The CRS-7 Dragon launch aboard Falcon 9 ended in catastrophic failure today. This is the first failure in the Falcon 9 program, and will of course ground the rocket for at least a few months while the investigation is carried out. The rocket was lost at about two and a half minutes into the flight. SpaceX later disclosed (via Elon Musk’s Twitter account) that there was an overpressure in the second stage oxygen tank; as the problem appears to start high up on the rocket before it disintegrates, this seems likely to have something to do with the failure, though it may not be the actual root cause. As it happened prior to staging, there was no first stage landing attempt; the first stage was destroyed along with the rest of the vehicle.
I have yet to watch the post-launch press conference, but in case you want to now, here it is (I will be watching it later):
A great deal of hardware was of course lost on this flight, including a student experiment that was being reflown following the loss of the last Cygnus vehicle, and the first of two International Docking Adapters, critical for the commercial crew program which will be parking at them in a couple of years (and which no other spacecraft presently can carry). Furthermore, this follows on the heels of a Progress failure unique in the history of the vehicle and does put the station at a disadvantage in terms of supplies; fortuitously, the station is currently at a reduced headcount to support the yearlong mission, so the supplies will stretch further. Presently, consumables are comfortably adequate through October, and there is a large Japanese cargo vessel, the HTV, scheduled to fly in August, so they should be okay. But it’s a blow to science research, and to commercial crew preparations as well as the overall Falcon 9 program.