Starship Survives Reentry, Completes IFT-4

SpaceX’s Starship-Super Heavy launch vehicle has completed its fourth Integrated Flight Test (IFT-4), lifting off from the company’s Starbase facility at 7:50 AM Central Time on Thursday, June 6th, 2024. IFT-4 achieved several striking successes for the system, including a splashdown of the Super Heavy booster, a controlled reentry of the Starship spacecraft, and a successful soft landing of Starship, despite significant damage during reentry. This major leap forward comes as pressure mounts on SpaceX to demonstrate technical milestones for the system.

The flight plan for IFT-4 was largely a repeat of the IFT-3 mission which flew in March of this year: a high-energy suborbital flight targeting reentry in the Indian Ocean. Ahead of the flight, SpaceX’s CEO Elon Musk expressed that the “primary goal” of IFT-4 was for Starship to survive the period of maximum heating during reentry. IFT-3 had ended with Starship breaking up after tumbling uncontrollably when it entered the atmosphere.

As with IFT-3, the Starship-Super Heavy stack completed a nominal ascent, albeit with one engine out on the booster, up through second stage cutoff. After separation, the Super Heavy booster completed its boostback burn to target a landing in the Gulf of Mexico. Super Heavy also performed the system’s first successful landing burn, culminating in a soft splashdown a few miles off the Texas coast despite losing another engine. Though this booster will not be recovered, the landing nevertheless marks a significant step towards the eventual reuse of the Super Heavy first stage.

The Starship spacecraft also improved its performance from the previous flight, maintaining a stable orientation in space and attempting its first controlled atmospheric entry. Starship demonstrated attitude control at hypersonic speeds using its unique body flap control surfaces, another major milestone for the system. Aerodynamic heating visibly caused severe damage to the vehicle, melting away a large portion of one of the spacecraft’s body flaps. Nevertheless, Starship retained control throughout the flight, ultimately reigniting its engines to achieve a soft landing in the Indian Ocean. This landing marks the first Starship landing since 2021, and the first time the Starship-Super Heavy system has successfully completed the flight plan first attempted on IFT-1 in April of 2023.

These major victories for SpaceX’s Starship come at a time of increasing pressure for the system to perform. Starship’s single biggest contractual obligation is its role as the Human Landing System for NASA’s Artemis III Moon landing mission, currently scheduled for September of 2026. Despite technical hurdles faced by the Orion spacecraft ahead of Artemis II, Starship readiness is a key schedule risk for Artemis III, running years behind its original milestone schedule. This risk has led NASA to consider altering the plan for Artemis III in case Starship is not ready to perform a landing in 2026. Still, NASA leadership has emphasized that any such changes are contingent upon SpaceX’s progress in the near future, and that Artemis III is still planned to include a landing for the time being.

Starship’s uncertain development timeline was also implicated in the cancellation of SpaceX’s dearMoon lunar tourism mission last week. The flight, publicly announced in 2018, would have seen billionaire Yusaku Maezawa and eight civilian passengers fly around the Moon in 2023. After being delayed indefinitely last year, the project’s cancellation marks the first time a former customer has abandoned Starship due to SpaceX’s failure to keep its own ambitious schedule. Though less consequential than its commitments to NASA, the event underscores the need for SpaceX to make progress with Starship if it hopes to meet the needs of its other customers.

Despite the challenges facing the program, today’s successful flight demonstrates that SpaceX is prepared to rise to meet them. The company’s arrangement with the FAA precludes the need for a mishap investigation ahead of the next flight, and with hardware for the next several flights in flow, SpaceX is well-positioned to forge ahead in its Starship development campaign. The turnaround time between test flights has been steadily decreasing since IFT-1 last year; that trend must continue in order to enable the cadence required for on-orbit refueling. At NAC HEO in April of this year, NASA noted that Starship’s first ship-to-ship propellant transfer demonstration, tentatively slated for 2025, will require launches just a few weeks apart. SpaceX have also recently resumed work on their Starship launch site in Florida, which will ultimately play a key role in allowing their flight rate to increase.

The success of IFT-4 marks a turning point for the Starship-Super Heavy system. With the basic launch and landing architecture proven for both stages, many ambitious milestones are yet to come, including both recovery and on-orbit operations. The road ahead is wide open – it is now up to SpaceX to demonstrate that they can keep up the momentum.