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SpaceX’s fourth Starship prototype has begun to take shape in Florida
SpaceX’s Florida Starship team appears to have taken the first step towards assembling Starship Mk4, the fourth full-scale prototype of the next-generation spaceship.
Although SpaceX’s Boca Chica, Texas Starship campus is undeniably in the lead with their first prototype, Starship Mk1, it appears that the company’s Florida campus is far ahead of Texas with their second Starship prototype.
At the moment, SpaceX has set up two separate Starship build teams in Florida and Texas with the intention of creating a sort of internal competition to see which group’s Starships are first to flight and first to orbit. For the most part, it’s assumed that this “competition” is less a fight to the finish line than it is an A/B test, a common software development practice in which separate teams pursue different methods of achieving the same goals.
In the likely event that SpaceX is performing a radical form of A/B testing with rocket prototypes, both teams are continuously sharing best-practices and lessons-learned as they work to find the best possible methods for fabricating hardware and assembling Starships. Nevertheless, in A/B testing, fundamentally different approaches also tend to result in development schedules and final products that are unique, even if the end results are similar.
In the context of Starship, this is exactly what can be observed at SpaceX’s Florida and Texas facilities. Similarities abound in the radical method of en plein air manufacturing being implemented, while the Starship Mk1 and Mk2 hardware being built and assembled are also relatively similar, even if they have some distinct characteristics.
For example, it’s been observed that Starship Mk2 has almost certainly been constructed out of steel rings that are significantly taller than those used to assemble Starship Mk1. Taller rings meant that Mk2 needed fewer overall rings to reach the same height as Mk1, a fact that likely contributed to the impressive speed with which SpaceX’s Florida team was able to stack and weld most of Starship Mk2’s aerostructure.
Star(ship)fleet
According to SpaceX CEO Elon Musk, those similarities (and slight differences) are likely to continue for at least several more generations of prototypes. At a September 28th presentation and update on Starship, Musk revealed his opinion that Starship could be ready for its first orbital test flight(s) as few as six months from then – sometime in Q2 2020, give or take. To get there, Musk estimated that at least 5-6 Starship prototypes would need to be built in the interim.
Starship Mk3 will be built in Texas – in fact, the first ‘seamless’ steel ring may have already been fabricated at SpaceX’s Boca Chica facilities. According to Musk, Starship Mk4 will be SpaceX Cocoa’s second prototype. Based on John Winkopp’s October 17th drone overview, it appears that SpaceX’s Florida team has mounted the first steel Starship Mk4 ring atop a new work mount, potentially marking the start of Starship Mk4 assembly.
SpaceX’s Texas team has prepared at least one full-scale sample of a single-weld (‘seamless’) steel ring, perhaps the start of Mk1’s successor, Starship Mk3. Meanwhile, SpaceX Cocoa – seemingly at some kind of impasse with the final integration and assembly of Starship Mk2 – has churned out a huge number of similarly smooth steel rings, to the extent that Teslarati previously (and incorrectly) surmised that the first Super Heavy booster was being fabricated.
During Musk’s September 28th presentation, he effectively confirmed that the almost two-dozen steel rings hanging out on SpaceX’s Cocoa, Florida campus were almost certainly the beginnings of Starship Mk4. However, given the sheer number of rings present (23), the reality is that what could be the entirety of Starship Mk4’s cylindrical tank and thrust structure section is probably sitting outside in Florida, waiting to be stacked. Altogether, those 23 rings could reach a height of more than 40m (130 ft), potentially more than is actually needed for a Starship tank section.
Last but not least, local photographer and spaceflight fan Jon Van Horne captured what looks like a new Starship tank dome in work at SpaceX’s prospective Kennedy Space Center (KSC) build site, known as Roberts Rd. Given that Starship Mk2 already has two domes installed and a third and final dome staged and ready for installation, this fourth dome is very likely the first for Starship Mk4.
In short, SpaceX’s Florida team is probably weeks ahead of Boca Chica in the process of building a second full-scale Starship prototype. Of course, the ultimate winner of this mock competition isn’t Florida or Texas, it’s SpaceX’s Starship program as a whole.
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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
