NASA sent astronauts safely into space for many years. Then, their missions were put on hold after Challenger exploded at launch, killing all the astronauts on board. Despite their best efforts to prevent another catastrophe, this would not be the last deadly shuttle. Columbia broke apart on its return to Earth. Follow along with the true stories of two tragic space flights. Then, review that you've learned with a recap timeline and a quick quiz to check how much doomed history you remember.