September 23, 1:00pm EDTThree weeks ago, SpaceX experienced an anomaly at our Launch Complex 40 (LC-40) at Cape Canaveral Air Force Station. This resulted in the loss of one of our Falcon 9 rockets and its payload.The Accident Investigation Team (AIT), composed of SpaceX, the FAA, NASA, the U.S. Air Force, and industry experts, are currently scouring through approximately 3,000 channels of engineering data along with video, audio and imagery. The timeline of the event is extremely short – from first signs of an anomaly to loss of data is about 93 milliseconds or less than 1/10th of a second. The majority of debris from the incident has been recovered, photographed, labeled and catalogued, and is now in a hangar for inspection and use during the investigation.At this stage of the investigation, preliminary review of the data and debris suggests that a large breach in the cryogenic helium system of the second stage liquid oxygen tank took place. All plausible causes are being tracked in an extensive fault tree and carefully investigated. Through the fault tree and data review process, we have exonerated any connection with last year’s CRS-7 mishap.The teams have continued inspections of LC-40 and the surrounding facilities. While substantial areas of the pad systems were affected, the Falcon Support Building adjacent to the pad was unaffected, and per standard procedure was unoccupied at the time of the anomaly. The new liquid oxygen farm – e.g. the tanks and plumbing that hold our super-chilled liquid oxygen – was unaffected and remains in good working order. The RP-1 (kerosene) fuel farm was also largely unaffected. The pad’s control systems are also in relatively good condition.SpaceX’s other facilities, from the Payload Processing Facility at the Cape, to the pad and hangar at LC-39A, are located several miles from LC-40 and were unaffected as well. Work continues at Pad 39A in preparation for bringing it online in November. The teams have been in contact with our Cape Canaveral and Kennedy Space Center partners and neighbors and have found no evidence of debris leaving the immediate area of LC-40.At SpaceX headquarters in Hawthorne, CA, our manufacturing and production is continuing in a methodical manner, with teams continuing to build engines, tanks, and other systems as they are exonerated from the investigation. We will work to resume our manifest as quickly as responsible once the cause of the anomaly has been identified by the Accident Investigation Team. Pending the results of the investigation, we anticipate returning to flight as early as the November timeframe.Other efforts, including the Commercial Crew Program with NASA, are continuing to progress. Getting back to flight safely and reliably is our top priority, and the data gathered from the present investigation will result in an even safer and more reliable vehicle for our customers and partners.
It is good news that SpaceX has been able to isolate the root cause. Particularly good to hear that manufacturing is continuing for engines, tanks, and other exonerated hardware.
SpaceX has taken some steps in their design to make sure that a single engine failure does not bring down the entire vehicle. The engines have firewalls separating them from each other and the rest of the rocket, there are blowout panels to direct pressure outward, and automatic shutoff valves to isolate dead engines. They've had one first stage engine failure that did not result in a mission failure due to this precaution. They have however now had two mission failures related to the second stage helium system. Would it be at all possible for them to make design changes so that a single COPV failure would not being down the rocket? I expect it would take a major redesign of the LOX tanks to do so, but two failures with similar causes might mean that has to be done.
Quote from: The_Ronin on 09/23/2016 05:00 pmI know we generally are not supposed to talk about what is on /r/SpaceX here but they have a thread about COPV harmonics being the root cause. That would be a bad thing, I think.How much performance/density would they lose if they moved the COPV tanks outside of the tank?IF that is indeed the case, harmonics per se isn't the problem - resonance is. And resonant frequency is easy to change in a system. Those tiny lead weights around the rim of your wheels? Those are there to provide a counteracting mass to damp out resonance in your spinning wheels. So, IF the problem is a harmonic resonance in the COPV tanks (e.eg., vibrations set up in response to rapidly loading propellants, THEN the solution is equally-simple. Add a tiny bit of mass, or simply change the physical arrangement of whatever part was oscillating, to damp the vibration and prevent the resonance.
I know we generally are not supposed to talk about what is on /r/SpaceX here but they have a thread about COPV harmonics being the root cause. That would be a bad thing, I think.How much performance/density would they lose if they moved the COPV tanks outside of the tank?
I struggle to understand how they can conclusively state it is a totally separate failure mode from CRS-7.
Jim was right (again). SpaceX should hire Jim.
Quote from: rockets4life97 on 09/23/2016 05:47 pmIt is good news that SpaceX has been able to isolate the root cause. Particularly good to hear that manufacturing is continuing for engines, tanks, and other exonerated hardware. Root cause has not been ID'd. They have isolated it to a very complex subsystem (and I struggle to understand how they can conclusively state it is a totally separate failure mode from CRS-7).
On the other, I think that if they had any level of confidence that a specific failure was the root cause they would have mentioned that in their update.
Quote from: PahTo on 09/23/2016 05:52 pmQuote from: rockets4life97 on 09/23/2016 05:47 pmIt is good news that SpaceX has been able to isolate the root cause. Particularly good to hear that manufacturing is continuing for engines, tanks, and other exonerated hardware. Root cause has not been ID'd. They have isolated it to a very complex subsystem (and I struggle to understand how they can conclusively state it is a totally separate failure mode from CRS-7).You don't need to understand why - you just need to read the statement which says they are unconnected. I tend to believe the engineers doing the investigating, since they have access to all the information.
