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SpaceX Super Heavy booster assembly to start “this week,” says Elon Musk
CEO Elon Musk says that SpaceX is on track to begin fabricating Starship’s first Super Heavy booster prototype later “this week” and even revealed plans to hop that booster in the very near future.
Taller than an entire two-stage Falcon 9 or Falcon Heavy rocket, Super Heavy will be the largest and most powerful liquid rocket booster ever built by a factor of two (or more). Measuring ~70m (~230 ft) tall, Super Heavy will weigh at least 3500 metric tons (7.7 million lb) when fully loaded with liquid oxygen and methane propellant. According to Musk, SpaceX’s thrust target for the booster is 7500 tons (~16.5 million lbf) – significantly more than twice the thrust of the Saturn V and Soviet N-1 rockets and more than three times the thrust of SpaceX’s own Falcon Heavy.
On paper, while multiple times larger and more powerful, Super Heavy will be substantially simpler than Falcon Heavy thanks to its single-core. Built out of the same simple steel rings used to assemble Starship prototypes, Super Heavy should also be substantially cheaper to build than Falcon Heavy. Thanks to the experience SpaceX has already gained through months of Starship production, testing, and iterative improvement, initial Super Heavy prototype production could have a much smoother start, but several major challenges remain.
SpaceX has structured its Starship development program in such a way that the hardest technical challenges are generally first in line. Raptor engine testing came first in September 2016, although SpaceX did simultaneously build and test a full-scale carbon composite liquid oxygen – a material choice that was ultimately made redundant by the move to steel in late 2018. Up next, Starhopper served as a sort of proof of concept for the assembly of a flightworthy steel rocket in an unprotected open-air tent.
Starship Mk1 came next and was built as a full-scale prototype in similarly spartan conditions – but with much thinner steel. Mk1 ultimately failed prematurely, serving as a catalyst for SpaceX to substantially upgrade its South Texas rocket production capabilities, as well as its manufacturing techniques. Beginning in January 2020, SpaceX completed a rapid-fire series of tests with three stout tank prototypes and five full-scale Starship tank sections over the next seven months, passing multiple challenging pressure tests, wet dress rehearsals, Raptor static fires, and even a 150m (500 ft) hop.
The biggest challenges still facing Starship (5+ minute Raptor burns, skydiver-style landings, heat shield qualification, orbital launch/reentry/reuse) are mostly unique to the orbital spacecraft. In other words, with all SpaceX has already accomplished so far with Starship development, it could very well be ready to build a fully-capable Super Heavy prototype right now.
Along those lines, Musk says that there’s a chance that SpaceX will be ready to hop a Super Heavy booster prototype as early as October 2020 – less than two months after the first prototype enters production. Musk also noted that the biggest technical challenge facing Super Heavy is its extraordinarily complex ‘thrust puck’ – a metal structure that must host up to 28 Raptor engines and transfer all of their thrust through the rest of the rocket.
Per past comments, SpaceX will begin booster testing – possibly up to and including the first few orbital launch attempts – with as few Raptor engines as possible. For Musk’s aforementioned booster hop test, Super Heavy could reportedly hop with as few as two Raptors installed. Beyond those early tests and Super Heavy thrust puck development, perhaps only other challenge facing SpaceX is finalizing Raptor’s design to the point that dozens of engines can be built in short order. As of now, SpaceX has completed 40 Raptor prototypes in 18 months, while every Starship/Super Heavy pair will need as many as 34 engines apiece.
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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 launched the all-electric, steering wheel-less, and pedal-less Cybercab last night at a quiet and small event in downtown Austin, Texas.
The launch, which marked the beginning of unsupervised ride-hailing for Tesla’s Robotaxi platform with Cybercab, has already caught the attention of the National Highway Traffic Safety Administration (NHTSA) who has more questions.
NHTSA opened an Audit Query (AQ) into the Cybercab’s Federal Motor Vehicle Safety Standards (FMVSS) certification that Tesla gave the vehicle. Manufacturers self-certify vehicles much of the time to avoid excessive regulatory delays.
Tesla Cybercab interior, note the lack of steering wheel and pedals. (Credit: @niccruzpatane/X< /a>)
However, the agency needs more information; it said in a summary:
“On September 3, 2026, Tesla began commercial deployment with a small number of its Cybercab vehicles in Austin, Texas. Tesla notified the Agency that it certified those Cybercab vehicles as compliant with all applicable Federal Motor Vehicle Safety Standards (FMVSS). Tesla also notified the Agency that it plans to gradually expand commercial deployment of the Cybercab to include additional vehicles and locations.”
It also went on to state that the Cybercab lacks traditional automotive controls, which is a groundbreaking move. The process is entirely new to the NHTSA, which gives the agency some leverage to put Tesla’s launch under a microscope:
“The vehicles lack permanently attached, conventional manual controls, such as a brake pedal, gas pedal, steering wheel, and mirrors. NHTSA is opening this AQ to examine the process and technical data on which Tesla relied when certifying the Cybercab and related issues. Among other things, NHTSA will consider the extent to which Tesla’s certification depended on determinations that certain FMVSS are inapplicable to the Cybercab.”
Tesla has added 45 Cybercab units to its fleet of Robotaxi-enabled cars in Austin, according to public documents the company submitted to the State of Texas over the past week. Enabling this level of self-driving is something Tesla has worked toward for many years, and now that it is finally here, it seems more than reasonable that regulatory agencies will have some questions.
Many outlets might try to frame this as a negative, but it is truly an agency looking to gain more information about groundbreaking tech that Tesla has been developing for years.
In an effort to keep riders, pedestrians, and property safe, any and all data accumulated from these first days, weeks, and months of rides will likely be shared with the NHTSA to enable broader rollout strategies across the United States and more in the future.
Tesla Robotaxi will be a 24/7 service: here’s when
Tesla Full Self-Driving will now overtake manual driving to avoid disaster
