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Relive SpaceX’s high-altitude Starship launch debut in 4K [video]
SpaceX has published a 4K recap of Starship serial number 8’s (SN8) spectacular high-altitude launch debut, highlighting all crucial aspects of the immensely successful test flight and hinting at the next steps forward.
On December 9th, after days of anticipation and delays for the unprecedented test flight, Starship SN8 sailed through a clean preflight flow, ignited three Raptor engines, and lifted off around 4:45 pm CST – just 15 minutes before the launch window was scheduled to close. In a move that would later be confirmed to be intentional, Starship’s ascent went exactly as planned with all three Raptors sequentially shutting down over the course of almost five minutes – necessary, said Elon Musk, to keep the rocket from “[blowing] through the [12.5-kilometer] altitude limit.”
Although technical difficulties prevented a high-altitude NASA reconnaissance jet from capturing aerial footage of the spectacle from up high, SpaceX certainly seems to have made do with more mundane platforms, capturing all aspects of Starship SN8’s launch in high definition.
At apogee, Starship SN8 vented most of the remaining liquid oxygen in its main tank and shut down the last active Raptor engine, kicking off an unprecedented guided freefall back to Earth. To achieve that feat, Starship SN8 had to reach apogee more or less vertical, begin falling tail-first, activate cold-gas thrusters and actuate four giant flaps to tilt belly-down, and use those same thrusters and flaps to maintain stability.
Likely reaching speeds of around 150 m/s (~330 mph) during that freefall, Starship SN8 made it look effortless, twitching its flaps and occasionally using a burst of thrusters to elegantly and stably glide back to about 1 km (~0.6 mi) above the ground. At that point, the rocket ignited one – and then two – Raptor engines with no apparent issue, gimballing violently and firing thrusters to flip its 9m by 50m (30 ft by 165 ft) hull ~120 degrees in a handful of seconds, ending in a tail-down landing configuration.
Up to that point, more than six minutes into the flight test, Starship SN8 had all but aced the gauntlet of firsts SpaceX had thrown at it, notably surpassing CEO Elon Musk’s expectation of a successful ascent but otherwise failed descent.
Instead, SN8 made it just a dozen or two seconds away from a soft landing before things went wrong. According to Musk, who commented after the fact, the Starship’s fuel (methane) header tank – a small secondary tank used to store landing propellant at high pressures – began to exhibit lower than needed pressures in the seconds before touchdown. Whether intentional or not, one of the two Raptors ignited during SN8’s flip maneuver shut down around ten seconds later, at which point the lone remaining engine throttled up only to have its plume turn an almost solid green.
In simple terms, without enough pressure in the fuel header, Raptor’s combustion turned very oxygen-rich, dramatically ramping up the heat and literally melting the engine’s copper-rich combustion chamber liner (hence the green hue). Had that tank been able to maintain pressure, it’s reasonable to assume that SN8 would have stuck a soft landing just like SN5 and SN6 did a few months prior. Thankfully, Musk says the source of the pressure issue was “minor” and, as SpaceX notes at the end of the recap, Starship SN9 is almost ready to carry the torch forward.
News
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
