1991, NASA introduced the world to Endeavor. This sixth orbiter was built to replace Challenger and Columbia both of which were destroyed in tragic mission accidents. An explosion in 1986 destroyed the shuttle, Challenger, a few seconds into its flight, killing all seven on board. Columbia exploded as it was ending a mission in 2003. Although the loss of fourteen astronauts was devastating, the shuttle program launched shuttle orbiters 135 times in thirty years. Its successes and contributions to science were many. The space shuttle program ended on July 21, 2011, when Atlantis completed its last mission.