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SpaceX tweaks Starship's Super Heavy rocket booster as design continues to evolve
CEO Elon Musk says that SpaceX continues to evolve the design of its next-generation Starship spacecraft and Super Heavy rocket booster, a process of continuous improvement the company has successfully used for a decade.
Designed to place more than 100 metric tons (220,000 lb) of payload into Low Earth Orbit (LEO), Starship would effectively double (and possibly triple) the expendable performance of SpaceX’s existing Falcon Heavy rocket. Critically, it would be able to dramatically outclass Falcon Heavy (and Falcon 9 even more so) in a fully reusable configuration, meaning that both the Starship upper stage and Super Heavy booster could be recovered and reused.
Since SpaceX first publicly revealed its next-generation launch vehicle and Mars ambitions in September 2016, the path to realizing the dream of a fully-reusable super heavy-lift launch vehicle has been decidedly windy. After making the radical decision to move entirely from carbon composites to stainless steel in late 2018, the Starship design has remained relatively similar, coalescing around a specific concept that has matured to full-scale tank tests. Now, Musk says that Super Heavy’s design was tweaked slightly to make the booster even taller than before, while he later noted that Starship’s design also continues to “[evolve] rapidly.”
According to Musk, the Super Heavy booster will be stretched by a steel ring or two, reaching a new height of ~70m (230 ft). In other words, Starship’s first stage alone will measure as tall as the entirety of a Falcon 9 or Falcon Heavy rocket – first stage, second stage, and payload fairing included. Powered by up to 37 Raptor engines, a Super Heavy booster could produce more than ~90,000 kN (19,600,000 lbf) of thrust at liftoff – an incredible 12 times as much thrust as SpaceX’s workhorse Falcon 9 rocket.
Starship, meanwhile, will be a beast of an orbital-class upper stage on its own, measuring at least 50m (165 ft) tall and weighing some 1350 metric tons (3 million lb) fully-fueled. Stacked on top of Super Heavy, a Starship ‘stack’ would reach a staggering 120m (395 ft) and weigh more than 5000 metric tons (11 million lb) once loaded with liquid oxygen and methane propellant.
In simple terms, Starship/Super Heavy should be the tallest, heaviest, and most powerful launch vehicle ever assembled once it heads to the launch pad for the first time. While SpaceX is making great daily progress its ever-growing South Texas rocket factory, built up from next to nothing in a matter of months, it could still be quite some time before that milestone is within reach.
SpaceX’s process of continuously tweaking and improving the design and production of its rockets does typically have that effect. However, it’s more a symptom of the company’s approach to hardware and software development. Instead of working slowly and carefully from nothing to a preconceived finished product, SpaceX typically seeks to design, build, and test the minimum viable product, gradually improving (or entirely replacing) past ideas, designs, and hardware until overarching goals are fully achieved.
With Falcon 9 and Falcon Heavy, this meant beginning with Falcon 1, a dead-simple proof-of-concept rocket. After successfully reaching orbit, SpaceX expanded its Falcon 9 development program, itself focused initially on the minimum viable product – a full-scale expendable rocket. Since Elon Musk founded SpaceX in 2002, the goal has always been to build a fully-reusable rocket – the company has simply chosen the far more sustainable and practical approach of tackling only a select few problems at a time.
The Starship and Falcon development programs aren’t directly comparable but it’s safe to say that Starship is currently still in the very early stages of hardware development. Shortly after revealing Super Heavy’s height growth, Musk noted that Starship’s design is also being tweaked.
Sketching out a rough series of upgrades that could feasibly be made to the reusable spacecraft’s currently design, Musk thinks that Starship’s conical tank domes (and thus Super Heavy’s, too) could be flattened. That might allow an extra ~3m (10 ft) of propellant tank space to be squeezed into the same 50m Starship length, improving performance by simply using the vehicle’s fixed volume more efficiently.
With a nascent factory quite literally churning out Starship hardware, these tweaks are a whole different animal. Thanks to data and insight gathered from testing actual full-scale Starship tanks, up to and including fully-assembled tank sections, SpaceX will be able to guide its continuous improvement with even greater precision, honing in on the next-generation rocket’s orbital launch debut.
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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
