SpaceX Webcast
A Falcon 9 rocket blasted into orbit from a launch pad at the Kennedy Space Center in Florida early Saturday morning at 1:45 a.m. local time.
In some ways, this was a fairly routine mission — it was SpaceX’s 73rd launch of the year, after all. And like many of this year’s other Falcon 9 launches, the “Starlink 10-9” mission was sending 23 broadband internet satellites into orbit. But after a rare failure earlier this month, this particular Falcon 9 rocket marked the company’s return to flight, putting the world’s most active booster back into service.
And by all accounts, it worked. The first stage booster, B-1069, completed its 17th orbital flight. Just read the instructions The Starlink spacecraft landed on a drone ship traveling in the Atlantic Ocean, after which the rocket’s second stage released its payload into a favorable orbit just over an hour after launch. The Starlink spacecraft will use their onboard thrusters to reach operational altitudes in the coming weeks.
Cracks in the sensory line
The Falcon 9 rocket malfunction occurred just 15 days ago, during a Starlink launch from Vandenberg Space Center, California, at 7:35 pm PDT on July 11. During the mission, just minutes after stage separation, an unusual buildup of ice was observed on the Merlin vacuum engine that powers the rocket’s second stage.
The company said the Merlin vacuum engine successfully completed its first burn after the second stage separated, but during this time a liquid oxygen leak occurred near the engine, leading to the ice buildup observed during the webcast.
Engineers and technicians quickly identified the source of the leak: a crack in a “sensing line” of a pressure sensor attached to the vehicle’s liquid oxygen system. “The line cracked due to high loads from engine vibrations and fatigue caused by the loosening of a clamp that secures the line,” the company said. With the update It was revealed ahead of the release on Saturday morning.
The leak overcooled the engines, reducing the amount of ignition fluid available before the second burn to reignite the Merlin to circularize the rocket’s trajectory before releasing the Starlink satellites, which ultimately ejected into a lower orbit and burned up in Earth’s atmosphere within a few days.
SpaceX said the failed sensing line is not needed — it’s not used in the flight safety system and can be replaced by a replacement sensor already on the engine — and that the sensing line will be removed from the second stage engine for future Falcon 9 launches.
SpaceX Director Sarah Walker said at a press conference Thursday that the sensing line was installed at the request of a customer for another mission. The only difference between this part and other typical sensing lines is that it has two connections instead of one, Walker said, which could have made it more susceptible to vibrations that could have caused the tiny cracks.
Return soon
SpaceX identified the cause of the malfunction within hours of the incident, worked with the FAA to quickly resolve it, and was cleared to resume flying on Thursday.
“It was remarkable how quickly the team identified the cause of the accident and then took the appropriate corrective actions to ensure success,” Walker said.
Prior to the failure on the night of July 11, SpaceX had not experienced a mission failure in any of the previous 297 launches of its Falcon 9 rocket dating back to the Amos 6 launch pad explosion in September 2016. The short gap between the failure earlier this month and Saturday’s resumption of flights is believed to be unprecedented in the history of spaceflight.
The company plans to launch two more Starlink missions on a Falcon 9 rocket this weekend, one from Cape Canaveral Space Station in Florida and one from Vandenberg Space Center in California, followed by three more missions before NASA’s crucial astronaut flight, Crew 9, begins as early as August 18.
That’s why NASA was involved in the investigation of the second stage failure. Steve Stich, NASA’s commercial crew program manager, said SpaceX did an “exceptional job” of identifying the root cause of the failure and then quickly inspecting the first stages of its Dragon spacecraft and Falcon 9 rocket to make sure there were no other sensors that could have caused a similar problem.
