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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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SpaceX just picked up another $1.6 billion from the Pentagon, with the U.S. Space Force awarding two task orders worth $1.6 billion to fly 18 Falcon 9 missions from Vandenberg Space Force Base in California through the end of 2027. The launches will carry satellites for the Space Based Sensing and Targeting portfolio, a set of programs meant to help the military detect and track airborne threats and relay that information across forces in near real time.
The award falls under National Security Space Launch Phase 3 Lane 1, the Space Force’s faster, commercial style procurement track for missions that do not require the military’s most demanding certification process. It is also the largest single order publicly disclosed under that program so far, and the first task order issued since the Space Force nearly tripled Lane 1’s contract ceiling from $5.6 billion to $17 billion on July 17.
SpaceX to become America’s Military data backbone for missiles, drones, and warfighters
Eric Zarybnisky, the Space Force’s acting portfolio acquisition executive for space access, said the entire process, from identifying the requirement to signing the contract, took about two months, including a month set aside for companies to prepare proposals.
SpaceX is not just launching these satellites. It already holds the contracts to build two of the programs within the same portfolio, $4.16 billion for the Space Based Airborne Moving Target Indicator system and $2.29 billion for the Space Data Network Backbone, which Teslarati covered in May. That means SpaceX is now responsible for both building key pieces of the military’s next generation sensing network and getting them into orbit.
With this latest award, SpaceX’s Pentagon contract total for 2026 alone tops $8 billion, adding to a defense portfolio that already includes the Golden Dome missile defense software group SpaceX joined in April and a string of GPS launches it inherited after ULA’s Vulcan rocket ran into a booster anomaly, which we detailed in March.
Lane 1’s vendor pool technically includes seven companies: SpaceX, ULA, Blue Origin, Rocket Lab, Stoke Space, Impulse Space, and Relativity Space. In practice, SpaceX remains the only provider with the combination of launch cadence, flight proven Falcon 9 hardware, and West Coast infrastructure to support a campaign requiring roughly one Vandenberg launch a month for the next year and a half.
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Some lawmakers have flagged the growing concentration of national security launches with one company as a risk worth watching. For now, the Space Force keeps backing SpaceX, with it being the company that shows up ready to launch.
Elon Musk shed two new bits of detail on Starship following its 13th test launch, which was an overwhelming success.
SpaceX launched Starship for the 13th time last Friday after two delays: one on Monday when several Raptor engines did not ignite, and another on Thursday due to unfavorable weather conditions in Starbase, Texas.
The launch was overwhelmingly successful. SpaceX was able to complete a necessary test of the heat shield tiles by increasing the acceleration of Starship from launch throughout the flight; 20 Starlink v3 satellites were released with no issue; the Super Heavy Booster landed safely in the Gulf of America, Ship successfully reignited engines while in space; and it also splashed down without incident in the Indian Ocean.
SpaceX Starship just nailed something it’s never done before
Nevertheless, more details are coming out about Starship, and Musk is doing the talking.
Starship Will Be Retrieved in the Ocean
Musk revealed on Tuesday night that Starship would be recovered by a ship in the Indian Ocean. SpaceX routinely tries to recover Starship after splashdown in an effort to find out more about the flight by examining the spacecraft afterward.
We’re sending a ship out to recover Starship https://t.co/fUqUZTITO9
— Elon Musk (@elonmusk) July 28, 2026
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This helps engineers find out more about why things might have happened, allows them to examine any potential damage or anomalies that might have occurred, and increases the chances of an even more successful flight next time thanks to the additional information recovered.
Ship Could Have Been Caught by Tower Arms, Musk claims
Musk has already indicated that SpaceX will plan to attempt a catch of Starship with the 14th test flight. While this would be a major accomplishment, it would be an expected next step, considering the fact that the Super Heavy Booster has already been caught by the chopsticks on numerous occasions.
The ship landing was precise, meaning that it would have been caught by the tower arms https://t.co/6nbNrRfX9P
— Elon Musk (@elonmusk) July 29, 2026
A ship catch would be a great indication of where SpaceX stands in terms of reusability and launch cadence. A successful catch with relatively no incidents would be a good sign that SpaceX is nearing a more frequent launch of Starship, but also that the reusability of the massive rocket would be something many would expect in the near future.
It is a necessity to make life multiplanetary.
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Elon Musk has updated his timeline for when humans will walk on Mars and for when ships will simply get there.
The objective of getting to Mars has been one of Musk’s biggest goals since becoming a serial entrepreneur and realizing that time on Earth is limited. Musk has said several times he hopes to die on Mars, and not by impact.
Musk now believes that people will be on Mars in “roughly 5 to 7 years.” He said that a Mars lander will get there “a few years sooner.”
People on Mars in roughly 5 to 7 years.
Mars lander a few years sooner.
— Elon Musk (@elonmusk) July 29, 2026
The response from Musk comes after NASA Administrator Jared Isaacman said that SpaceX’s biggest priority is the Moon and not Mars. Because of this, Isaacman conceded that he believes nuclear power and propulsion investments will provide “potentially the pathway with the fewest miracles required to put four people on Mars in the next 10 to 15 years.”
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Of course, this is what NASA can do through taxpayer funding and nuclear investments, he added.
Musk’s grand ambitions are much more optimistic than most, and it is certainly a double-edged sword. This is not the first time timelines for Mars have been somewhat lofty, especially to those normal thinkers like you and me, not super geniuses like Musk.
In fact, the SpaceX and Tesla frontman has said on at least a dozen occasions that we could be on Mars in the coming years. Musk said 2020 would be the big year as early as 2009. In 2020, he was “highly confident” of a landing in 2026, and had even said 2024 in a best-case scenario.
The point is, the range has varied, and it’s anyone’s guess when we’ll get there. This latest adjustment to the timeline is typical of Musk, and while the Moon has seemingly taken priority over Mars, it is still worth mentioning that the ultimate goal is to make life multiplanetary, and it starts potentially with the Red Planet.
SpaceX scores another massive Pentagon deal to support military satellites
Elon Musk sheds two new bits of detail on Starship after 13th test launch
