The space shuttle Challenger was one of NASA’s greatest triumphs. It was the second shuttle to reach space, in April 1983. It successfully completed nine milestone missions. Challenger was the vehicle by which several cultural firsts happened in the space shuttle program. The first American female astronautrode up on Challenger on STS-7 in June 1983.  The first African-American reached space on STS-8. On STS-41G in 1984, two women, flew on one mission for the first time, as well as the first Canadian, Marc Garneau. Other milestones Challenger marked included the first night launch and landing (STS-8) and the first operational Spacelab flight (STS-51B).

Christa McAuliffe, a 37-year-old high school social studies teacher from New Hampshire, won a competition that earned her a place among the seven-member crew of the Challenger’s tenth mission. She underwent months of shuttle training but then, beginning January 23, was forced to wait six long days as the Challenger’s launch countdown was repeatedly delayed because of weather and technical problems. Finally, on January 28, Challenger was launched at 11:38 a.m. Eastern time in front of more media attention than usual, as it was carrying the first teacher to go in space. Seventy-three seconds later, hundreds on the ground, including Christa’s family, stared in disbelief as the shuttle exploded in a forking plume of smoke and fire. Millions more watched the wrenching tragedy unfold on live television. There were no survivors.  President Ronald Reagan appointed a special commission headed by former secretary of state William Rogers and former astronaut Neil Armstrong. The investigation determined that the explosion was caused by the failure of an “O-ring” seal in one of the two solid-fuel rockets. The elastic O-ring did not respond as expected because of the cold temperature at launch time, which began a chain of events that resulted in the massive explosion.

Challenger’s explosion changed the space shuttle program in several ways. Plans to fly other civilians in space (such as journalists) were shelved for 22 years. Satellite launches were shifted from the shuttle to reusable rockets. On February 1, 2003, a second space-shuttle disaster rocked when Columbia disintegrated upon reentry of the Earth’s atmosphere. All aboard were killed including the first Indian-American astronaut and first Indian woman in space, Kalpana Chawla.

Reference:

http://www.history.com/this-day-in-history/challenger-explodes

http://www.space.com/18084-space-shuttle-challenger.html