From left to right, Gus Grissom, Ed White, and Roger Chaffee, pose in front of Launch Complex 34 which is housing their Saturn 1 launch vehicle. (NASA photo via Wikimedia Commons)

On this date in 1967, three American astronauts died in a training accident on the launch pad in Florida.

Here are some things you may not have known about Apollo 1.

Following the successes of the Mercury and Gemini programs, the next step in landing a man on the moon was the three-man Apollo program. The astronauts chosen as the first crew for the Apollo program were Gus Grissom, one of the original Mercury Seven astronauts, Ed White, who had been the first American to walk in space, and rookie Roger B. Chaffee. Chaffee’s spot had originally been given to Donn F. Eisele, who was grounded after dislocating his shoulder during weightlessness training on board a training craft nicknamed a “vomit comet.”

Gus Grissom was born in Indiana in 1926. After serving in the Army Air Forces during the end of World War II, Grissom returned home an earned a degree in mechanical engineering from Purdue University in 1950. He reenlisted in the Air Force after graduating and served during the Korean War, flying 100 combat missions. In 1958 he was selected by NASA to be part of a preliminary group of pilots for the Mercury program. He was nearly disqualified when he was found to suffer from hay fever, but was allowed to continue once it was determined that there wasn’t any ragweed pollen in space.

Grissom was the second American in space in Liberty Bell 7. Grissom’s first space flight lasted 15 and a half minutes. After splashdown, the hatch cover exploded open filling the capsule with seawater. Grissom’s spacesuit also filled with water, but he was rescued. The capsule sank and wasn’t recovered until 1999.

Grissom became the first American to fly into space twice when he piloted Gemini 3 with John W. Young. It was the first manned Gemini mission. The mission lasted a little under five hours.

Ed White was born in Texas in 1930. He graduated from West Point in 1952 and served in the Air Force, stationed in West Germany. He narrowly missed qualifying for the U.S. Olympic team in the 400-meter hurdles. He was part of the second group of astronauts and was chosen to fly on Gemini 4. On that flight he was the first American to leave a space capsule. He enjoyed the experience so much that he had to be ordered to return to the capsule. A mechanical issue made it difficult to open and close the hatch door, which had to be latched to re-enter Earth’s atmosphere. The capsule and crew returned safely following a four-day mission.

Roger Chaffee was born in Michigan in 1935. He graduated with a degree in Aeronautical Engineering from Purdue. He served as a naval aviator, logging more than 2,000 hours in jet aircraft. He was part of the third group of astronauts and served on the ground as a capsule communicator for Ed White’s Gemini 4 mission.

On January 27, 1967, the crew was loaded into the spacecraft as part of a “plugs-out” test to see if the module would operate on internal power. The test was considered non-hazardous because the the vehicle was not fueled and all pyrotechnic systems were disabled. At 2:45 p.m., the hatch was closed and the cabin was filled with oxygen at 2 psi more than atmospheric pressure. At 6:31 p.m., one of the astronauts yelled “Hey!” or “Fire!.” Two seconds later, Chaffee reported a fire in the cockpit. Seven seconds later, a garbled transmission seemed to say “We’ve got a bad fire — Let’s get out .. We’re burning up.” The last communication ended a little less than 16 seconds after the first report of a fire. The fire caused the pressure inside the capsule to rise to 29 PSI which led the inner ...