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SpaceX rolls Super Heavy booster to orbital launch mount
For the third time in four months, SpaceX has rolled the first potentially flightworthy Super Heavy booster towards Starbase’s orbital launch mount.
Combined with a large crane – fitted with a jig solely used to lift boosters – moving to a spot just beside the booster, it’s clear that SpaceX is preparing to reinstall Super Heavy Booster 4 (B4) on the orbital launch mount. In the context of its unusual history, though, what happens next to the first more or less finished prototype of the largest rocket booster ever built is less clear.
After a shockingly quick assembly over the course of six summer weeks, Super Heavy Booster 4 rolled out of Starbase’s ‘high bay’ facility and headed to the nearby orbital launch complex, where it was installed on a custom ‘mount’ designed to support booster testing and orbital launches. It’s now clear that during that early August photo opportunity and fit test, Booster 4 was nowhere close to finished. Nor, apparently, was it anywhere close to complete one month later when it returned to the orbital pad for the second time after another few weeks of work back at the high bay.
Three months (almost 14 weeks or 100 days) after the Super Heavy prototype’s second trip to the pad, SpaceX has yet to attempt to put the booster through a single proof test. There also appears to be a significant amount of work left to finish installing external ‘aerocovers’ and a heat shield meant to enclose all 29 of its Raptor engines. In the three-year history of Starbase, there isn’t a single prototype of the roughly two-dozen SpaceX has built, tested, and even flown that’s spent even half as long as Super Heavy B4 between apparent structural completion and its first test. Perhaps the fact that Booster 4 is a first-of-its-kind pathfinder explains SpaceX’s uncharacteristic sluggishness or reluctance to actually test the rocket.
In every other instance, SpaceX’s approach to Starship development has been to move incredibly quickly, build a large number of prototypes, and rapidly test those prototypes – often resulting in catastrophic failures. Data is gathered from those failures (SN1, SN3, SN4, SN8, SN9, SN10, SN11, and half a dozen smaller test tanks serve as examples), changes are made, and then the new and improved prototypes that follow repeat the process until SpaceX arrives at a successful design.
Super Heavy B4’s circuitous path has been almost nothing like those of its predecessors. That could also be partly explained by the unavailability of a stand or facilities capable of truly proof testing a Super Heavy, which necessitates a supply of around 3200 tons (7M lb) of liquid nitrogen (LN2; for a cryogenic proof test with full tanks), another 3200 tons of a combination of liquid methane (LCH4) and oxygen (LOx), and the ability to ignite – and survive – as many as 29 to 33 Raptor engines. The suborbital stands SpaceX has used to proof Starships and even Super Heavy Booster 3 don’t even have half the storage capacity required to fully test a booster and the mounts and their surroundings would likely be catastrophically damaged or destroyed by the thrust and blast created by dozens of Raptors.
Still, SpaceX could have theoretically put Booster 4 through a partial cryoproof and maybe fired up as many as nine Raptors at once – not a replacement for full proof testing but still plenty to ensure Super Heavy’s structural integrity and gather invaluable data on clustered Raptor performance. Instead, of course, Super Heavy B4 has sat at Starbase’s former landing zone for more than three months while teams removed engines, reinstalled engines, half-installed a full Raptor heat shield; and installed two of six or seven ‘aerocovers’ needed to protect heat exchangers, racks of pressure vessels, and hydraulic systems installed on the booster’s aft.
This is all to say that from the outside looking in, Booster 4’s path towards testing and flight has been almost entirely different from that of any other Starship prototype. While still quick in comparison with other launch vehicle development programs, relative to other Starship and Super Heavy prototypes, the rate of B4 progress has been far slower – strongly implying that something is seriously wrong with the booster, that SpaceX no longer feels that partial testing is worth the effort, that finishing Booster 4 just hasn’t been a priority for several months, or some combination of the above.
What that ultimately means is that it’s almost impossible to predict what Super Heavy B4’s future holds beyond the clear evidence that SpaceX will soon reinstall to reinstall it on an orbital launch mount that’s much closer to completion than it was the last time B4 was installed. At this point, it’s just as likely that the booster’s third launch mount installation will just be another mechanical fit test, though the hope is that it will kick off full-scale pneumatic and cryogenic proof testing. It could even culminate in the static fire of some or all of its 29 Raptor engines, which have been installed for several months.
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
