With engines on, SpaceX rocket given last-second delay order

In what was a brutal reminder that NASA can (and should) delay a launch at any time if there's a perceived problem, SpaceX's highly anticipated liftoff was stopped short just before its Falcon 9 rocket should have been streaking toward the sky, and Dragon's historic rendezvous.

For those watching live this morning, it can be the most deflating way to experience a launch. Once the engines are on it feels like a sure thing, but there are no gaurantees until the craft is lifting from the pad, and even then there are mechanisms in place to facilitate an abort — all the way until Dragon docks with the International Space Station.

From NASA's release about the abort:

A SpaceX Falcon 9 aborted its launch May 19 moments after its engines ignited when computers detected higher pressure readings than allowed. The center engine pressure built above limits and a shutdown occurred one-half second before liftoff, SpaceX officials said.

The reason isn't always known. Sometimes a reading just looks wrong and a no-go decision is made. This time around it sounds as if they have a good idea at what the anomaly was with Dragon-Falcon:

"We had a nominal ignition for all nine (engines)," Shotwell said. "Engine 5 started fine and (its chamber pressure) started trending high."

She said the high pressure could be the result of high temperatures possibly from too little fuel flowing into the engine, though it is too early to know for sure. "We're going to have to spend more time looking at the data."

The rocket was poised on Space Launch Complex-40 at Cape Canaveral Air Force Station, Fla., Saturday morning for the attempt. Its hangar is next to the launch pad. Shotwell said the company is prepared to take the engine out of the rocket if it needs to and put in an engine already at the Cape.

SpaceX and NASA could attempt a launch "as early as Tuesday, May 22, but that determination won't be made until the engine itself is inspected, said [SpaceX president] Gwynne Shotwell." There's also a chance on the day after.

We'll have more for you as we know.

Via NASA

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