STS-135 T-18 Days - January 27, 1967, Apollo 1 - Fire!

Preparations were underway for the first manned Apollo flight.  There had been several unmanned flights.  All very successful.  Things were looking good.

Grissom, White, & Chaffee in Apollo 1

On January 27th, 1967 the three crewmembers for the first flight were doing a run through of the countdown.  It was a dress rehearsal for the launch that was scheduled for February 21st.  Shortly after sealing the capsule in the test, a fire was ignited in the cabin.  Virgil Grissom, Edward White, and Roger Chaffe all died.

It was the first casualty of American astronauts in the space crafts.  It was a blow to the nation, the program, and everyone associated with the astronauts.

Plaque Placed on Memorial at Launch Pad 34

Apollo was grounded for twenty months afterwards, while the program was reviewed and problems corrected.  The direct cause of the fire was determined to be a spark that ignited an abundance of material, that in the pure oxygen environment of the capsule, made even items like Velco, highly combustible.  This was a reminder of how incredibly risky it was to sit in a small capsule at the top of a missile and then light it up.

The space program had been moving quickly and in retrospect, there had been signs that this could be a problem.  The astronauts had even raised concerns over this exact risk during prior preparations and spacecraft inspections.  Many changes were made to the spacecraft and their operation. The redesigned command module was scheduled for October 1968.

http://en.wikipedia.org/wiki/Apollo_1