Right up to t-minus 0.5 seconds it looked like there was going to be a launch. Unfortunately the Falcon 9 computer shutdown the rocket just as it was set to launch due to a high pressure reading on engine number 5, one of nine engines on the Falcon 9 first stage.
The next launch attempt, assuming everything is ok with the rocket, will be at 07:44:34 GMT (3:44:34 a.m. EDT) Tuesday, May 22nd. If they can't launch on the 22nd, SpaceX has said they can try approximately every three days though they could also try on the 23rd.
At this point SpaceX said they need to access the launch pad and have a look at engine number 5, the one that was reading high. If the engine needs to be replaced an engine is available, though would mean taking the rocket from the launch pad to the SpaceX hangar and swapping out the engine. That option is available and would only take a few days if needed.
This launch by SpaceX is the second demonstration flight of their Dragon spacecraft as part of NASA's Commercial Orbital Transportation Services (COTS) program.
During the mission, Dragon must perform a series of complex tasks, each presenting significant technical challenges.
- Day 1/Launch Day: SpaceX's Falcon 9 rocket launches a Dragon spacecraft into orbit from the Cape Canaveral Air Force Station.
- Day 2: Dragon orbits Earth as it travels toward the International Space Station.
- Day 3: Dragon's sensors and flight systems are subject to a series of complicated tests to determine if the vehicle is ready to berth with the space station; these tests include maneuvers and systems checks that see the vehicle come within 1.5 miles of the station.
- Day 4: NASA decides if Dragon is allowed to attempt to berth with the station. If so, Dragon approaches; it is captured by station's robotic arm and attached to the station. This requires extreme precision even as both Dragon and station orbit the earth every 90 minutes.
- Day 5 - TBD: Astronauts open Dragon's hatch, unload supplies and fill Dragon with return cargo.
- TBD: After approximately two weeks, Dragon is detached from the station and returns to Earth, landing in the Pacific, hundreds of miles west of Southern California.