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SpaceX CEO Elon Musk posts uncut Raptor, drone videos of Starhopper’s flight test debut
Some two hours after Starhopper’s inaugural untethered flight, SpaceX CEO Elon Musk took to Twitter to post an uncut video showing the ungainly rocket’s launch and landing from the perspective of both a drone and Starhopper’s lone Raptor engine.
As noted by commenters, Starhopper’s first flight also marks perhaps an even more fascinating milestone: it’s technically the first launch ever of a full-flow staged-combustion (FFSC) rocket engine. Whether or not the development hell Raptor required is or was worth it to SpaceX, the company has become the first and only entity on Earth to develop and fly a FFSC engine, beating out the national space agencies of both the United States and Soviet Union, both of which built – but never flew – prototypes.
Instead of inexplicably shelving a mature prototype development and test program, SpaceX iterated through several subscale Raptor prototypes, test-fired the engines for more than 1200 seconds total, used that data to design and build full-scale Raptors, and finally sped into a hardware-rich test campaign with six (soon to be seven) new engines. After SpaceX settled on a full-flow staged-combustion cycle and methane/oxygen (methalox) propellant, Raptor conducted its first full-scale tests all the way back in 2014, performing preburner flow and ignition tests at NASA’s Stennis Space Center.
Two years and many additional subcomponent tests later, SpaceX successfully performed the inaugural static fire test of its first completed subscale Raptor, a huge milestone for any rocket engine. In the 12 months following its first static fire (September 2016), SpaceX performed dozens of static fire tests with several subscale engines, putting the new propulsion system through >1200 seconds of combined testing.
A year after that, SpaceX was still testing subscale engines but the first full-scale Raptor engine was just a few months away from completing assembly in Hawthorne and heading to McGregor to kick off full-scale static fire testing. Indeed, four months after CEO Elon Musk’s September 2018 update, Raptor serial number 01 (SN01) shipped to Texas in late January and successfully ignited for the first time on February 3rd. SpaceX’s finalized full-scale Raptor engine is designed to produce more than 2000 kN (450,000 lbf, 200 tons) of thrust at full-throttle.
Since that inaugural ignition, SpaceX’s propulsion team – perhaps to their detriment, under orders from Musk – pushed SN01 and several of its successors to their limits as quickly as possible, resulting in severe, irreparable damage in several cases. On the other hand, the no-holds-barred, ‘hardware-rich’ (i.e. destructive) test program has allowed SpaceX to relatively quickly solve several major bugs that prevented the engine from passing longer test fires.
Raptor SN05 was originally expected to support Starhopper’s first flight(s) but had to be passed up after suffering damage in one of its final June 2019 acceptance tests. Raptor SN06 became the first engine – likely thanks to tweaks afforded by data gathered from its failed brethren – to pass all of those acceptance tests, leading to its eventual installation on Starhopper in early July.
Raptor’s impressive development culminated on July 25th with the engine’s first untethered flight while attached to Starhopper, a 9m-diameter (30 ft) low-fidelity prototype that is more or less a mobile test stand for the next-generation SpaceX engine. Raptor is now the only FFSC engine in history that has powered a flight-capable vehicle’s launch and landing, even if said flight featured an apogee of just 20-30 meters (65-100 ft).
“In full-flow staged combustion (FFSC), even more complexity is added as all propellant that touches the engine must necessarily end up traveling through the main combustion chamber to eke every last ounce of thrust out of the finite propellant a rocket lifts off with. As such, FFSC engines can be about as efficient as the laws of physics allow any given chemical rocket engine to be, at the cost of exceptional complexity and brutally difficult development.“
SpaceX delays Starhopper’s first flight a few days despite Raptor preburner test success
For more on what exactly makes full-flow staged-combustion engines uniquely capable and challenging to develop, the subject has been covered at length in past Teslarati articles.
According to Musk, the next major challenge facing Starhopper and (presumably) Raptor SN06 is far more ambitious 200-meter (650 ft) hop and flight test that could happen as soon as the first half of August.
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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
