What’s the point of building the world’s most powerful rocket if you can’t bring it back in one piece? That’s the question that has hung over SpaceX’s Starship program in 2025 as the company readies its 10th integrated test flight on Aug. 24 from Starbase, Texas. The engineering rides this time are higher than ever.
The Super Heavy booster, tail number B16, rolled to the pad Aug. 21, its stainless steel skeleton shining in the South Texas sunlight. At 232 feet tall, the booster contains 33 methane-fueled Raptor engines, with each engine capable of generating more than 500,000 pounds of thrust. Sitting atop it will be Ship 37, the 171-foot-tall upper stage fueled by six Raptors three sea-level-optimized and three vacuum-optimized for space flight. Combined, they create the biggest and strongest launch vehicle ever constructed, and it is completely reusable.
The Raptor engine itself is a centerpiece of SpaceX’s propulsion strategy. Using a full-flow staged combustion cycle, it burns liquid methane and liquid oxygen at extremely high pressures, enabling greater efficiency and reusability potential. Following the hardware failure in Flight 8 where a center Raptor’s inadvertent propellant mixing and ignition cascaded into total vehicle loss SpaceX implemented additional preload on key joints, a nitrogen purge system, and propellant drain improvements. Future iterations, dubbed Raptor 3, are expected to integrate further reliability upgrades.
For Flight 10, the launch process will once more depend on the orbital launch tower’s “chopstick” arms, an enormous automated system that can hoist and pile up the two stages. The system is being developed not just for assembly but ultimately to catch back the returning boosters, obviating the use of landing legs. No catch attempt will be made on this mission, but information gleaned from booster landing burns will drive that future capability.
The mission profile is aggressive. Following stage separation, B16 will execute a controlled descent to the Gulf of Mexico, testing a landing burn beginning with a middle ring engine before shifting to two center engines. The test is designed to prove redundancy in the event of center engine failure. SpaceX engineers also intend to hover the booster over the ocean prior to splashdown, a maneuver aimed at smoothing precision control during terminal descent.
Ship 37’s goals are similarly essential. The second stage will try to deploy eight Starlink simulators flat payloads the same size as the next third-generation satellites and reignite a Raptor in orbit, achievements the previous three flights have been unable to accomplish. It will also perform reentry tests, including testing smoothed and tapered edge heat shield tiles to counteract hot spots, and testing other materials like metallic tiles with active cooling. The reentry trajectory is purposefully aggressive, loading the rear flaps to their structure at peak dynamic pressure.
The engineering issues are not hypothetical. Flight 9 was brought to an end when a fuel tank pressurization diffuser in the second stage failed, causing methane to leak into the nosecone and attitude control loss. The diffuser function to keep hot pressurization gas from directly striking liquid fuel or tank walls is crucial for stable tank pressures. SpaceX has since strengthened inspection procedures and optimized diffuser design to avoid repetition.
The program has also experienced ground test glitches. Ship 36 exploded in June during an attempt to conduct a static fire because of damage to a composite overwrapped pressure vessel (COPV) that held gaseous nitrogen. This led to reduced operating pressures, increased proof testing, and protective covers for COPVs. To preclude delays, SpaceX adapted the Orbital Launch Mount to enable static fire testing on the pad, avoiding the damaged Massey test facility.
NASA is waiting with bated breath. The agency’s Artemis 3 lunar landing mission hinges on a future variant of Starship that can perform on-orbit cryogenic propellant transfer a milestone now slated for fiscal year 2026. “The key milestone that we are watching for, and everyone is watching for, is when they will be able to demonstrate the cryogenic propulsion transfer,” Lori Glaze, NASA’s acting associate administrator for Exploration Systems Development, testified in July.
In spite of frequent losses of the upper stage in 2025, leadership at SpaceX is still optimistic. Acting NASA head Sean Duffy, following meetings with company executives, said, “They feel very comfortable on Starship, they feel like they’re on pace with the lander, on track, so they feel very good. They said if there’s a hold up for Artemis 3, it’s not going to be them.”
If Flight 10 achieves success in both booster and ship splashdown, it will be the first time a Block 2 Starship upper stage executes its intended mission profile a key milestone towards the vehicle’s ultimate objective: quick, reusable access to orbit and beyond.
