NASA’s Day of Remembrance is observed worldwide on the last Thursday of January to honor the memory of astronauts and astronaut candidates who sacrificed their lives in the pursuit of space exploration. This observance is closely timed to the anniversaries of three significant tragedies in NASA's history: the Apollo 1 catastrophe, the Space Shuttle Challenger disaster, and the Space Shuttle Columbia disaster, which collectively resulted in the deaths of 17 astronauts. Memorial events, including wreath-laying ceremonies, take place at NASA centers and at the Tomb of the Unknown Soldier at Arlington National Cemetery in Virginia. The Apollo 1 tragedy occurred on January 27, 1967, followed by the Challenger disaster on January 28, 1986, and the Columbia disaster on February 1, 2003. NASA previously held separate memorials for each tragedy but consolidated them into a single day of remembrance to honor all fallen heroes. Participants can engage in official ceremonies, learn about the contributions of these individuals, and visit local planetariums or space museums.