NASA honored its fallen space explorers during its annual "Day of Remembrance" on Thursday (Jan. 23). The agency held events at a number of its facilities around the nation, including Kennedy Space Center (KSC) in Florida and Johnson Space Center in Houston.

The Apollo I and space shuttle Challenger and Columbia astronauts were remembered during an annual ceremony at Kennedy Space Center.

NASA is hosting a Day of Remembrance at the Kennedy Space Center tomorrow to honor astronauts who have sacrificed their lives while furthering the cause of space exploration and discovery. The event is held every year to honor the crews of Apollo I and space shuttles Challenger and Columbia.