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SpaceX destacks “420” Starship, Super Heavy pair for the third time
Update: Shortly before SpaceX CEO Elon Musk revealed that Super Heavy booster B4 and Starship S20 are no longer assigned to the rocket’s orbital launch debut, the company ‘destacked’ the pair for the third time.
Ship 20 was removed from Booster 4 on March 19th, two days before Musk’s tweets. That’s not unusual: it was actually Ship 20’s third removal from Super Heavy. However, almost as soon as the Starship was rolled out of the way, SpaceX began making visible preparations to also remove Super Heavy B4 from Starbase’s orbital launch mount. As of March 24th, the booster has been attached to a large crane for more than a day and a newly upgraded transport stand has been rolled into place beside the launch mount. It’s somewhat odd that the booster hasn’t already been removed but that step could happen at almost any moment, now – albeit likely in daylight.
Once both Ship 20 and Booster 4 have been removed, it’s hard to imagine that they will ever return to the orbital launch mount. In fact, at minimum, Super Heavy B4 will probably be retired almost immediately. Super Heavy B7 – a superior, refined, and upgraded prototype by almost every measure – is already almost fully assembled and could likely begin basic testing within a week or two.
SpaceX CEO Elon Musk says that Super Heavy Booster B4 and Starship S20 are no longer scheduled to support the first orbital-class test flight of the world’s largest rocket.
Rumors, signs, and reports of the significant change have been flowing among unofficial spaceflight communities for months. Booster 4 and Ship 20 were first confirmed by Elon Musk to be the pair assigned to Starship’s orbital test flight (OTF) in the summer of 2021. When the pair first rolled out to the launch pad in early August, Musk seemed confident that they could be ready for an orbital launch attempt within a month or two. The same was true in November 2021, when Musk stated that the same Starship and Super Heavy pair could be ready for their first launch as early as January or February 2022.
Musk’s latest update on Starship’s orbital test flight continues that schedule optimism but also introduces several major changes – changes that could easily take several months to fully work through.
Crucially, Musk revealed that the first Starship to attempt an orbital-class launch will now feature upgraded Raptor V2 engines – engines that require an entirely new thrust structure design. That already all but guaranteed that B4 and S20 had been overtaken but Musk also explicitly confirmed that they would be replaced with a new pair in a later tweet.
That new pair – widely assumed to be Super Heavy B7 and Starship S24 – feature a wide range of design changes, including substantially modified header tanks, an entirely new nosecone design, new layouts for secondary systems (pressurization, avionics, heat exchangers, etc.), and more. Most importantly, their thrust structures – giant ‘pucks’ machined out of steel – have been tweaked to support new Raptor V2 engines instead of the Raptor V1 and V1.5 engines that have been installed and tested on all Starship and Super Heavy prototypes to date.
Musk believes that SpaceX will be able to build (and presumably qualify) all 39 of the Raptors Ship 24 and Booster 7 will need before the end of April and fully install them – as well as all the heat shield components that must be fitted around them – by the end of May 2022. It’s unclear if the SpaceX CEO is accounting for the extensive proof testing Ship 24 and Booster 7 will likely need to complete before being qualified for flight, including cryogenic proof tests, wet dress rehearsals, and at least a few static fire tests.
In fact, SpaceX has only performed a single three-engine static fire test with a fully outdated Super Heavy prototype. Before the company is confident in its booster design, it’s practically a certainty that one or more prototypes will be put through a lengthy test campaign that gradually evolves from igniting a few engines to igniting all 29 or 33 Raptors. That may actually be one of the reasons SpaceX appears to be retiring Booster 4 without a single static fire or flight test – performing all the requisite work may have ultimately been perceived as a dead-end when every future Starship and Super Heavy prototype will feature a heavily redesigned engine.
This is to say that much like Musk’s last few Starship OTF schedule estimates, May 2022 also appears to be extremely optimistic. Booster 7 could potentially be ready for cryogenic proof testing any day now but Ship 24 is still in five large pieces and probably at least a month from any form of test readiness. Still, there are some reasons for optimism. If Booster 7 actually does start basic proof testing this month or early next without waiting for its Raptor engines or for heat shield installation, SpaceX could theoretically complete cryoproofing, begin installing one or a few new Raptors at a time, and iteratively progress from static firing a few to all 33 engines as the engines are arriving at Starbase.
At a minimum, even if that razor-sharp test schedule isn’t possible, Booster 7 would at least have a month or so of extra testing over Ship 24, minimizing the disproportionate amount of testing each prototype will likely need to be qualified for flight. Unlike Booster 4, Ship 20 has completed several static fires and cryoproofs without any apparent issue.
For now, SpaceX continues to prepare Ship 24 sections for stacking and appears to be buttoning up Booster 7, which could easily be ready to roll out for basic testing within a few weeks – and maybe sooner.
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
