Well, the Falcon 9 countdown went down to zero, the engine ignition sequence started, but was aborted by the computer controlling the launch because of a sensor reading that the chamber pressure on number five engine was abnormally high.
The Falcon launch sequence is designed to hold the rocket on the launch pad with its engines firing until the computer confirms that all engines are operating normally.
Unfortunately, the constraints of a launch to the International Space Station mean that there cannot be another launch attempt today. The next attempt will most likely be made on Tuesday morning at 3:44 am Eastern.
SpaceX and Falcon have had last minute aborts like this before, and it usually comes down to a tolerance setting being too restrictive. Gwynne Shotwell, president of SpaceX, mentioned at the pre-launch press conference that they have in fact never had a test engine firing or launch happen on the first attempt. They will need that if they are to launch at the exact moment that puts Dragon on a trajectory for rendezvous with the space station.
Well, this is only the third Falcon launch, so the reality is that it is a test of the rocket as well as of the capsule. SpaceX will do a scrub turn-around and be ready to attempt a launch again on Tuesday. If not for the constraints of launching to ISS, they could probably have another attempt in a couple of hours – they have demonstrated many times now an ability to go from abort to turn-around to launch in that time frame, something that no other rocket can do.
Here’s hoping the Falcon finally soars on its next launch attempt, but I have to say I’ve waited a long time for this, and a little bit longer won’t be the end of the world.