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SpaceX to use superalloys in Mars rocket Raptor engines, says Elon Musk
A few days after he touched upon methods of creating BFR propellant on Mars, SpaceX CEO Elon Musk mentioned in a tweet that the launch company was using cutting-edge combinations of metals (known as superalloys) to ensure the efficiency and reliability of its Raptor rocket engine, a critical requirement for BFR to enable sustainable colonization of Mars.
In response to a tweeted question about types of metal alloys currently in use at SpaceX, Musk briefly delved into the complexities of building BFR’s propulsion system, particularly with respect to alloys capable of surviving the intense conditions inside a rocket engine:
“[SpaceX is using] SX 300 & soon SX 500. Kind of a modern version of Inconel superalloys. High strength at temperature, extreme oxidation resistance. Needed for ~800 atmosphere, hot, oxygen-rich turbopump on Raptor rocket engine.” – Elon Musk
There’s a lot to break down for the layperson in Musk’s tweet. First and foremost, commenters (your author included) immediately jumped to the conclusion that “SX 300/500” referred to some sort custom SpaceX material, given that SX is a frequent shorthand for SpaceX used in the enthusiast community. In reality, it was quickly discovered that the requirements Musk described for the material – namely “high strength at temperature [&] extreme oxidation resistance” – were nearly the exact same qualities of single-crystal superalloys, extremely advanced metal formulations also notated as SC or SX. It’s quite the apt coincidence that SpaceX will apparently rely on SX alloys for critical components of BFR propulsion.
A 2017 test-firing of the mature development Raptor, roughly 50% less powerful than the full-scale system. (SpaceX)
Single-crystal superalloys employ small amounts of exotic elements in order to better ensure truly unusual crystal formation in metal structures. In the case of SX alloys, the optimal result is a monolithic metal structure that effectively has no visible grain (think wood grain but in metal) – the resulting metal would be a huge monolithic crystal, in other words, uniform down to a near-atomic level. These SX superalloys are already used regularly for industrial applications requiring the ability to reliably operate in extremely corrosive high-pressure, high-temperature environments for long periods of time, most frequently seen in gas turbines for energy generation and airplane propulsion.
Per Musk, SpaceX intends to take those alloys a step further, developing its own SX-300 and SX-500 iterations for the purpose of building a reliable, robust turbopump for the Raptor propulsion system. In pursuit of the greatest possible efficiency, Raptor’s turbopump will run oxygen-rich, meaning that the inherently imperfect combustion process will lean towards excess oxygen in the exhaust, rather than excess methane. In simple terms, this choice is partially motivated by the fact that oxygen molecules are slightly lighter than methane molecules (15.999u vs. 16.04u). More importantly, the higher the pressure in the turbopump, the higher the pressure in Raptor’s combustion chamber, which directly correlates with more efficient combustion and thus a more efficient rocket engine overall. All improvements to its subcomponents will inherently end up benefiting SpaceX’s BFR booster and spaceship, the latter of which is already nearing initial prototype construction.
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- SpaceX’s current Texas facilities feature a test stand for Raptor, the engine intended to power BFR and BFS to Mars. (SpaceX)
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- SpaceX’s Raptor proceeds through the complex process of ignition. (SpaceX)
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- SpaceX’s subscale Raptor engine has completed more than 1200 seconds of testing in less than two years. (SpaceX)
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- SpaceX’s three-bay Raptor test stand as of April 17. The middle bay is currently home to the subscale Raptor test program. (Aero Photo)
While SpaceX cut its original Raptor specifications by roughly 50% compared to its 2016 goals, it appears that the company’s ambitions for the downsized Raptor are smaller in name only. In a May 2018 presentation, Chief of Propulsion Tom Mueller foreshadowed those future ambitions while humbly acknowledging that the Merlin 1D powering Falcon 9 and Heavy is already a masterpiece of engineering: “Merlin holds the thrust to weight record for now… but Raptor’s coming.”
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News
Tesla’s new Holiday perk is timed perfectly to make FSD a household name
Tesla AI4 owners get FSD (Supervised) through Christmas, New Year’s Eve and well into the post-holiday travel season.
Tesla quietly rolled out a free Full Self-Driving (Supervised) trial for roughly 1.5 million HW4 owners in North America who never bought the package, and the timing could very well be genius.
As it turns out, the trial doesn’t end after 30 days. Instead, it expires January 8, 2026, meaning owners get FSD (Supervised) through Christmas, New Year’s Eve and well into the post-holiday travel season. This extended window positions the feature for maximum word-of-mouth exposure.
A clever holiday gift
Tesla watcher Sawyer Merritt first spotted the detail after multiple owners shared screenshots showing the trial expiring on January 8. He confirmed with affected users that none had active FSD subscriptions before the rollout. He also observed that Tesla never called the promotion a “30-day trial,” as the in-car message simply reads “You’re Getting FSD (Supervised) For the Holidays,” which technically runs until after the new year.
The roughly 40-day period covers peak family travel and gatherings, giving owners ample opportunity to showcase the latest FSD V14’s capabilities on highway trips, crowded parking lots and neighborhood drives. With relatives riding along, hands-off highway driving and automatic lane changes could become instant conversation starters.
Rave reviews for FSD V14 highlight demo potential
FSD has been receiving positive reviews from users as of late. Following the release of FSD v14.2.1, numerous owners praised the update for its smoothness and reliability. Tesla owner @LactoseLunatic called it a “huge leap forward from version 14.1.4,” praising extreme smoothness, snappy lane changes and assertive yet safe behavior that allows relaxed monitoring.
-->Another Tesla owner, @DevinOlsenn, drove 600 km without disengagements, noting his wife now defaults to FSD for daily use due to its refined feel. Sawyer Merritt also tested FSD V14.2.1 in snow on unplowed New Hampshire roads, and the system stayed extra cautious without hesitation. Longtime FSD tester Chuck Cook highlighted improved sign recognition in school zones, showing better dynamic awareness. These reports of fewer interventions and a more “sentient” drive could turn family passengers into advocates, fueling subscriptions come January.
Elon Musk
Elon Musk predicts AI and robotics could make work “optional” within 20 years
Speaking on entrepreneur Nikhil Kamath’s podcast, Musk predicted that machines will soon handle most forms of labor, leaving humans to work only if they choose to.
Elon Musk stated that rapid advances in artificial intelligence and robotics could make traditional work unnecessary within two decades.
Speaking on entrepreneur Nikhil Kamath’s podcast, Musk predicted that machines will soon handle most forms of labor, leaving humans to work only if they choose to.
Work as a “hobby”
During the discussion, Musk said the accelerating capability of AI systems and general-purpose robots will eventually cover all essential tasks, making human labor a choice rather than an economic requirement. “In less than 20 years, working will be optional. Working at all will be optional. Like a hobby,” Musk said.
When Kamath asked whether this future is driven by massive productivity growth, Musk agreed, noting that people will still be free to work if they enjoy the routine or the challenge. He compared future employment to home gardening, as it is something people can still do for personal satisfaction even if buying food from a store is far easier.
“Optional” work in the future
Elon Musk acknowledged the boldness of his claim and joked that people might look back in 20 years and say he was wrong. That being said, the CEO noted that such a scenario could even happen sooner than his prediction, at least if one were to consider the pace of the advancements in AI and robotics.
-->“Obviously people can play this back in 20 years and say, ‘Look, Elon made this ridiculous prediction and it’s not true,’ but I think it will turn out to be true, that in less than 20 years, maybe even as little as ten or 15 years, the advancements in AI and robotics will bring us to the point where working is optional,” Musk said.
Elon Musk’s comments echo his previous sentiments at Tesla’s 2025 Annual Shareholder Meeting, where he noted that Optimus could ultimately eliminate poverty. He also noted that robots like Optimus could eventually provide people worldwide with the best medical care.
Elon Musk
Elon Musk reiterates why Tesla will never make an electric motorcycle
Tesla CEO Elon Musk preemptively shut down speculations about a Tesla road bike once more.
Tesla CEO Elon Musk preemptively shut down speculations about a Tesla road bike once more, highlighting that the electric vehicle maker has no plans to enter the electric motorcycle market.
Musk posted his clarification in a post on X.
Musk’s reply to a fun AI video
X user @Moandbhr posted an AI video featuring the Tesla CEO on the social media platform, captioning it with “Mr. Elon Musk Just Revealed the Game-Changing Tesla Motorcycle.” The short clip depicted Musk approaching a sleek, single-wheeled vehicle, stepping onto it, and gliding off into the distance amid cheers. The fun video received a lot of traction on X, gaining 3.1 million views as of writing.
Musk replied to the post, stating that a Tesla motorcycle is not going to happen. “Never happening, as we can’t make motorcycles safe. For Community Notes, my near death experience was on a road bike. Dirt bikes are safe if you ride carefully, as you can’t be smashed by a truck,” Musk wrote in his reply.
Musk’s Past Comments on Two-Wheelers
Musk also detailed his reservations about motorcycles in a December 2019 X post while responding to questions about Tesla’s potential ATV. At the time, he responded positively to an electric ATV, though he also opposed the idea of a Tesla road-going motorcycle. Musk did state that electric dirt bikes might be cool, since they do not operate in areas where large vehicles like Class 8 trucks are present.
-->“Electric dirt bikes would be cool too. We won’t do road bikes, as too dangerous. I was hit by a truck & almost died on one when I was 17,” Musk wrote in his post.
Considering Musk’s comments about dirt bikes, however, perhaps Tesla would eventually offer a road bike as a recreational vehicle. Such a two-wheeler would be a good fit for the Cybertruck, as well as future products like the Robovan, which could be converted into an RV.
Tesla’s new Holiday perk is timed perfectly to make FSD a household name
Elon Musk predicts AI and robotics could make work “optional” within 20 years
