September 23, 2017

Video: Ariane 5 countdown halted after engine start

Video credit: Arianespace

Liftoff of an Ariane 5 rocket from a tropical launch pad in South America was halted moments after its main engine ignited Tuesday in a rare last-second abort for the heavy-lift launcher.

The Ariane 5 was counting down to liftoff at 2151 GMT (5:51 p.m. EDT; 6:51 p.m. French Guiana time), but the launch was aborted after an otherwise trouble-free countdown.

Two umbilical arms, one for liquid hydrogen and another for liquid oxygen, retracted from the Ariane 5’s upper stage in the final 10 seconds of the countdown, and the Ariane 5’s Vulcain 2 main engine fired as the clock reached zero.

The Vulcain 2 engine, burning super-cold hydrogen fuel, was supposed to throttle up to around 300,000 pounds of thrust at full power. An automated check of the engine’s readiness was supposed to be completed before computers gave the command to light the Ariane 5’s twin solid rocket boosters seven seconds later.

But the computers apparently noticed something wrong, and ordered an automatic abort. The Vulcain 2 engine shut down safely, and officials reported the Ariane 5 and its two passengers — the Intelsat 37e and BSAT 4a communications satellites — were secured following the abort.

The Ariane 5 will be rolled back to its final assembly building for engineers to investigate the problem and reconnect the umbilical lines between the launcher and its mobile platform, requiring at least several days before Arianespace can make another launch attempt.

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