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SpaceX’s Starship explosion explained by Elon Musk

The burning wreckage of Starship SN4, May 29th. (SPadre)

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Shortly after a briefing following SpaceX’s flawless astronaut launch debut, CEO Elon Musk casually revealed the best explanation yet for why a Starship prototype violently exploded during testing on May 29th.

On that fated Saturday, SpaceX successfully completed the fifth static fire of a Raptor engine installed on a full-scale Starship prototype, preceded by about an hour and a half of vehicle checks and propellant loading. Unfortunately, around a minute after Raptor shut down, what was quickly identified as liquid methane began spurting out of a specific section at the base of Starship, rapidly creating a massive cloud as the cryogenic propellant boiled and turned into gas. The specific source is unclear but moments later, something under Starship SN4 provided the shock or spark needed to ignite the expanding fire hazard, producing a spectacularly large and violent explosion.

Unsurprisingly, the accidental fuel-air explosion that was created obliterated Starship SN4 in the blink of an eye, shredding its lower (liquid oxygen) tank into steel confetti and immediately breaching the upper (liquid methane) tank, which fell to the ground and subsequently exploded again. The launch mount Starship was staged on was also damaged beyond repair and has been fully dismantled and scrapped in the two days since the anomaly. Thankfully, however, SpaceX already has replacement mounts and ships well on their way to carrying Starship SN4’s torch forward and Elon Musk already seems to understand what caused the prototype’s demise.

Shortly after a post-launch briefing celebrating and discussing SpaceX’s inaugural astronaut launch on May 30th, Reuters reporter Joey Roulette was able to ask Musk about Starship SN4’s spectacular demise the day prior. The SpaceX CEO was quoted saying that “what we thought was going to be a minor test of a quick disconnect ended up being a big problem”, confirming suspicions based on careful analysis of public views of the explosion that it was caused by issues with Starship’s ground support equipment (GSE).

Starhopper’s quick-disconnect umbilical panel is pictured here in May 2019. Starship SN4 used a similar mechanism, although the plumbing is now located inside the vehicle’s circumference. (NASASpaceflight – bocachicagal)

In Musk’s statement, “quick disconnect” (QD) refers to an umbilical port that connects a launch vehicle to GSE, enabling the loading and offloading of propellant and fluids, clamping down the rocket, and providing a wired telemetry and communications link for ground controllers. QDs must perform all those tasks while also being able to rapidly release and disconnect, allowing the rocket to lift off while still protecting its sensitive ports for ease of reuse.

In theory, Starship’s quick-disconnect umbilical panel is even more complex, as it will have to simultaneously enable the ship to be fueled and controlled while sitting on top of a Super Heavy booster and permit in-orbit docking and refueling. Given that Starships are currently being tested independently on spartan launch mounts, it’s unclear if the current generation of prototypes has been outfitted with advanced QD panels. More likely, Musk was referring to a test of a less advanced QD panel similar to the rough version used on Starhopper last year, and SpaceX simply wanted to test its ability to disconnect and reconnect to Starship on command.

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SpaceX’s existing Starship launch mount was heavily damaged by SN4’s explosion and has since been fully dismantled. (NASASpaceflight – bocachicagal)
Starship SN4’s remains have already been cleared from the pad. (NASASpaceflight – bocachicagal)

If that’s the case, the likeliest explanation for SN4’s explosion is that that quick disconnect was unable to fully reconnect after the test, resulting in a leak from the liquid methane port when SpaceX began to detank the rocket. Instead of the highly-pressurized fluid flowing smoothly back to ground storage tanks, the liquid methane sprayed wildly, akin to the effect one might observe when attempting to block off an active water source with an open palm.

Work on a second launch mount was already ongoing when Starship SN4 exploded on May 29th. (NASASpaceflight – bocachicagal)
Starship SN5 and SN6 are simultaneously being assembled in SpaceX’s new vertical assembly building (VAB). (NASASpaceflight – bocachicagal)

Compared to the many possible ways a fueled Starship could fail, a propellant leak started by a faulty umbilical panel is about as convenient as they come. Starship SN4 may have been violently destroyed as a result, turning a relatively small error into exceptionally painful lesson but SpaceX has already had some success building full-scale prototypes at an almost unbelievably low cost – likely less than $10M apiece. Starship SN5 appears to be just shy of ready to take SN4’s place on the launch mount, although SpaceX will have to build an entirely new launch mount before it can resume testing.

At the same time, Starship SN5’s successor – SN6 – is just one stacking event away from reaching a level of completion similar to SN4 and SN5. All told, Starship SN4’s demise is just another part of the process of developing a new kind of rocket by building and testing hardware – failure can be a valuable tool when managed properly. Based on past observations, SpaceX could be ready to continue testing (and hopefully flying) Starship prototypes before the end of the month.

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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 Model Y proudly takes its place as China’s best-selling SUV in May

The Model Y edged out competitors like the BYD Song Plus.

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Credit: Tesla China

The Tesla Model Y claimed its position as China’s best-selling SUV in May, with 24,770 units registered, according to insurance data from China EV DataTracker

The Model Y edged out competitors like the BYD Song Plus, which recorded 24,240 registrations, as well as Geely’s gasoline-powered Xingyue L, which took third place with 21,014 units registered, as noted in Car News China report.

Return To The Top

The Model Y’s return to the top of China’s SUV market follows a second-place finish in April, when it trailed the BYD Song Plus by just 684 units. Tesla China had 19,984 new Model Y registrations in April, while BYD had 20,668 registrations for the Song Plus. 

For the first five months of 2025, Tesla sold 126,643 Model Ys in China, outpacing the Song Plus at 110,551 units and BYD’s Song Pro at 80,245 units. This is quite impressive as the new Tesla Model Y is still a premium vehicle that is significantly more expensive than a good number of its competitors.

Year-Over-Year Challenges

Despite its SUV crown, Tesla’s year-over-year performance in China is still seeing headwinds. May sales totaled 38,588 units, a 30% year-over-year decline. From January to May, Tesla delivered 201,926 vehicles in China, a 7.8% drop year-over-year. These drops, however, are notably affected by the company’s changeover to the new Model Y in the first quarter.

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Exports from Tesla’s Shanghai Gigafactory also fell, with 90,949 vehicles being shipped from January to May 2025. This represents a decline of 33.4% year-over-year, though May exports rose 33% to 23,074 units.

China’s electric vehicle market, meanwhile, showed robust growth. Total NEV sales, which includes battery electric vehicles (BEVs) and plug-in hybrids (PHEVs), reached 1,021,000 units in May, up 28% year-over-year. BEV sales alone hit 607,000 units, a 22.4% increase.

Considering the fact that China’s BEV market is extremely competitive, the Tesla Model Y’s rise to the top of the country’s SUV rankings is extremely impressive.

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Waymo temporarily halts service in select San Francisco and LA areas amid protests

The suspensions came after several Waymo Jaguar I-Pace robotaxis were vandalized and set ablaze during the demonstrations.

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Credit: ABC7/YouTube

Waymo, Alphabet’s autonomous vehicle subsidiary, has suspended its driverless taxi operations in parts of Los Angeles and San Francisco amid violent protests linked to U.S. Immigration and Customs Enforcement (ICE) raids in the state. 

The suspensions came after several Waymo Jaguar I-Pace robotaxis were vandalized and set ablaze during the demonstrations.

Waymo Catches Strays Amid Anti-ICE Protests

Protests erupted in Los Angeles and San Francisco in response to the Trump administration’s immigration raids, which ultimately resulted in California Governor Gavin Newsom calling the White House’s deployment of National Guard troops unconstitutional. 

Amidst the protests, images and videos emerged showing several Waymo robotaxis being defaced and destroyed. At least five Waymo robotaxis ended up being caught in the crossfire, and at least one vehicle ended up being burned to the ground. 

The incident resulted in the Los Angeles Police Department advising people to avoid downtown areas due to toxic fumes from the robotaxis’ burning lithium-ion batteries. As noted in a KRON4 report, Waymo ultimately halted service in affected areas “out of an abundance of caution.”

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Robotaxi Sentiments

The cost of the attacks is notable. Each Waymo robotaxi is valued between $150,000 and $200,000, per a 2024 Wall Street Journal report. Interestingly enough, this is not the first time that Waymo’s robotaxis ended up on the receiving end of angry protesters. On February 24, a Jaguar I-PACE robotaxi was set ablaze and vandalized by a crowd in San Francisco. Videos taken at the time showed a mob of people attacking the vehicle. 

Despite the recent attacks on its robotaxis, Waymo has stated it has “no reason to believe” its vehicles were specifically targeted during the protests, as per a report from The Washington Post. A company spokesperson also noted that some of the Waymo robotaxis that were defaced and destroyed during the violent demonstrations had been completing drop-offs near the protest zones.

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Investor's Corner

xAI targets $5 billion debt offering to fuel company goals

Elon Musk’s xAI is targeting a $5B debt raise, led by Morgan Stanley, to scale its artificial intelligence efforts.

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(Credit: xAI)

xAI’s $5 billion debt offering, marketed by Morgan Stanley, underscores Elon Musk’s ambitious plans to expand the artificial intelligence venture. The xAI package comprises bonds and two loans, highlighting the company’s strategic push to fuel its artificial intelligence development.

Last week, Morgan Stanley began pitching a floating-rate term loan B at 97 cents on the dollar with a variable interest rate of 700 basis points over the SOFR benchmark, one source said. A second option offers a fixed-rate loan and bonds at 12%, with terms contingent on investor appetite. This “best efforts” transaction, where the debt size hinges on demand, reflects cautious lending in an uncertain economic climate.

According to Reuters sources, Morgan Stanley will not guarantee the issue volume or commit its own capital in the xAI deal, marking a shift from past commitments. The change in approach stems from lessons learned during Musk’s 2022 X acquisition when Morgan Stanley and six other banks held $13 billion in debt for over two years.

Morgan Stanley and the six other banks backing Musk’s X acquisition could only dispose of that debt earlier this year. They capitalized on X’s improved operating performance over the previous two quarters as traffic on the platform increased engagement around the U.S. presidential elections. This time, Morgan Stanley’s prudent strategy mitigates similar risks.

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Beyond debt, xAI is in talks to raise $20 billion in equity, potentially valuing the company between $120 billion and $200 billion, sources said. In April, Musk hinted at a significant valuation adjustment for xAI, stating he was looking to put a “proper value” on xAI during an investor call.

As xAI pursues this $5 billion debt offering, its financial strategy positions it to lead the AI revolution, blending innovation with market opportunity.

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