More than three weeks ago during the launch of the Dragon spacecraft to the International Space Station the Falcon 9 second stage suffered an anomaly that resulted in the lost of the spacecraft and its payloads.
Today Elon Musk announced that the preliminary investigation into the accident indicates that a strut inside the Liquid Oxygen (LOX) tank on the 2nd stage failed causing the liquid helium bottle to dislodge and hit the top of the LOX tank causing the explosion. Elon stressed multiple times during the call that this is a preliminary result so far.
Musk: strut failed at 1/5th rated force, no evidence of damage to it in closeout photos before launch.
— Jeff Foust (@jeff_foust) July 20, 2015
SpaceX have tested 1000s of the struts since the accident and have found a number of failures below rated value, including one that failed below 2,000 lbs.
After testing at an enormous number, found one that fialed at below 2,000 lb. level. Did some material analysis, problem w/ grain structure
— Parabolicarc.com (@spacecom) July 20, 2015
During the call Elon admitted that SpaceX did not perform Quality Control on the strut that failed and instead relied in the part meeting the specification as provided by the supplier. They will be revising their processes to ensure all parts of the rocket are fully QCed for future flights. While this will increase SpaceX costs during construction of the rocket they didn’t expect it to have much if any of an impact on the cost of the rocket.
Elon also announced that Dragon V1 didn’t have the ability to deploy the chutes in case of an emergency during ascent, the next flight will have the ability should it be needed which would have most likely have resulted in pressurized cargo being saved. They expect to delay flights until September but at present don’t know who will be the first flight manifest will most likely change. Again because this is preliminary so may change should another cause become obvious.
Elon also announced that due to the investigation the flight of Falcon Heavy will most likely be delayed until April 2016.
Elon also admitted that most of the people who now work for SpaceX have never seen a failure due to all the successful launches in the last seven years. This had caused most of them to become complacent about the difficulty of launching rockets. They have now learned the hard way just what is involved.