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SpaceX Starship prototype bears down on first Raptor engine tests
SpaceX’s fifth full-scale Starship prototype is fast approaching its first Raptor static fire tests after the company recently delivered one of the newest engines to the launch site.
Known as Starship SN5, the ship is the fifth SpaceX has built since full-scale prototype development began in early 2019, as well as the fourth full-scale ship the company has completed since it began producing upgraded hardware in January 2020. SN5 rolled from SpaceX’s Boca Chica, Texas rocket factory to nearby test and launch facilities on June 24th, less than a month after Starship SN4 was destroyed by operator error minutes after completing its fourth Raptor static fire in four weeks.
While Starship SN5 was already more or less complete, SN4’s explosive demise damaged the launch mount (used to secure and fuel prototypes) beyond repair, forcing SpaceX to rapidly build and outfit a replacement. SpaceX finished that replacement mount around June 20th, installed SN5 on it a few days later, and then spent about a week finalizing and inspecting both components.
After barely a month of downtime, Starship SN5 kicked off its first gauntlet of tests late on June 30th, carrying on into the early morning of July 1st. As usual, SpaceX began with an ambient-temperature pressure test, filling Starship’s tanks with neutral nitrogen gas to check for leaks. This time around, SN5 must have been put together with exceptional care, as the company was able to immediately proceed into the ship’s first cryogenic proof test just a few hours later.
CEO Elon Musk has yet to offer any confirmation but the implication is that SN5 performed beautifully during its first liquid nitrogen proof test. Notably, based on NASASpaceflight.com’s excellent unofficial coverage, SN5’s cryo proof was uniquely ambitious. It’s unclear what if the test infrastructure, SN5, general confidence in the vehicle, or some combination of the above components were upgraded, but SpaceX appeared to load Starship SN5 with liquid nitrogen incredibly quickly, taking just 20-30 minutes to fully fuel the rocket. Given that all of that liquid nitrogen (some 1000+ metric tons or ~3.2 million gallons) is being loaded through a single “quick disconnect” panel, it’s no mean feat and far outweighs SpaceX’s already speedy Falcon 9 and Heavy propellant loading.
SpaceX is famously the only current launch vehicle operator known to “sub-cool” its rockets’ propellant, effectively squeezing a performance boost of 5-10% out of the same rocket hardware by making said propellant colder – and thus denser. That performance increase comes with tradeoffs, though, adding significantly tighter operational constraints, lowering delay tolerances, and necessitating an extremely quick propellant load. Sub-cooled liquid oxygen and methane has always been part of SpaceX’s plans for Starship, so fast-load tests were inevitable, but it’s a great sign that the company is starting to seriously think about capabilities that will be necessary for efficient orbital launches.
Meanwhile, labeled “27”, the engine – logically assumed to be Raptor SN27 – SpaceX has just installed on Starship SN5 is also of interest. On top of Musk’s recent confirmation that SpaceX is already building Raptor SN30 (probably SN31 or SN32, now), SN27’s assignment to Starship SN5 confirms that the company has managed to complete (and test) at least one next-generation engines every other week since the first full-scale engine shipped to McGregor, Texas in February 2019.
For a brand new engine as complex as Raptor, that’s an impressive production milestone. Per Musk, the end-goal is to produce at least one Raptor per day in the near term – a necessity given that each Starship and Super Heavy booster pair will require at least 37 engines. To feasibly build a fleet of tens – let alone hundreds or thousands – of Starships and boosters, one engine per day is arguably the bare minimum required just for early orbital launch attempts and initial operations.
According to published schedules, Starship SN5’s first live wet dress rehearsal (WDR) and static fire tests could happen as early July 8th, with backups on the 9th and 10th. Coincidentally, SpaceX’s next orbital Falcon 9 launch is also expected on the 8th, meaning that both Starship and Falcon 9 could fire up more or less simultaneously.
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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
