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SpaceX Starship booster’s ‘hot gas’ thrusters make first public appearance
‘Hot gas’ thrusters meant to boost the efficiency of SpaceX’s Starship spacecraft and Super Heavy boosters have been spotted in public for the first time.
On the evening of June 21st, spaceflight photographer Brady Kenniston – on assignment for NASASpaceflight – caught the first glimpses ever of what amounts to the newest rocket engine designed and built by SpaceX. As yet unnamed, SpaceX CEO Elon Musk has consistently referred to the new engine as a “hot gas thruster” for several years, though virtually no concrete details have ever been shared.
The reason behind the lack of major visible progress is simple enough: until Starship is ready for serious orbital testing, hot-gas thrusters just aren’t necessary. Instead, SpaceX has relied on tried and true cold gas thrusters derived – or quite literally taken, in the case of Starhopper – from those used on Falcon 9 and Falcon Heavy boosters to maintain attitude control in space and safely land back on Earth.
For Starhopper and Starships SN5 and SN6, all three of which focused on simple hop tests, those cold-gas thrusters primarily augmented Raptor’s thrust vectoring capabilities by fine-tuning vehicle rotation and attitude. On Starships SN8, SN9, SN10, SN11, and SN15, cold-gas thrusters played a more substantial role in their more complex medium-altitude test flights, flipping each ship horizontal at apogee, helping to maintain stability during skydiver-style freefalls back to Earth, and augmenting three Raptor engines during the final landing flip and landing burn.
By all appearances, the thrusters did their jobs perfectly on all nine test flights. However, those eight suborbital prototypes could all afford to expend large portions of their mass budgets on a plethora of pressure vessels filled with tons of nitrogen gas. More importantly, empty Starships and their Super Heavy boosters are expected to weigh anywhere from 10-50 times more than Falcon 9’s booster and upper stage, and SpaceX’s suborbital prototypes have also required much less performance (delta V) than operational ships and boosters will need.
Cold gas (nitrogen) thrusters are too inefficient and the exponential aspects of rocket engineering too cruel for what works on Falcon to efficiently meet the needs of Starship and Super Heavy. SpaceX’s long-planned solution has been the development of a bipropellant thruster that would borrow from Raptor expertise and use the same methane and oxygen propellant – albeit in their high-pressure gaseous forms. If properly realized, such a thruster could offer around five times the efficiency and thrust of a similarly-sized cold-gas system – a boon for maneuvering and manipulating massive 100-250 ton (~250,000-550,000 lb) ships and boosters in space.
In theory, moving from nitrogen to methalox thrusters also means that Starship could refuel its thrusters using a tiny fraction of the vast supply of liquid methane and oxygen propellant it will already be carrying to the Moon or Mars. Ultimately, though, Musk says that those hot gas attitude control thrusters will debut on the Super Heavy booster assigned to Starship’s first orbital test flight. While SpaceX’s initial July target now appears to be out of the question, all flight and pad hardware could still be ready to launch as early as August or September.
Update: One month after Elon Musk stated that SpaceX was “aiming” to have hot gas thrusters on the first flightworthy Super Heavy booster, the CEO says those thrusters would be “an unnecessary complication for now” and “are being removed to speed up time to” Starship’s first orbital launch.
Elon Musk
Elon Musk’s xAI brings 1GW Colossus 2 AI training cluster online
Elon Musk shared his update in a recent post on social media platform X.
xAI has brought its Colossus 2 supercomputer online, making it the first gigawatt-scale AI training cluster in the world, and it’s about to get even bigger in a few months.
Elon Musk shared his update in a recent post on social media platform X.
Colossus 2 goes live
The Colossus 2 supercomputer, together with its predecessor, Colossus 1, are used by xAI to primarily train and refine the company’s Grok large language model. In a post on X, Musk stated that Colossus 2 is already operational, making it the first gigawatt training cluster in the world.
But what’s even more remarkable is that it would be upgraded to 1.5 GW of power in April. Even in its current iteration, however, the Colossus 2 supercomputer already exceeds the peak demand of San Francisco.
Commentary from users of the social media platform highlighted the speed of execution behind the project. Colossus 1 went from site preparation to full operation in 122 days, while Colossus 2 went live by crossing the 1-GW barrier and is targeting a total capacity of roughly 2 GW. This far exceeds the speed of xAI’s primary rivals.
Funding fuels rapid expansion
xAI’s Colossus 2 launch follows xAI’s recently closed, upsized $20 billion Series E funding round, which exceeded its initial $15 billion target. The company said the capital will be used to accelerate infrastructure scaling and AI product development.
The round attracted a broad group of investors, including Valor Equity Partners, Stepstone Group, Fidelity Management & Research Company, Qatar Investment Authority, MGX, and Baron Capital Group. Strategic partners NVIDIA and Cisco also continued their support, helping xAI build what it describes as the world’s largest GPU clusters.
xAI said the funding will accelerate its infrastructure buildout, enable rapid deployment of AI products to billions of users, and support research tied to its mission of understanding the universe. The company noted that its Colossus 1 and 2 systems now represent more than one million H100 GPU equivalents, alongside recent releases including the Grok 4 series, Grok Voice, and Grok Imagine. Training is also already underway for its next flagship model, Grok 5.
Elon Musk
Tesla AI5 chip nears completion, Elon Musk teases 9-month development cadence
The Tesla CEO shared his recent insights in a post on social media platform X.
Tesla’s next-generation AI5 chip is nearly complete, and work on its successor is already underway, as per a recent update from Elon Musk.
The Tesla CEO shared his recent insights in a post on social media platform X.
Musk details AI chip roadmap
In his post, Elon Musk stated that Tesla’s AI5 chip design is “almost done,” while AI6 has already entered early development. Musk added that Tesla plans to continue iterating rapidly, with AI7, AI8, AI9, and future generations targeting a nine-month design cycle.
He also noted that Tesla’s in-house chips could become the highest-volume AI processors in the world. Musk framed his update as a recruiting message, encouraging engineers to join Tesla’s AI and chip development teams.
Tesla community member Herbert Ong highlighted the strategic importance of the timeline, noting that faster chip cycles enable quicker learning, faster iteration, and a compounding advantage in AI and autonomy that becomes increasingly difficult for competitors to close.
AI5 manufacturing takes shape
Musk’s comments align with earlier reporting on AI5’s production plans. In December, it was reported that Samsung is preparing to manufacture Tesla’s AI5 chip, accelerating hiring for experienced engineers to support U.S. production and address complex foundry challenges.
Samsung is one of two suppliers selected for AI5, alongside TSMC. The companies are expected to produce different versions of the AI5 chip, with TSMC reportedly using a 3nm process and Samsung using a 2nm process.
Musk has previously stated that while different foundries translate chip designs into physical silicon in different ways, the goal is for both versions of the Tesla AI5 chip to operate identically. AI5 will succeed Tesla’s current AI4 hardware, formerly known as Hardware 4, and is expected to support the company’s Full Self-Driving system as well as other AI-driven efforts, including Optimus.
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Tesla Model Y and Model 3 named safest vehicles tested by ANCAP in 2025
According to ANCAP in a press release, the Tesla Model Y achieved the highest overall weighted score of any vehicle assessed in 2025.
The Tesla Model Y recorded the highest overall safety score of any vehicle tested by ANCAP in 2025. The Tesla Model 3 also delivered strong results, reinforcing the automaker’s safety leadership in Australia and New Zealand.
According to ANCAP in a press release, the Tesla Model Y achieved the highest overall weighted score of any vehicle assessed in 2025. ANCAP’s 2025 tests evaluated vehicles across four key pillars: Adult Occupant Protection, Child Occupant Protection, Vulnerable Road User Protection, and Safety Assist technologies.
The Model Y posted consistently strong results in all four categories, distinguishing itself through a system-based safety approach that combines structural crash protection with advanced driver-assistance features such as autonomous emergency braking, lane support, and driver monitoring.
This marked the second time the Model Y has topped ANCAP’s annual safety rankings. The Model Y’s previous version was also ANCAP’s top performer in 2022.
The Tesla Model 3 also delivered a strong performance in ANCAP’s 2025 tests, contributing to Tesla’s broader safety presence across segments. Similar to the Model Y, the Model 3 also earned impressive scores across the ANCAP’s four pillars. This made the vehicle the top performer in the Medium Car category.
ANCAP Chief Executive Officer Carla Hoorweg stated that the results highlight a growing industry shift toward integrated safety design, with improvements in technologies such as autonomous emergency braking and lane support translating into meaningful real-world protection.
“ANCAP’s testing continues to reinforce a clear message: the safest vehicles are those designed with safety as a system, not a checklist. The top performers this year delivered consistent results across physical crash protection, crash avoidance and vulnerable road user safety, rather than relying on strength in a single area.
“We are also seeing increasing alignment between ANCAP’s test requirements and the safety technologies that genuinely matter on Australian and New Zealand roads. Improvements in autonomous emergency braking, lane support, and driver monitoring systems are translating into more robust protection,” Hoorweg said.
Elon Musk’s xAI brings 1GW Colossus 2 AI training cluster online
Tesla AI5 chip nears completion, Elon Musk teases 9-month development cadence
