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Elon Musk says SpaceX’s second Starship booster prototype is almost finished
SpaceX CEO Elon Musk says that the second Starship booster prototype is “almost done” and has revealed that work on the first flightworthy booster has yet to begin.
For unknown reasons, SpaceX has recently changed the naming scheme for Starship and Super Heavy boosters. The booster SpaceX is currently assembling in Boca Chica has been referred to as “Booster 2” by Musk himself but, according to NASASpaceflight, is internally known as Booster 3 or B3, replacing its former Booster Number 3 (BN3) designation.
Regardless, SpaceX began stacking the Super Heavy booster prototype now known as B3 in mid-May. Around six weeks later, 23 or 24 rings have been stacked to create a partially finished prototype 9m (~30 ft) wide and approximately 42m (~140 ft) tall.
Just like Super Heavy ‘pathfinder’ BN1, which was scrapped almost the instant it reached its full height last March, Booster 3 appears to destined to stand 36 rings – 65m (~215 ft) – tall once complete. While drastically oversimplifying the process of vertically assembling the largest rocket booster ever built, that means that Super Heavy B3 is just shy of two-thirds (~65%) complete.
By simply averaging the time it’s taken for SpaceX to stack B3 to a height of 42 meters, the booster could reach its full height around three weeks from now (July 15th, give or take a week). For the most part, the most challenging and unfamiliar parts of Super Heavy B3 manufacturing and assembly have already been completed. Relative to Starship, which SpaceX has now built more than half a dozen prototypes of, Super Heavy is just a stretched Starship with no flaps, no nosecone, a far more complex engine section, and a forward dome section that needs to support car-sized grid fins.
Super Heavy’s larger propellant tanks also require a methane transfer tube – used to carry methane through the booster’s lower liquid oxygen tank – more than twice as tall as anything built for Starship. By all appearances, that ~35m (~115 ft) tall transfer tube has already been safely installed inside B3’s incomplete tanks. Around June 14th, B3’s lower two-thirds were effectively completed when its LOx tank stack was mated to the booster’s 29-Raptor engine section.
Outfitted with complex structural modifications to support massive grid fins and the first advanced ‘hot gas’ maneuvering thrusters ever spotted in public, Booster 3’s forward dome is already in the process of being welded to a stack of three steel rings. Once complete, the rest of Super Heavy B3 integration is fairly simple as far as rocket assembly goes and will require four more welding operations. Like BN1, there’s a good chance that SpaceX will mate Booster 3’s upper (methane) tank separately and then install the ~24m (~80 ft) tall, 13-ring section on top of the LOx stack to effectively complete the booster’s main structure
Of course, after the structure is complete, SpaceX will still need to finish plumbing, wiring, and generally outfitting a Super Heavy booster for the first time ever. Finally, while it remains to be seen just how finished B3 will actually find itself before heading to the launch pad, that process could also involve installing and testing four massive steel grid fins and, most importantly, up to 29 Raptor engines – a figure only beaten by the Soviet Union’s ill-fated N1 rocket.
Perhaps most significantly, Musk also revealed that B3 is not the Super Heavy booster assigned to Starship’s first orbital launch attempt, meaning that SpaceX will have to complete Booster 3 testing and build Booster 4 before that orbital test flight can occur. Given that Booster 3 assembly is on track to take more than nine weeks, Starship’s first orbital launch attempt is thus unlikely to happen before late August or September.
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Tesla confirms that it finally solved its 4680 battery’s dry cathode process
The suggests the company has finally resolved one of the most challenging aspects of its next-generation battery cells.
Tesla has confirmed that it is now producing both the anode and cathode of its 4680 battery cells using a dry-electrode process, marking a key breakthrough in a technology the company has been working to industrialize for years.
The update, disclosed in Tesla’s Q4 and FY 2025 update letter, suggests the company has finally resolved one of the most challenging aspects of its next-generation battery cells.
Dry cathode 4680 cells
In its Q4 and FY 2025 update letter, Tesla stated that it is now producing 4680 cells whose anode and cathode were produced during the dry electrode process. The confirmation addresses long-standing questions around whether Tesla could bring its dry cathode process into sustained production.
The disclosure was highlighted on X by Bonne Eggleston, Tesla’s Vice President of 4680 batteries, who wrote that “both electrodes use our dry process.”
Tesla first introduced the dry-electrode concept during its Battery Day presentation in 2020, pitching it as a way to simplify production, reduce factory footprint, lower costs, and improve energy density. While Tesla has been producing 4680 cells for some time, the company had previously relied on more conventional approaches for parts of the process, leading to questions about whether a full dry-electrode process could even be achieved.
4680 packs for Model Y
Tesla also revealed in its Q4 and FY 2025 Update Letter that it has begun producing battery packs for certain Model Y vehicles using its in-house 4680 cells. As per Tesla:
“We have begun to produce battery packs for certain Model Ys with our 4680 cells, unlocking an additional vector of supply to help navigate increasingly complex supply chain challenges caused by trade barriers and tariff risks.”
The timing is notable. With Tesla preparing to wind down Model S and Model X production, the Model Y and Model 3 are expected to account for an even larger share of the company’s vehicle output. Ensuring that the Model Y can be equipped with domestically produced 4680 battery packs gives Tesla greater flexibility to maintain production volumes in the United States, even as global battery supply chains face increasing complexity.
Elon Musk
Tesla Giga Texas to feature massive Optimus V4 production line
This suggests that while the first Optimus line will be set up in the Fremont Factory, the real ramp of Optimus’ production will happen in Giga Texas.
Tesla will build Optimus 4 in Giga Texas, and its production line will be massive. This was, at least, as per recent comments by CEO Elon Musk on social media platform X.
Optimus 4 production
In response to a post on X which expressed surprise that Optimus will be produced in California, Musk stated that “Optimus 4 will be built in Texas at much higher volume.” This suggests that while the first Optimus line will be set up in the Fremont Factory, and while the line itself will be capable of producing 1 million humanoid robots per year, the real ramp of Optimus’ production will happen in Giga Texas.
This was not the first time that Elon Musk shared his plans for Optimus’ production at Gigafactory Texas. During the 2025 Annual Shareholder Meeting, he stated that Giga Texas’ Optimus line will produce 10 million units of the humanoid robot per year. He did not, however, state at the time that Giga Texas would produce Optimus V4.
“So we’re going to launch on the fastest production ramp of any product of any large complex manufactured product ever, starting with building a one-million-unit production line in Fremont. And that’s Line one. And then a ten million unit per year production line here,” Musk stated.
How big Optimus could become
During Tesla’s Q4 and FY 2025 earnings call, Musk offered additional context on the potential of Optimus. While he stated that the ramp of Optimus’ production will be deliberate at first, the humanoid robot itself will have the potential to change the world.
“Optimus really will be a general-purpose robot that can learn by observing human behavior. You can demonstrate a task or verbally describe a task or show it a task. Even show it a video, it will be able to do that task. It’s going to be a very capable robot. I think long-term Optimus will have a very significant impact on the US GDP.
“It will actually move the needle on US GDP significantly. In conclusion, there are still many who doubt our ambitions for creating amazing abundance. We are confident it can be done, and we are making the right moves technologically to ensure that it does. Tesla, Inc. has never been a company to shy away from solving the hardest problems,” Musk stated.
Elon Musk
Rumored SpaceX-xAI merger gets apparent confirmation from Elon Musk
The comment follows reports that the rocket maker is weighing a transaction that could further consolidate Musk’s space and AI ventures.
Elon Musk appeared to confirm reports that SpaceX is exploring a potential merger with artificial intelligence startup xAI by responding positively to a post about the reported transaction on X.
Musk’s comment follows reports that the rocket maker is weighing a transaction that could further consolidate his space and AI ventures.
SpaceX xAI merger
As per a recent Reuters report, SpaceX has held discussions about merging with xAI, with the proposed structure potentially involving an exchange of xAI shares for SpaceX stock. The value, structure, and timing of any deal have not been finalized, and no agreement has been signed.
Musk appeared to acknowledge the report in a brief reply on X, responding “Yeah” to a post that described SpaceX as a future “Dyson Swarm company.” The comment references a Dyson Swarm, a sci-fi megastructure concept that consists of a massive network of satellites or structures that orbit a celestial body to harness its energy.
Reuters noted that two entities were formed in Nevada on January 21 to facilitate a potential transaction for the possible SpaceX-xAI merger. The discussions remain ongoing, and a transaction is not yet guaranteed, however.
AI and space infrastructure
A potential merger with xAI would align with Musk’s stated strategy of integrating artificial intelligence development with space-based systems. Musk has previously said that space-based infrastructure could support large-scale computing by leveraging continuous solar energy, an approach he has framed as economically scalable over time.
xAI already has operational ties to Musk’s other companies. The startup develops Grok, a large language model that holds a U.S. Department of Defense contract valued at up to $200 million. AI also plays a central role in SpaceX’s Starlink and Starshield satellite programs, which rely on automation and machine learning for network management and national security applications.
Musk has previously consolidated his businesses through share-based transactions, including Tesla’s acquisition of SolarCity in 2016 and xAI’s acquisition of X last year. Bloomberg has also claimed that Musk is considering a merger between SpaceX and Tesla in the future.
Tesla confirms that it finally solved its 4680 battery’s dry cathode process
Tesla Giga Texas to feature massive Optimus V4 production line
