Falcon 9 Completes RTF, Resumes Cadence

On July 27, 2024 at 1:45 AM EDT, Falcon 9 returned to flight following its stand down on July 11, returning the workhorse of American rocketry to service. Carrying the Starlink 10-9 group, the mission is a return to form for one of the most flown rockets of the decade. Lofting 23 satellites into low earth orbit, the mission aims to resume the rapid cadence that the company requires to support not only their Starlink constellation, but broader ambitions with both Falcon and Starship. Following nominal orbit raising burns, the spacecraft were deployed to begin their own orbit raising maneuvers and checkout. 

SpaceX and the FAA, after the anomaly on July 11, were quick to launch concurrent investigations in order to ensure a safe and rapid return to flight. It was discovered that during the first burn of Falcon 9’s second stage engine, a liquid oxygen leak developed within the insulation around the upper stage Merlin vacuum engine. The second stage engine continued to operate through the duration of its first burn, and completed its first planned shutdown, where it entered the coast phase of the mission in the intended elliptical parking orbit.

As per normal Starlink operations, a second burn of the upper stage engine was planned to circularize the orbit ahead of satellite deployment. However, the liquid oxygen leak on the upper stage led to the excessive cooling of engine components, most importantly those associated with delivery of ignition fluid to the engine. This ultimately led to a hard-start of the engine, which precluded the rest of the mission.The stage continued to attempt its end-over-end deployment sequence – standard practice for Starlink satellites. These satellites, inserted into a lower than intended orbit, were ultimately not able to successfully raise their orbit and ultimately re-entered the Earth’s atmosphere. The second stage also re-entered, having been passivated after the anomaly.

The entire Falcon 9 fleet stood down almost immediately, with several missions shuffling their schedules to account for both the internal investigation and FAA inquiry. With the return to flight of Falcon, operating under a waiver from the FAA, it is likely that only Starlink missions will be conducted while necessary modifications are made to upcoming Falcon 9 vehicles. This stand down represents a significant pause in operations for the company, who have cemented themselves as one of the cornerstones of the launch industry. SpaceX has accrued a significant backlog, with many government and commercial missions depending on Falcon 9. As the investigation concludes, it is expected that SpaceX will adjust their schedule to meet customer demand and ensure crucial public and private missions make it to their intended destinations. 

Crucially, the agency relies on Falcon 9 to support operations at the International Space Station, launching both Crew and Cargo Dragon as well as the Cygnus spacecraft for the time being. In a press conference on July 27, NASA leadership laid out the path forward for the next human mission to launch atop Falcon 9, the joint NASA-SpaceX Crew-9 rotation to the International Space Station. The joint American-Russian crew, commanded by rookie Zena Cardman, will spend roughly 6 months on the International Space Station, relieving the Crew-8 mission currently on station. Joining Cardman will be veteran flyers Nick Hague and Stephanie Wilson, who have flown two and four times respectively. The final member of the crew will be Aleksandr Gorbunov of Roscosmos, making his first flight. While the target date for Crew-9 remains August 18th, NASA may conduct additional checkout and reviews for the mission, given the stand down and investigation. This may ultimately push the mission further into August, but NASA leadership stressed good cooperation between the agency and SpaceX. Crew-8 has until September 30th on station before their Dragon spacecraft, Endeavour, needs to come home due to on orbit life limitations.

Following the Crew-9 mission, the next human mission to be launched on Falcon 9 is Polaris Dawn, a private mission which will conduct the first civilian spacewalk. This mission, led by Inspiration4 commander Jared Isaacman, will push the spacecraft to a record high orbit – where the crew will conduct a 14 day free-flying mission before completing their two hour spacewalk. The mission, slated to launch on July 31, has been delayed in lockstep with the rest of Falcon’s manifest, moving Crew-9 ahead of it in the manifest. 

Since Falcon 9 has returned to flight, three successful Starlink missions have flown, highlighting SpaceX’s commitment to flying the vehicle to meet their internal demand and remain a cadence leader. Much of the US space economy relies on Falcon to work, and current US Space Policy is dependent on the success of this vehicle for access to vital government facilities and strategic capability offered by the vehicle. For the SpaceX team, return to flight is a testament to the unwavering nature of their workhorse launcher, one which is sure to have a long career for decades to come.

Edited by Beverly Casillas