The IMU, the Initial Measurement Unit, and the Service Module

John Defterios: "It gets very quiet. There doesn't get to be much communications between the spacecraft and the crew" He says it was tense because they knew that there had been an explosion at the base of the command module. The first clock in county through zero, they hit the atmosphere one time,. They hit the entry interface, and blackout starts, calm goes off, and then you sit there again. It was amazing.