The Challenger explosion of Jan. 28, 1986
-- 30 years ago today -- claimed the lives of seven astronauts and required NASA to rethink safety procedures for the shuttle program. The loss of life included the first teacher in space, Christa McAuliffe, who planned to offer six recorded lessons (and some live ones as well) for elementary school children.
Those lessons were reconstructed in 2007 in this NASA document, called the "Lost Lessons".
"Though lost in the sense that they perished with Challenger and her crew, recounting, redoing, and examining them is, in a sense, a resurrection. As such, they become a tribute to Christa and her courageous crewmates, the Challenger Seven," wrote project editor Jerry Woodfill in the introduction.
MORE: Remembering Challenger 30 Years After Disaster
While the loss of McAuliffe was deeply felt, reconstructing the lessons became a more happy occasion. In 2007, Barbara Morgan -- McAuliffe's backup for the "teacher in space" slot on the space shuttle -- was about to fly and wanted to do some of the lessons in orbit. Using archival footage, hardware notes and any NASA documents historians could find, NASA reassembled the plans as best as possible. Here is a brief summary of the six recorded lessons.