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SpaceX installs full set of car-sized grid fins on second Super Heavy booster
SpaceX appears to have installed a full set of car-sized grid fins on Starship’s second flightworthy Super Heavy booster, leaving the massive rocket just a few steps away from completion.
Measuring ~69m (~225 ft) tall and 9m (~30 ft) wide, Super Heavy Booster 5 (B5) – like B4 before it – will be one of two of the largest rocket boosters ever built once completed. In broad strokes, Super Heavy B4 and B5 are the same. Aside from near-identical dimensions, both have been built to hold up to 29 Raptor engines while Starbase has already begun receiving parts of the first 33-engine Super Heavy. That means that Booster 4 and 5 – while both potentially capable of flight – are also pathfinders for an upgraded version of Super Heavy with similar dimensions but the potential to produce more than 40% more thrust once Raptor 2 production takes over.
While more similar than not, there are significant differences between SpaceX’s first and second flightworthy Super Heavy boosters.
The biggest visible differences are tweaks SpaceX has made to the Super Heavy assembly process. Booster 4 was assembled out of mostly naked steel rings and only had thousands of feet of external plumbing, wiring, raceways, and hardware installed after it was stacked to its full height. That may partially be because CEO Elon Musk had ordered SpaceX to complete the first full-height Starship stack by early August, requiring the build team to prioritize speed above all else.
Regardless, SpaceX appears to be outfitting Super Heavy Booster 5’s exterior before and during the process of stacking the booster to its final height. Most sections of 3-4 steel rings have had partial plumbing and raceways preinstalled, meaning that Booster 5 will be far closer to test readiness than Booster 4 once stacking is complete. Booster 4, on the other hand, required at least several more weeks of outfitting after SpaceX briefly rolled the rocket to the orbital launch pad for a full-stack photo-op and fit check.
On October 12th, after rapidly stacking Super Heavy B5’s upper methane tank to completion, SpaceX began installing the booster’s four car-sized grid fins. Fixed in place and assembled out of welded steel unlike the Falcon family’s deployable, cast titanium fins, Super Heavy grid fins are several times larger and heavier but still serve the same purpose of stabilizing boosters during atmospheric reentry, descent, and landing. Like Booster 4, SpaceX has also installed all four Booster 5 grid fins before stacking the Super Heavy to its full 69-meter height.
Based on B4, that final stack could happen just a few days from now, though there are signs that it might take B5 a fair bit longer. Notably, whereas Booster 4’s aft liquid oxygen (LOx) tank was already fully stacked by the start of grid fin installation, Booster 5’s LOx section is still waiting on its thrust dome. That thrust section was most recently spotted inside a production tent on October 11th – far more thoroughly outfitted than Booster 4’s aft but awaiting installation nonetheless.
That slight difference in timing pales in comparison to a massive tube that may or may not have been installed inside Super Heavy B5 late last month and that definitely wasn’t installed in B4. Without official information, it’s hard to know for sure, but the general community consensus is that this new tube (possibly one of two installed inside Booster 5’s LOx tank) is some kind of header tank or sump meant to collect propellant for Super Heavy’s boostback and/or landing burn.
If SpaceX really is adding header tanks to Super Heavy, it would drastically increase the complexity of booster plumbing, potentially explaining why Super Heavy B5’s thrust section installation is taking longer than B4. Only time (and hopefully a tweet or two from Musk) will tell.
Elon Musk
Tesla confirms that work on Dojo 3 has officially resumed
“Now that the AI5 chip design is in good shape, Tesla will restart work on Dojo 3,” Elon Musk wrote in a post on X.
Tesla has restarted work on its Dojo 3 initiative, its in-house AI training supercomputer, now that its AI5 chip design has reached a stable stage.
Tesla CEO Elon Musk confirmed the update in a recent post on X.
Tesla’s Dojo 3 initiative restarted
In a post on X, Musk said that with the AI5 chip design now “in good shape,” Tesla will resume work on Dojo 3. He added that Tesla is hiring engineers interested in working on what he expects will become the highest-volume AI chips in the world.
“Now that the AI5 chip design is in good shape, Tesla will restart work on Dojo3. If you’re interested in working on what will be the highest volume chips in the world, send a note to AI_Chips@Tesla.com with 3 bullet points on the toughest technical problems you’ve solved,” Musk wrote in his post on X.
Musk’s comment followed a series of recent posts outlining Tesla’s broader AI chip roadmap. In another update, he stated that Tesla’s AI4 chip alone would achieve self-driving safety levels well above human drivers, AI5 would make vehicles “almost perfect” while significantly enhancing Optimus, and AI6 would be focused on Optimus and data center applications.
Musk then highlighted that AI7/Dojo 3 will be designed to support space-based AI compute.
Tesla’s AI roadmap
Musk’s latest comments helped resolve some confusion that emerged last year about Project Dojo’s future. At the time, Musk stated on X that Tesla was stepping back from Dojo because it did not make sense to split resources across multiple AI chip architectures.
He suggested that clustering large numbers of Tesla AI5 and AI6 chips for training could effectively serve the same purpose as a dedicated Dojo successor. “In a supercomputer cluster, it would make sense to put many AI5/AI6 chips on a board, whether for inference or training, simply to reduce network cabling complexity & cost by a few orders of magnitude,” Musk wrote at the time.
Musk later reinforced that idea by responding positively to an X post stating that Tesla’s AI6 chip would effectively be the new Dojo. Considering his recent updates on X, however, it appears that Tesla will be using AI7, not AI6, as its dedicated Dojo successor. The CEO did state that Tesla’s AI7, AI8, and AI9 chips will be developed in short, nine-month cycles, so Dojo’s deployment might actually be sooner than expected.
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.
Tesla confirms that work on Dojo 3 has officially resumed
Elon Musk’s xAI brings 1GW Colossus 2 AI training cluster online
