SpaceX will start the next Starship test flight in early June

LOS ANGELES – SpaceX has set a June 5 launch date for its next integrated Starship test flight, with a focus on demonstrating the ability to leave both stages of the vehicle intact.

SpaceX announced on May 24 that it plans to launch Starship during its fourth integrated flight test, also known as IFT-4, as early as June 5, pending receipt of an updated license from the Federal Aviation Administration. That launch, like the previous three, will take place from the company’s Starbase location in South Texas.

After demonstrating that the Starship’s upper stage, launched by its Super Heavy booster, can reach space, the company now wants to show that it can return both the booster and the ship intact.

“The fourth flight test shifts our focus from reaching orbit to demonstrating the ability to return and reuse Starship and Super Heavy,” the company said. “The primary objectives are to conduct a landing and soft landing in the Gulf of Mexico with the Super Heavy booster, and achieve controlled entry of the Starship.”

Unlike the third test flight in March, SpaceX is not planning any in-flight tests with Starship, such as opening the vehicle’s payload door or transferring propellant. The vehicle will follow a similar trajectory with the ship landing in the Indian Ocean. “This flight path does not require a deorbit burn for reentry, maximizing public safety while providing the ability to meet our primary goal of a controlled spacecraft reentry,” the company said.

SpaceX has made several upgrades to Starship’s hardware and software since its March flight, incorporating lessons learned from that mission. One change the company pushed for was to jettison the special intermediate section between the booster and the ship, designed to allow for “hot-staging,” in which the ship ignites its engines while still attached to the booster. Discarding that intermediate stage after Super Heavy’s post-separation boostback burn, SpaceX stated, will “reduce booster mass for the final stage of flight.”

The company also released details on May 24 about the problems it encountered during the third Starship flight. While Starship reached space, the vehicle was lost during reentry. The Super Heavy booster broke up separately during the final stages of its descent over the Gulf of Mexico.

SpaceX said Starship “began to lose the ability to control its attitude” several minutes after turning off its engine while on a suborbital trajectory. Video of the flight showed the vehicle rolling slowly. That loss of attitude control led to an automated decision not to perform a scheduled engine restart.

“The lack of attitude control resulted in a non-nominal entry, with the ship seeing much greater than expected heating in both protected and unprotected areas,” SpaceX said, with telemetry lost at an altitude of 40 miles.

The company believes the attitude control problem was caused by clogging of valves in thrusters used for roll control. SpaceX added more thrusters for redundancy while also upgrading the thruster hardware “for better stall resistance.”

SpaceX said the Super Heavy booster fired 13 of its 33 Raptor engines after separation for a boostback burn, but six of the engines began to shut down, leading to an early termination of the boostback burn. Only two of the thirteen engines ignited for the final landing, as SpaceX attempted a soft landing of the booster on the ocean surface. SpaceX said it lost contact with the booster 1,500 feet (462 meters) above the surface.

The engine failures, SpaceX concluded, were caused by filter blockage in liquid oxygen lines, which prevented propellant from reaching the engines. SpaceX experienced similar problems on previous Starship launches and made changes to the engine design to prevent this. “Super Heavy boosters for Flight 4 and beyond will receive additional hardware in oxygen tanks to further improve propellant filtration capabilities,” SpaceX said, along with unspecified “additional hardware and software changes” to improve the reliability of the Raptor launch improve engine.

SpaceX CEO Elon Musk said in April that he hoped the upcoming flight would demonstrate that the Super Heavy booster could land on a “virtual tower” in the Gulf of Mexico. “If the virtual tower landing works, then we will actually try to come back on Flight 5 and land on the tower” at Starbase, he said, part of the company’s plan to quickly reuse Starship vehicles. “That is very much a success-oriented schedule, but it is within the realm of possibility.”

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