The Sea Launch Zenit 3SL rocket is moments away from liftoff on March 12. Photo: Sea Launch

Investigators have determined a ground software error before liftoff doomed the Sea Launch Zenit 3SL rocket during a botched flight earlier this month that destroyed the first ICO mobile communications satellite.

The international Sea Launch consortium said Wednesday that a core team of Boeing experts had heard strong evidence and supporting rationale a software logic error was to blame. Partners Yuzhnoye of Ukraine and Russia's Energia detected the problem during post-launch data reviews.

The third Sea Launch flight began at 1449 GMT (9:49 a.m. EST) on March 12, lifting off from the Odyssey launch platform positioned on the equator at 154 degrees West in the Pacific Ocean.

Shortly before the launch, however, the faulty ground software failed to close a valve in the rocket's second stage pneumatic system. This system performs several actions, including operation and movements for the stage's steering engine.

Sea Launch says the pneumatic system had lost more than 60 percent of its pressure, which reduced the engine's capability and meant the rocket did not gain the altitude and speed necessary to achieve orbit.

Officials did not say Wednesday how the software error happened. Sea Launch completed two successful flights in 1999.

About eight minutes into the flight, as the Zenit's second stage was nearing the completion of its firing, the launch was aborted under command of the onboard automatic flight termination system. The rocket issued the command once it sensed a "deviation in attitude."

Engineers report a solid telemetry link, or communications path from the rocket, was maintained for 15 seconds after flight termination and intermittent data was received for an additional 5 minutes through NASA's orbiting Tracking and Data Relay Satellite System.

The rocket and its satellite cargo crashed into the Pacific Ocean about 2,700 miles southeast of the launch site.

Sea Launch says all other systems appear to have performed as expected during the flight.

Independent investigations of the failure are ongoing by the Sea Launch partners to look beyond the software glitch and review the overall program "to ensure potential failure points do not exist elsewhere," the consortium said.

Starting in April, the full Sea Launch Failure Review Oversight Board, headed by chief engineer Jim Maser, with representatives from customers and the aerospace industry will study and approve the investigation's findings and recommendations of what actions should be taken to fix the problem.

Once the board completes its work, probably by mid-May, a return-to-flight program will begin so Sea Launch can resume missions by this summer.