Falcon 1 - Third Flight - Hi Res (From www.spacex.com)

NOTE: The original video can be downloaded from www.spacex.com
On August 3, 2008, Space Exploration Technologies Corporation (SpaceX) attempted their first operational flight of the Falcon 1 rocket - the third flight of the Falcon 1.
The first flight failed due to a leak in a fuel line, and the second failed due to an anomaly during stage separation which caused the spent first stage to collide with the engine bell of the second stage. This resulted in oscillations due to fuel slosh from which the guidance computer was unable to recover. According to SpaceX, this problem has since been resolved.
As such, there was much optimism prior to the third (and first operational) flight of Falcon 1, and we all hoped for a successful orbital flight.
Unfortunately, flight 3 also resulted in loss of vehicle and, since this was an operation flight, payload. The payload consisted of the Trailblazer satellite for the US Air Force, the NanoSail-D and PREsat nanosatellites for NASA and a space burial payload for Celestis.
The analysis of the flight determined that the cause of failure was due to the new Merlin 1-C engine which was used for the first time on this flight.
The previous two flights used the Merlin 1-A, which is an ablatively cooled engine. The Merlin 1-C uses a regeneratively cooled engine (an engine which uses the propellants as a coolant). This results in longer fuel lines leading the the combustion chamber, and a longer burn-out time for the 1-C.
After main engine cut-off (MECO), these longer fuel lines allowed some of the unburnt propellant to enter the combustion chamber, which then combusted and produced enough impulse to overcome the impulse delivered by the pneumatic pushers (which are used to literally push the spent first stage away from the second) at separation.
The end result of this was that the first stage came back into the second stage, resulting in catastrophic failure. I assume this is due to the second stage failing to ignite due to separation sensors, etc, though this is just speculation on my part.
SpaceX have announced that the problem has been overcome, and we all look forward to the fourth (and hopefully successful) flight of Falcon 1 in September (tentative date).
Good luck SpaceX! We are all pulling for you.
Onwards and upwards!

[@muscahead2]

Oh they did

[@RedFoxOne.]

Maybe they will do better next time