 Today marks the 48th anniversary of the Apollo 1 fire. It was NASA's first tragedy, and it's the story we're going to go through in very brief detail today on Vintage Space. On January 27th of 1967, the Apollo 1 crew, Gus Grissom, Ed White, and Roger Chaffee, was going through the Plugs Out Test. This was a routine pre-launch test designed to put the spacecraft through a simulated countdown and launch using the spacecraft's own internal power systems. The plugs, connecting it to the external power from the ground, were out. The test was problematic from the start. Grissom smelled something like sour butter milk in his oxygen feed. There were communications problems, and a high flow of oxygen triggered a master alarm. These delays all led to holds, but at 6.31 in the evening, the crew was finally ready to get back to the Plugs Out Test. But at that moment, instrumentation from inside the spacecraft registered a spike in oxygen flow, and at the same time, movement of one of the astronauts in their couches. Four seconds later, the word fire was heard over the commas. Fires in the white room leapt into action in an attempt to free the crew, but the flames licking the side of the spacecraft made it impossible. The pressure inside the spacecraft built up until the hull ruptured, and flames poured into the white room, sending some men fleeing. But even those who stayed couldn't free the crew. By the time they got the hatch open, all three men were dead. They had a fixiated when smoke got into their oxygen system. The 8-Man Apollo 204 view board, that was the mission's internal designation, was created just hours after the fire. The spacecraft, spacecraft 12, was taken apart piece by piece alongside spacecraft 14, an identical block 1 model of the Apollo command module. The two-month investigation revealed exposed and frayed wires and a possible corrosive fluid leak in the coolant system. A spark from any one of these wires could have started the fire, which would have become explosive in the test environment. The spacecraft was designed to be pressurized with 5 pounds per square inch of pure oxygen in space. But to simulate that pressure differential at sea level, the spacecraft was actually pressurized to 16.7 pounds per square inch of pure oxygen. Any kind of spark would have immediately turned into an explosion in that kind of environment. Sealing the crew's fate was the hatch design. It was designed to open inward, which meant that the crew lying on their couches would have had to reach above them and behind them to pull against the pressure rising inside the spacecraft. It was the same for the men on the outside in the white room. No one could push against the pressure building up inside the spacecraft. After the fire, the hatch was redesigned, the plugs out test was reclassified as hazardous, and the spacecraft's environment was changed. During launch it would be a mixed oxygen-nitrogen environment, and it would slowly bleed out to be replaced by pure oxygen for the rest of the flight. With the end of the decade fast approaching, NASA recovered extremely quickly. In October of 1968, the first manned Apollo mission, Apollo 7, flew a textbook flight demonstrating that the redesigned, blocked-to-apollo spacecraft was indeed ready to fly to the moon. If you have any favorite anecdotes about the Apollo 1 crew, about Grissom, White, or Chaffee, leave them below so we can remember the men for all they accomplished. For more old-timey space content every day of the week, be sure to follow me on Twitter as AST Vintage Space, and with new episodes going up every Tuesday and Friday, subscribe right here so you never miss an episode.