

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.”
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News
Waymo temporarily halts service in select San Francisco and LA areas amid protests
The suspensions came after several Waymo Jaguar I-Pace robotaxis were vandalized and set ablaze during the demonstrations.

Waymo, Alphabet’s autonomous vehicle subsidiary, has suspended its driverless taxi operations in parts of Los Angeles and San Francisco amid violent protests linked to U.S. Immigration and Customs Enforcement (ICE) raids in the state.
The suspensions came after several Waymo Jaguar I-Pace robotaxis were vandalized and set ablaze during the demonstrations.
Waymo Catches Strays Amid Anti-ICE Protests
Protests erupted in Los Angeles and San Francisco in response to the Trump administration’s immigration raids, which ultimately resulted in California Governor Gavin Newsom calling the White House’s deployment of National Guard troops unconstitutional.
Amidst the protests, images and videos emerged showing several Waymo robotaxis being defaced and destroyed. At least five Waymo robotaxis ended up being caught in the crossfire, and at least one vehicle ended up being burned to the ground.
The incident resulted in the Los Angeles Police Department advising people to avoid downtown areas due to toxic fumes from the robotaxis’ burning lithium-ion batteries. As noted in a KRON4 report, Waymo ultimately halted service in affected areas “out of an abundance of caution.”
Robotaxi Sentiments
The cost of the attacks is notable. Each Waymo robotaxi is valued between $150,000 and $200,000, per a 2024 Wall Street Journal report. Interestingly enough, this is not the first time that Waymo’s robotaxis ended up on the receiving end of angry protesters. On February 24, a Jaguar I-PACE robotaxi was set ablaze and vandalized by a crowd in San Francisco. Videos taken at the time showed a mob of people attacking the vehicle.
Despite the recent attacks on its robotaxis, Waymo has stated it has “no reason to believe” its vehicles were specifically targeted during the protests, as per a report from The Washington Post. A company spokesperson also noted that some of the Waymo robotaxis that were defaced and destroyed during the violent demonstrations had been completing drop-offs near the protest zones.
Investor's Corner
xAI targets $5 billion debt offering to fuel company goals
Elon Musk’s xAI is targeting a $5B debt raise, led by Morgan Stanley, to scale its artificial intelligence efforts.

xAI’s $5 billion debt offering, marketed by Morgan Stanley, underscores Elon Musk’s ambitious plans to expand the artificial intelligence venture. The xAI package comprises bonds and two loans, highlighting the company’s strategic push to fuel its artificial intelligence development.
Last week, Morgan Stanley began pitching a floating-rate term loan B at 97 cents on the dollar with a variable interest rate of 700 basis points over the SOFR benchmark, one source said. A second option offers a fixed-rate loan and bonds at 12%, with terms contingent on investor appetite. This “best efforts” transaction, where the debt size hinges on demand, reflects cautious lending in an uncertain economic climate.
According to Reuters sources, Morgan Stanley will not guarantee the issue volume or commit its own capital in the xAI deal, marking a shift from past commitments. The change in approach stems from lessons learned during Musk’s 2022 X acquisition when Morgan Stanley and six other banks held $13 billion in debt for over two years.
Morgan Stanley and the six other banks backing Musk’s X acquisition could only dispose of that debt earlier this year. They capitalized on X’s improved operating performance over the previous two quarters as traffic on the platform increased engagement around the U.S. presidential elections. This time, Morgan Stanley’s prudent strategy mitigates similar risks.
Beyond debt, xAI is in talks to raise $20 billion in equity, potentially valuing the company between $120 billion and $200 billion, sources said. In April, Musk hinted at a significant valuation adjustment for xAI, stating he was looking to put a “proper value” on xAI during an investor call.
As xAI pursues this $5 billion debt offering, its financial strategy positions it to lead the AI revolution, blending innovation with market opportunity.
News
SpaceX to debut new Dragon capsule in Axiom Space launch
Ax-4’s launch marks the debut of SpaceX’s latest Crew Dragon and pushes Axiom closer to building its own space station.

Axiom Space’s Ax-4 mission targets the International Space Station (ISS) with a new SpaceX Crew Dragon capsule.
The Axiom team will launch a new SpaceX Dragon capsule atop a Falcon 9 rocket from NASA’s Kennedy Space Center in Florida on Wednesday at 8:00 a.m. EDT (1200 GMT). The Ax-4 mission launch was initially set for Tuesday, June 10, but was delayed by one day due to expected high winds.
As Axiom Space’s fourth crewed mission to the ISS, Ax-4 marks the debut of an updated SpaceX Crew Dragon capsule. “This is the first flight for this Dragon capsule, and it’s carrying an international crew—a perfect debut. We’ve upgraded storage, propulsion components, and the seat lash design for improved reliability and reuse,” said William Gerstenmaier, SpaceX’s vice president of build and flight reliability.
Axiom Space is a Houston-based private space infrastructure company. It has been launching private astronauts to the ISS for research and training since 2022, building expertise for its future station. With NASA planning to decommission the ISS by 2030, Axiom has laid the groundwork for the Axiom Station, the world’s first commercial space station. The company has already begun construction on its ISS replacement.
The Ax-4 mission’s research, spanning biological, life, and material sciences and Earth observation, will support this ambitious goal. Contributions from 31 countries underscore the mission’s global scope. The four-person crew will launch from Launch Complex 39A, embarking on a 14-day mission to conduct approximately 60 scientific studies.
“The AX-4 crew represents the very best of international collaboration, dedication, and human potential. Over the past 10 months, these astronauts have trained with focus and determination, each of them exceeding the required thresholds to ensure mission safety, scientific rigor, and operational excellence,” said Allen Flynt, Axiom Space’s chief of mission services.
The Ax-4 mission highlights Axiom’s commitment to advancing commercial space exploration. By leveraging SpaceX’s Dragon capsule and conducting diverse scientific experiments, Axiom is paving the way for its Axiom Station. This mission not only strengthens international collaborations but also positions Axiom as a leader in the evolving landscape of private space infrastructure.
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