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Here’s why SpaceX’s latest Starship rocket exploded after touchdown
In what has become a bit of a tradition, CEO Elon Musk has taken to Twitter again to explain the outcome of SpaceX’s latest Starship launch and landing attempt in more detail.
This time around, Musk’s debriefing comes after Starship serial number 10 (SN10) briefly became the first prototype of its kind to land in one piece – an extremely encouraging milestone for SpaceX. Less than 15 minutes later, though, an uncontrolled fire somehow breached the rocket’s stainless steel propellant tanks, resulting in a violent depressurization and explosion that tore Starship SN10 to pieces.
SN10’s momentarily successful landing came less than 30 days after Starship SN9’s own launch and landing attempt, which debuted a quick-fix design change meant to sidestep a different issue that caused Starship SN8 to fail shortly before touchdown last December. As it turns out, that design change – which SN9 never really had the chance to test – may have been Starship SN10’s downfall.
Starships must perform highly unusual maneuvers during their skydiver-style approach to atmospheric descent and the aggressive flip required to transition from that belly-down attitude into a propulsive vertical landing configuration. To enable those acrobatics, Starships need secondary ‘header’ tanks that permit the high-pressure storage of landing propellant.
Instead of having to maintain Starship’s building-sized main tanks at high pressures, header tanks make it far easier to safely store and feed propellant to Raptor engines. Most importantly, they help avoid prevent fuel flow interruptions or bubbles that can easily damage or destroy high-performance liquid rocket engines like Starship’s Raptors.
After Starship SN8’s last-second landing failure on December 8th, SpaceX concluded that low pressure in the liquid methane header tank was largely to blame. Normally pressurized with methane gas in a cutting-edge process called autogenous pressurization, SpaceX ultimately seemed to think that that process was the root cause and responded by adding an alternative helium pressurization workaround at the last second. Long-term, helium is not a viable solution as it’s virtually impossible to resupply in-situ (on the fly), meaning that any Starships reliant upon helium would find themselves stranded on the Moon or Mars.
Starship SN9 ultimately failed a few seconds earlier than Starship SN8 when one of its Raptor engines failed to ignite, precluding a true flight test of the helium pressurization fix. As it turns out, Musk believes that that very fix may have doomed Starship SN10.
As Starship SN10 forged ahead past the points of failure that killed SN8 and SN9, the SpaceX CEO thinks that one or more of the vehicle’s three Raptor engines began to ingest some of that helium pressurant as they emptied their methane header tank. As a result, engine thrust would have dropped below expected values, preventing Starship SN10 from slowing down for a truly soft landing. Instead, the Starship hit the ground traveling a solid 25 mph (~10 m/s), obliterating its tiny landing legs and damaging its skirt section.
It’s unclear if that hard landing was the sole cause of SN10’s subsequent explosion, as both official and unofficial webcasts of the launch appear to show a major fire starting well before touchdown and continuing to burn up to the point of failure. Regardless, Musk says that “multiple fixes” are in work for Starship SN11, which is currently speeding towards a launch attempt as early as next week. It remains to be seen if those planned “fixes” will delay SN11’s launch plans.
Tesla has reached a notable benchmark in its autonomous driving program after its Robotaxi fleet surpassed one million miles of unsupervised operation. The company made the announcement during its Cybercab event in Austin on September 3.
Tesla Vice President of AI Ashok Elluswamy told attendees he was happy to report the fleet had achieved one million miles of unsupervised Robotaxi operation as a testament to safety.
The new total marked a sharp increase from the 380,000 unsupervised miles Tesla disclosed during its second-quarter 2026 earnings update in late July.
In roughly six weeks, the company added about 620,000 miles. That acceleration followed Tesla’s decision to remove in-vehicle safety monitors from most of its operations outside the San Francisco Bay Area.
Credit: Tesla
Tesla first launched Robotaxi service in Austin in June 2025 with safety drivers present. It later began fully unsupervised rides and expanded into Dallas, Houston, Miami, Orlando, and Tampa. The San Francisco Bay Area remains the exception, where a safety monitor still rides in the vehicle under California permitting rules.
The company has not released a city-by-city breakdown of the one million unsupervised miles.
The milestone arrived as Tesla began offering public Cybercab rides in Austin. The purpose-built vehicle has no steering wheel or pedals and is designed only for autonomous ride-hailing. Production versions joined the existing fleet of modified Tesla vehicles already operating in the service.
Tesla’s unsupervised mileage is growing at a double-digit weekly rate according to earlier company comments, yet its fleet size remains modest compared with established competitors. Waymo has accumulated more than 200 million fully autonomous rider-only miles. Tesla has described its own unsupervised operations as having recorded zero notable incidents in the period leading up to the July update.
The one-million-mile figure reflects Tesla’s shift from supervised testing to broader driverless service in multiple states. It also highlights the company’s strategy of using both existing Model Y vehicles and the new Cybercab to scale its network.
Credit: Tesla
Whether the rapid recent growth continues will depend on further city expansions, regulatory approvals, and the performance of the purpose-built Cybercab in everyday paid rides. Tesla has not specified how many of the latest miles involved the new vehicle versus the rest of the fleet.
The announcement underscores Tesla’s progress toward a larger robotaxi network while illustrating the remaining gap in total autonomous experience relative to longer-operating rivals.
Tesla AI lead Ashok Elluswamy said this week that 24-hour Robotaxi service is close. Replying on X to a rider who wanted Cybercab trips all night, he wrote that the capability would arrive “next month or so” once “the next tech to merge on the v15 plan” is ready.
The comment landed on September 4, one day after Tesla opened public Cybercab rides in Austin. It is the clearest near-term timeline yet for overnight unsupervised operation. Tesla’s paid Robotaxi network currently runs from 6 a.m. to 10 p.m. seven days a week across Austin, Dallas, Houston, Miami, Orlando, and Tampa.
next month or so. the next tech to merge on the v15 plan will enable it.
— Ashok Elluswamy (@aelluswamy) September 4, 2026
That 16-hour window is shorter than the 6 a.m. to 2 a.m. schedule the company used for much of the prior year.
Elluswamy did not name the specific feature or say whether the change would apply first to purpose-built Cybercabs, the existing Model Y fleet, or both. He also offered no city-by-city rollout list. The link to Full Self-Driving v15 is nevertheless significant.
Tesla has described v15 as a step-change architecture with seven parallel improvement tracks and roughly ten times more parameters than earlier builds. Early versions of that software already operate on the Robotaxi fleet and contain about 40 percent of the planned gains.
By July 2026, the unsupervised fleet had logged more than 380,000 miles across six cities in two states with what the company called an impeccable safety record and no notable incidents caused by the vehicles themselves. Tesla has repeatedly argued that camera-based end-to-end neural networks, rather than extra sensors, are the core of the solution.
Overnight service would test that claim in lower-light conditions and would also raise vehicle utilization, a key variable for Robotaxi unit economics. The company has already begun using public Superchargers at night and is building dedicated Robotaxi charging sites.
Riders have asked why software must change if the cars already drive in the dark. The practical answer appears to be reliability and scale: Tesla has held back mass expansion until more of the v15 stack is merged, citing the need for higher confidence before putting thousands of unoccupied vehicles on streets around the clock.
If the next module arrives on the timetable Elluswamy sketched, 24-hour service could begin in October 2026 in at least some markets.
That would mark a shift from a daytime-bounded pilot to a service that can run whenever demand exists, including the late-night hours that have so far remained out of reach.
Tesla is beginning to roll out Full Self-Driving Supervised v14.3.9 with a new active safety layer that can take control even when the driver is operating the car manually.
Tesla AI said the software can activate FSD on the driver’s behalf when an imminent collision is detected and Automatic Emergency Braking may not be enough. It may also engage if the system detects heavy distraction or an accidental FSD disengagement.
FSD Supervised v14.3.9 starting to roll out shortly
This release includes a new active safety feature set: FSD Supervised can now activate on your behalf when an imminent collision is detected and Automatic Emergency Braking (AEB) may not be enough.
It may also engage if we…
— Tesla AI (@Tesla_AI) September 4, 2026
The capability is essentially Automatic Collision Evasion. However, unlike conventional AEB, which mainly applies the brakes in a straight line, this feature can use steering, braking, and acceleration together if the car calculates that stopping alone will not prevent impact and a safer path exists. The system may change lanes or move toward a shoulder when conditions allow, then continue driving after the immediate threat is handled rather than simply coming to a stop.
The intervention is meant as a last-resort safety net, not a replacement for attentive driving.
Tesla Full Self-Driving v14.3.7 early review: FSD saved me from an accident
Tesla’s own description still frames FSD as supervised assistance. Secondary reports on internal release notes say the feature can fire while the car is being driven manually if cabin-camera monitoring suggests the driver is not sufficiently attentive, such as reaching toward the back seat, or if FSD appears to have been turned off unintentionally.
After the emergency maneuver, the car is expected to alert the driver and request a return to manual control.
The safety case is straightforward. Many collisions happen in the last second because a driver is looking away, fumbles a control, or faces an obstacle that braking cannot fully solve. A system that can both recognize that AEB is insufficient and execute a coordinated evasive path can reduce those remaining high-severity events.
Re-engaging after accidental disengagement also addresses a practical failure mode: a small steering nudge that drops FSD at the worst moment. The advantage is a background safety net that uses the same vision stack already running in v14, instead of leaving the car solely to emergency braking once the driver is no longer in command.
The feature still depends on FSD being enabled and, according to reports, an active FSD purchase or subscription. It does not make the vehicle unsupervised. Drivers remain responsible, and Tesla has not published how often the system is expected to intervene or how it will handle false positives.
If the rollout is conservative and the false-alarm rate stays low, the update is a meaningful step: FSD is no longer only a feature the driver turns on. In the rare moments when disaster is already forming, it can step in.
Tesla crosses major Unsupervised Self-Driving milestone
Tesla Robotaxi will be a 24/7 service: here’s when
