On the morning of January 27, 1967, three astronauts – Gus Grissom, Ed White, and Roger Chaffee were killed in a fire in the Apollo Command Module during pre-flight simulation test at Cape Canaveral.

To simulate outer-space conditions the command module was pressurized and filled with pure oxygen. At 6:31 AM Roger Chaffee radios that there is a fire in the cockpit. Just 13 seconds later the cockpit exploded, killing all three astronauts.

Two of the astronauts were already famous national heroes. Two years earlier Americans watched Col. Ed White become the first American to conduct a space-walk, during the Gemini-4 mission, viewed by an amazed television audience.

Virgil “Gus” Grissom was famous for being just the second American in space (Alan Shepard was the first), and who was one of the leading candidates for an eventual moon landing mission.

Roger Chaffee had worked as a capsule communicator for the Gemini 3 and Gemini 4 projects. Apollo 1 was to be his first spaceflight mission.

After the disaster an investigation was done to determine exactly what went wrong: What was found was an exposed wire underneath Grissom’s seat, and leaky plumbing carrying a flammable and corrosive coolant caused a spark, which in a pressurized cabin filled with pure oxygen is a bad mixture.

Because of the extreme pressure inside the cabin, the astronauts inside, as well as people outside, were unable to open the hatch, which was essentially fused shut. The men were trapped inside a ticking time bomb with no possible escape.

This disaster was a huge setback for NASA and America in the “race to the moon” against Russia. All manned Apollo flights would be banned for 20 months.

With its moon program in jeopardy, NASA completely overhauled the Apollo spacecraft. 

The redesigned capsule — with a quick-release hatch — carried 24 men to the moon; 12 of them landed and walked on its surface.

The hatch of the capsule went on display at NASA Kennedy Space Center for the first time in 50 years in 2017.