News
Stoke Space to build SpaceX Raptor engine’s first real competitor
Seattle startup Stoke Space has revealed plans to develop an efficient rocket engine similar to the Raptors that power SpaceX’s Starship.
Formed in October 2019, Stoke Space secured its first significant round of funding – $9.1 million – less than three years ago. At that time, CEO and co-founder Andy Lapsa says that the startup had just five employees, no permanent workspace, and a “barren field” for a test site. Within 18 months, Stoke Space had turned that empty field into an impressive test facility, conducted numerous component tests, and assembled its first full-scale rocket engine – an exotic UFO-like device unlike any seen before.
It also raised another $65 million – enough funding to begin earnestly developing a potentially revolutionary rocket capable of launching more than 1.65 tons (~3600 lb) into orbit for less than half a million dollars. To realize that extremely ambitious goal, Stoke Space has taken the even more ambitious step of attempting to make the first rocket it develops fully reusable. Simultaneously, the company has incorporated several exotic technologies into that rocket, recently culminating in a surprise announcement that it will attempt to develop one of the most difficult types of engines to power that rocket’s booster stage.
The update that's rolling out to the fleet makes full use of the front and rear steering travel to minimize turning circle. In this case a reduction of 1.6 feet just over the air— Wes (@wmorrill3) April 16, 2024
Full-flow staged combustion
At the end of an extended interview and tour with YouTuber Tim Dodd (The Everyday Astronaut), CEO Andy Lapsa revealed that Stoke Space has decided to build a full-flow staged combustion (FFSC) engine for the first stage of its reusable rocket. FFSC is the most efficient type of combustion cycle available for a chemical bipropellant rocket engine, but it’s also the most difficult to develop.
A full-flow engine attempts to squeeze every possible ounce of performance out of the propellant it consumes. The most powerful and efficient chemical rocket engines must consume huge volumes of propellant in a short amount of time without destroying the launch vehicle they’re attached to. To create pressure and spin the pumps that are needed to feed that propellant into their main combustion chamber, engines often burn a small amount of propellant in a separate gas generator or preburner. Gas-generator engines vent that exhaust overboard, reducing efficiency but making for a much simpler design. Staged-combustion engines use preburners to create gas that pumps liquid propellant, and that exhaust gas is eventually injected into the main combustion chamber.
Full-flow staged combustion sets itself apart by having two separate pumps and preburners for oxidizer and fuel. Unlike simpler variants of staged combustion, FFSC engines turn all of their propellant into gas before injecting it into the combustion chamber. That hot gas increases the heat of combustion and the pressure inside the combustion chamber, ensuring that virtually all of the propellant that flows through the engine is combusted and turned into thrust as efficiently as possible. FFSC is exceptionally difficult because of the extra-high temperatures and pressures it requires, as well as the need for an oxygen-rich preburner and pump. In a high-pressure, hot-oxygen environment, virtually anything imaginable – including most metals – will spontaneously combust.
Only complex custom-designed alloys can survive those conditions. SpaceX’s Raptor, the only FFSC engine that has ever flown, is especially difficult because it’s meant to be highly reusable. To be successful, Raptor will have to survive those conditions dozens or even hundreds of times in a row with little to no maintenance in between.
The first booster engine Stoke Space ever attempts to build will be a reusable full-flow staged combustion engine powered by liquid methane and liquid oxygen – essentially a smaller version of SpaceX’s Raptor. Stoke’s booster is otherwise familiar and features deployable landing legs like SpaceX’s Falcon boosters. Lapsa says it will likely also have grid fins.
Reusing the upper stage
In some ways, the upper stage of Stoke’s first rocket is even more ambitious. Powered by hydrogen and oxygen propellant, Stoke has designed a conical capsule-like upper stage with an integral fairing. The upper stage’s propulsion is exotic and unique. A large pump will feed propellant to up to 30 combustion chambers distributed around the rim of its heat shield. The exhaust coming from those 30 chambers will expand and partially push against the upper stage’s equally exotic metallic, liquid-cooled heat shield. That expansion against the heat shield improves the efficiency of the upper stage and means that its engine will technically be an aerospike.
Stoke has already begun testing a full-scale version of the upper stage’s UFO-like rocket engine with 15 combustion chambers. Since testing began in the second half of 2022, Stoke has completed dozens of static fires. Everyday Astronaut’s tour also revealed that the startup has made significant progress fabricating and assembling its first full-scale upper stage prototype – tanks, nosecone, heat shield, engine, and all.
Reminiscent of SpaceX’s Grasshopper and Starhopper campaigns, Stoke plans to conduct hop tests with that prototype if it makes it through qualification testing. On February 7th, Stoke also revealed that it’s begun testing a crucial component of its full-flow booster engine. All told, Stoke Space is making progress at a remarkable pace and continues to tackle the hardest problems. The startup has also avoided widely publicizing any specific deadlines, instead choosing to let hardware and tangible results speak for themselves. Only time will tell if that approach pays off, but Stoke is off to an exceptionally impressive start in an industry full of impressive rocket startups.
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.
News
Tesla named official AV operator in Austin ahead of robotaxi launch
Tesla robotaxis could begin operating around Austin any day now, as echoed by an update to the city’s website.
Just as Tesla prepares to launch its own commercial robotaxi services in Austin, Texas this month, the company has now appeared on the state’s website as an official operator of autonomous vehicles (AVs).
As of Monday, Tesla has been listed as an AV operator on Austin’s official Department of Motor Vehicles (DMV) site, ahead of the company’s expected launch of the long-awaited service sometime this month. The news, which X user Tesla Yoda first spotted, precedes some reports suggesting the robotaxi service could launch in the coming days, and it comes as the city becomes an increasingly competitive stomping ground for the emerging technology.
Although Tesla has been included on the list, the website says that Tesla is still in the testing phase, alongside most of the other AV operators in the city. At this time, Alphabet-owned robotaxi company Waymo is the only operator listed as being in the deployment phase, while Hyundai-owned company Motional is listed as being in the mapping phase.
Tesla is set to initially deploy the service as a limited pilot program using the company’s existing Model Y vehicles, and it will start by testing them in the safest areas of the city within geo-mapped boundaries as extra safety precautions upon launch.
🚨 Elon says by end of June, the public should be ready to take a Robotaxi in Austin without an invitation
Initial launch will be small and riders will be picked by Tesla https://t.co/zEQOkXnE6s
— TESLARATI (@Teslarati) May 29, 2025
Below you can see the full list of AV operators on the Austin DMV website at the time of writing, including both the Alphabet-owned Waymo and the Amazon-run Zoox.
Current list of AV operators in Austin
- ADMT
- Phase: testing
- Parent company: VW
- AVRide
- Phase: testing
- Parent company: AVRide Inc
- Motional
- Phase: mapping
- Parent company: Hyundai
- Waymo
- Phase: deployment
- Parent company: Alphabet (Google)
- Tesla
- Phase: testing
- Parent company: Tesla
- Zoox
- Phase: testing
- Parent company: Amazon
READ MORE ON AUTONOMOUS VEHICLES: Elon Musk just revealed more about Tesla’s June Robotaxi launch
Tesla’s Austin robotaxi launch, Full Self-Driving, and other AV companies
The news follows a report from Bloomberg a few weeks ago saying that Tesla was considering a launch date of June 12 for the service, though the validity of that report is still unclear. Additionally, Tesla could still change its plans on a launch date, though the company’s inclusion on the Austin DMV AV operators list appears to be a good sign either way.
The company has also been running internal pilot programs for the robotaxi service in Austin and around the Bay Area, California, with around 300 test operators operating the vehicles in the Texas city since at least April. Last fall, CEO Elon Musk also said that employees had already been piloting a ride-hailing program around the Bay.
Tesla has long touted its Full Self-Driving (FSD) program as the solution to autonomy, with the system utilizing cameras and real-time driver footage to train its AI neural network on how to drive. By comparison, most other companies utilize cameras and radar systems together, while relying on geo-mapped systems to determine where the robotaxi can operate.
Waymo launched driverless ride-hailing services in Austin through a partnership with Uber, though the company has also been running paid robotaxi rides in various parts of California since last year through its Waymo One app. Other companies such as the Amazon-owned firm Zoox and the Hyundai-led company Motional are also preparing to deploy services in Austin and other U.S. cities.
Tesla’s ‘Project Alicorn’ and what it means for the Robotaxi platform
xAI targets $5 billion debt offering to fuel company goals
SpaceX to debut new Dragon capsule in Axiom Space launch
Tesla named official AV operator in Austin ahead of robotaxi launch
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