According to the Sea Launch Failure Review Oversight Board, all data presented indicate a ground software logic error as single root cause. A ground software command failed to close a pneumatic system valve on the second stage of the vehicle prior to lift-off.

As a result of launching with this valve in the incorrect position, a sequence of events followed, involving excessive loss of helium. Ultimately, the rocket did not reach orbital velocity, leading to a premature shutdown of second-stage engine and termination of the flight at approximately 8 minutes into the mission.

The Board received independent reports and presentations from the Sea Launch partners, as well as from representatives from a joint Russian and Ukrainian commission.

See also:

• Zenit-3SL 2013-02-01
• Zenit-3SL 2007-01-30
• Zenit-3SL 2004-06-29

Launch Failures Chronology