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NASA NTRS1989

The Atlas/Centaur lightning strike incident

Consideration is given to an incident on March 26, 1987, in which an Atlas/Centaur 67 vehicle carrying a naval communication satellite was struck by a triggered, cloud-to-ground lightning flash about 48 s into the flight. The lightning current coupled a transient signal into the wiring of the Centaur digital computer unit, ultimately causing the breakup of the vehicle. The meteorological conditions at the time of the launch and the lightning flash triggered by the Atlas/Centaur 67 vehicle are analyzed on the basis of studies of the incident by the NASA Investigation Board.

Christian, H. J.↗

NASA NTRS1988

The Atlas-Centaur 67 incident

The conditions leading to the breakup of the Atlas-Centaur 67 (AC-67) vehicle launched on March 26, 1987 during a typical winter-time storm are analyzed, and a most probable lightning strike scenario was developed based on inspection of the AC-67 debris, the AC-68 vehicle, and appropriate drawings, electrical diagrams, and photographs. It is shown that, during ascent, the vehicle encountered increasingly larger electric fields and flew through clouds that produced precipitation static on the vehicle, eventually triggering a cloud-to-ground lightning, comprised of at least four return strokes. The resulting lightning current coupled a signal into the wiring which goes to the AC-67 digital computer unit (DCU), effecting a single-word memory alteration and causing the DCU to issue a hardover engine gimbal command. This led to an excessive angle of attack, large dynamic loads, and the breakup of the AC-67.

Christian, H. J.↗