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.
- A to-scale comparison of Falcon 1, Pegasus XL, MLV, and Falcon 9. (Teslarati/Stratolaunch/Wikipedia)
- 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.
- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
- Jeff Thornburg stands in front of Stratolaunch’s NASA Stennis Space Center test stand. (Stratolaunch)
- The PGA preburner seen after installation at Stennis. (Stratolaunch)
- The control center. (Stratolaunch)
- MLV is released from Stratolauncher. (Stratolaunch)
- A concept video produced by Stratolaunch shows the Roc launching a Kraken rocket. (Stratolaunch, via Wired)
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Lifestyle
Tesla hit by Iranian missile debris in Israel
A Tesla in Israel absorbed a direct hit from missile debris, and the glassroof held.
On March 30, 2026, Lara Shusterman was in Netanya, Israel when Iranian ballistic missiles triggered air raid sirens across the city. While she remained in safety, her 2024 Tesla Model Y did not escape untouched. A heavy piece of missile debris struck the car’s massive glass roof, leaving a deep crater but without shattering. In a Facebook post to the Tesla Israel community the following morning, Shusterman described what happened: “The glass did not shatter into dangerous shards. She stopped the damage and pushed the metal part to the ground.” She closed by thanking Elon Musk and the Tesla team for building what she called “security and a sense of trust even in extreme situations.”
Netanya is a coastal city in central Israel, roughly 18 miles north of Tel Aviv and has been among the areas most frequently struck during Iran’s ongoing missile campaign, following coordinated U.S. and Israeli strikes on Iranian military infrastructure. Falling shrapnel from intercepted missiles is a common occurrence.
- Tesla Model Y glass roof shattered from a piece of falling Iranian missile debris
- A piece of Iranian missile debris that struck Lara Shusterman’s Tesla Model Y in Netanya, Israel on March 30, 2026, after being intercepted by Israeli air defenses.
- Tesla Model Y glass roof shattered from a piece of falling Iranian missile debris
The incident is a testament to Tesla’s structural engineering. Tesla’s glass roof is designed to support over four times the vehicle’s own weight. That strength has shown up in real-world accidents too. In 2021, a Model Y in California was struck by a falling tree during a storm, with the glass roof holding firm and the cabin remaining intact. In another widely reported incident, a Tesla Model Y plunged 250 feet off the cliff at Devil’s Slide in California in January 2023, with all four occupants, including two young children, surviving.
Disturbing details about Tesla’s 250-foot cliff drop emerge amid initial investigation
Tesla officially launched sales in Israel in early 2021 and captured over 60 percent of Israel’s EV market in the first year. The brand’s foothold in Israel remains significant. Tens of thousands of Teslas are now on Israeli roads, making incidents like Shusterman’s easy to corroborate. On the same week her Model Y took the hit, the U.S. Space Force awarded SpaceX a $178.5 million contract to launch missile tracking satellites, a separate but fitting reminder of how intertwined the Musk ecosystem has become with the realities of modern conflict.
Elon Musk
Elon Musk calls out $2 trillion SpaceX IPO valuation as ‘BS’
In a swift rebuke on X, Elon Musk dismissed reports claiming SpaceX had confidentially filed for an initial public offering targeting a valuation above $2 trillion, labeling the information as unreliable.
Elon Musk is quick to call out any false information regarding him or his companies on his social media platform, known as X.
A recent report that claimed SpaceX was aiming to go public with an IPO in the coming weeks at a massive valuation of $2 trillion was called out by Musk, who referred to it as “BS.”
In a swift rebuke on X, Elon Musk dismissed reports claiming SpaceX had confidentially filed for an initial public offering targeting a valuation above $2 trillion, labeling the information as unreliable.
The exchange highlights ongoing media speculation about the rocket company’s future and Musk’s frustration with what he views as inaccurate financial reporting. The report came from Bloomberg.
Don’t believe everything you read.
Bloomberg publishes bs.
— Elon Musk (@elonmusk) April 3, 2026
The controversy erupted on April 2, 2026, when influencer Mario Nawfal amplified claims from Bloomberg.
The outlet posted that SpaceX had boosted its IPO target valuation above $2 trillion, describing it as potentially one of the largest public offerings in history. Musk challenged the story.
It echoes past instances where Musk has corrected valuation rumors about his companies, emphasizing that speculation often outpaces reality.
Background context adds nuance.
Earlier reports indicated SpaceX had filed confidential IPO paperwork with the U.S. Securities and Exchange Commission, potentially positioning it for a record-breaking debut that could eclipse Saudi Aramco’s 2019 listing.
Initial estimates pegged a possible valuation north of $1.75 trillion, building on a post-merger figure around $1.25 trillion after SpaceX absorbed xAI. A subsequent Bloomberg update claimed advisers were floating figures above $2 trillion to investors, with the offering potentially raising up to $75 billion.
SpaceX remains a private powerhouse. Its achievements include thousands of Starlink satellites providing global broadband, routine Falcon 9 rocket reusability, and a mission to slash launch costs, along with ambitions for Starship to enable Mars colonization.
The company also benefits from government contracts with NASA and the Department of Defense. A public listing could democratize access for retail investors while subjecting SpaceX to greater scrutiny and quarterly reporting pressures.
Critics of the reports point to the confidential nature of filings, which limits verifiable details. Musk has previously downplayed inflated valuations, once calling an $800 billion figure for SpaceX “too high.”
Supporters argue that hype around mega-IPOs, especially amid the ongoing AI fervor, fuels premature narratives that distract from core technical milestones, such as full Starship reusability and Starlink constellation expansion.
The incident reflects broader tensions in tech finance. Anonymous sourcing in valuation stories can drive market chatter and betting activity, yet it risks misinformation.
Bloomberg defended its reporting through multiple articles citing “people familiar with the matter,” but Musk’s blunt dismissal resonated widely on X, with users piling on to question media reliability.
Whether SpaceX ultimately goes public remains uncertain. Musk has teased an IPO tied to Starlink maturity, but priorities center on engineering breakthroughs over Wall Street timelines. For now, the $2 trillion figure joins a list of rumored milestones that Musk insists should be taken with skepticism.
Elon Musk
Elon Musk reveals date of SpaceX Starship v3’s maiden voyage
The announcement arrives after Flight 11 on October 13 of last year, which concluded a busy 2025 testing campaign. Since then, SpaceX has focused on ground testing, including cryoproofing of Ship 39 and preparations for Booster 19, the first V3 Super Heavy.
SpaceX CEO Elon Musk has revealed the timeline for the next Starship launch. It will be the first launch using SpaceX’s revamped design for Starship, as its v3 rocket will take its maiden voyage sooner than many might expect.
Musk announced on April 3 on X that the next Starship flight test, and the first flight of the upgraded v3 ship and booster, is 4 to 6 weeks away. The update signals the end of a nearly six-month hiatus since the program’s last launch.
Elon says the first V3 Starship launch will occur in 4-6 weeks
It will be the first Starship launch since Flight 11 on October 13, 2025 https://t.co/QnnYPTdbUu
— TESLARATI (@Teslarati) April 3, 2026
The upcoming mission, designated as Starship’s 12 integrated flight test (IFT-12), marks a significant milestone. It will be the debut of the v3 configuration, featuring a taller Super Heavy Booster and Starship upper stage. The changes SpaceX has made with the v3 rocket and booster are an increased propellant capacity and the more powerful Raptor 3 engines.
Earlier predictions from Musk in March had pointed to an April timeframe, but the latest timeline now targets a launch window in early to mid-May 2026.
The V3 iteration represents a substantial evolution from previous Starship prototypes. Engineers have optimized the design for improved manufacturability, higher thrust, and greater efficiency. Raptor 3 engines deliver significantly more power while reducing weight and production costs compared to earlier variants.
With these enhancements, SpaceX aims to boost payload capacity toward 200 metric tons to low Earth orbit in a fully reusable configuration — a dramatic leap from the roughly 35-ton target of prior versions. Such capabilities are critical for ambitious goals, including NASA’s Artemis lunar missions and eventual crewed flights to Mars.
The announcement arrives after Flight 11 on October 13 of last year, which concluded a busy 2025 testing campaign. Since then, SpaceX has focused on ground testing, including cryoproofing of Ship 39 and preparations for Booster 19, the first V3 Super Heavy.
Recent activities have involved static fires, activation of the new Pad 2 at Starbase in Boca Chica, Texas, and integration of Raptor 3 engines.
A prior incident with an early V3 booster on the test stand in late 2025 contributed to the delay, necessitating additional assembly and qualification work.
Musk’s timeline updates have become a hallmark of the Starship program, often described with characteristic optimism.
SpaceX’s Starship V3 is almost ready and it will change space travel forever
While past targets have occasionally shifted by weeks, the rapid iteration pace remains impressive. However, don’t be surprised if this timeline shifts again, as Musk has been overly optimistic in the past with not only launches, but products under his other companies, too.
SpaceX continues to refine launch infrastructure, including new propellant loading systems and tower mechanisms designed to support higher cadence operations. A successful V3 flight could pave the way for more frequent tests, tower catches of both booster and ship, and progression toward operational reusability.
The v3 debut is viewed as a transition point for Starship, moving beyond experimental flights toward a system capable of supporting large-scale deployment of Starlink satellites, lunar landers, and interplanetary transport.
Success on IFT-12 would demonstrate not only the new hardware’s performance but also SpaceX’s ability to recover from setbacks and maintain momentum.
As the 4-to-6-week countdown begins, anticipation builds at Starbase. Teams are finalizing vehicle stacking, conducting final pre-flight checks, and preparing for regulatory approvals. The world will be watching to see if Starship V3 can deliver on its promise of transforming humanity’s access to space.












