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SpaceX’s first two Super Heavy boosters making good progress towards test debuts
SpaceX is making good progress on Starship’s first two Super Heavy boosters, both of which could potentially be ready for their first major test campaigns before the end of the year.
On November 19th, some ten weeks after the process began, SpaceX craned Super Heavy B5’s methane (LCH4) tank on top of its oxygen (LOx) tank, marking the end of major structural assembly for the 69m (~225′) tall booster. A team of welders has since been working around the clock to weld the two tanks together and complete a transfer tube that routes methane propellant down through B5’s oxygen tank.
Two days prior, CEO Elon Musk shared a photo of SpaceX’s other Super Heavy booster (B4) which has been slowly progressing towards test readiness for more than three months. It’s unclear why SpaceX has been so sluggish to prepare Super Heavy B4 for testing but with B5 finally approaching the finish line, the company will soon find itself in a position where it will need to decide which booster to proceed with towards the program’s near-term end goal: the first orbital Starship test flight.
Once Booster 5’s two halves are welded together, only a few things will set it and Booster 4 apart. In recent weeks, SpaceX’s slow progress on Super Heavy B4 relented a bit as technicians began closing out the booster’s raceway (a conduit for plumbing, wiring, and avionics) with basic covers. More importantly, SpaceX also began reinstalling Raptor engines and installing heat shielding around those engines for the first time. In the photo Musk published on November 17th, that heat shield is easily visible and there are signs that it will ultimately enclose the entire outer ring of 20 Raptor Boost engines above their nozzles.
Once complete, that shield will theoretically protect each engine’s nest of sensitive plumbing and wiring during static fires; ascent, boostback, and landing burns; and – most importantly – reentry. Unlike Falcon boosters, which always perform a ~30-second, three-engine ‘reentry burn’ to slow down and cushion the blow of reentry heating, SpaceX plans to recover steel Super Heavy boosters without reentry burns. In theory, that should making booster recovery more efficient, allowing another dozen or so tons of propellant to go towards sending Starship to orbit instead of landing.
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As of November 17th, SpaceX has reinstalled all 29 Raptor engines on Booster 4, partially finished the outer ring of Raptor heat shields, and set the stage for more heat shielding around its 9 center engines and the gap between those inner and outer Raptors. Shielding the Raptor Center engines in a way that still seals off Super Heavy’s aft will be even more challenging given that all nine need to be able to freely gimbal to vector their thrust, while the outer ring of 20 Raptor Boost (RB) engines are fixed in place. At pace of work established over the last few months, it will likely take SpaceX several more weeks to finish that heat shield and install seven ‘aerocovers’ over racks of sensitive equipment installed around Booster 4’s base.
Super Heavy Booster 5, on the other hand, has taken a slightly different path through assembly. Unlike Booster 4, which first rolled out as little more than a giant steel tank with Raptors half-installed, SpaceX appears to have installed most of Booster 5’s external plumbing, wiring, equipment racks, and maybe even the start of its Raptor heat shield during assembly instead of after. Perhaps as a result, SpaceX has taken more than ten weeks to stack Booster 5 versus 2.5 weeks for Booster 4. But given that Booster 4 still doesn’t appear to be complete some 18 weeks after its assembly began, there’s a chance that Booster 5 will ultimately take 4-6 weeks less to reach initial test readiness.
If SpaceX does complete Super Heavy B5 well ahead of B4’s schedule, it will soon find itself with two test-ready Starship boosters but only one orbital-class stand with which to test them, potentially forcing the company to make some interesting decisions.
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Tesla Semi factory looks almost complete during Thanksgiving weekend
Based on recent drone videos, the Tesla Semi factory looks practically ready to start operations.
It appears that the Tesla Semi factory near Giga Nevada is already hard at work preparing for the initial production of the Class 8 all-electric truck. This was, at least, hinted at in a recent drone flyover of the facility from a longtime watcher.
The Tesla Semi factory after Thanksgiving
Drone operator and Tesla Semi advocate @HinrichsZane recently shared some footage he captured of the upcoming facility during the Thanksgiving weekend. Based on his video, it appears that Tesla gave its employees in the area the weekend off. One thing is evident from the video, however, and that is the fact that the Tesla Semi factory looks practically ready to start operations.
The Tesla Semi watcher did point out that the electric vehicle maker is still busy bringing in production equipment into the facility itself. Once these are installed, it would not be surprising if initial production of the Tesla Semi begins.
A new Tesla Semi
The upcoming completion of the Tesla Semi factory near Gigafactory Nevada seems all but inevitable in the coming months. What would be especially interesting, however, would be the vehicles that would be produced on the site. During Elon Musk’s presentation at the 2025 Annual Shareholder Meeting, a glimpse of the production Tesla Semi was shown, and it looks quite a bit different than the Class 8 all-electric truck’s classic appearance.
As could be seen in the graphic from the CEO’s presentation, the updated Tesla Semi will feature slim lightbar headlights similar to the new Tesla Model Y, Cybertruck, and the Cybercab. Tesla also teased a number of aerodynamic improvements that increased the truck’s efficiency to 1.7 kWh per mile. Extended camera units, seemingly for FSD, could also be seen in the graphic.
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Tesla scores major hire as Apple scientist moves to Optimus team
Chen, who advanced from individual contributor to technical lead during his time at Apple, noted that he was blown away by Tesla’s efforts and synergy.
Former Apple research scientist Yilun Chen has left the tech giant to join Tesla’s Optimus AI team. Chen, who advanced from individual contributor to technical lead during his time at Apple, noted that he was blown away by Tesla’s efforts and synergy.
Apple veteran closes a major chapter
In a farewell note, Yilun Chen reflected on his tenure at Apple as a period defined by rapid growth and exposure to notable internal projects, some of which remain unreleased. His roles spanned engineering, research, early product incubation, and hands-on prototyping, allowing him to build expertise across both mature and emerging teams.
Chen credited mentors, colleagues, and cross-functional collaborators for shaping his trajectory, calling the experience unforgettable and emphasizing how each team taught him different lessons about scaling technology, guiding product vision, and navigating fast-moving research environments. “Each role has offered me invaluable unique lessons… My deepest gratitude goes to my colleagues, mentors and friends,” he wrote.
Tesla’s Optimus lab secured the hire
Chen said the move to Tesla was driven by the momentum surrounding Optimus, a humanoid robot powered by LLM-driven reasoning and Physical AI. After visiting Tesla’s Optimus lab, he admitted that he was “totally blown away by the scale and sophistication of the Optimus lab and deep dedication of people when I got to visit the office.”
His first week at Tesla, he noted, involved spontaneous deep-tech discussions, a flat team structure, rapid prototyping cycles, and what he called a “crazy ideas with super-fast iterations” culture. Chen emphasized that the team’s ambition, as well as its belief that humanoid robots are now within reach, creates an energy level that feels aimed at changing the world.
-->“You can feel the energy to change the world here,” he wrote in a post on social media.
Elon Musk
Elon Musk gives nod to SpaceX’s massive, previously impossible feat
It was the booster’s 30th flight, a scenario that seemed impossible before SpaceX became a dominant force in spaceflight.
Elon Musk gave a nod to one of SpaceX’s most underrated feats today. Following the successful launch of the Transporter-15 mission, SpaceX seamlessly landed another Falcon 9 booster on a droneship in the middle of the ocean.
It was the booster’s 30th flight, a scenario that seemed impossible before SpaceX became a dominant force in spaceflight.
Elon Musk celebrates a veteran Falcon 9 booster’s feat
SpaceX completed another major milestone for its Smallsat Rideshare program on Friday, successfully launching and deploying 140 spacecraft aboard a Falcon 9 from Vandenberg Space Force Base. The mission, known as Transporter-15, lifted off two days later than planned after a scrub attributed to a ground systems issue, according to SpaceFlight Now. SpaceX confirmed that all payloads designed to separate from the rocket were deployed as planned.
The Falcon 9 used for this flight was booster B1071, one of SpaceX’s most heavily flown rockets. With its 30th mission completed, it becomes the second booster in SpaceX’s fleet to reach that milestone. B1071’s manifest includes five National Reconnaissance Office missions, NASA’s SWOT satellite, and several previous rideshare deployments, among others. Elon Musk celebrated the milestone on X, writing “30 flights of the same rocket!” in his post.
Skeptics once dismissed reusability as unfeasible
While rocket landings are routine for SpaceX today, that was not always the case. Industry veterans previously questioned whether reusable rockets could ever achieve meaningful cost savings or operational reliability, often citing the Space Shuttle’s partial reusability as evidence of failure.
-->In 2016, Orbital ATK’s Ben Goldberg argued during a panel that even if rockets could be reusable, they do not make a lot of sense. He took issue with Elon Musk’s claims at the time, Ars Technica reported, particularly when the SpaceX founder stated that fuel costs account for just a fraction of launch costs.
Goldberg noted that at most, studies showed only a 30% cost reduction for low-Earth orbit missions by using a reusable rocket. “You’re not going to get 100-fold. These numbers aren’t going to change by an order of magnitude. They’re just not. That’s the state of where we are today,” he said.
Former NASA official Dan Dumbacher, who oversaw the Space Launch System, expressed similar doubts in 2014, implying that if NASA couldn’t make full reusability viable, private firms like SpaceX faced steep odds.
Tesla Semi factory looks almost complete during Thanksgiving weekend
Tesla scores major hire as Apple scientist moves to Optimus team
