Fifty-two years ago today, three astronauts died in a fire during a preflight test for the first flight of Apollo.
Virgil Grissom, Edward White and Roger Chaffee died in the command module fire. The mission was to be the first crewed flight of Apollo, and was scheduled to launch Feb. 21, 1967, according to NASA.

Courtesy of NASA

Courtesy of NASA
The investigation that followed the tragedy, and the reworking of the command modules that resulted, delayed crewed flights for more than a year.
In the spring of 1967, NASA’s Associate Administrator for Manned Space Flight, Dr. George E. Mueller, announced that the mission originally scheduled for Grissom, White and Chaffee would be known as Apollo 1, and said that the first Saturn V launch, scheduled for November 1967, would be known as Apollo 4. The eventual launch of AS-204 became known as the Apollo 5 mission. No missions or flights were ever designated Apollo 2 or 3, according to NASA.
The second launch of a Saturn V took place on schedule in the early morning of April 4, 1968. Known as AS-502, or Apollo 6, the flight was a success, though two first-stage engines shut down prematurely, and the third-stage engine failed to reignite after reaching orbit.
It wasn’t until 1969 that the astronauts of Apollo 11, Neil Armstrong, Edwin “Buzz” Aldrin and Michael Collins, walked on the moon.
To read more about the Apollo I tragedy, click here.