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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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Tesla has reopened reservations for its long-delayed next-generation Roadster, asking buyers for a $50,000 deposit just days before an October 1 reveal event in Waco, Texas. The move revives a reservation process first launched in 2017 and later paused when Tesla pulled pricing from its website in 2021.
The reservation page requires an immediate $5,000 credit-card payment, described as fully refundable, followed by a $45,000 wire transfer due within 10 days, which is identical to what was expected previously. Reservations are not considered final until the wire clears.
The structure matches the 2017 terms Tesla used when it first collected deposits after unveiling a prototype. Tesla has not published a confirmed retail price or production start date on the order page.
Go buy a Roadster pic.twitter.com/n7rhouAmIS
— TESLARATI (@Teslarati) September 21, 2026
The October 1 event is scheduled in Waco, about 90 minutes north of Tesla’s Austin headquarters and near SpaceX’s McGregor rocket test site. Tesla sent invitations to existing reservation holders and posted a “Go for launch” teaser on September 12.
The Federal Aviation Administration (FAA) established a temporary flight restriction over the McGregor area from September 18 through October 2, consistent with plans for a demonstration involving SpaceX-designed cold-gas thrusters. Elon Musk has previously described the optional package as enabling extreme acceleration or brief hovering. Tesla has said the event will include pricing, specifications, and production targets.
The second-generation Roadster was first shown in November 2017 during Tesla’s Semi launch. Musk promised production in 2020, with claimed performance of 0-60 mph in 1.9 seconds, more than 250 mph top speed, and roughly 620 miles of range.
Those targets have slipped repeatedly.
Tesla later pointed to 2022, 2023, 2024, and 2025-2026 before indicating production would not begin until 2027 or 2028 at Gigafactory Texas. Design work has continued, with reports of a sharper, Cybertruck-influenced look replacing the original curvy prototype.
Original reservation holders who paid $50,000 in 2017, or $250,000 for the Founders Series, have waited nearly nine years without a production car. Some high-profile customers canceled. Tesla’s decision to reopen orders now, after previously shutting them down, tests whether new buyers will commit substantial funds before seeing a finalized production vehicle. The October 1 event is intended to answer remaining questions about what those buyers will actually receive and when.
Tesla’s Full Self-Driving (Supervised) is heading to Czechia after the Czech Ministry of Transport recognised the Dutch RDW’s provisional type approval, making the country the seventh EU member state to clear the system for public roads. Tesla Europe announced on 21 September 2026 that “FSD Supervised is now approved in Czechia” and that rollout “will begin soon.”
The decision marks a notable reversal. Earlier in 2026, Prague had declined to automatically recognise the Netherlands’ April approval, citing concerns over speed-limit compliance, traffic-sign recognition and driver-attention monitoring, and arguing that a coordinated EU approach was preferable. Officials said months of expert review, talks with Tesla and other member states, and real-world data from countries already using the system resolved those issues.
🚨 Tesla FSD heading to Czechia 🇨🇿 pic.twitter.com/mkzlM9QjrB
— TESLARATI (@Teslarati) September 21, 2026
“Safety remains the top priority,” the ministry stated.
FSD Supervised remains a Level 2 driver-assistance system: the driver must stay engaged and is legally responsible. Eligible vehicles need AI4, the company’s most up-to-date hardware version. Tesla is expected to push the feature over the air in the coming days, following the pattern seen after earlier national approvals.
Europe’s rollout began when Dutch regulator RDW issued a provisional EU type approval on 10 April 2026 after extensive testing. Mutual recognition then produced a rapid cascade: Lithuania (20 May), Estonia (29 May), Denmark (9 June), Belgium (10 June) and Slovenia (7 September). Czechia now completes that list of seven.
The approvals cover only a modest share of the EU population, but they add political weight ahead of a 6 October vote by the Technical Committee on Motor Vehicles. A qualified majority, at least 15 of 27 member states representing 65 percent of the EU population, could open the remaining markets, including large ones such as Germany, France, Italy and Spain that have so far preferred to wait for a bloc-wide decision.
For Czech Tesla owners, the immediate prize is access to the same supervised highway and city driving already available in the other six countries. For Tesla, each new market generates additional European driving data and strengthens the case that FSD Supervised can operate safely under the continent’s varied road rules. The Czech approval is therefore both a local milestone and another incremental step toward a wider European launch.
The Federal Aviation Administration (FAA) has established a Temporary Flight Restriction over SpaceX’s McGregor, Texas, rocket development and test facility, a move widely viewed as preparation for Tesla’s October 1 Roadster reveal. The restriction took effect September 18 and runs through October 2.
NOTAM FDC 6/3825 covers a 1.5-nautical-mile radius around the site near Waco and extends from the surface to 10,000 feet above ground level. The FAA cited hazards under 14 CFR 91.137(a)(3) and barred aircraft and drones from the zone. Tesla’s invitation to reservation holders already placed the event in Waco, about 20 minutes from McGregor, making the timing and location more than coincidental.
A TFR has appeared around SpaceX’s McGregor Testing Site up to 10,000ft and runs through until the 2nd of October 👀 pic.twitter.com/rcZ4p4JkLm
— Niall Anderson (@INiallAnderson) September 18, 2026
What stands out is the altitude. Typical recent TFRs at McGregor for engine static fires and component tests have used far lower ceilings, often around 2,000 feet. Raising the limit to 10,000 feet is unusually high even compared with some Starbase restrictions and signals operations that go beyond a standard ground-level engine test.
That extra airspace has fueled speculation about the long-promised SpaceX Package for the Roadster. Elon Musk has described cold-gas thrusters that could deliver sub-one-second 0-60 times and, more dramatically, brief lift-off. Reports earlier this year indicated Tesla planned a remote-controlled demonstration at McGregor in which the car would leave the ground with no one inside; spectators kept hundreds of yards away because of the noise.
The 10,000-foot envelope would give operators a large safety buffer even if the vehicle only hovers a short distance.
Tesla has not confirmed a flight demo. The company has only used the phrase “Go for launch” and posted a teaser image of the car on what looks like a launch pad. The TFR itself mentions only hazards. Still, closing airspace this high and this close to the reveal date strongly suggests the event will include more than a static display.
Whether the Roadster actually hovers on October 1 remains to be seen. What is certain is that the FAA has cleared a large vertical slice of Texas sky for whatever Tesla and SpaceX intend to show. Reservation holders heading to Waco will be among the first to find out if the car can do more than drive.
Tesla Roadster is available for order once again following brief hold
Tesla Full Self-Driving expands to another European country
