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Ex-SpaceX engine expert to help design rockets built for launch on world’s largest jet

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8 years ago

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Stratolaunch, an aerospace company funded by Microsoft-made billionaire Paul Allen to build the world’s largest flightworthy aircraft, has announced a decision to build its own liquid-fueled rockets, to be air-launched from the aforementioned mega-plane.

Targeting an inaugural launch of the first version of the rocket – currently nicknamed “Kraken” – as early as 2022, Stratolaunch has chosen Jeff Thornburg, formerly SpaceX’s Vice President of Propulsion Engineering and the father of the company’s Mars-focused Raptor engine, to lead its foray into in-house rocket propulsion development and manufacturing.

But first: building the world’s largest aircraft

Stratolaunch’s first task at hand, however, is to begin flight-testing the largest (hopefully) operational aircraft in history, a prerequisite for the company’s longer-term orbital rocket and spaceplane aspirations. Nicknamed “Roc” after a mythical (and fictional) bird so large it could carry an elephant, the plane certainly lives up to its namesake. Featuring a full six of the same engines that power Boeing’s once-record-breaking 747 airliner and a wingspan that could easily fit three smaller 737 airliners with room to spare, it is genuinely difficult (if not impossible) to successfully convey the sheer scale of Roc outside of witnessing it in person.

Stationed in California’s Mojave Desert, the aircraft’s one and only copy is, for the most part, completed and has spent the brunt of 2018 conducting runway taxi tests, hopefully culminating in an inaugural flight test later this year or early next year. Designed to lift orbital-class rockets weighing as much as 250 metric tons (550,000 lb) to an altitude of at least 9100 meters (30,000 feet), the primary benefit of using aircraft as launch platforms derives from the simple fact that the atmospheric density at 30,000 feet is more than three times less than that at sea level. Similar to aircraft, rocket performance dramatically improves as atmospheric density decreases: less atmosphere means lower drag and pressure.

Rockets that launch from sea-level have to grapple with the difficulties of Earth’s relatively thick atmosphere at that height, with major launch events like “Max-Q” being big concerns almost solely because the dense air exerts major forces on launch vehicles and demands extreme measures like throttling down booster engines (very inefficient) and optimizing structures for aerodynamic efficiency despite the fact that rockets spend very little time operating in a significant atmosphere.

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A launch pad without a rocket (sort of)

However, the simple fact of the matter is that billionaire Paul Allen’s colossal aircraft essentially does not have a single air-launched rocket in the world that can properly take advantage of its capabilities. Originally sized and designed with an air-launched version of SpaceX’s Falcon 9 in mind, that relationship folded amicably after roughly a year (2012), at which point SpaceX realized it would need to almost completely redesign a unique variant of Falcon 9. Your author will readily admit that they have admired the insanity of such a massive plane while still severely doubting its practical utility.

Thankfully, it appears that Allen is adamantly opposed to the idea that Stratolaunch is some silly whim to build the world’s largest plane. Rather, he is exceptionally reserved and pragmatic when discussing the aerial launch platform, according to a recent and extensive interview by Wired Magazine’s Steven Levy.

“Allen isn’t one to show exuberance, and when he speaks about the plane he focuses on its future utility. ‘When you see that giant plane, it’s a little nutty,’ he says. ‘And you don’t build it unless you’re very serious, not only about wanting to see the plane fly but to see it fulfill its purpose. Which is getting vehicles in orbit.’ – Paul Allen, 2018

 

Currently, Orbital ATK’s (now Northrop Grumman Innovation Systems) air-launched Pegasus XL rocket is the only “customer” in the world that can realistically use Stratolaunch as a launch platform, not exactly an impressive or sustainable launch vehicle with a maximum performance of less than 450 kg (~1000 lbs) to low Earth orbit for an incredible ~$40 million per (expendable) flight.

To answer that call and ensure Stratolaunch’s utility, the company reportedly began seriously considering its own in-house expendable and reusable rockets and propulsion systems sometime in 2016, plans that have since grown concrete and been publicly embedded into Stratolaunch’s overarching mission. Nicknamed “Kraken” after the mythical sea monster, the company hopes to develop an initially expendable rocket system capable of launching 3400 – 6000 kg (~7500 – 13250 lbs) into low Earth orbit with single booster and triple booster variants. Further down the line, Stratolaunch is eyeing the design and production of a fully and rapidly reusable orbital spaceplane, potentially including a version that would carry astronauts into space.

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Normally, one might simply roll their eyes at yet another startup touting small(ish) expendable rockets with first launches no earlier than the early 2020s – the market is getting to be absurdly and impossibly overcrowded at this point. However, Stratolaunch differs for one fundamental and reason: they have placed ex-SpaceX propulsion executive and expert Jeff Thornburg at the helm of the company’s freshly public rocket propulsion wing. While at SpaceX, Mr. Thornburg spent all but one of his five years with the company (2011-2015) single-mindedly focused on the development and engineering of all aspects of the Raptor rocket engine, a next-generation propulsion system designed to enable SpaceX’s sustainable colonization of Mars.

Raptor is an exceptional rocket engine thanks in no small part to Thornburg’s brilliance as a propulsion engineer, and that same brilliance and half-decade of experience at the most successful rocket startup in existence could ultimately prove a massive boon for Stratolaunch’s otherwise interesting but unexceptional expendable rocket concepts.

Put simply, under Jeff Thornburg’s direction and with access to founder Paul Allen’s considerable wealth, Stratolaunch is undoubtedly worth keeping a close eye in the future, both far and near.

For prompt updates, on-the-ground perspectives, and unique glimpses of SpaceX’s rocket recovery fleet check out our brand new LaunchPad and LandingZone newsletters!

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Eric Ralph is Teslarati's senior spaceflight reporter and has been covering the industry in some capacity for almost half a decade, largely spurred in 2016 by a trip to Mexico to watch Elon Musk reveal SpaceX's plans for Mars in person. Aside from spreading interest and excitement about spaceflight far and wide, his primary goal is to cover humanity's ongoing efforts to expand beyond Earth to the Moon, Mars, and elsewhere.

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Elon Musk

Tesla’s mysterious Robovan makes a sneak peek with Optimus in Terafab video

Elon Musk shared a new Terafab video showing Optimus, Robovans, and a stunningly futuristic campus.

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8 hours ago

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August 6, 2026

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SpaceX Terafab rendering

Elon Musk posted a new video of Terafab on X Thursday morning, and the most eye-catching details in it were not the building itself, but two products still awaiting production: Optimus and the Robovan.

The concept render, credited to SpaceX, shows Optimus robots working the grounds of the roughly 2.5-mile-long facility planned for the Gibbons Creek site in Grimes County, while a Robovan glides along an elevated roadway cutting through the building itself, sharing the frame with a Tesla Semi and a Cybercab.

Robovan is the boxy, driverless people and cargo mover Musk unveiled alongside Cybercab at Tesla’s “We, Robot” event in October 2024. He pitched it as a way to move up to 20 passengers at once, or handle freight instead, at a target cost he claimed could fall under a dollar a mile, with no steering wheel or pedals, the same layout as Cybercab. Nearly two years later, Robovan still has no confirmed production timeline and has not shown up in any factory footage, which makes Thursday’s render one of the only recent looks at the vehicle in any form.

Optimus has moved further along. Tesla began converting Fremont’s old Model S and Model X assembly line into a Gen 3 Optimus production line earlier this year, and Musk visited the site on July 1 to mark the changeover. A second, larger Optimus plant is under construction at Giga Texas, targeting volume production in summer 2027 and eventual capacity of 10 million units a year. Tesla AI lead Ashok Elluswamy said this month the robot has “big shoes to fill” in replacing the S and X line, while Musk has repeatedly called Optimus the company’s biggest product of any kind, with a long-term price he has pegged between $20,000 and $30,000.

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“Terafab Texas will be the largest and most valuable building on Earth by far,” Musk wrote alongside the clip. “And it will be stunningly beautiful.”

One quote post summed up the reaction: “Futuristic scene with RoboVan + Cybercab + Tesla Semi + Optimus.”

Beyond the vehicles, the architecture wrapped around them stands out too. The building’s facade is canted at sharp angles, with illuminated horizontal bands running through what appears to be a multi level interior visible from outside. Below the elevated roadway, pedestrians walk along a plaza next to a reflecting pool, and the skyline behind the campus is dotted with angular spires that read more like sculpture than infrastructure, a departure from the strictly utilitarian look of Gigafactory Texas or Starbase.

The timing tracks with what Terafab representative Riley Trennell told Grimes County residents on Wednesday, when he said renderings of the facility would be released “within days.” Musk’s post followed less than 24 hours later, and Texas Governor Greg Abbott’s office sent out its own release Thursday confirming the project. As Teslarati reported this morning, Terafab’s tax abatement agreements with Grimes County are now signed and active, and SpaceX has sent the county its first $10 million payment under that deal. The dollar figure tied to this phase of construction, per Reuters, is $16.8 billion, one of the first hard capital expenditure numbers attached to Terafab since Musk unveiled the joint Tesla-SpaceX-xAI venture in March.Reaction on X ranged from enthusiastic to skeptical. “God Bless Texas! Everything is bigger and better in Texas!” one reply read. Another was more measured: “Terafab in a decade…..”

Whether the finished building matches the render is a separate question from whether Musk wanted people talking about the render itself. Less than a day after posting, the video had already crossed 5.5 million views.

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Cybertruck

Tesla Cybertruck production snaps back after ugly supplier fight

Cybertrucks are piling up again at Giga Texas after Tesla’s court win against a parts supplier.

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15 hours ago

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August 6, 2026

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Tesla Cybertruck production resumes after supplier dispute: Credit: Joe Tegtmeyer | X
Tesla Cybertruck production resumes after supplier dispute: Credit: Joe Tegtmeyer | Youtube

Cybertruck production at Giga Texas is showing its first visible recovery since Tesla sued a supplier last month over withheld manufacturing tooling.

Aerial observer Joe Tegtmeyer flew over the Austin factory Wednesday morning and counted roughly 100 or more Cybertrucks filling the outbound lot, a sharp jump from the thin numbers seen in recent weeks. The flyover came a day after a judge granted Tesla a temporary restraining order against Angstrom Automotive Group, the parts supplier at the center of the dispute.

Tesla filed an emergency lawsuit in late July after Angstrom told the automaker it planned to close the Troy, Texas facility where Tesla’s die-cast tools, trim dies and other Cybertruck stamping equipment were housed. According to Tesla’s complaint, a shipment of 700 finished parts never left the building, and when Tesla sent representatives to retrieve its equipment, accompanied by law enforcement, they were turned away. Angstrom allegedly then asked for an extra $250,000 a week to keep operating, which Tesla’s filing described as holding its own property for ransom.

Tesla quietly made the Cybertruck even stronger

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The restraining order gives Tesla immediate right of entry to Angstrom’s facility to recover the tooling. It is temporary, with a fuller hearing still to come, but the speed of Wednesday’s rebound suggests the Angstrom shortage was indeed the main bottleneck limiting Cybertruck output. Outbound lot counts are an imperfect measure of actual production, since finished trucks can sit for days before shipping, but a lot that full after a lean stretch is a meaningful signal.

Cybertruck output at Giga Texas has fluctuated all year as Tesla worked through supply issues and introduced new trims, including a cheaper Dual Motor AWD version that drew strong early demand.

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Elon Musk

Space finally faced the people living next to its next Terafab mega-project

SpaceX confirmed Terafab’s Grimes County site is locked in, with construction starting within months.

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24 hours ago

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August 5, 2026

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SpaceX and Terafab representatives sat across from Grimes County residents for the first time on Wednesday, telling a packed Commissioners Court room that the $55 billion chip manufacturing project is now a done deal at the Gibbons Creek Reservoir site.

The meeting followed a $10 million check SpaceX sent the county earlier this week, satisfying a payment deadline built into the tax abatement agreement both sides signed in June. Elon Musk shared a post on X confirming the payment, and County Judge Joe Fauth told the San Antonio Express-News his office deposited the check after it beat its deadline.

Wednesday’s session, first reported by KBTX, moved the project from paperwork to construction. Terafab representative Riley Trennell told residents the JETI tax break agreements with Iola ISD and Anderson-Shiro CISD are signed and active, and that civil work and foundation prep are starting almost immediately. Renderings of the facility could be released within days, he said, with construction beginning within months.

Elon Musk launches TERAFAB: The $25B Tesla-SpaceXAI chip factory that will rewire the AI industry

Musk first announced Terafab in March as a joint venture between Tesla, SpaceX and xAI aimed at producing over a terawatt of AI compute annually, an amount that dwarfs the roughly 20 gigawatts the entire global chip industry produces today. Intel joined as a manufacturing partner in April. Musk has said the project needed its own day in the spotlight rather than being squeezed into an earnings call, and for months the Grimes County site remained unconfirmed even as reporting pointed there.

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SpaceX attorney Buck Brannon used Wednesday’s meeting to note that the company’s abatement is roughly 78 percent, not the 100 percent some earlier reports suggested. In exchange, SpaceX will pay Grimes County a fixed $20 million a year for 35 years, a total of $710 million, which Brannon said exceeds the $14 million Tesla paid Travis County in 2025.

SpaceX also addressed environmental concerns that have followed the project since Musk’s Terafab partnership with Intel was announced. Representatives said Terafab will not raise electric bills for other ratepayers, will not deplete local water supplies and will not draw down the Navasota River. SpaceX confirmed it owns the Navasota River pumping station, which it plans to use to divert stormwater into the Gibbons Creek Reservoir, and said it will build its own natural gas plants to power the facility rather than pulling from the ERCOT grid.

Grimes County commissioners also approved an addendum letting county employees use ten approved AI chatbots for work, including Grok.

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