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SpaceX Starship stacked with ballast for hop test debut

Starship SN4 has been outfitted with a ballast weight to enable its inaugural flight test. (NASASpaceflight - bocachicagal)

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SpaceX has installed a custom-built ballast atop its fourth full-scale Starship prototype, a sign that the company is rapidly approaching the ship’s first Starhopper-style hop test.

Although CEO Elon Musk officially “redirected” SpaceX’s resources away from Starship’s first flight and towards Crew Dragon’s NASA astronaut launch debut, the company continues to work around the clock to ready Starship SN4 for the program’s biggest test yet. Designed with the goal of creating a fully-reusable, ultra-capable launch vehicle that is unprecedentedly affordable, SpaceX’s Starship spacecraft and Super Heavy booster have made impressive progress over the last 12 or so months.

In July and August 2019, Starhopper – a low-fidelity testbed and proof of concept – successfully performed two untethered hop tests, ultimately flying more than 150m (~500 ft) above ground before safely touching down. Three months later, the first full-scale Starship prototype was destroyed almost immediately after its first pressure test began, a failure that lead SpaceX to expedite factory upgrades. Just six months later, SpaceX has completed multiple successful tests, including pressure tests that pushed beyond the pressures needed for safe human spaceflight, several full wet dress rehearsals (WDRs) with live propellant, and three Raptor engine static fires. In fewer words, Starship is ready for its next big test: flight.

SpaceX technicians prepare to complete a jerryrigged ballast weight for Starship SN4. (NASASpaceflight – bocachicagal)

However, Starship SN4 currently has just one Raptor engine installed and will remain in that configuration for its inaugural hop, expected to reach a maximum altitude identical to Starhopper (150m/500ft). The odd configuration means that the rocket will be propelled by asymmetric thrust, as Starship’s ‘thrust puck’ engine section is designed to hold three Raptor engines in a triangular formation. Raptor is capable of producing up to 200 metric tons (~440,000 lbf) of thrust with an unclear level of throttle control (likely mediocre according to comments made by Elon Musk).

Impressively, although it might seem reasonable to assume that Starship SN4 is about as heavy as the ~120 ton Starhopper, the clear and present need to install substantial ballast suggests otherwise. Combined with comments made during SN4’s April 2020 transport from factory to launch site, it appears that even SpaceX’s early Starship engine sections weigh just 50-60 metric tons (110,000-125,000 lb) empty. That weight doesn’t account for the flaps, heat shield, nose section, or many other heavy components that orbital Starships will eventually need but is still impressive.

Starship SN4 was transported to the launch pad on April 23rd. (NASASpaceflight – bocachicagal)
On May 27th, SpaceX installed a massive ballast weight on top of the Starship prototype. (NASASpaceflight – bocachicagal)

That impressive weight reduction, Raptor’s inability to safely throttle low, and the FAA’s lack of interest in dozens (up to hundreds) of tons of explosive propellant flying above or around populated areas poses its own challenges for the first full-scale Starship flight. The addition of ballast helpfully solves (or at least alleviates) several of those issues. Notably, ballast can prevent SpaceX from having to fuel Starship SN4 with dozens of extra tons of explosive propellant to counteract the high thrust of its single engine and permit a safe launch and landing.

At the same time, if Starship SN4’s wet weight is reduced by carrying less propellant during its first flight, that actually exacerbates the problem of Raptor’s small throttle range, as a lighter ship would be much harder to manage as the engine rapidly burns propellant and thus loses mass. With ballast, Raptor won’t have to throttle as low as it would otherwise have to to ensure a gentle rate of deceleration. Built out of sheet steel and two spare rolls of the same steel used to form Starship rings, Starship SN4’s new ballast likely increases its dry mass by some 50% or more (25+ metric tons).

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(NASASpaceflight – bocachicagal)
Starship SN4’s solid steel ballast. (NASASpaceflight – bocachicagal)

Pending Crew Dragon’s inaugural astronaut launch, now scheduled no earlier than 3:22 pm EDT (19:22 UTC), May 30th after weather delayed the first May 27th launch attempt, Starship SN4 has no testing periods on the calendar at the moment. Speaking around May 23rd, Musk stated that the ship was likely at least a “few weeks” away from its flight debut, suggesting that the ship will perform another static fire test to prepare for its first hop as early as next week. Stay tuned for updates as SpaceX’s works towards two very exciting Crew Dragon and Starship milestones.

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Eric Ralph is Teslarati's senior spaceflight reporter and has been covering the industry in some capacity for almost half a decade, largely spurred in 2016 by a trip to Mexico to watch Elon Musk reveal SpaceX's plans for Mars in person. Aside from spreading interest and excitement about spaceflight far and wide, his primary goal is to cover humanity's ongoing efforts to expand beyond Earth to the Moon, Mars, and elsewhere.

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Tesla starts showing how FSD will change lives in Europe

Local officials tested the system on narrow country roads and were impressed by FSD’s smooth, human-like driving, with some calling the service a game-changer for everyday life in areas that are far from urban centers.

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Credit: Grok Imagine

Tesla has launched Europe’s first public shuttle service using Full Self-Driving (Supervised) in the rural Eifelkreis Bitburg-Prüm region of Germany, demonstrating how the technology can restore independence and mobility for people who struggle with limited transport options. 

Local officials tested the system on narrow country roads and were impressed by FSD’s smooth, human-like driving, with some calling the service a game-changer for everyday life in areas that are far from urban centers.

Officials see real impact on rural residents

Arzfeld Mayor Johannes Kuhl and District Administrator Andreas Kruppert personally tested the Tesla shuttle service. This allowed them to see just how well FSD navigated winding lanes and rural roads confidently. Kruppert said, “Autonomous driving sounds like science fiction to many, but we simply see here that it works totally well in rural regions too.” Kuhl, for his part, also noted that FSD “feels like a very experienced driver.”

The pilot complements the area’s “Citizen Bus” program, which provides on-demand rides for elderly residents who can no longer drive themselves. Tesla Europe shared a video of a demonstration of the service, highlighting how FSD gives people their freedom back, even in places where public transport is not as prevalent.

What the Ministry for Economic Affairs and Transport says

Rhineland-Palatinate’s Minister Daniela Schmitt supported the project, praising the collaboration that made this “first of its kind in Europe” possible. As per the ministry, the rural rollout for the service shows FSD’s potential beyond major cities, and it delivers tangible benefits like grocery runs, doctor visits, and social connections for isolated residents. 

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“Reliable and flexible mobility is especially vital in rural areas. With the launch of a shuttle service using self-driving vehicles (FSD supervised) by Tesla in the Eifelkreis Bitburg-Prüm, an innovative pilot project is now getting underway that complements local community bus services. It is the first project of its kind in Europe. 

“The result is a real gain for rural mobility: greater accessibility, more flexibility and tangible benefits for everyday life. A strong signal for innovation, cooperation and future-oriented mobility beyond urban centers,” the ministry wrote in a LinkedIn post

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Tesla China quietly posts Robotaxi-related job listing

Tesla China is currently seeking a Low Voltage Electrical Engineer to work on circuit board design for the company’s autonomous vehicles.

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Credit: Tesla

Tesla has posted a new job listing in Shanghai explicitly tied to its Robotaxi program, fueling speculation that the company is preparing to launch its dedicated autonomous ride-hailing service in China. 

As noted in the listing, Tesla China is currently seeking a Low Voltage Electrical Engineer to work on circuit board design for the company’s autonomous vehicles.

Robotaxi-specific role

The listing, which was shared on social media platform X by industry watcher @tslaming, suggested that Tesla China is looking to fill the role urgently. The job listing itself specifically mentions that the person hired for the role will be working on the Low Voltage Hardware team, which would design the circuit boards that would serve as the nervous system of the Robotaxi. 

Key tasks for the role, as indicated in the job listing, include collaboration with PCB layout, firmware, mechanical, program management, and validation teams, among other responsibilities. The role is based in Shanghai.

China Robotaxi launch

China represents a massive potential market for robotaxis, with its dense urban centers and supportive policies in select cities. Tesla has limited permission to roll out FSD in the country, though despite this, its vehicles have been hailed as among the best in the market when it comes to autonomous features. So far, at least, it appears that China supports Tesla’s FSD and Robotaxi rollout.

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This was hinted at in November, when Tesla brought the Cybercab to the 8th China International Import Expo (CIIE) in Shanghai, marking the first time that the autonomous two-seater was brought to the Asia-Pacific region. The vehicle, despite not having a release date in China, received a significant amount of interest among the event’s attendees. 

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Elon Musk and Tesla AI Director share insights after empty driver seat Robotaxi rides

The executives’ unoccupied tests hint at the rapid progress of Tesla’s unsupervised Robotaxi efforts.

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Ashok Elluswamy

Tesla CEO Elon Musk and AI Director Ashok Elluswamy celebrated Christmas Eve by sharing personal experiences with Robotaxi vehicles that had no safety monitor or occupant in the driver’s seat. Musk described the system’s “perfect driving” around Austin, while Elluswamy posted video from the back seat, calling it “an amazing experience.”

The executives’ unoccupied tests hint at the rapid progress of Tesla’s unsupervised Robotaxi efforts.

Elon and Ashok’s firsthand Robotaxi insights

Prior to Musk and the Tesla AI Director’s posts, sightings of unmanned Teslas navigating public roads were widely shared on social media. One such vehicle was spotted in Austin, Texas, which Elon Musk acknowleged by stating that “Testing is underway with no occupants in the car.” 

Based on his Christmas Eve post, Musk seemed to have tested an unmanned Tesla himself. “A Tesla with no safety monitor in the car and me sitting in the passenger seat took me all around Austin on Sunday with perfect driving,” Musk wrote in his post.

Elluswamy responded with a 2-minute video showing himself in the rear of an unmanned Tesla. The video featured the vehicle’s empty front seats, as well as its smooth handling through real-world traffic. He captioned his video with the words, “It’s an amazing experience!”

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Towards Unsupervised operations

During an xAI Hackathon earlier this month, Elon Musk mentioned that Tesla owed be removing Safety Monitors from its Robotaxis in Austin in just three weeks. “Unsupervised is pretty much solved at this point. So there will be Tesla Robotaxis operating in Austin with no one in them. Not even anyone in the passenger seat in about three weeks,” he said. Musk echoed similar estimates at the 2025 Annual Shareholder Meeting and the Q3 2025 earnings call.

Considering the insights that were posted Musk and Elluswamy, it does appear that Tesla is working hard towards operating its Robotaxis with no safety monitors. This is quite impressive considering that the service was launched just earlier this year.

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