![](https://www.nasa.gov/sites/default/files/images/722342main_challenger_full_full.jpg)
NASA lost seven of its own on the morning of Jan. 28, 1986, when a booster engine failed, causing the Shuttle Challenger to break apart just 73 seconds after launch. In this photo from Jan. 9, 1986, the Challenger crew takes a break during countdown training at NASA's Kennedy Space Center. via NASA http://www.nasa.gov/multimedia/imagegallery/image_gallery_2437.html