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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.

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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SpaceX just got the green light Starship has waited years for

The FAA has cleared Starship Flight 14, setting up SpaceX’s first orbital attempt on Monday.

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SpaceX has cleared the last regulatory hurdle standing between Starship and its first trip to orbit. The Federal Aviation Administration issued the launch license for Starship Flight 14 late Saturday, keeping the mission on track for liftoff Monday, September 28, from Pad 2 at Starbase, Texas.

The 75 minute launch window opens at 7:15 a.m. Central, and Boca Chica Beach closures are also scheduled for September 29 and 30 as backup dates. This will be Starship’s first revenue generating mission.

The license was the missing piece after SpaceX completed a full wet dress rehearsal with Booster 21 and Ship 41 on September 24. At the time, the company said the flight remained on track pending regulatory approval. Because Flight 14 flies an orbital profile, the FAA had to sign off on a modified license that met its safety, payload and financial responsibility requirements.

Observers combing through the new FAA paperwork also noticed that lightning no longer appears among Starship’s listed launch hazards. If that holds, it matters more for where Starship is headed than for Monday’s attempt. Florida and Louisiana, home to LC-39A and the planned Starbase Louisiana site, see some of the most frequent lightning in the United States.

SpaceX tells the FCC that Starship Flight 14 is going to orbit

Flight 14 is the mission SpaceX has been building toward for months. Ship 41 will carry 26 Starlink V3 satellites, the first operational V3 units to be deployed, and attempt roughly six orbits at about 275 kilometers over a flight lasting just under 10 hours. SpaceX says the ship will only perform its orbital insertion burn after flight controllers confirm enough hardware redundancy remains for the deorbit burn at the end of the mission. Ship 41 is targeting a splashdown in the Pacific west of Chile, while Super Heavy will return to the Gulf of Mexico.

The date carries some symbolism as well. A Monday launch would come 10 years and one day after Elon Musk first presented the Interplanetary Transport System, the design that became Starship, at the International Astronautical Congress in Guadalajara, Mexico.

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SpaceX has not announced what comes next, but air traffic planning slides reported this week, list Flight 15 no earlier than October 19 and a first Starship launch from LC-39A in Florida no earlier than October 30. Both dates depend on how Monday goes.

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SpaceX completes another secret Pentagon launch, adding to suspected Starshield buildout

SpaceX launched the classified USSF-385 mission from Vandenberg, landing its booster on a tenth flight.

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US Golden Dome space defense system (Concept render by Grok)

SpaceX launched another classified mission for the U.S. Space Force from California early Saturday morning, and the Falcon 9 booster that carried it landed on a drone ship in the Pacific for the tenth time. The USSF-385 mission lifted off from Space Launch Complex 4E at Vandenberg Space Force Base at 7:00 a.m. PT.

Booster B1100 touched down on Of Course I Still Love You roughly eight and a half minutes after liftoff. It was the booster’s tenth flight and tenth successful landing, following the NROL-95 national security mission and eight Starlink launches. Its previous flight, a Starlink Group 15 mission on August 22, came just 35 days earlier. SpaceX ended its livestream shortly after the landing, which is standard for classified payloads, and neither the company nor the Space Force has said what the rocket carried.

USSF-385 is the fourth Space Force launch from the same Vandenberg pad in roughly six weeks, following USSF-366 on August 15, USSF-153 on September 10, and USSF-259 on September 17. When SpaceX flew USSF-366 in August, independent trackers noted that the rocket’s stage drop zones matched SpaceX’s Starlink Group 15 missions, pointing to Starshield, the government version of the Starlink satellite bus. The Space Force later cataloged 23 satellites after both USSF-366 and USSF-153, while USSF-259 placed 17 satellites into a different orbital plane, per KeepTrack. Launch databases describe USSF-385 the same way, though the payload remains officially unidentified.

Starlink’s Starshield wins contract with US Space Force

The cadence lines up with the contracts, because in July, the Space Force awarded SpaceX $1.6 billion in task orders for 18 Falcon 9 missions from Vandenberg through the end of 2027. SpaceX also holds contracts to build pieces of that same network, which pushed its Pentagon contract total for 2026 past $8 billion.

Saturday’s flight was also the sixth and final Falcon 9 launch from Vandenberg in September, according to Spaceflight Now, while only one Falcon 9 flew from the East Coast this month as SpaceX shifts its Florida infrastructure toward Starship. Launch trackers list it as SpaceX’s 112th mission of 2026 and the 108th Falcon 9 flight of the year, with SLC-4E turned around about six and a half days after its previous launch.

The West Coast pad will not stay quiet for long, considering SpaceX has another Starlink mission scheduled from SLC-4E on September 30. Meanwhile, in Texas, the company is two days away from Starship Flight 14, which is targeting Monday at 7:15 a.m. CT for the vehicle’s first attempt to reach orbit.

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Tesla hints at new Roadster design in surprise clip

Tesla ended its Semi event with a Roadster teaser revealing a new front light bar.

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Tesla Battery Day event (Credit: Ryan McCaffrey/Twitter)

Tesla closed out its Semi event in Nevada on Thursday night with a nod to its own history, dropping a short Roadster teaser that suggests the production car will look noticeably different from the prototype first shown in 2017.

“We can’t have a Semi event without the Roadster,” Tesla engineering executive Lars Moravy told the crowd before the clip played. The line was a deliberate callback. Tesla first revealed the next generation Roadster in November 2017 by driving it out of the back of a Semi trailer at the truck’s original unveiling in Hawthorne, California.

The new video opens on trailer doors swinging apart in the dark. A thin white light bar glows across what appears to be the nose of the car, Tesla and SpaceX logos flash over the frame, and the Roadster name appears before the clip ends on “See you next week.” Tesla posted the nine second clip on X after the livestream wrapped.

The light bar is the most concrete design detail so far. The 2017 prototype used two separate curved headlamp pods, while a connected front light strip would bring the Roadster in line with the Cybertruck, Cybercab, Semi, and refreshed Model Y. Sawyer Merritt was among the first to point out what looked like part of a SpaceX logo in the video, something Tesla has not addressed.

That logo fits the buildup around the optional SpaceX Package, which Elon Musk has long said would use cold gas thrusters to improve acceleration and possibly allow the car to briefly leave the ground. Tesla’s “Go for launch” post on September 12 set the October 1 date, and invitations sent to reservation holders place the event in Waco, Texas, at 8:30 p.m. Eastern. Waco sits roughly 20 minutes from SpaceX’s McGregor rocket test site, where the FAA has put a temporary flight restriction in place from September 18 through October 2, covering a 1.5 nautical mile radius from the surface up to 10,000 feet.

Tesla is also taking money ahead of the reveal. The company reopened Roadster reservations earlier this week with a $5,000 refundable card payment, followed by a $45,000 wire transfer due within 10 days. That puts buyers at $50,000 committed before Tesla has published a price.

The original pitch set a high bar: 0 to 60 mph in 1.9 seconds before any upgrades, 620 miles of range, a top speed above 250 mph, and production in 2020. That timeline has slipped repeatedly, and Tesla has since pointed to production at Gigafactory Texas no earlier than 2027. The company has said next Thursday’s event will include pricing, specifications, and production targets, the three details original reservation holders have been waiting on for nearly nine years.

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