Arianespace resets next launch to late September after finding electrical equipment problem

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WASHINGTON — Arianespace is rescheduling the Ariane 5 launch meant for yesterday to the end of the month, having traced the source of the computer-triggered mission abort to a solid-propellant booster problem.

The launch provider said Sept. 6 that an electrical equipment issue in one of the boosters interrupted the automated lift-off sequence Tuesday, cancelling the mission.

Yesterday’s mission scrub — a rare event for the Ariane 5 — occurred after the rocket’s first stage liquid engine started burning, but before ignition of the two strap-on solid-fuel boosters.

“This interruption is perfectly compliant with our procedures which authorize a launch only if 100% of launcher equipment is fully operational,” Arianespace said in a Sept. 6 statement. “This rule guarantees the reliability and robustness of our launch system.”

Carrying 240 metric tons of propellant each, the Ariane 5’s twin solid boosters provide 90 percent of the rocket’s liftoff thrust. The company said it will further investigate the cause of the booster issue.

Arianespace confirmed after the launch hold that both satellites — Intelsat’s high-throughput Intelsat-37e and Broadcasting Satellite System Corporation’s Bsat-4a — were safe. The company said Sept. 6 that both remain inside the rocket’s payload fairing.

Arianespace said it will seek to complete the launch, known as VA239, “around the end of September 2017.” All other missions this year remain on track, the company said.