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SpaceX Starship saved by ‘burst disk’ after Raptor static fire ends badly
Around 7:15 pm local time, SpaceX Starship prototype SN8 fired up one or several Raptor engines for the third time ever, catching onlookers – only expected a dress rehearsal – by surprise. An hour later, CEO Elon Musk revealed that SpaceX had effectively lost control of the rocket.
Unfortunately for SpaceX, this is not the first incident in which a fire led to a loss of Starship control. Back in May 2020, Starship serial number 4 (SN4) – the first full-scale prototype to have a Raptor installed – completed its third successful static fire test. Moments later, a vent line adjacent to the engine section caught fire, burning for a minute or two. Ultimately, likely due to destroyed wiring or plumbing, SpaceX seemingly lost control of SN4 and had to wait a full two days for cryogenic propellant to boil off and evaporate before teams could approach the rocket to inspect, repair, and regain control.
Now, more likely than not, Starship SN8 has suffered a similar – but not identical – failure, cutting some level of control. Elon Musk took to Twitter about an hour after the rocket’s third Raptor static fire, revealing that SpaceX had lose control of Starship’s pneumatics, referring to hydraulic systems needed to operate most of the rocket’s valves. For SN8, that meant nothing but bad news.
As cryogenic liquids (and all things in general) warm up, they expand, taking up more volume. To counteract that never-ending process of cryogenic propellant warming up, boiling, and turning to gas, fresh propellant is almost continually loaded while warmer gas is vented, thus maintaining safe tank pressures. If the ability to vent those gases is lost, the ability to maintain safe pressures goes with it.
As Musk noted above, Starship SN8 thankfully – and unexpectedly – had one or several burst disks installed, referring to single-use mechanical valves designed to open (i.e. burst) above a specific pressure. SN8’s nosecone burst disk did just that, bursting to create an outlet for the pressure building inside the rocket and thus preventing the small nose-based liquid oxygen (LOx) tank from exploding.
Unfortunately, the precursor to Starship losing control is a much less positive story. According to Musk, one of the Raptor engines SN8 ignited may have suffered a significant failure, melting one or more critical engine components. It’s unclear how exactly a seemingly contained engine failure evolved into a total loss of Starship hydraulics but it’s safe to say that redundancy will be added and updated designs will be implemented to ensure that a similar failure doesn’t reoccur.
Notably, both unofficial LabPadre and NASASpaceflight.com livestreams clearly showed Starship quite literally dripping molten metal for more than two minutes after the static fire. Whatever the cause of that extremely hot fire, anything that can continuously melt metal for minutes will have almost assuredly ravaged Starship SN8’s aft and the Raptor engines installed therein. It’s nothing short of miraculous that SN8’s main LOx tank wasn’t breached, as well.
Ultimately, SN8 will likely need extensive repairs – and one, two, or even three replacement engines – before it can safely restart testing and proceed towards its 15 km (~9.5 mi) launch debut. Additionally, SpaceX’s lack of valve control likely means that the company will have to wait at least 24+ hours before workers can safely return to the launch pad and begin those inspections and repairs.
Update: The roadblock was removed around 11pm local time and SpaceX workers appear to have already returned to the pad, signifying that Starship SN8 has been fully detanked and is safe to approach. Inspections and repairs will likely begin as soon as possible.
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Tesla Cybercab tests are going on overdrive with production-ready units
Tesla is ramping its real-world tests of the Cybercab, with multiple sightings of the vehicle being reported across social media this week.
Tesla is ramping its real-world tests of the Cybercab, with multiple sightings of the autonomous two-seater being reported across social media this week. Based on videos of the vehicle that have been shared online, it appears that Cybercab tests are underway across multiple states.
Recent Cybercab sightings
Reports of Cybercab tests have ramped this week, with a vehicle that looked like a production-ready prototype being spotted at Apple’s Visitor Center in California. The vehicle in this sighting was interesting as it was equipped with a steering wheel. The vehicle also featured some changes to the design of its brake lights.
The Cybercab was also filmed testing at the Fremont factory’s test track, which also seemed to involve a vehicle that looked production-ready. This also seemed to be the case for a Cybercab that was spotted in Austin, Texas, which happened to be undergoing real-world tests. Overall, these sightings suggest that Cybercab testing is fully underway, and the vehicle is really moving towards production.
Production design all but finalized?
Recently, a near-production-ready Cybercab was showcased at Tesla’s Santana Row showroom in San Jose. The vehicle was equipped with frameless windows, dual windshield wipers, powered butterfly door struts, an extended front splitter, an updated lightbar, new wheel covers, and a license plate bracket. Interior updates include redesigned dash/door panels, refined seats with center cupholders, updated carpet, and what appeared to be improved legroom.
There seems to be a pretty good chance that the Cybercab’s design has been all but finalized, at least considering Elon Musk’s comments at the 2025 Annual Shareholder Meeting. During the event, Musk confirmed that the vehicle will enter production around April 2026, and its production targets will be quite ambitious.Â
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Tesla gets a win in Sweden as union withdraws potentially “illegal” blockade
As per recent reports, the Vision union’s planned anti-Tesla action might have been illegal.Â
Swedish union Vision has withdrawn its sympathy blockade against Tesla’s planned service center and showroom in Kalmar. As per recent reports, the Vision union’s planned anti-Tesla action might have been illegal.
Vision’s decision to pull the blockade
Vision announced the blockade in early December, stating that it was targeting the administrative handling of Tesla’s facility permits in Kalmar municipality. The sympathy measure was expected to start Monday, but was formally withdrawn via documents sent to the Mediation Institute and Kalmar Municipality last week.
As noted in a Daggers Arbete report, plans for the strike were ultimately pulled after employer group SKR highlighted potential illegality under the Public Employment Act. Vision stressed its continued backing for the Swedish labor model, though Deputy negotiation manager Oskar Pettersson explained that the Vision union and IF Metall made the decision to cancel the planned strike together.
“We will not continue to challenge the regulations,” Petterson said. “The objection was of a technical nature. We made the assessment together with IF Metall that we were not in a position to challenge the legal assessment of whether we could take this particular action against Tesla. Therefore, we chose to revoke the notice itself.”
The SKR’s warning
Petterson also stated that SKR’s technical objection to the Vision union’s planned anti-Tesla strike framed the protest as an unauthorized act. “It was a legal assessment of the situation. Both for us and for IF Metall, it is important to be clear that we stand for the Swedish model. But we should not continue to challenge the regulations and risk getting judgments that lead nowhere in the application of the regulations,” he said.Â
Vision ultimately canceled its planned blockade against Tesla on December 9. With Vision’s withdrawal, few obstacles remain for Tesla’s long-planned Kalmar site. A foreign electrical firm completed work this fall, and Tesla’s Careers page currently lists a full-time service manager position based there, signaling an imminent opening.
Tesla Semi Program Director Dan Priestly teased the major improvements to the all-electric Class 8 truck on Thursday night, following the company’s decision to overhaul the design earlier this year.
Priestley said he drove the Semi on Thursday, and the improvements appear to be welcomed by one of the minds behind the project. “Our customers are going to love it,” he concluded.
Just drove the redesigned Semi. Our customers are going to love it. https://t.co/KZ88sf1CDL
— Dan Priestley (@danWpriestley) December 19, 2025
The small detail does not seem like much, but it is coming from someone who has been involved in the development of the truck from A to Z. Priestley has been involved in the Semi program since November 2015 and has slowly worked his way through the ranks, and currently stands as the Director of the program.
Tesla Semi undergoes major redesign as dedicated factory preps for deliveries
Tesla made some major changes to the Semi design as it announced at the 2025 Annual Shareholder Meeting that it changed the look and design to welcome improvements in efficiency.
Initially, Tesla adopted the blade-like light bar for the Semi, similar to the one that is present on the Model Y Premium and the Cybertruck.
Additionally, there are some slight aesthetic changes to help with efficiency, including a redesigned bumper with improved aero channels, a smaller wraparound windshield, and a smoother roofline for better aero performance.
All of these changes came as the company’s Semi Factory, which is located on Gigafactory Nevada’s property, was finishing up construction in preparation for initial production phases, as Tesla is planning to ramp up manufacturing next year. CEO Elon Musk has said the Semi has attracted “ridiculous demand.”
The Semi has already gathered many large companies that have signed up to buy units, including Frito-Lay and PepsiCo., which have been helping Tesla test the vehicle in a pilot program to test range, efficiency, and other important metrics that will be a major selling point.
Tesla will be the Semi’s first user, though, and the truck will help solve some of the company’s logistics needs in the coming years.
Tesla Cybercab tests are going on overdrive with production-ready units
Tesla gets a win in Sweden as union withdraws potentially “illegal” blockade
