News
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.”
Follow us for live updates, peeks behind the scenes, and photos from Teslarati’s East and West Coast photographers.
Teslarati – Instagram – Twitter
Tom Cross – Twitter
Pauline Acalin – Twitter
Eric Ralph – Twitter
Investor's Corner
SpaceX is launching a secret spacecraft that could change how things are made in space
SpaceX’s secret disk-shaped Starfall capsule is targeting a market no reentry vehicle has cracked.
SpaceX is targeting Tuesday, June 23 for the first flight of Starfall, a reentry capsule the company has developed almost entirely in private. The Falcon 9 launch window opens at 6:43 a.m. ET from Space Launch Complex 40 at Cape Canaveral Space Force Station, with a backup window available the same time on June 24. SpaceX has made no public announcement about the vehicle, only providing launch details. Everything known about it has come through FAA and FCC regulatory filings.
What makes Starfall different starts with its shape. Rather than the traditional cone used by Dragon and every other cargo return capsule in operation, Starfall is a flat disk that measures roughly 10.2 feet (3.1 meters) wide and just 2.5 feet (0.75 meters) tall, and weighing 4,630 pounds (2,100 kg) and capable of returning up to 2,200 pounds (1,000 kilograms) of payload from orbit. The disk geometry maximizes structural efficiency and payload volume relative to mass, and the heat shield mechanically jettisons just before splashdown, allowing recovery teams to retrieve both the capsule and the shield separately from the Pacific Ocean.
The difference with Starfall from existing competitors, such as Varda Space Industries, which has largely built the orbital manufacturing market and returns heavy payloads per flight is that Starfall’s specification is roughly 30 times more per mission, and is designed to be mass-produced and launched on either Falcon 9 or Starship. That combination of volume and launch access is something no standalone startup can replicate, and it puts SpaceX in direct competition with the companies that currently pay it to reach orbit.
SpaceX to launch military missile tracking satellites through new Space Force contract
The intended market is orbital manufacturing: pharmaceuticals, protein crystals, semiconductors, and advanced optical fiber that physically cannot be produced in the presence of gravity. FAA documents describe Starfall’s long-term purpose as building a “self-sustaining commercial in-space manufacturing market” and as a potential successor to the industrial capabilities of the International Space Station, which is set to retire in the late 2020s. Military rapid global cargo delivery is a parallel application under active discussion with the Pentagon.
The reason some industries seek manufacturing in space comes down to gravity. On Earth, gravity causes materials to settle, separate, and deform during production. In microgravity, those constraints disappear.
SpaceX’s already controls launch access, which means it currently functions as the landlord for every competitor in the orbital manufacturing return space. Starfall converts that landlord position into vertical ownership, and it would no longer just carry other companies’ capsules to orbit, but rather operate the capsule, own the return logistics, and capture the service revenue directly. Viewed alongside Starlink, Colossus, and the xAI merger, Starfall fits a consistent pattern: SpaceX identifying infrastructure layers that others depend on and moving to own them outright. Orbital manufacturing return is the next layer on that list.
If Tuesday’s reentry, parachute sequence, and recovery demonstration goes as planned, the second FAA-approved test flight follows. A successful pair of demos would position SpaceX to begin offering Starfall as a commercial service, likely first to pharmaceutical and materials science customers before scaling toward the military and broader manufacturing segments.
The Tesla Semi was spotted mounted with ground truth validation equipment as the company nears its looming launch. The Semi is Tesla’s Class 8 all-electric truck, and has been utilized in its earlier stages by many companies like PepsiCo. and Frito-Lay, who have been using it in a pilot program.
The Semi was spotted in Sunnyvale, California, and sports a typical ground truth validation unit that Tesla routinely uses on its vehicles. Ground truth validation is essentially the process of training supervised algorithms to ensure they can perform reliably. Tesla typically performs this on vehicles that are being released soon:
Spotted the new semi adorned with ground truthing equipment. Haven’t seen anyone post this so figured I’d share.
The future is autonomous!!@SawyerMerritt @wholemars pic.twitter.com/qkPDHPUQZ6
— Danny (@dannywinner1) June 21, 2026
The Semi being spotted with this type of validation rig is important because it means the company is working on solidifying a Full Self-Driving model for its commercial vehicle offering. This would be a massive development for not only Tesla but also the logistics industry as a whole.
There are strict regulations on driving hours for commercial truck drivers, and autonomy is a way to potentially combat these issues. FSD is already a widely effective way that owners of typical passenger vehicles take stress out of travel. Even launching a semi-autonomous platform for truck drivers to use to increase safety, reduce fatigue, and increase productivity would be a huge development.
Tesla Semi gets strange-but-understandable comparison from Jay Leno
The Semi has already proven to be an ideal solution for companies that use commercial logistics. It has increased efficiency and reduced operating costs for many companies that have been able to use it in pilot programs.
There are expected to be some bumps along the way. Tesla saw some challenges with FSD on the Cybertruck, as it had never had a vehicle with cameras at that height, so some of the features with FSD were not immediately available. Just a week ago, Tesla launched Actually Smart Summon (ASS) for Cybertruck, nearly three years after the vehicle was first delivered to customers.
President Donald Trump unveiled an upgraded Boeing 747-8 at Joint Base Andrews on June 19, 2026, describing the Qatar-gifted aircraft as an interim Air Force One equipped with advanced communications systems, including Starlink, Elon Musk’s SpaceX satellite internet service.
The plane, valued at around $400 million and modified for presidential use, serves as a bridge until the delayed VC-25B replacements arrive. Trump highlighted its luxury features and new technology during remarks to service members.
Trump stated:
“We have communication equipment up there that nobody’s ever seen before. It’s the highest level and, uh, including Starlink. My friend Elon is going to be very happy, but, uh, Starlink and we have, uh, four or five different sets of double and triple communications like people haven’t seen.”
He added:
“And it represents what can happen with hard work, innovation, and aggressive timelines because we did this quickly and yet there’s never been communication like is on this plane.”
🚨 President Trump confirmed today that the new Air Force One is equipped with Starlink:
“We have communication equipment up there that nobody’s ever seen before, it’s the highest level and including Starlink…my friend Elon is going to be very happy.” pic.twitter.com/IhkDmtr5hL
— TESLARATI (@Teslarati) June 20, 2026
The aircraft features a redesigned red, white, and blue livery and has been outfitted with Starlink satellite connectivity alongside other secure systems.
Trump praised the plane’s uniqueness, calling it among the world’s most luxurious. The gift from Qatar and subsequent modifications have drawn attention, with the jet positioned as a solution for presidential travel. It is expected to support operations, including potential ceremonial roles such as Fourth of July flyovers.
The event marked the formal introduction of the converted jet, which will help maintain capabilities while the primary Air Force One fleet undergoes modernization. Defense observers note the inclusion of commercial satellite technology like Starlink as part of efforts to ensure resilient communications, crucial to keep the country running as the President is in the sky.
President Trump’s comments underscored appreciation for rapid upgrades and innovation in equipping the aircraft. The plane remains a U.S. government asset and is slated for eventual transfer related to presidential library purposes after its service.
SpaceX is launching a secret spacecraft that could change how things are made in space
Tesla Semi spotted with ground truth validation equipment as launch looms
