SpaceX is having trouble with Starship’s upper stage after back-to-back failures, but engineers are making remarkable progress with the rocket’s enormous booster.
The most visible sign of SpaceX making headway with Starship’s first stage—called Super Heavy—came at 9:40 am local time (10:40 am EDT; 14:40 UTC) Thursday at the company’s Starbase launch site in South Texas. With an unmistakable blast of orange exhaust, SpaceX fired up a Super Heavy booster that has already ne to the edge of space. The burn lasted approximately eight seconds.
This was the first time SpaceX has test-fired a “flight-proven” Super Heavy booster, and it paves the way for this particular rocket—designated Booster 14—to fly again soon. SpaceX confirmed a reflight of Booster 14, which previously launched and returned to Earth in January, will happen on next Starship launch With Thursday’s static fire test, Booster 14 appears to be closer to flight readiness than any of the boosters in SpaceX’s factory, which is a short distance from the launch site.
SpaceX said 29 of the booster’s 33 methane-fueled Raptor engines are flight-proven. “The first Super Heavy reuse will be a step towards our goal of zero-touch reflight,” SpaceX wrote on X.
A successful reflight of the Super Heavy booster would be an important milestone for the Starship program, while engineers struggle with problems on the rocket’s upper stage, known simply as the ship.
What a Difference
Super Heavy’s engines are capable of producing nearly 17 million pounds of thrust, twice the power of NASA’s Saturn V rocket that sent astronauts toward the Moon. Super Heavy is perhaps the most complex rocket booster ever built. It’s certainly the largest. To get a sense of how big this booster is, imagine the fuselage of a Boeing 747 jumbo jet standing on end.
SpaceX has now launched eight full-scale test flights of Starship, with a Super Heavy booster and Starship’s upper stage stacked together to form a rocket that towers 404 feet (123.1 meters) tall. The booster portion of the rocket has performed well so far, with seven consecutive successful launches since a failure on Starship’s debut flight.
Most recently, SpaceX has recovered three Super Heavy boosters in four attempts. SpaceX has a wealth of experience with recovering and reusing Falcon 9 boosters. The total number of Falcon rocket landings is now 426.
SpaceX reused a Falcon 9 booster for the first time in March 2017. This was an operational flight with a communications satellite on a mission valued at several hundred million dollars.
Ahead of the milestone Falcon 9 reflight eight years ago, SpaceX spent nearly a year refurbishing and retesting the rocket after it returned from its first mission. The rocket racked up more mileage on the ground than it did in flight, first returning to its Florida launch base on a SpaceX drone ship and then moving by truck to SpaceX’s headquarters in Hawthorne, California, for thorough inspections and refurbishment.
Once engineers finished that work, they transported the booster to SpaceX’s test site in McGregor, Texas, for test-firings, then finally returned the rocket to Florida for final launch preparations.
There will be no such journey for the Super Heavy booster. First of all, it’s a lot more difficult to transport than the shorter, skinnier Falcon 9. Super Heavy’s design also features improvements informed by lessons learned in the Falcon 9 program. This helped SpaceX get the Super Heavy on the cusp of a reflight in less than three months.
You can watch a replay of Thursday’s static fire test in this video from NASASpaceflight.com.
With Starship and the Super Heavy booster, SpaceX should get more points for difficulty. Super Heavy is larger and has more engines than the Falcon 9, so theoretically, there are more things that could go wrong. And instead of touching down with landing legs at a separate location, SpaceX uses mechanical arms to catch Starship’s booster as it returns to the launch pad.
This approach should allow engineers to rapidly reuse Super Heavy boosters. Eventually, SpaceX will do the same with Starships returning from orbit.
Still Investigating
At the same time that engineers are taking steps forward with the Super Heavy booster, the other big piece of Starship is holding up SpaceX’s launch cadence in Texas. The upper stage, or ship, failed at roughly the same point in flight on SpaceX’s two most recent test flights in January and in March.
These test flights were the first use of an upgraded, larger ship known as Block 2 or Version 2. On both flights, Starship lost power from its engines and tumbled out of control roughly eight minutes after liftoff, breaking apart and dropping fiery debris near the Bahamas and the Turks and Caicos Islands.
The failures prevented SpaceX from testing Starship’s upgraded heat shield, one of the most significant upgrades introduced with Block 2. The plan for both flights was to send Starship on a trajectory through space halfway around the world, then perform a guided reentry over the Indian Ocean, targeting a pinpoint splashdown northwest of Australia. A successful reentry and splashdown at sea could give SpaceX officials confidence to attempt a full orbital flight of Starship, culminating in a catch at the launch site in Texas.
Instead, SpaceX repeated the same launch profile from the January mission on the following flight in March. The company will likely do the same on Flight 9, the next Starship launch.
SpaceX has closed out the investigation into the accident that cut short the January test flight, according to the Federal Aviation Administration. The FAA announced Monday that it accepted the results of SpaceX’s investigation, which determined the “probable root cause for the loss of the Starship vehicle was stronger than anticipated vibrations during flight [that] led to increased stress on, and failure of, the hardware in the propulsion system.”
Ultimately, the vibrations led to a fire in the engine compartment before the engines shut down and the vehicle lost control.
The FAA said SpaceX identified and implemented 11 corrective actions to prevent the same failure from happening again. Officials haven’t announced a probable root cause for the launch failure in March. The FAA said SpaceX’s investigation remains open. But the circumstances and timing of the failure suggest it could share a similar underlying cause.
Whatever the case may be, Starship’s back-to-back failures to start the year are a setback. Elon Musk, SpaceX’s founder and CEO, wanted the company to launch as many as 25 Starship flights in 2025. At this point, achieving half that number might be a stretch.
This means critical tests of the ship’s reentry and return to the launch site, in-orbit refueling capability, and the first Starship missions to deploy larger versions of SpaceX’s Starlink Internet satellites are on hold. Earlier this year, Musk suggested the Starship refueling demonstration would slip into 2026, which isn’t good news for NASA.
The US space agency has multibillion-dollar contracts with SpaceX to develop a version of Starship to land astronauts on the Moon’s south pole as part of the Artemis lunar program. For those missions, SpaceX must launch around 10 (the exact number remains unclear) Starship refueling flights to low-Earth orbit to top off the propellant tanks for the ship before it heads to the Moon.
This will require not just a thorough demonstration of SpaceX’s refueling architecture but also recovery and reuse of boosters and ships to maintain a launch rate fast enough to complete all of the refueling flights over a period of a few weeks to a few months.
SpaceX hasn’t released a schedule for the next Starship flight, but it’s probably at least a month away. The ship assigned to the next test flight is still in its factory at Starbase. Its next move will be to roll out to a test stand for its own engine firing, then SpaceX will likely move it back to the factory for inspections and finishing touches. Then, SpaceX will roll the ship to the launch pad, where crews will raise it on top of the Super Heavy booster in the final days before liftoff.
This story originally appeared on Ars Technica.
