News
Ex-SpaceX engineer leads Stratolaunch to major rocket engine test milestone
Led by rocket propulsion expert Jeff Thornburg, Stratolaunch – famous for owning the largest fixed-wing aircraft ever built – has completed the first hot-fire test of a full-scale rocket engine component known as the preburner, a major milestone in the development of any launch vehicle or propulsion system.
Despite the significant size and power of the component, destined to support an engine that will generate 200,000 pounds (~900 kN) of thrust, Thornburg and his team of engineers and technicians have managed to go from designing the preburner to successfully hot-firing a full-scale test article, an extraordinary achievement by any measure.
The team made amazing progress this week! Check out the #PGAEngine preburner’s first hot-fire test at @NASAStennis. #NewUSEngine pic.twitter.com/kKTnf0bj1S
— Stratolaunch (@Stratolaunch) November 6, 2018
Aside from SpaceX, Blue Origin, and Aerojet-Rocketdyne, Stratolaunch is the only private entity developing – let alone testing full-scale parts for – a liquid-fueled rocket engine as large as PGA. Shorthand for the Stratolaunch’s late founder and bankroller Paul G. Allen, PGA is a fuel-rich staged combustion cycle engine that uses liquid hydrogen and oxygen (hydrolox) fuel and oxidizer, typically resulting in high efficiency. In terms of scale and thrust, PGA is very closely comparable to SpaceX’s Merlin 1D engine, which uses kerosene instead of hydrogen but produces roughly 190,000 lbf (850 kN) of thrust and stands 4 feet (1.2m) wide and ~10 feet (~3m) tall.
Another major difference between PGA and Merlin 1D is the fact Merlin 1D’s nozzle is largely optimized for sea level while PGA is being built for a rocket that will be “launched” from a massive plane flying around 35,000 feet (~10.5 km), ultimately resulting in a nozzle that is much wider and longer, featuring nearly the same proportions as fully vacuum-optimized engines like SpaceX’s MVac. By widening the nozzle relative to the rest of the engine, rocket engines are able to operate far more efficiently at higher altitudes, where Earth’s atmosphere thins and exerts less pressure on the escaping exhaust gases. This is visualized well by the visible expansion of rocket exhausts during launches, morphing from a straight cylinder to a massive teardrop-shaped plume. At lower altitudes (and thus higher atmospheric pressures), wider nozzles can produce extreme turbulence and will ultimately shake themselves to destruction, preventing their usage on ground-launched rocket boosters.
Judging from official renders of the engine, PGA’s in-atmosphere variant appears to utilize a form of regenerative nozzle cooling very similar to that used on M1D, where liquid propellant flows through thin capillaries sandwiched between two or more layers of metal to cool the nozzle much like cold water chills the skin of an uninsulated water bottle.
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- A to-scale comparison of Falcon 1, Pegasus XL, MLV, and Falcon 9. (Teslarati/Stratolaunch/Wikipedia)
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- A render of Stratolaunch’s impressive PGA engine. Note the giant nozzle relative to the throat. (Stratolaunch)
Testing rocket engine preburners
In the case of staged combustion cycle hydrolox rocket engines, a small portion of liquid oxygen and all of the liquid hydrogen (hence “fuel-rich”) are mixed and combusted to generate hot gas that then spools up the engine’s primary turbopump(s), ultimately drawing fuel and oxidizer into the combustion quickly enough to ignite the engine and generate sustained thrust. The components that get those main turbopumps started are known collectively as the preburner, which is what Stratolaunch successfully tested – at full-scale – for the first time ever last week. For any liquid rocket engine that cannot solely rely on propellant tank pressure to deliver fuel to the combustion chamber, full-scale tests of preburners or gas-generators effectively mark the moment that engines truly become real.
“This is the first step in proving the performance and highly efficient design of the PGA engine. The hot-fire test is an incredible milestone for both the propulsion team and Stratolaunch.” – Jeff Thornburg, VP of Propulsion, Stratolaunch
Stratolaunch’s propulsion team will continue to test the preburner for longer durations and at higher power levels over the next several months, likely optimizing operations and tweaking or upgrading the preburner’s hardware as real tests produce valuable lessons-learned. Built entirely with additive manufacturing (3D printing), the team should be able to rapidly iterate on the physical design of the engine, a rarity in a field where traditional fabrication methods can take weeks or months to produce complex turbomachinery components with mercilessly strict tolerances.
According to Thornburg, the ultimate goal is to continue that additive-manufacturing-only strategy throughout the development of this rocket engine, theoretically enabling unprecedented design flexibility while also slashing production time throughout. PGA will ultimately power the creatively-named Medium Launch Vehicle (MLV), a small-ish air-launched rocket designed to place a respectable 3400 kg into low Earth orbit (LEO) as early as 2022, as well as a Heavy version of MLV and, potentially, a reusable spaceplane somewhere down the line.
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- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
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- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
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- Jeff Thornburg stands in front of Stratolaunch’s NASA Stennis Space Center test stand. (Stratolaunch)
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- The PGA preburner seen after installation at Stennis. (Stratolaunch)
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- The control center. (Stratolaunch)
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- MLV is released from Stratolauncher. (Stratolaunch)
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- A concept video produced by Stratolaunch shows the Roc launching a Kraken rocket. (Stratolaunch, via Wired)
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Elon Musk
Tesla’s Q1 delivery figures show Elon Musk was right
On the surface, the numbers reflect a mature EV market facing competition, softening demand, and the loss of certain incentives. Yet they also quietly validate a prediction Elon Musk has repeated for years: Tesla’s traditional auto business is becoming far less central to the company’s future.
Tesla reported its Q1 delivery figures on Thursday, and the figures — solid but unspectacular — show that CEO Elon Musk was right about what the company’s most important production and division would be.
We are seeing that shift occur in real time.
Tesla delivered 358,023 vehicles in the first quarter of 2026, according to the company’s official report released April 2.
The figure represents modest year-over-year growth of roughly 6 percent from Q1 2025’s 336,681 deliveries but a sharp sequential drop from Q4 2025’s 418,227. Production reached 408,386 vehicles, while energy storage deployments hit 8.8 GWh.
On the surface, the numbers reflect a mature EV market facing competition, softening demand, and the loss of certain incentives. Yet they also quietly validate a prediction Elon Musk has repeated for years: Tesla’s traditional auto business is becoming far less central to the company’s future.
Musk has long argued that vehicles alone will not define Tesla’s value.
Optimus Will Be Tesla’s Big Thing
In September 2025, Musk stated bluntly on X that “~80% of Tesla’s value will be Optimus,” the company’s humanoid robot.
He has described Optimus as potentially “more significant than the vehicle business over time.” Those comments were not abstract futurism. In January 2026, during the Q4 2025 earnings call, Musk announced the end of Model S and X production, framing it as an “honorable discharge,” he called it.
Those are the biggest factors.
~80% of Tesla’s value will be Optimus.
— Elon Musk (@elonmusk) September 1, 2025
The Fremont factory space, once dedicated to those flagship sedans, is being converted into an Optimus manufacturing line, with a long-term target of one million robots per year from that single facility alone.
The Q1 2026 numbers arrive at precisely the moment this strategic pivot is accelerating. Model 3 and Y deliveries totaled 341,893 units, while “other models” (including Cybertruck, Semi, and the final wave of S/X) added 16,130.
Growth is no longer explosive because Tesla is no longer chasing volume at all costs. Instead, the company is reallocating capital and factory floor space toward autonomy, energy storage, and robotics, businesses Musk believes will command far higher margins and enterprise value than incremental car sales.
Delivery Hits and Misses are Becoming Less Important
Wall Street’s pre-release consensus had pegged deliveries near 365,000. Coming in below that estimate might have rattled investors focused solely on automotive metrics. Yet Musk’s thesis has never been about maximizing quarterly vehicle shipments.
Tesla, he has insisted, “has never been valued strictly as a car company.”
The modest Q1 auto performance, paired with the deliberate wind-down of legacy programs and the ramp of Optimus, underscores that point. While EV demand stabilizes, Tesla is building the infrastructure for Robotaxis and humanoid robots that could dwarf today’s car business.
The future is here, and it is happening. It’s funny to think about how quickly Tesla was able to disrupt the traditional automotive business and force many car companies to show their hand. But just as fast as Tesla disrupted that, it is now moving to disrupt its own operation.
Cars, once the only recognizable and widely-known division of Tesla, is now becoming a background effort, slowly being overtaken by the company’s ambitions to dominate AI, autonomy, and robotics for years to come.
Critics may still view the shift as risky or premature. But the Q1 figures, solid but unspectacular in the auto segment, illustrate exactly what Musk has been signaling: the era when Tesla’s valuation rose and fell with every Model Y delivery is ending.
The company’s long-term bet is on AI-driven products that turn vehicles into high-margin robotaxis and factories into robot foundries. Thursday’s delivery report did not just meet the market’s tempered expectations; it proved Elon Musk was right all along.
The car business, once everything, is quietly becoming an important piece of a much larger puzzle.
Investor's Corner
Tesla reports Q1 deliveries, missing expectations slightly
The figure, however, fell short of Wall Street’s consensus estimate of 365,645 units, reflecting ongoing headwinds in the global EV market.
Tesla reported deliveries for the first quarter of 2026 today, missing expectations set by Wall Street analysts slightly as the company aims to have a massive year in terms of sales, along with other projects.
Tesla delivered 358,023 vehicles in the first quarter of 2026, marking a 6.3 percent increase from 336,681 vehicles in Q1 2025.
The figure, however, fell short of Wall Street’s consensus estimate of 365,645 units, reflecting ongoing headwinds in the global EV market. Production reached approximately 362,000 vehicles, with Model 3 and Model Y accounting for the vast majority. The results come as Tesla navigates softening demand, intensifying competition in China and Europe, and the expiration of key U.S. federal tax incentives.
🚨 BREAKING: Tesla delivered 358,023 vehicles in Q1 2026
Tesla also reported record energy deployments of 8.8 GWh
Wall Street had delivery consensus estimates of 365,645 pic.twitter.com/EVNAu5L3UT
— TESLARATI (@Teslarati) April 2, 2026
Energy storage deployments provided a bright spot, hitting a record 8.8 GWh in Q1. This underscores the accelerating momentum in Tesla’s energy segment, which has become a critical growth driver even as automotive volumes stabilize.
Year-over-year, the energy business continues to outpace vehicle sales, with analysts noting strong backlog demand for Megapack systems amid rising grid-scale needs for renewables and AI data centers.
Looking ahead, analysts project full-year 2026 vehicle deliveries in the range of 1.69 million units—a modest 3-5% rise from roughly 1.64 million in 2025.
Growth is expected to accelerate in the second half as production ramps and new incentives emerge in select markets. However, risks remain: persistent high interest rates, price competition from legacy automakers and Chinese EV makers, and potential margin pressure could cap upside.
Tesla has not issued official full-year guidance, but executives have signaled confidence in sequential quarterly improvements driven by cost reductions and refreshed lineups.
By the end of 2026, Tesla plans several major product launches to reignite momentum. The refreshed Model Y, including a new 7-seater variant already rolling out in select markets, is expected to boost family-oriented sales with updated styling, efficiency gains, and interior enhancements.
Autonomous ambitions remain central to Tesla’s mission, and that’s where the vast majority of the attention has been put. Volume production of the Cybercab (Robotaxi) is targeted to begin ramping in 2026, potentially unlocking new revenue streams through unsupervised Full Self-Driving (FSD) deployment.
A next-generation affordable EV platform, possibly under $30,000, is also in advanced planning stages for 2026 or 2027 introduction. On the energy front, the Megapack 3 and larger Megablock systems will drive further deployment scale.
While Q1 highlights transitional challenges in autos, Tesla’s diversified roadmap, spanning refreshed consumer vehicles, commercial trucks, Robotaxis, and explosive energy growth, positions the company for a stronger second half and beyond. Investors will watch Q2 closely for signs of sustained recovery, especially with new vehicles potentially on the horizon.
Elon Musk
NASA sends humans to the Moon for the first time since 1972 – Here’s what’s next
NASA’s Artemis II launched four astronauts toward the Moon on the first crewed lunar mission since 1972.
NASA’s Space Launch System rocket launches carrying the Orion spacecraft with NASA astronauts Reid Wiseman, commander; Victor Glover, pilot; Christina Koch, mission specialist; and CSA (Canadian Space Agency) astronaut Jeremy Hansen, mission specialist on NASA’s Artemis II mission, Wednesday, April 1, 2026, from Operations and Support Building II at NASA’s Kennedy Space Center in Florida. NASA’s Artemis II mission will take Wiseman, Glover, Koch, and Hansen on a 10-day journey around the Moon and back aboard SLS rocket and Orion spacecraft launched at 6:35pm EDT from Launch Complex 39B. (NASA/Bill Ingalls)
NASA launched four astronauts toward the Moon on April 1, 2026, marking the first crewed lunar mission since Apollo 17 in December 1972. The Artemis II mission lifted off from Kennedy Space Center aboard the Space Launch System rocket at 6:35 p.m. EDT, sending commander Reid Wiseman, pilot Victor Glover, mission specialist Christina Koch, and Canadian astronaut Jeremy Hansen on a 10-day journey around the far side of the Moon and back.
The mission does not include a lunar landing. It is a test flight designed to validate the Orion spacecraft’s life support systems, navigation, and communications in deep space with a crew aboard for the first time. If the crew reaches the planned distance of 252,000 miles from Earth, they will set a new record for the farthest any human has ever traveled, surpassing even the Apollo 13 distance record.
As Teslarati reported, SpaceX holds a central role in what comes next. The Starship Human Landing System is under contract to carry astronauts to the lunar surface for Artemis IV, now targeting 2028, after NASA restructured its mission sequence due to delays in Starship’s orbital refueling demonstration. Before any Moon landing happens, SpaceX must prove it can transfer propellant between two Starships in orbit, something no rocket program has done at this scale.
The last time humans left Earth’s orbit was 53 years ago. Gene Cernan and Harrison Schmitt of Apollo 17 were the final people to walk on the Moon, a record that stands to this day. Elon Musk has long argued that returning is not optional. “It’s been now almost half a century since humans were last on the Moon,” Musk said. “That’s too long, we need to get back there and have a permanent base on the Moon.”
The Artemis program involves 60 countries signed onto the Artemis Accords, and this mission sets several firsts beyond distance. Glover becomes the first person of color to travel beyond low Earth orbit, Koch the first woman, and Hansen the first non-American astronaut to reach the Moon’s vicinity. According to NASA’s live mission updates, the spacecraft’s solar arrays deployed successfully after liftoff and the crew completed a proximity operations demonstration within the first hours of flight.
Artemis II is step one. The Moon landing and the permanent lunar base come later. But after more than five decades, humans are heading back.
Tesla’s Q1 delivery figures show Elon Musk was right
Tesla reports Q1 deliveries, missing expectations slightly
NASA sends humans to the Moon for the first time since 1972 – Here’s what’s next
Elon Musk says Tesla is developing a new vehicle: ‘Way cooler than a minivan’
Elon Musk launches TERAFAB: The $25B Tesla-SpaceXAI chip factory that will rewire the AI industry
