Wednesday was the 29th anniversary of the space shuttle Challenger disaster, and NASA officials conducted remembrance ceremonies at several different sites around the country to pay tribute to fallen astronauts.
Challenger exploded 73 seconds into flight, at about 11:40 a.m. Eastern time on Jan. 28, 1986.
The explosion killed seven crew members, including Christa McAuliffe, who would have been the first teacher in space.
The explosion was caused by a rocket booster failure, which ignited the fuel tank.
Additional ceremonies honored the memories of the three crew members killed in 1967′s Apollo 1 fire, the seven astronauts lost when Challenger exploded in 1986 and the seven crew members who died when the shuttle Columbia broke apart upon re-entry to Earth’s atmosphere in 2003.
“NASA’s Day of Remembrance honors members of the NASA family who lost their lives while furthering the cause of exploration and discovery,” agency officials said in a statement.