SpaceX Describes Lessons from Starship Flight 3 and Sets June 5 as Target Launch Date for Flight 4 – Spaceflight Now

Cameras aboard the spacecraft’s upper stage, flown during Flight 3 (Starship IFT-3), show the vehicle surrounded by plasma as it reenters the atmosphere on March 14, 2024. Image: SpaceX

SpaceX is preparing to launch its massive Starship rocket on its fourth test flight from its Starbase facilities in south Texas as soon as June 5. The target launch date comes just under three months after Flight 3 on March 14.

In a pair of posts on its website, SpaceX outlined the lessons learned from Flight 3, the mission objectives for Flight 4, and the differences in the timing of everything between these two parts of the development campaign.

Flight 4’s launch window is scheduled for June 5 at 7 a.m. CDT (8 a.m. EDT (12 p.m. UTC). However, as SpaceX points out, they are still waiting for regulatory approval from the Federal Aviation Administration (FAA).

On this final go-around, SpaceX will not attempt some of the additional flight items it attempted during Flight 3, such as operating the payload bay door or reigniting the vacuum engines on the upper stage.

“The fourth flight test shifts our focus from reaching orbit to demonstrating the ability to return and reuse Starship and Super Heavy,” SpaceX said in a statement. “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.”

Lesson learned

In a blog post, SpaceX outlined some items from Flight 3 that went as planned and others that led to the accident. One of the successes was completing a propellant transfer demonstration, which involved “moving liquid oxygen from a main tank to the main tank.”

“This test provided valuable data for the eventual ship-to-ship transfer of propellant, enabling missions such as returning astronauts to the moon under NASA’s Artemis program,” SpaceX said in a statement.

Similar to Flight 2, Flight 3 also saw a successful ascent of the rocket through stage separation. Building on that second flight, the most recent flight also saw the Starship’s upper stage make a full ascent.

However, during Flight 3, SpaceX said a blocked filter “where liquid oxygen is supplied to the engines” on the Super Heavy booster “caused a loss of intake pressure in the engine oxygen turbopumps.” It said this is likely the cause of an early shutdown of six of the 13 Raptor engines used during the boostback burn.

SpaceX’s Starship rocket will launch for the third time in program history on Thursday, March 14, 2024. Image: Adam Bernstein/Spaceflight Now

When it came time for the landing burn, the six engines that were shut down prematurely were shut down and of the seven remaining engines, only two were determined to successfully reach ‘mainstage ignition’.

“The booster had a lower than expected landing force when contact was lost approximately 1,500 feet (462 meters) above the Gulf of Mexico just under seven minutes into the mission,” SpaceX explained.

SpaceX said more hardware improvements are coming to the oxygen tanks for the Flight 4 Super Heavy booster and those beyond “to further improve propellant filtration capabilities.” They will also add new hardware and software “to increase the start-up reliability of the Raptor engines under landing conditions.”

During its return from space, the Starship’s upper stage suffered from a lack of attitude control as the rocket began to unintentionally roll, resulting in “the ship seeing much greater than expected heating in both protected and unprotected areas .”

“The most likely cause of the unplanned roll was determined to be clogging of the valves responsible for roll control,” the company said. “SpaceX has since added additional roll control thrusters to upcoming spacecraft to improve attitude control redundancy and upgrade hardware for better stall resistance.”

Timeline adjustments

In addition to some changes to the hardware and software, keen-eyed observers of mission timelines will also notice some other important differences. One of the notable changes before launch concerns the fueling process.

During Flight 3, SpaceX began loading the spaceship’s upper stage with liquid oxygen, first at T-53 minutes, followed by loading liquid methane onto the ship two minutes later. Flight 4 reverses that and first carries liquid methane at T-49 minutes and then liquid oxygen two minutes after that.

Similarly, Flight 3 with the Super Heavy booster began loading liquid oxygen at T-42 minutes and then liquid methane a minute later. Flight 4 starts with liquid methane at T-40 minutes and then with liquid oxygen three minutes after that.

SpaceX hasn’t given a reason for the reversals in the fueling process, but they have done quite a bit of work to modify the storage tanks for both the liquid oxygen and liquid methane in the tank farm near the platform. The vertical tanks have been replaced by horizontal tanks in recent months as part of the work on the ground systems.

All told, Starship’s refueling timing will be about four minutes shorter than the last flight. It also only takes about 11 minutes longer than it takes to fully fuel a Falcon 9 rocket.

The launch timeline has also been slightly adjusted. While the end of the mission, coupled with “An exciting landing!” remains at approximately the same time (in the ballpark of 1 hour and 5 minutes), largely streamlining Flight 4 by removing some of the additional flight targets.

However, three major events have been added to the timeline: one near launch and two near the end of the mission.

After the Super Heavy booster performs the boostback burn, just before the four-minute mark, SpaceX will jettison the hot-stage adapter, which was added between Starship’s first and second flights.

SpaceX said they are doing this “to reduce booster mass for the final stage of flight.”

The other two events added in this next round include the so-called “landing flip” at T+01:05:38, followed by the landing burn five seconds later.

“Flight 4 will follow a similar trajectory to the previous test flight, with the Starship targeting a landing in the Indian Ocean,” SpaceX said. “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.”

Path to launch

As SpaceX noted on Friday, the target launch date of Wednesday, June 5 is subject to FAA approval. The SpaceX-led investigation into Flight 3 accidents remains ongoing, but the company hopes to use a pre-existing approval mechanism within FAA rules to resume flying before the investigation is fully concluded.

“During Flight 3, neither vehicle’s automated flight safety system activated and no vehicle debris was impacted outside the predefined hazard areas,” SpaceX said. “Pending the FAA’s findings that there are no impacts to public safety, a modification of the permit for the next flight may be issued without formally closing the investigation into the accident.”

When reached for comment Friday, the FAA told Spaceflight Now that it had received SpaceX’s request for a public safety decision and if they agree, SpaceX could in fact fly while the investigation into the accident continues .

“The FAA is responsible for and committed to protecting the public during commercial space transportation launch and reentry operations,” the FAA said. “On April 5, SpaceX requested that the FAA make a public safety decision as part of the ongoing investigation into the Starship OFT-3 accident. The FAA is reviewing the request and will be guided by data and safety at every step of the process.”

A slide of the Human Landing System version of Starship, shown during a presentation this week by Logan Kennedy, NASA’s surface lead for the HLS program. Graphics: SpaceX/NASA

Launching as much and as often as possible is important for the development process of SpaceX and also for NASA. The rocket has been contracted to support a crewed landing on the moon’s surface during the Artemis 3 mission, currently scheduled for September 2026. A nearly one-year delay from the previous date of December 2025 was previously announced announced by NASA this year.

During a budget hearing with the Senate committee earlier this week, NASA Administrator Bill Nelson said they are closely monitoring Starship’s development as Flight 4 approaches.

“Artemis 3, if you compare it to the Apollo program, is a combination of Apollo 9, 10 and 11, which was the moon landing, and part of Apollo 8 that orbited the moon 10 times,” Nelson said. “It is a difficult task and when we land it will depend on SpaceX having its lander ready.”

“Now they’ve achieved all their milestones and in a few weeks they’re going to launch that huge rocket with 33 Raptor engines in its tail, and they’re going to do even more to show its spaceworthiness. Nelson added. “I hope SpaceX will be ready with their lander.”

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