SpaceX’s two-week launch pause ended just after midnight Saturday with the Starlink 10-9 mission, which saw the Falcon 9 resume flying its workhorse rocket after being grounded by an upper stage accident on July 11.
The Falcon 9 rocket lifted off from Launch Complex 39A at NASA’s Kennedy Space Center at 1:45 a.m. EDT (5:45 a.m. UTC), marking the 50th dedicated Starlink launch of 2024. Successful deployment of the payload was confirmed just one hour after liftoff.
The Federal Aviation Administration, the agency that oversees U.S. commercial space activity, has given SpaceX permission to resume launches of its Falcon 9 rocket before a formal accident investigation is completed.
The FAA approved a public safety determination requested by SpaceX, one of two routes available to a launch company that suffers an accident during a mission to resume rocket launches.
“After a comprehensive investigation, the FAA has determined that the anomaly that occurred during the SpaceX Starlink Group 9-3 launch on July 11 did not pose a public safety issue,” the FAA said in a statement Thursday. “This public safety determination means that Falcon 9 aircraft can resume flight operations while the full investigation continues, provided all other license requirements are met.”
SpaceX’s Falcon 9 rocket, the most-flying space launch vehicle, experienced a liquid oxygen leak in its upper stage during the Starlink 9-3 mission, which launched from Vandenberg Space Center in California on July 11. During the first burn, viewers of the launch could see large amounts of ice building up around the rocket’s engine section.
“The cause of the leak was identified as a crack in a sensing line for a pressure sensor attached to the aircraft’s oxygen system,” SpaceX said in a blog post on Thursday. “The line cracked due to fatigue caused by high stress from engine vibrations and loosening of the clamp that normally secures the line.”
“Despite the leak, the second stage engine continued to operate through its first burn, then completed engine shutdown and entered the coasting phase of the mission on the planned elliptical parking orbit.”
The FAA has given the go-ahead to resume flight, SpaceX Dragon mission manager Sarah Walker said during a briefing on the upcoming Crew 9 astronaut launch at NASA’s Johnson Space Center on Friday. She added that NASA was involved throughout the process.
“NASA was officially present at all of the data briefings and data drill-downs that we did with the FAA,” Walker said. “We had time for questions and answers, we exchanged more data, [the FAA] Yesterday, they agreed with our conclusions and made the final decision that we are ready to resume flying.”
She said the liquid oxygen leak had caused ice to form around the engine section, slowly sending ignition fluid into the combustion chamber and making the Merlin vacuum engine “difficult to start.”
“This caused damage to the engine hardware and a loss of control of the upper stage,” Walker said.
Steve Stich, manager of NASA’s commercial crew program, said he and SpaceX viewed video of the fiery start and that it helped them investigate the accident.
SpaceX said in a blog post Thursday that neither the upper stage nor the Starlink satellites posed a risk to the public, and further emphasized that the first stage booster (tail number B1063) performed without issue and landed safely on the “Of Course I Still Love You” drone just over eight minutes after liftoff.
The fix involves removing the problematic sensor, which was left in its original configuration from a previous customer mission, and Stich said it would be a learning experience “about the attention to detail that spaceflight demands.”
“Small changes are important, and we looked at the changes and NASA didn’t find any issues,” Stich said. “SpaceX did a great job of re-looking at this part and other parts of the vehicle that may have had the same issue. It was only slightly similar to what was there before, and it was qualified, but probably not tested as thoroughly as it should have been.”
“So I think it’s been a great lesson for all of us.”
SpaceX decided to remove the problematic sensor (which Walker said overlapped with other sensors on the engine) to prevent similar issues in the future, and the company tested the update at its facility in McGregor, Texas.
The Falcon 9 upper stage that will support the Crew-9 mission is expected to be tested there soon.
“A second phase of hot-fire testing will take place around July 30th, which will be to test some of the new modifications being made to the vehicle as a result of the extraordinary event,” Stich said.
Return to start
The FAA’s decision clears the way for the company to resume launches of its flagship rocket. Since last weekend, SpaceX has deployed several maritime assets to support launch operations: Two Florida-based drone ships were deployed along with a recovery vessel to retrieve the payload fairing.
The return to flight mission could be followed by two more launches: the Starlink 10-4 mission from Space Launch Complex 40 (SLC-40) and the Starlink 9-4 mission from Vandenberg.
The resumption of launches is crucial not only for SpaceX’s Starlink constellation, but also for customers such as NASA and its Polaris program, which plans to launch a Northrop Grumman Corp. Cygnus spacecraft on its NG-21 cargo resupply mission to the International Space Station, then fly Crew 9 astronauts to the orbital outpost.
Jared Isaacman and three other private astronauts are also waiting their turn to depart aboard the Crew Dragon Resilience for the roughly five-day Polaris Dawn mission, the highlight of which will be the first-ever commercial spacewalk.
NASA announced Friday that the mission is scheduled to launch from LC-39A after Aug. 18, with launch opportunities through early September. Stich said the timing will depend on the time it takes to convert the launch pad from a Falcon 9 to a Falcon Heavy configuration and launch the Europa Clipper as scheduled in October.
SpaceX has several flagship missions scheduled for the second half of 2024, including the launch of its CRS-31 Cargo Dragon mission to the ISS, scheduled for sometime in September.
