Feb 18 1983
From The Space Library
A panel investigating the loss of two solid-fuel rocket boosters after the launch of STS-4 said that a switch in the. booster decelerators was at fault.
Premature separation of one of two riser attachments on each main chute occurred about 365-seconds after liftoff, when the frustrums were exploded away from the booster, instead of at impact with the water. A switch designed to release the chutes when the boosters hit the water had freed the parachutes from the boosters before impact, probably because of severe shock when the explosion separated the frustrum from the boosters.
Before STS-5, NASA modified the decelerating system to fix both risers firmly to each booster, to eliminate switch separation, and to prevent shock from affecting other subsystems. The booster deceleration worked perfectly during STS-5. (NASA Release 83-19)
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