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SpaceX Super Heavy tank prototype survives crush testing
A tank prototype similar to SpaceX’s next-generation Super Heavy rocket booster has survived a series of tests that repeatedly attempted to destroy it.
Known as Booster 7.1 or B7.1, the tank is the latest in a long line of ‘test tanks’ designed to verify the performance of Starship and Super Heavy and qualify new designs and manufacturing techniques without risking an entire upper stage or booster. In general, that means that test tanks are as minimal as possible and much shorter than either Starship stage, but they’re also assembled out of nine-meter-wide (30 ft) steel barrels and domes almost identical to the sections that make up Starship and Super Heavy.
For most of the duration of SpaceX’s steel Starship program, ‘test tank’ work has followed a fairly consistent and linear development path, where tanks were used to verify design changes before those changes were implemented on more expensive prototypes. B7.1 firmly ignored that norm.
While it’s not an exact match, the tank – built out of two stacked rings and dome sections and measuring about 11 meters (~36 ft) tall – has a Super Heavy thrust structure (where Raptor engines would attach) and external stiffeners known as stringers that are (mostly) exclusive to Starship boosters.
As its name suggests, B7.1 shares many of the significant design changes that SpaceX had already implemented on Super Heavy Booster 7 (B7). The company began testing B7 months before B7.1, subjecting the full-size booster to multiple cryogenic proof tests and Raptor thrust simulation testing to qualify its new thrust ‘puck’ and several other structural changes. SpaceX began testing B7.1 in late June, shortly before Super Heavy Booster 7 was damaged by an unplanned explosion that halted its first Raptor engine test campaign. B7.1 testing then restarted in mid-July and was completed by the end of the month.
For unknown reasons, SpaceX’s decision to build and test Booster 7 before B7.1 meant that any significant issues discovered during subsequent B7.1 testing could disqualify the booster for flight testing, potentially wasting the months of work and tens of millions of dollars already invested in the prototype. Ultimately, though, B7.1 appeared to sail through multiple cryogenic proofs and crush tests without any catastrophic issues. Only on the last crush test did any part of the test tank finally give way, and the resulting damage was minor.
B7.1’s testing made use of a relatively new two-piece stand. The tank was first installed on a sturdy base using clamps similar to those on the Starbase orbital launch site’s (OLS) launch mount. Then, a hat-like structure was placed on top of the tank, resting on the surface that a Starship upper stage would sit on during launch. Massive ropes were finally dropped down to attach to hydraulic cylinders on the base. Once B7.1 was loaded with benign cryogenic liquid nitrogen (LN2), replicating most of the thermal and mechanical stresses of real oxygen/methane propellant, the hydraulic cylinders retracted, pulling the cap down to evenly exert massive crushing forces down the vertical axis of the test tank. Simultaneously, additional rams installed underneath B7.1 may have simulated the thrust of 13 central Raptor engines.
It’s unclear what exactly SpaceX was testing. The goal of the test could have been as simple as verifying that Super Heavy Booster 7 can withstand the weight of a fully-fueled Starship (~1350 tons / ~3M lb) sitting on top of it. It could have also been used to simulate an entire orbital launch from Super Heavy’s perspective, replicating many of the forces Starship boosters will experience between liftoff and landing. Given that Booster 7’s upgraded thrust puck had already made it through stress testing, B7.1 didn’t have much to add there, but it may have been useful for estimating the compressive strength of the current Super Heavy booster design.
Regardless of what B7.1 did or didn’t prove, it did so with very little drama. After four long days of testing, at least two of which involved attempting to crush the tank, the only truly noteworthy visual event was evidence of a slight buckle near the top of the tank during its last crush test. A few days later, with the test stand ‘cap’ removed, B7.1 survived one final test in which SpaceX likely attempted to pressurize the tank until it burst. Instead, the tank didn’t so much as develop a leak, reiterating – contrary to their occasional tin-can-like appearances – just how sturdy Starship and Super Heavy really are.
With nothing more to give, SpaceX will likely scrap B7.1. Meanwhile, Super Heavy Booster 7 remains stuck inside one of SpaceX’s Starbase assembly bays after being forced back to the factory by unintentionally explosive testing. The fate of that booster is unclear but SpaceX has removed all or most of its 33 Raptor engines over the last few weeks while simultaneously expediting work on Booster 8, which may ultimately take B7’s place.
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
