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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.
- SpaceX’s current Texas facilities feature a test stand for Raptor, the engine intended to power BFR and BFS to Mars. (SpaceX)
- SpaceX’s Raptor proceeds through the complex process of ignition. (SpaceX)
- SpaceX’s subscale Raptor engine has completed more than 1200 seconds of testing in less than two years. (SpaceX)
- 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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Elon Musk
Elon Musk breaks his silence on the Starlink impact to Ukraine drones
Musk says the US military and president set Starshield limits, not SpaceX, amid Ukraine complaints.
Elon Musk says the speed limit cutting out Ukraine’s military Starlink terminals is not SpaceX’s decision. In a post on X Wednesday, Musk wrote that “Starshield systems are owned and controlled by the US government. Any limits on speed or usage are decided by the US military and ultimately POTUS.” He added that Starlink is a commercial service limited to civilian or defensive activities and “cannot be used for offensive military action, as doing so would be inappropriate for a commercial company.”
He was replying to Mykhailo Fedorov, Ukraine’s former defense minister, who had thanked Musk for restoring connectivity at speeds up to 160 km/h and said removing the Starshield limit entirely is “now critical for Ukraine’s defense.”
Starshield systems are owned and controlled by the US government. Any limits on speed or usage are decided by the US military and ultimately POTUS.
Starlink is a commercial service owned and controlled by SpaceX. Usage of Starlink is limited to civilian or defensive activities and cannot be used for offensive military action, as doing so would be inappropriate for a commercial company.
— Elon Musk (@elonmusk) October 14, 2026
The complaint started Tuesday night, when Ukrainian officials said military terminals began losing service above roughly 100 mph. Presidential adviser Serhiy Beskrestnov said the defense forces got no warning and several missions were disrupted, as Teslarati reported earlier Wednesday. The 7th Rapid Reaction Corps told Reuters connections dropped for 10 to 20 seconds at speeds well below the limit, which made drones harder to control. Poland’s foreign minister, Radoslaw Sikorski, asked Musk on X whether he is “playing politics with your products again.”
That is why the Starlink and Starshield distinction matters. SpaceX introduced Starshield in 2022 as the government version of Starlink, with an initial focus on Earth observation, communications and hosted payloads. It won a Space Force contract in 2023 with a $70 million ceiling. In December 2024, the Pentagon moved Ukraine’s terminals onto Starshield, covering about 3,000 units across two contracts. Ukraine’s military connections therefore run through a service that Musk now says sits under Washington’s control.
While Musk’s post describes who holds authority, it does not infer that anyone ordered the limit, and neither SpaceX nor the US government has confirmed who set it. Ukrainian officials have pointed to the timing, which follows President Trump’s push for an energy ceasefire and Musk’s Saturday post that “Zelensky has gone too far.” The BBC noted Trump denied threatening to restrict intelligence sharing with Kyiv, and no evidence has been presented that Washington requested the cap.
The episode also revives a promise from 2025. After Poland accused him of threatening Ukraine’s access, Musk said Starlink “will never turn off its terminals” and would not be used as a bargaining chip. Poland has since supplied more than 29,000 terminals to Ukraine. Teslarati also covered Kyiv’s search for Starlink alternatives in 2025, and the latest dispute gives that search new urgency.
Investor's Corner
Tesla opens the Q&A for its biggest earnings call yet
Tesla opens its Q3 earnings Q&A, and Cybercab, Robotaxi, Optimus and regulators loom over October 21.
Tesla has opened its shareholder question portal for the Q3 2026 earnings call, with the Say Q&A page already listing questions. Investors have until 4:00 p.m. EDT on October 20 to submit and vote on what management should answer.
The call is set for Wednesday, October 21. Tesla will post results after the market closes, with a live webcast at 4:30 p.m. CT, or 5:30 p.m. ET, through its investor relations site.
Say ranks questions by the number of shares behind the votes, which gives institutional holders extra weight over the retail crowd.
Ahead of Q2, retail investors asked why Robotaxi growth had stalled, when Cybercab would start customer rides, and where the Optimus Gen 3 ramp stood, while an institutional holder asked how Tesla and SpaceX would split Terafab duties. Cybercab has since answered one of those. Tesla said last week it has 300 plus Cybercabs serving Austin, up eightfold in 30 days, with Dallas named as the next city. The questions now are likely to move from when to how fast.
There is also a regulatory question hanging over the call. NHTSA has demanded sworn answers on how the pedal free Cybercab was certified against federal safety standards, with responses due October 30, nine days after the call. Whether an analyst raises it live is unknown, but it is the kind of exposure that tends to find its way into a Q&A.
The numbers will not be the main draw. Tesla already reported 486,532 deliveries and 13.7 GWh of storage for the quarter. Consensus sits around 43 to 45 cents per share on roughly $27.8 billion in revenue, according to Zacks, after a Q2 report that missed on EPS. Goldman Sachs, which holds a Neutral rating and a $360 target, argues the outlook for Robotaxi, FSD and Optimus will matter more to the stock than the quarter itself.
The call also lands six days after the rescheduled Roadster event, which Tesla will stream on X on Thursday, October 15, at 7:55 p.m. CT. If the Roadster shows up with a production date or a SpaceX thruster package, expect it to climb the voting list before the deadline.
Elon Musk
Ukraine says Starlink is cutting out its military drones as Poland calls out Elon Musk
Ukrainian officials allege SpaceX limited military Starlink speeds, disrupting drone missions; SpaceX has not commented.
Ukrainian officials are accusing SpaceX of placing a speed limit on the military version of Starlink that their forces use to fly drones, but SpaceX has not confirmed that any change was made. Presidential adviser Serhiy Beskrestnov said in a Telegram post on Wednesday that Starshield terminals have begun losing service when they move faster than about 100 miles per hour, according to a Reuters report. “Our defense forces did not receive a warning about this limitation, and this led to the disruption of several missions,” he wrote.
Ukraine’s 7th Rapid Reaction Corps told Reuters that connections dropped for 10 to 20 seconds at just 68 to 75 mph, which made the drones harder to control. Volunteer Serhiy Sternenko, citing military reports, said the dropouts are now starting at 37 to 43 mph. These accounts come from Ukrainian officials and military sources and have not been independently verified. Regular civilian terminals were reportedly not affected, according to EUalive.
.@POTUS: We told Zelensky, ‘You can do whatever you want to Russia, but don’t hit the refineries because that’s a world problem.’ And what does he do? He goes and hits the diesel fuel. He better damn well stop. https://t.co/CdRlMcPlKr
— Rapid Response 47 (@RapidResponse47) October 10, 2026
SpaceX has not publicly commented or explained what, if anything, changed. Beskrestnov and other Ukrainian officials believe the issue is intentional and point to the timing. Washington has been pressing Kyiv to stop long range strikes on Russian oil refineries after President Trump called for an “energy ceasefire,” and Musk posted on Saturday that “Zelensky has gone too far.” EUalive noted that neither Ukrainian nor Polish officials have presented evidence that the limit was ordered by Washington or by SpaceX, so the link to politics remains an allegation. Other explanations, such as a technical or policy change affecting fast moving terminals, have not been ruled out.
Poland’s foreign minister, Radosław Sikorski, responded on X by quote tweeting a Kyiv Independent report and writing: “Hey, @elonmusk, big man, are you playing politics with your products again? As your European customers, we are watching you.” Poland is the largest funder of Ukraine’s Starlink service, having supplied more than 29,000 terminals and covering operating costs Sikorski has put at roughly $50 million a year. The wording echoes their 2025 clash, when Musk told Sikorski to “be quiet, small man.” At the time of writing, neither Musk nor SpaceX had responded to the claims.
Hey, @elonmusk, big man, are you playing politics with your products again?
As your European customers, we are watching you.— Radosław Sikorski 🇵🇱🇪🇺 (@sikorskiradek) October 14, 2026
The dispute sits on top of a long history. Musk confirmed in February 2022 that Starlink was active in Ukraine after a request from a Ukrainian minister. That October, SpaceX asked the Pentagon to share the bill and Musk said the cost was approaching $20 million a month, before he reversed course and said SpaceX would keep paying. In December 2024 the Pentagon moved some of those terminals onto the Starshield service, the government version now at the center of the complaints.
SpaceX has also changed how its network treats certain terminals in Ukraine before, and that time it was with Kyiv’s cooperation. In February, Ukrainian officials confirmed that terminals believed to be used by Russian troops were disabled after coordination with SpaceX, a step that Ukrainian commanders later said hurt Russian assaults. Whether anything similar is behind the latest reports is unclear, which is why Kyiv is asking for answers.
Ukraine is already looking at backups. Defense tech company Stetman is developing its own satellite system, UASAT-NANO, and officials in Europe have discussed alternatives to Starlink since early 2025, though none match its scale yet.



