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SpaceX’s Starhopper readies for more ambitious Raptor-powered flight tests
For the second time in two months, SpaceX technicians have begun to install a Raptor engine on Starhopper, a full-scale Starship testbed theoretically capable of low-velocity, moderate-altitude ‘hops’.
Back in late March, Raptor and Starhopper were joined for the first time, enabling a lengthy series of attempted tests that were followed by two engine ignitions and tethered hops before Raptor was removed for inspection. In the two months since that first round of integrated testing, SpaceX has significantly upgraded Starhopper and its spartan launch facilities, all focused on transforming the odd vehicle from a largely fixed test stand into a giant, mobile Grasshopper.
All the way back in 2012, SpaceX began testing Falcon 9 recovery and reusability concepts with a low-fidelity prototype known as Grasshopper – essentially a minimalist Falcon 9 first stage with ad hoc legs and a single Merlin engine. It supported a series of 8 major test flights – all successful and a source of valuable data – before the vehicle’s 2013 retirement. An upgraded Grasshopper – known instead as Falcon 9 Reusable Development Vehicle (F9R Dev1) – began testing around the same time and continued even higher altitude vertical takeoff/vertical landing (VTVL) tests until its untimely demise in August 2014.
Starhopper is quite similar, although it is also serving as a testbed for a far more varied range of technologies due to the fact that it has been developed before the inaugural launch of its namesake (Starship/Super Heavy). By the time SpaceX started Grasshopper/F9R tests, Falcon 9 had already completed several successful launches. With Starhopper, SpaceX is building and testing its first 9m-diameter ‘flight’ hardware, its first propellant tanks built out of steel, its first flight-capable rocket fueled by methane and oxygen, and its first mobile Raptor testbed, among numerous other things. The challenges are inherently much greater, but SpaceX has the luxury of taking the opposite approach it took towards Falcon 9 and building a launch vehicle entirely around its intended reusability, rather than trying to squeeze a method of reusability around an already-flying rocket.
Saurid Oddities
As noted by NASASpaceflight.com in a June 2nd article, SpaceX seems to be juggling its growing selection of newly-produced and tested Raptor engines in pursuit of Starhopper’s return to flight. According to the publication’s reliable sources,
“Up until recently, [SpaceX] was planning to utilize Raptor SN4 for [Starhopper’s first] untethered hops. However, the company has now decided to utilize this engine only for fit checks, and will instead perform the hops with SN5 – the latest Raptor to come out of SpaceX’s factory in Hawthorne, California.” – NASASpaceflight.com, June 2nd, 2019
This indicates that the Raptor engine delivered to Boca Chica on June 1st and currently in the process of being installed on Starhopper is actually more of a stand-in* for a future Raptor, SN05. The reasons behind this Raptor shuffle elude detection, but it’s possible that the simplest explanation – also posed by NASASpaceflight – is the correct one. By shipping a Raptor that may not be ready for flight tests, SpaceX could likely save anywhere from a few days up to a few weeks by doing everything short of lifting off under the powered of Raptor SN04.
*By all appearances, SN04 is a flight-grade Raptor that has completed assembly and likely been test-fired in McGregor, Texas. Why it may currently be resigned to a “stand-in” role is unknown.
It appears that the Raptor engine is not centered, could it be that they are going straight with the 3 engine test. (Idk honestly, I wonder why this is?) @elonmusk are things about to get epic?? pic.twitter.com/sne5v7SMhy— Austin Barnard? (@austinbarnard45) June 1, 2019
Very curiously, upon Raptor SN04’s South Texas arrival, it appears that SpaceX technicians have indeed rapidly installed the engine on Starhopper, but in a position that is decidedly off-center. Pictured above, the photo could have simply caught the engine while technicians were moving it to its actual installation spot, but it could also indicate that SpaceX is speeding towards Starhopper’s first triple-Raptor test flights.
Starhopper delays?
In line with the last-second switch from Raptor SN04 to Raptor SN05 as the engine-to-be for untethered hops, SpaceX has pushed the start of that test series from approximately May 31st to June 11th. More likely than not, the ~11-day delay is meant to allow time for Raptor SN05’s McGregor, Texas acceptance testing, given that – per CEO Elon Musk – the engine wasn’t even finished as of May 22nd.
On the other hand, with Raptor SN05 now scheduled to support Starhopper hop tests as early as mid-June, it begs the question of whether SpaceX is instead working towards expedited triple-Raptor testing. For unknown reasons, neither Raptor SN03 or SN04 are apparently ready to support flight operations, although both have been thoroughly hot-fired in McGregor. Perhaps each engine is a distinct prototype with a different level of experimental readiness, or perhaps SpaceX is just testing certain engines (like SN03) more extensively than others (SN05).
Regardless, SpaceX now seems to have 3-4 intact, functional Raptor engines (excluding SN01; destroyed during stress testing), 2-3 of which are actively testing or being worked on a day’s drive north of Boca Chica. SN02 – having successfully supported a brief duo of ignition tests with Starhopper – could still be intact and test-ready. SN03 is an unknown quantity, but SN04 is clearly in excellent shape and is probably close to flight-readiness if it isn’t already. This is to say that SpaceX likely already has three Raptors on hand that are capable of supporting multi-engine Starhopper testing, whether or not such a test regime would actually be valuable.
Musk has noted that both orbit-capable Starship prototypes will be far closer to finished products and will thus fly with “at least 3 engines” (3 sea level engines, as it would turn out) or even “all 6” (3 sea level, 3 vacuum-optimized). In the meantime, Starhopper stands with an off-centered Raptor, awaiting the arrival of a different Raptor to kick off a second hop test program. If nothing else, SpaceX’s Starship/Super Heavy development program is operating in a spectacularly hardware-rich fashion, lending itself to the breakneck-pace of iteration and improvement SpaceX is famous for.
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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.
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 crosses major Unsupervised Self-Driving milestone
Tesla Robotaxi will be a 24/7 service: here’s when
