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SpaceX’s odd Starbase propellant storage tank prototype passes first test
Likely to the relief of many, SpaceX appears to have successfully tested a prototype of the custom-built Starbase propellant storage tanks that will eventually hold thousands of tons of fuel and oxidizer.
For reasons unknown, SpaceX’s built its first ground support equipment (GSE) ‘test tank’ – a subscale prototype designed to quickly verify basic production quality and design goals – months after it began mass-producing operational storage tanks. In fact, of the seven total GSE tanks expected to be built, SpaceX has already completed seven, installed five, and scrapped one. Known as GSE4, SpaceX actually used modified parts of that scrapped tank to assemble the GSE test tank that first rolled to Starbase’s launch (and test) facilities on August 23rd.
Two days later, SpaceX subjected the small tank to its first test.
Given that SpaceX appears to have almost retroactively assembled the GSE4 test tank after building the final products, the results from its testing were always going to be significantly more anxiety-inducing than any of the more than half-dozen other tanks the company has tested in the last year and a half. Having already fabricated, assembled, or even installed six of seven planned GSE tanks, the discovery of major issues during testing could potentially cause months of delays by forcing SpaceX to perform lengthy repairs or even fully scrap all six existing tanks and start over.
Thankfully, at least for the time being, it appears that SpaceX can write off those potential worst-case scenarios. On August 25th, SpaceX took advantage of a test window initially believed to be for Starship S20 and put the cobbled-together GSE4 tank through its paces for the first time. As with previous test tanks, all SpaceX can really do is fill the prototype with liquid nitrogen (LN2), a non-flammable alternative to liquid oxygen or methane propellant that is approximately as cold and heavy. As a storage tank prototype, though, GSE4 has no need for hydraulic ram setups used to simulate the thrust of Raptor engines on several previous prototypes.
As such, one or several cryogenic proof tests were all that were ever really in GSE4’s future. On GSE4’s first test, SpaceX performed a more or less normal cryogenic proof, completely filling the tank with LN2, closing its vents, and then allowing the natural process of LN2 boiloff to raise the tank to the desired test pressure. However, unlike other test tanks, GSE4 never actually appeared to reopen its main vents. In fact, SpaceX may have never actually drained liquid nitrogen from the test tank, instead simply letting it slowly warm up and boil off into gas that was seemingly managed and vented by ground systems instead of the tank itself.
As a result, GSE4 stayed frosty (indicating a significant amount of remaining liquid nitrogen) for more than eight hours, strongly implying that it was either very slowly drained or simply allowed to warm up naturally. Given that large cryogenic storage tanks really don’t have to be significantly pressurized to complete their job, it’s possible that GSE4’s first test was primarily meant to verify the basic structural integrity of a tank that’s slightly different than those on Starship and, more importantly, test a different method of pressure and fluid management where most of that work is done by external, permanent systems on the ground.
That’s exactly what one might expect of rocket tankage slightly modified to serve as ground storage tanks. SpaceX’s GSE tanks never have to act as self-contained units and can instead rely almost entirely on separate systems.
Aside from verifying that that slightly different method of tank operations works as expected, GSE4’s first test likely also allowed SpaceX to better characterize the thermal properties of the thin steel skin and domes that are Starship and GSE tanks. Unlike GSE4, operational GSE tanks will be enclosed inside 12m (~40 ft) wide ‘cryo shells’ designed to insulate their cryogenic contents, but the insulative properties of the inner tanks (or the lack there of, rather) will still determine how well that insulation works and how much is actually needed to reach the desired boiloff rates. A contractor hired by SpaceX has already completed all seven cryo shells, so any results gathered from GSE4 will obviously be more of a check than a developmental test, but data is still data.
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
