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SpaceX Starship prototype in limbo after engine test lights rocket on fire

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The fate of SpaceX’s fourth full-scale Starship prototype appears to be in limbo after a third (seemingly successful) engine ignition test unintentionally caught the rocket on fire.

Now more than 12 hours after Starship SN4 fired up its new Raptor engine, the ~30m (~100 ft) tall, 9m (~30 ft) wide prototype is apparently trapped with one or both of its propellant tanks still partially filled with liquid (or gaseous) methane and/or oxygen. An initial road closure scheduled from noon to 6pm local quickly came and went and SpaceX and Cameron County Texas have since modified the paperwork, extending the closure a full 24 hours. In other words, SpaceX has reason to believe that Starship SN4 may continue to be unsafe (i.e. pressurized) as many as ~30 hours after it technically completed its third static fire test – extremely unusual, to say the least.

There’s only one obvious conclusion to draw. Whether it was something invisible to the public eye or damage related to the off-nominal fire that burned for some 15 minutes after Raptor shut down, SpaceX appears – to some extent – to have lost control of Starship SN4.

At the moment, it’s unclear what is wrong and what SpaceX is attempting to do to resolve the problem. Based on photos of Starship SN4 taken before the fire, there is good news and bad news from what can be publicly ascertained. Controlled from the ground by unprotected wires strung up and down the rocket and connected at its base, the uncontrolled fire that burned in at least two locations around Starship’s aft may have severed some or all of those critical connections.

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Starship SN4’s third successful Raptor test caused a secondary fire that has put the vehicle in a state of limbo. (LabPadre)

That would render Starship – potentially perfectly healthy and operational – almost entirely uncontrollable, while also potentially removing SpaceX’s access to telemetry. In other words, the company may currently have no idea how pressurized all or part of Starship SN4 is and may also have little to no control of some or all of the rocket. For that to be true, Starship SN4 would, however, have to have less than fully redundant control hardware. To perform hops, for example, the ship would need both wired and radio links capable of sending telemetry and receiving commands to remain both on the ground and after liftoff.

It’s possible that Starship SN4 has the necessary hardware installed but that it wasn’t activated for the static fire test (think “Starship will never leave the ground, why would we need to enable wireless controls?”). It’s also possible that the blown pipe and methane leak that appeared to cause the secondary fire damaged crucial propellant management hardware (valves, pumps, etc.) or was just a symptom of an even worse overpressure event that damaged or destroyed multiple such systems.

Given that safety is almost certainly the priority, chances are that some combination of fairly mild hardware failure and telemetry/control loss has left SpaceX with just enough uncertainty that it can’t risk sending technicians to the launch site to inspect the damage and reestablish control. As a result, the only option left is to quite literally sit and wait until it’s once again safe to approach the rocket. Thankfully, at this point, the risk of the mystery problem actually destroying Starship SN4 is very low. If, as it appears, only its methane tank is affected, leaving some unknown quantity of latent liquid methane trapped inside, it’s possible that waiting will actually solve the problem and safe the rocket.

Starship SN4 is pictured a few hours before its ill-fated third static fire test. (NASASpaceflight – bocachicagal)
On a positive note, it appears that the concerning amount of dark smoke created in the first minute or two of the post-test fire was caused by a huge amount of tape/insulation/???? wrapped around part of Starship’s test stand in the hours before its May 19th test attempt.(NASASpaceflight – bocachicagal)

The fact that Starship hasn’t exploded yet strongly implies either that the amount of propellant trapped is minuscule or that the vast majority of SN4’s propellant management systems (including vents) remain functional. Assuming that’s the case, any remaining cryogenic propellant will eventually boil into gas, increasing the pressure inside Starship’s tanks, while those tanks will continue to vent to prevent an explosion or rupture. Eventually, Starship SN4 will be empty once again and SpaceX will be able to approach the rocket to regain control and begin inspections and repairs.

Regardless, after such an unintentionally eventful static fire test, it’s extremely unlikely that SN4 will be ready for its inaugural flight test within the next few days. Stay tuned for updates as SpaceX works to regain control over the fourth full-scale Starship prototype.

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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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Elon Musk reveals shocking Tesla Optimus patent detail

What looked promising on paper and in simulations failed to deliver the reliability required for a robot expected to handle delicate tasks like folding laundry, assembling electronics, or assisting in factories and homes.

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Credit: Tesla

Elon Musk revealed a shocking detail on the Tesla Optimus patent that was revealed last week. Despite it being made public for the first time, Musk said the company has already moved on from the design, an incredible truth about the development of new technology: things move fast.

Musk dropped a bombshell about the Tesla Optimus humanoid robot hand patent that was released last week. Musk, candidly replying to a post late at night on X, revealed that what is a new technology to many fans and insiders is actually old news to those developing the tech directly.

“We already changed the design,” Musk said. “This one didn’t actually work.”

Patents, after all, are often viewed as blueprints for future products. Yet Musk revealed that the rolling contact mechanism—intended to provide smooth, low-friction articulation in the fingers—had already been scrapped after real-world testing exposed its shortcomings.

What looked promising on paper and in simulations failed to deliver the reliability required for a robot expected to handle delicate tasks like folding laundry, assembling electronics, or assisting in factories and homes.

The hand has been one of the biggest challenges for Tesla engineers since Optimus development started years ago. Musk has said that there is not enough recognition for how incredible and useful the human hand is, and designing one for a humanoid robot has been the biggest challenge of all.

Tesla is stumped on how to engineer this Optimus part, but they’re close

This moment underscores the persistent engineering hurdles in achieving reliable humanoid hand dexterity. Human fingers are marvels of evolution: 27 bones, intricate tendons, ligaments, and a network of sensors working in perfect harmony. Replicating that in metal and silicon is extraordinarily difficult.

Rolling contacts promised reduced wear and precise motion, but testing likely revealed issues with durability under repeated stress, grip stability on varied surfaces, or the micro-precision needed for fine motor skills.

These aren’t minor tweaks, but instead they represent fundamental challenges that have plagued robotics teams for decades. Even advanced competitors struggle here—hands remain the Achilles’ heel of most humanoids because the margin for error is razor-thin.

A fraction of a millimeter off, and a robot drops a glass or fails to button a shirt.

What makes Musk’s reply remarkable is how it signals Tesla’s direct communication style on prototype limitations. While many companies guard failures behind glossy marketing and vague timelines, Tesla openly shares setbacks.

Musk was forthcoming about the failure of this recent design. This transparency builds trust with investors, engineers, and fans. It shows Tesla treats Optimus development like true science: rapid iteration, rigorous testing, and zero tolerance for hype that doesn’t match reality.

The disclosure from Musk also highlights Tesla’s blistering pace of development. By the time the patents are published, which is often over a year after the initial filing, the technology has already evolved.

Optimus is far from a static product, and it’s a living project advancing weekly.

In the high-stakes race for general-purpose robots, Tesla’s approach stands out. Admitting a finger-joint design “didn’t actually work” isn’t a weakness—it’s confidence.

True innovation demands confronting failure head-on, and Musk just reminded the world that Optimus is being engineered that way. The next version of those hands is already in testing, and it will be better because Tesla isn’t afraid to say what didn’t work.

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Tesla is sending its humanoid Optimus robot to the Boston Marathon

Tesla’s Optimus robot is heading to the Boston Marathon finish line

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Tesla’s Optimus humanoid robot will be stationed at the Tesla showroom at 888 Boylston Street in Boston, right along the final stretch of the Boston Marathon today, ready to cheer on runners and pose for photos with spectators.

According to a Tesla email shared by content creator Sawyer Merritt on X, Optimus will be at the Boston Boylston Street showroom on April 20, coinciding with Marathon Monday weekend. The Boston Marathon finishes on Boylston Street, and the surrounding area draws hundreds of thousands of spectators along with international broadcast coverage. Placing Optimus there puts it in front of a massive public audience at zero advertising cost.

The Tesla showroom is at 888 Boylston Street, between Gloucester Street and Fairfield Street. The final mile of the marathon runs directly along Boylston Street, with runners passing the big stores before reaching the finish line at Copley Square.

Optimus was first announced at Tesla’s AI Day event on August 19, 2021, when Elon Musk presented a vision for a general-purpose robot designed to take on dangerous, repetitive, and unwanted tasks. In March 2026, Optimus appeared at the Appliance and Electronics World Expo in Shanghai, where on-site staff stated that mass production of the robot could begin by the end of 2026. Before that, it showed up at the Tesla Hollywood Diner opening in July 2025 and at a Miami showroom event in December 2025.

Tesla’s well-calculated display of Optimus gives the public a low-pressure first encounter with a robot that Tesla is preparing  to soon deploy at scale. The company has previously indicated plans to manufacture Optimus robots at its Fremont facility at up to 1 million units annually, with an Optimus production line at Gigafactory Texas targeting 10 million units per year.

Tesla showcases Optimus humanoid robot at AWE 2026 in Shanghai

Musk has said that Optimus “has the potential to be more significant than the vehicle business over time,” and separately that roughly 80 percent of Tesla’s future value will come from the robot program. Whether that holds depends on production execution. For now, Boston gets a preview of what that future looks like, standing at the finish line on Boylston Street while 32,000 runners pass by.

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Tesla expands Unsupervised Robotaxi service to two new cities

This expansion builds directly on Tesla’s existing operations. Robotaxi has been ramping unsupervised rides in Austin for months and maintains activity in the San Francisco Bay Area.

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Credit: Tesla

Tesla has taken a major step forward in its autonomous ride-hailing ambitions.

On April 18, the company’s official Robotaxi account announced that Robotaxi service is now rolling out in Dallas and Houston, Texas. The update signals the rapid scaling of unsupervised autonomous operations in the Lone Star State.

The announcement includes a compelling 14-second video captured from inside a Model Y. Shot from the passenger perspective, the footage shows the vehicle navigating suburban roads in both cities with zero driver intervention, with no Safety Monitor to be seen.

Tesla also shared geofence maps highlighting the initial service areas: a compact zone in Houston covering parts of Willowbrook and Jersey Village, and a similarly defined area in Dallas near Highland Park and central neighborhoods.

This expansion builds directly on Tesla’s existing operations. Robotaxi has been ramping unsupervised rides in Austin for months and maintains activity in the San Francisco Bay Area.

With Dallas and Houston now live, Texas hosts three active hubs—an impressive concentration that triples the company’s Lone Star footprint in just weeks. The move aligns with Tesla’s Q4 2025 earnings guidance, which outlined a broader H1 2026 rollout across seven U.S. cities, including Phoenix, Miami, Orlando, Tampa, and Las Vegas.

Texas offers favorable regulations, high ride-share demand, and relatively straightforward suburban-to-urban driving patterns ideal for early autonomous scaling. While initial geofences appear modest—roughly 25 square miles per city—Tesla has historically expanded these zones quickly as it gathers real-world data.

Tesla confirms Robotaxi expansion plans with new cities and aggressive timeline

Unsupervised operation marks a critical milestone: passengers can summon, ride, and exit without safety drivers, a leap beyond many competitors still requiring human oversight.

For Tesla, the implications are significant. Successful scaling in major metros could accelerate the transition to a fully driverless fleet, unlocking new revenue streams and validating years of Full Self-Driving investment.

Riders gain convenient, potentially lower-cost mobility, while the company edges closer to Elon Musk’s vision of Robotaxis transforming urban transport.

As Tesla pushes into more cities this year, today’s launch in Dallas and Houston underscores its momentum. Hopefully, Tesla will be able to expand unsupervised rides to another U.S. state soon, which will mark yet another chapter in this short-but-encouraging Robotaxi story.

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