Challenger Explosion - $5.5 Billion

The Space Shuttle Challenger was destroyed 73 seconds after takeoff due on January 28, 1986 due to a faulty O-ring. It failed to seal one of the joints, allowing pressurized gas to reach the outside. This in turn caused the external tank to dump its payload of liquid hydrogen causing a massive explosion. The cost of replacing the Space Shuttle was $2 billion in 1986 ($4.5 billion in today's dollars). The cost of investigation, problem correction, and replacement of lost equipment cost $450 million from 1986-1987 ($1 Billion in today's dollars).