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SpaceX's Elon Musk works through holidays on Starship's "most difficult part"
SpaceX CEO Elon Musk says he has been working through the holidays at the company’s Boca Chica facilities to get Starship’s “most difficult part” ready for the next-generation spacecraft’s next prototype and flight tests.
Known as tank domes or bulkheads, Musk says that the hardware is the most difficult part of building and assembly Starship’s primary structure, referring to the steel engine section, tanks, and pointed nose that comprise most of the spaceship’s body. Starship’s primary structure must stand up to the rigors of all aspects of flight, including highly-pressurized propellant tanks, extreme G-forces during launches, orbital reentry, and more.
It was never officially determined whether the failure was intentional or not but during the first Starship prototype’s (Mk1) last test campaign, the vehicle experience an overpressure event while being filled with liquid oxygen or nitrogen. Localized to the weld connecting the upper tank dome to Starship’s cylindrical tank section, the dome essentially sheared off at the weld and launched hundreds of feet into the air, sending a shockwave through the vehicle that crumpled many of its steel structures as if they were aluminum foil.
It’s likely that Starship Mk1’s failure was an intentional overpressure event, meaning that SpaceX may have purposely pressed the vehicle’s tanks beyond their design limits to determine how structurally sound they were. What is less clear is whether the rocket burst before or after reaching its theoretical design limit.
For reference, SpaceX’s Falcon 9 rocket operates with its fuel and oxygen tanks pressurized to about 50 psi (3.5 atm) with localized pressures likely doubling or tripling near the bottom of both tanks during the first minute or two of launch. Some amateur back-of-the-envelope calculations from videos of Starship Mk1’s burst event suggest that it was pressurized to at least 60-75 psi (4-5 atm) at its upper tank dome, meaning that the pressure on its two lower domes and tank walls would have been even higher. If correct, those unofficial figures mean that Mk1 actually performed quite well considering the ramshackle facilities and unprecedentedly spartan methods used to fabricate and assemble it.
As such, Musk likely considers Starship’s tank domes the “most difficult part of [its] primary structure” in large part because of how difficult it is to make giant propellant tank domes simultaneously light and strong. Musk has previously implied that Starship Mk1 was more 200 tons (450,000 lb) empty while the ultimate goal for the spacecraft’s empty weight is closer to 120 tons, and a large portion of that weight savings will likely have to come from making its tank domes as light as possible.
In line with that educated speculation, the last month or so of SpaceX’s Starship work in Boca Chica, Texas has been marked by a distinct focus on building tank domes. In fact, Musk himself tweeted that he had worked all night with SpaceX engineers in Boca Chica in a bid to get dome production ready for Starship’s Mk3 prototype, the first Super Heavy hardware, and many more rockets to come.
Prior to Musk’s tweet, a Starship tank dome was actually shipped all the way from Florida to Texas and arrived earlier this month. Meanwhile, technicians have been briskly building up an additional dome using what appears to be a different method of integration involving new parts. SpaceX is currently attempting to weld Starship’s tank domes together from several dozen pre-formed sheets of stainless steel.
The sheets of steel assembled into the dome Musk showed on December 27th likely arrived in Boca Chica on December 13th, implying that SpaceX has managed to complete the majority of the first dome prototype – using a new process – in barely two weeks.
After SpaceX lifted the partially-completed dome off one of its custom assembly jigs, workers almost instantly began staging new sections of steel, beginning the process of integrating yet another tank dome – now likely the fourth on-site in Boca Chica. Meanwhile, at a nearby section of SpaceX’s Boca Chica production facilities, yet another dome was visible on the 28th. In short, SpaceX should soon have more than enough tank domes to complete the next Starship prototype – said to be a significantly improved and refined design compared to Mk1.
Known as Starship Mk3 (or Starship SN01), Musk says that the rocket – currently just a miscellaneous collection of separate parts – could (“hopefully”) be ready for its first flight as soon as February or March 2020.
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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.
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