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SpaceX sends “radically redesigned” Starship engine to Texas for hot-fire tests

As of September 2017, subscale Raptor engines had been cumulatively fired for more than 1200 seconds in just 12 months of testing. (SpaceX)

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7 years ago

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SpaceX has shipped one of the first of a group of Starship engines known as Raptor, described last month by CEO Elon Musk as “radically redesigned”. A culmination of more than 24 months of prototype testing, the first flight-worthy Raptor could be ignited for the first time as early as February.

According to Musk, three of these redesigned Raptors will power the first full-scale BFR prototype, a Starship (upper stage) test article meant to conduct relatively low-altitude, low-velocity hop tests over the southern tip of Texas. Those tests could also begin next month, although a debut sometime in March or April is increasingly likely.

Effectively designed on a blank slate, Raptor began full-scale component-level tests in 2014 at NASA’s Mississippi-based Stennis Space Center, evolving from main injector development to oxygen preburner hot-fires in 2015. Soon after Raptor’s prototype preburner design was validated at Stennis, SpaceX moved testing to its privately-owned and operated facilities in McGregor, Texas, where Raptor static fire testing has remained since.

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Just days before CEO Elon Musk was scheduled to reveal SpaceX’s next-generation rocket (BFR, formerly known as the Interplanetary Transport System or ITS) in September 2016, he announced in a tweet that propulsion engineers and technicians had successful hot-fired an integrated Raptor prototype – albeit subscale – for the first time ever. Just 12 months later, Musk once again took to the stage to announce an update to BFR’s design, while also revealing that prototype Raptor engines had already completed more than 1200 seconds (20 minutes) of cumulative hot-fire tests, an extremely aggressive and encouraging rate of progress for such a new engine.

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Although Raptor undoubtedly borrows heavily from much of the same expertise that designed Merlin 1 and operated and improved it for years, that is roughly where the similarities between Raptor and M1D end. M1D, powered by refined kerosene (RP-1) and liquid oxygen, uses a combustion cycle (gas-generator) that is relatively simple and reliable at the cost of engine efficiency, although SpaceX propulsion expertise still managed to give M1D the highest thrust-to-weight ratio of any liquid rocket engine ever flown. Still, measured by ISP (instantaneous specific impulse), M1D’s inefficient kerolox gas-generator cycle ultimately means that the engine simply can’t compete with the performance of engines with more efficient propellants and combustion cycles.

While SpaceX’s Falcon 9 and Heavy rockets – powered by Merlin 1D and Merlin Vacuum – are more than adequate in and around Earth orbit, a far more efficient engine was needed for the company to enable the sort of interplanetary colonization Musk had in mind when he created SpaceX. Raptor was the answer. Ultimately settling on liquid methane and oxygen (methalox) as the propellant and a full-flow staged-combustion (FFSC) cycle, Raptor was designed to be extraordinarily reliable and efficient in order to safely power a spacecraft (BFS/Starship) meant to ferry dozens or hundreds of people to and from Mars.

An excellent NASASpaceflight article explores the engine’s journey from a blank sheet to integrated static-fire tests and offers a deeper explanation of the technical details.

Raptor enters a new era

For all the extensive and invaluable testing SpaceX has done with a series of prototype Raptor engines, the engines tested were subscale versions with around 30% the thrust of the c. 2016 Raptor and around 40-50% of the updated c. 2017 iteration, producing almost the same amount of thrust as Merlin 1D (914 kN to Raptor’s ~1000 kN). In September 2018, Musk described Raptor as an “approximately…200-ton (~2000 kN) thrust engine” that would eventually operate with a chamber pressure as high as 300 bar (an extraordinary ~4400 psi), requiring at least one of the FFSC engine’s two preburners (used to power separate turbopumps) to operate at a truly terrifying ~810 bar (nearly 12,000 psi).

Conveniently stood beside a Merlin 1D engine also ready for hot-fire acceptance testing, the Raptor engine spotted departing SpaceX’s Hawthorne, CA factory last week was reportedly immense in person, towering over an M1D engine. Raptor also featured a mass of spaghetti-like plumbing (complexity necessary for its advanced combustion cycle), with a significant fraction of the metallic pipes and tubes displaying mirror-like finishes. Most notable was an obvious secondary preburner/turbopump stack and the lack of any exhaust port, whereas M1D relies on a single turbopump and exhausts the gases used to power it. Raptor’s full-flow staged-combustion cycle uses separate oxygen and methane preburners to power separate turbopumps, significantly improving mass flow rate and smoothing out combustion mixing.

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Unlike all previous hot-fired Raptors, those shipping now to McGregor, Texas are expected to be the first completed engines with a finalized design, arrived at only after a period of extensive testing and iterative improvement. They also appear to be full-scale, meaning that the test bays dedicated to Raptor will likely need to be upgraded (if they haven’t been already) to support a two- or threefold increase in maximum thrust.

SpaceX’s Starship hopper will need three finalized engines, meaning that the Raptor now in McGregor, Texas may not have been the first to arrive. Nevertheless, the shipment of full-scale hardware is always an extremely encouraging milestone for any advanced technology development program, while also foreshadowing the first imminent static-fires of the “radcally redesigned” rocket engine. With hardware now at the test site before January is out, a February test debut – one month behind a January debut teased by Elon Musk last December – is not out of the question.

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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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Tesla CEO Elon Musk teases Optimus job that’s straight out of Robocop

“If somebody’s committed a crime, we might be able to provide a more humane form of containment of future crime. You now get a free Optimus, and it’s just going to follow you around and stop you from doing crime.”

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4 hours ago

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November 11, 2025

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Credit: @heydave7/X

Tesla CEO Elon Musk teased a potential job for the company’s Optimus robot last week that is straight out of the movie “Robocop.”

“Robocop” aimed to show a futuristic look at law enforcement in a Sci-fi thriller that was among the first iterations of how robots could be used for police work.

The 1987 film showcased an injured cop turning into an armed cyborg, and although Tesla’s Optimus won’t be a human-robot hybrid, Musk’s idea for the humanoid project is similar.

Musk said last week at the Annual Shareholder Meeting, where shareholders voted to approve his $1 trillion compensation plan, that Optimus could be the future of law enforcement, nearly revolutionizing the way criminals are prosecuted.

He hinted that Optimus could actually be used as a chaperone of sorts, arguing that it was a “more humane form of containment of future crime.” Musk said:

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“If somebody’s committed a crime, we might be able to provide a more humane form of containment of future crime. You now get a free Optimus, and it’s just going to follow you around and stop you from doing crime. Other than that, you get to do anything; it’s just going to stop you from committing crime. That’s really it. You don’t have to put people in prisons and stuff. It’s pretty wild to think of all the possibilities, but I think it’s clearly the future.”

Musk’s overall idea for Optimus is to change the way people are able to exist, from those law-abiding citizens to others who have their run-ins with the law. Instead, the Tesla CEO believes there could be a different way to handle everything, including punishment.

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It was not the only thing that Musk indicated could be changed significantly by the presence of humanoid robots, as he also said a universal basic income could be established with the help of products like Optimus.

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Elon Musk teases huge merger: ‘Trending towards convergence’

“My companies are, surprisingly in some ways, trending towards convergence.”

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7 hours ago

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November 11, 2025

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Elon Musk recently amplified the thoughts of Morgan Stanley analyst Adam Jonas, who had insight into the “Muskonomy” of his potentially interconnected ventures, something that was proposed at the recent Tesla Shareholder Meeting with xAI.

Musk’s words indicate a potential strategic fusion that could serve as a blueprint for future innovation–but it is dependent on a conglomeration between the many entities the CEO serves.

As Tesla grapples with scaling Optimus and preparing for its imminent production and the development of the Full Self-Driving suite, xAI’s computational edge could provide leverage for the millions of miles of data the company accumulates, providing a more stable and accurate development strategy for the autonomous and AI efforts it has put its chips all in on.

After Tesla Shareholders voted to deny Tesla and xAI’s potential financial partnership through an investment, Jonas said it was an issue that would have to be revisited due to its importance.

xAI has the opportunity to provide an incredible strategic and financial bolstering to Tesla, especially with how important a role data plays in the development of the company’s biggest products.

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Jonas wrote in a note to investors:

“They’re gonna have to revisit this. We don’t think investors understand just how important xAI is to Tesla and the broader Muskonomy. Tesla’s relationship with xAI (financially and strategically) is deterministic to the long-term success of Tesla due in part to the natural synergies of data, software, hardware, and manufacturing in recursive loops. The values (and value systems) of both Tesla and xAI are endowed by the values of their shared creator. We believe this co-determination becomes more obvious in the next phases of physical AI/ autonomy for Tesla in the year ahead.”

Musk said, in response to Jonas’ note, that his companies are “surprisingly in some ways, trending toward convergence.”

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Mergers and shared ecosystems between companies are not new moves out of Musk’s playbook, as it has been done in the past, especially with Tesla acquiring other entities.

It did it with SolarCity in 2016 and with Maxwell Technologies in 2019. Investments between Musk companies have occurred before, too, as SpaceX dumped $2 billion into xAI last July.

He’s also said on several occasions that he could eventually bring everything together into some sort of single entity. In July 2024, he said:

“I’m not opposed to the idea in principle, but I’m not sure there is a pragmatic or legal way to merge them. There is also value in equity incentives of people at the companies being tied to that company’s accomplishments.”

This point is especially relevant now with Musk’s recently approved compensation package.

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He also said in June, during an interview with CNBC , that “It’s not out of the question” for xAI to merge with Tesla, but it would have to be approved by shareholders. Just a few days later, he said he would not support xAI merging with Tesla; however, he put it in investors’ hands.

It’s more than just a deal; it’s symbiotic. Musk being at the helm of various companies, all intertwined with one another, helps foster recursive innovation. Despite these advantages, there are still a handful of things to consider, especially from a regulatory perspective.

However, it is not competition; it’s convergence. In Musk’s universe, especially from a business sense, mergers are not endpoints, but instead launchpads for ambitions that aim to take each company from Earth to lands beyond our atmosphere.

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Tesla makes Elon Musk’s new compensation package official

This is an important thing to note, as much of the media coverage regarding Musk’s pay package seems to indicate that the company and the shareholders are simply giving the CEO the money. He has to come through on each of these tranches to unlock the $1 trillion.

Published

8 hours ago

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November 11, 2025

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Credit: @JoeTegtmeyer/X

Tesla has made CEO Elon Musk’s new compensation package official, as it filed a Form 4 with the Securities and Exchange Commission (SEC) on Monday.

The package officially gives Musk the opportunity to acquire over 423 million shares of Tesla stock (NASDAQ: TSLA), dependent on his ability to achieve twelve performance-based tranches that will bring growth to the company and its shareholders.

Tesla (TSLA) shareholders officially approve Elon Musk’s 2025 performance award

Musk’s new compensation package was approved by investors last Thursday at the company’s Annual Shareholder Meeting, as over 75 percent of voters supported the CEO’s new plan, which could be valued at over $1 trillion if he is able to come through on all twelve tranches.

The twelve tranches include growth goals related to vehicle deliveries, the Optimus humanoid robot project, and Tesla’s valuation. If Musk is able to achieve each tranche, he would help Tesla achieve an over $8 trillion market cap.

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The 12 tranches include:

  1. $2 trillion market cap + Deliver 20 million Tesla vehicles cumulatively
  2. $2.5 trillion market cap + Reach 10 million active Full Self-Driving (FSD) subscriptions
  3. $3 trillion market cap + Deliver 1 million Optimus humanoid robots
  4. $3.5 trillion market cap + Operate 1 million Robotaxis commercially
  5. $4 trillion market cap + Hit $50 billion in adjusted EBITDA (earnings before interest, taxes, etc.)
  6. $4.5 trillion market cap + Hit $80 billion in adjusted EBITDA
  7. $5 trillion market cap + Hit $130 billion in adjusted EBITDA
  8. $5.5 trillion market cap + Hit $210 billion in adjusted EBITDA
  9. $6 trillion market cap + Hit $300 billion in adjusted EBITDA
  10. $6.5 trillion market cap + Hit $400 billion in adjusted EBITDA
  11. $7.5 trillion market cap + Hit $400 billion in adjusted EBITDA for four straight quarters in a row
  12. $8.5 trillion market cap + Hit $400 billion in adjusted EBITDA for four straight quarters in a row

Achieving the twelve levels of the new compensation package would also give Musk what he’s really after: a larger ownership share in Tesla, which would help him achieve more control, something he feels is necessary for the rollout of the Optimus robot “army.”

Musk does not earn a dime if he does not achieve any of the tranches above.

This is an important thing to note, as much of the media coverage regarding Musk’s pay package seems to indicate that the company and the shareholders are simply giving the CEO the money. He has to come through on each of these tranches to unlock the $1 trillion.

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