Following a nominal liftoff, Falcon 9 experienced a problem shortly before first stage shutdown, resulting in loss of mission. Preliminary analysis suggests the vehicle experienced an overpressure event in the upper stage liquid oxygen tank approximately 139 seconds into flight. Telemetry indicates first stage flight was nominal and that Dragon remained healthy for some period of time following separation.
Our teams are reviewing data to determine root cause and we will be able to provide more information following a thorough fault tree analysis. Below is a link to the CRS-7 post launch briefing with representatives from SpaceX, NASA and the FAA, additional updates will be posted as they become available.