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SpaceX has completed its investigation into what caused an engine failure during a Falcon 9 launch on July 11th<\/a>. The company has submitted a \u201cmishap report\u201d to the Federal Aviation Administration (FAA)\u00a0and is ready to return the Falcon 9 rocket to flight as soon as tomorrow.<\/p>\n<\/div>\n The company\u2019s investigation team, working with the FAA, was able to determine the July 11th failure was caused by a liquid oxygen leak that developed during the initial burn of the Falcon 9\u2019s second stage engine. It says the leak originated from a crack in a pressure sensor sense line that\u2019s part of the rocket\u2019s oxygen system. A clamp that normally constrains the sense line had come loose, subjecting it to excessive engine vibrations that eventually caused it to fatigue and crack.<\/p>\n<\/div>\n The leaking liquid oxygen on the Falcon 9 rocket\u2019s upper stage caused \u201cexcessive cooling of engine components, most importantly those associated with delivery of ignition fluid to the engine,\u201d according to a statement on SpaceX\u2019s website<\/a>. Instead of a second controlled burn, the engine experienced what SpaceX describes as a \u201chard start,\u201d damaging it and causing the upper stage to lose altitude control.<\/p>\n<\/div>\n The first stage of the Falcon 9 performed as expected during the July 11th launch and landed safely for reuse, but the second stage incident resulted in the Starlink satellites carried by the Falcon 9 being deployed at a lower orbit where \u201can enormously high-drag environment\u201d caused all 20 of them to re-enter the Earth\u2019s atmosphere and hopefully burn up.<\/p>\n<\/div>\n To allow the Falcon 9 to return to flight as soon as possible, SpaceX engineers will simply remove the sense line and sensor that failed on the second stage\u2019s engine. \u201cThe sensor is not used by the flight safety system and can be covered by alternate sensors already present on the engine.\u201d The company has also inspected, cleaned, and replaced some of the sense lines and clamps on its \u201cactive booster fleet.\u201d The changes have already been tested by SpaceX at its facility in McGregor, Texas, under FAA oversight.<\/p>\n<\/div>\n Now that the investigation is complete, the Falcon 9 rocket is no longer grounded and can return to service. The company\u2019s website<\/a> says that SpaceX is targeting July 27th at 12:21AM ET for the next Falcon 9 launch carrying 23 Starlink satellites from NASA\u2019s Kennedy Space Center, with additional launch window opportunities available later in the day, and on July 28th.<\/p>\n<\/div>\n