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SpaceX’s first orbital Starship rocket engine is almost ready for testing
CEO Elon Musk says that SpaceX is “about a month away” from testing a rocket engine that will be essential for Starship and its Super Heavy booster to reach their full potential.
Known as Raptor Vacuum, the engine – as its name suggests – is a variant of the base Raptor engine optimized for maximum performance and efficiency in the vacuum of space. Although Starship could technically still function and likely reach orbit with only sea level-optimized Raptors installed, it would likely significantly limit the amount of payload it could carry into Earth orbit and would especially harm the ship’s performance to higher orbits and other planets.
Back in May 2019, Musk revealed that SpaceX had shifted gears again, forgoing a plan to begin orbital Starship flight operations with only sea level Raptors, gradually designing and phasing in RaptorVac engines much further down the road. Instead, SpaceX restarted (relatively) urgent work on the vacuum variant and Musk hinted that it would “aspirationally” be ready to support launches in the near term. A few weeks shy of a year later, Musk says that Raptor Vacuum testing could begin as early as June 2020.

For a variety of reasons, even if based directly off of an existing design, vacuum-optimized engines are typically much more complex than a comparable sea level variant. While efficiency is always relatively important for rocket engine design, it becomes even more paramount when dealing with vacuum rocketry, as the entire point of a dedicated vacuum-optimized engine is to eke as much efficiency as possible out of a launch vehicle’s orbital stage(s).

For example, even from a purely visual perspective, Merlin Vacuum (MVac) is substantially different when compared to the Merlin 1D engine it’s based on. Due to a number of major and largely unknown differences, the engines’ shared components are largely invisible. It’s unclear how similar they are but it’s safe to say that they share at least ~50% commonality. Obviously, the most apparent part of the difference between a vacuum-optimized engine and an atmosphere-optimized engine is the bell nozzle: MVac has a nozzle that is dramatically larger than M1D.
Raptor will be no different, with the sea-level variant featuring a nozzle about 1m (3.2 ft) in diameter, whereas RaptorVac’s bell will have a diameter closer to 2.5m (~8 ft). With SpaceX’s apparent May 2019 pivot back to working on RaptorVac now, the company has been working on a dedicated vacuum variant of the high-performance methane-oxygen engine for at least a full year. Now, perhaps beginning as early as June or July, Musk suggests that the first RaptorVac engine (SN0? SN1?) is almost ready to commence static fire testing.



The nature of that testing is a bit of a mystery. While it will almost certainly occur at SpaceX’s McGregor, Texas test and development facilities, it’s unclear if Raptor Vacuum’s first static fire test campaign will be attempted with the engine’s extended nozzle installed. Back in October 2019, Musk suggested that yes, Raptor Vacuum version 1.0 would have a nozzle small enough to operate at sea level without destroying itself or its test facilities. With Merlin Vacuum engines, SpaceX performs acceptance tests in Texas but only without their nozzle extensions installed. If Musk’s October 2019 comments remain true, that may not be the case for RaptorVac.
Either way, it will be thoroughly interesting to note the differences between RaptorVac and its sea level-optimized predecessor if or when Elon Musk or SpaceX releases photos of their newest engine as it nears its first major tests. Simultaneously, SpaceX is also readying a sea-level Raptor for its inaugural static fire test while attached to a full-scale Starship prototype, while the first test with three Raptor engines installed could be attempted just a few weeks from now.
Elon Musk
Tesla Cybercabs narrowly miss deadly Amazon cargo plane crash
An Amazon cargo plane crash near Miami’s airport stopped feet from dozens of Tesla Cybercabs.
An Amazon Prime Air Boeing 767 cargo jet overran the runway at Miami International Airport on Sunday afternoon, killing five people and injuring five more. The jet, operated by North Carolina based carrier 21 Air as Flight 7598, touched down around 2 p.m. after arriving from San Juan, Puerto Rico, then crossed the airport perimeter, plowed across NW 67th Avenue and struck multiple vehicles before catching fire, according to the Associated Press.
Photos and video from the scene show the aircraft’s nose stopped within meters of a fenced staging lot holding dozens of gold painted Tesla Cybercabs, the steering wheel free robotaxi Tesla began putting on public roads in Austin last week. Miami-Dade Fire Rescue has confirmed the plane struck “multiple vehicles” but has not said whether any Cybercabs were among them, and neither Tesla nor airport officials have addressed the fleet directly.
The Cybercabs had not yet entered commercial service in Miami. Tesla’s existing Robotaxi operation there runs on modified Model Y vehicles and has been unsupervised since Ashok Elluswamy confirmed the detail on X in July.
Footage of the plane crash from earlier today | #ONLYinDADE pic.twitter.com/iGoOtnd6cD
— ONLY in DADE (@ONLYinDADE) September 6, 2026
Elon Musk offered the briefest of reactions. Replying to a Zero Hedge post about the Cybercabs sitting so close to the wreckage, he wrote a single word: “Weird.” He has not commented further, and Tesla has not issued a statement.
The timing puts Tesla’s newest vehicle near an unrelated but highly visible tragedy just days after its Austin debut, a launch that had already drawn scrutiny from federal regulators. The National Highway Traffic Safety Administration opened an audit how Tesla certified the Cybercab as compliant with federal vehicle safety standards, a process Teslarati covered after the vehicle’s September 3 launch event. That inquiry concerns the car’s lack of a steering wheel and pedals, not the Miami crash.
Investigators from the FAA and NTSB are focused on the plane, not the parking lot beside it. Flight data reviewed by outlets including Simple Flying show the 767 touched down around 170 knots, well above the 135 to 140 knot range typical for the aircraft, though investigators have not determined a cause. Amazon said it is working with authorities and that its priority is the safety of everyone affected.
Whether any Cybercabs were damaged, and what Tesla plans for the fleet parked near one of the country’s busiest airports, remain open questions.
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Tesla crosses major Unsupervised Self-Driving milestone
Tesla has reached a notable benchmark in its autonomous driving program after its Robotaxi fleet surpassed one million miles of unsupervised operation. The company made the announcement during its Cybercab event in Austin on September 3.
Tesla Vice President of AI Ashok Elluswamy told attendees he was happy to report the fleet had achieved one million miles of unsupervised Robotaxi operation as a testament to safety.
The new total marked a sharp increase from the 380,000 unsupervised miles Tesla disclosed during its second-quarter 2026 earnings update in late July.
In roughly six weeks, the company added about 620,000 miles. That acceleration followed Tesla’s decision to remove in-vehicle safety monitors from most of its operations outside the San Francisco Bay Area.

Credit: Tesla
Tesla first launched Robotaxi service in Austin in June 2025 with safety drivers present. It later began fully unsupervised rides and expanded into Dallas, Houston, Miami, Orlando, and Tampa. The San Francisco Bay Area remains the exception, where a safety monitor still rides in the vehicle under California permitting rules.
The company has not released a city-by-city breakdown of the one million unsupervised miles.
The milestone arrived as Tesla began offering public Cybercab rides in Austin. The purpose-built vehicle has no steering wheel or pedals and is designed only for autonomous ride-hailing. Production versions joined the existing fleet of modified Tesla vehicles already operating in the service.
Tesla’s unsupervised mileage is growing at a double-digit weekly rate according to earlier company comments, yet its fleet size remains modest compared with established competitors. Waymo has accumulated more than 200 million fully autonomous rider-only miles. Tesla has described its own unsupervised operations as having recorded zero notable incidents in the period leading up to the July update.
The one-million-mile figure reflects Tesla’s shift from supervised testing to broader driverless service in multiple states. It also highlights the company’s strategy of using both existing Model Y vehicles and the new Cybercab to scale its network.

Credit: Tesla
Whether the rapid recent growth continues will depend on further city expansions, regulatory approvals, and the performance of the purpose-built Cybercab in everyday paid rides. Tesla has not specified how many of the latest miles involved the new vehicle versus the rest of the fleet.
The announcement underscores Tesla’s progress toward a larger robotaxi network while illustrating the remaining gap in total autonomous experience relative to longer-operating rivals.
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Tesla Robotaxi will be a 24/7 service: here’s when
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.