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SpaceX wiggles Starhopper’s Raptor engine, tests parts ahead of hover test debut

Repeating a test conducted in June with Raptor SN04, SpaceX tested Starhopper and Raptor SN06's thrust vectoring capabilities on July 12th. (NASASpaceflight - bocachicagal)

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6 years ago

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On the evening of July 12th, SpaceX technicians put Starhopper’s freshly-installed Raptor – serial number 06 (SN06) – through a simple but decidedly entertaining test, effectively wiggling the engine in circles.

Designed to verify that Raptor’s thrust vectoring capabilities are in order and ensure that Starhopper and the engine are properly communicating, the wiggle test is a small but critical part of pre-flight acceptance and a good indicator that the low-fidelity Starship prototype is nearing its first hover test(s). Roughly 48 hours after a successful series of wiggles, Starhopper and Raptor proceeded into the next stage of pre-flight acceptance, likely the final more step before a tethered static fire.

Routine for all Falcon rockets, SpaceX’s exceptionally rigorous practice of static firing all hardware at least once (and often several times) before launch has unsurprisingly held firm as the company proceeds towards integrated Starhopper and Starship flight tests. Despite the fact that Raptor SN06 completed a static fire as recently July 10th, SpaceX will very likely put Starhopper and its newly-installed Raptor through yet another pre-flight static fire, perhaps its fourth or fifth test this month.

Although it would undoubtedly be easier, cheaper, and faster to skip that post-delivery static fire, it will simultaneously lower the risk of Raptor failing mid-flight and verify that Starhopper itself is healthy and ready for untethered hovering. Although SpaceX could likely live without Starhopper in the event that it’s lost during flight-testing, any failure capable of destroying the vehicle itself is at least as capable of severely damaging or completely destroying the spartan but still expansive test and launch facilities the company built over the course of several months.

SpaceX has been hard at work gradually building, expanding, and upgrading its South Texas launch facilities since December 2018. (NASASpaceflight – bocachicagal, 04/27/2019)

Would you like some testing with your testing?

Follow July 12th’s nighttime Raptor wiggle test, July 13th was mainly quiet and filled with inspections of Starhopper, Raptor, and other various work. The day after, however, SpaceX proceeded through several hours of propellant loading, ending with what looked like less energetic versions of the Raptor preburner ignition tests Starhopper previously performed with Raptor SN02.

In a staged-combustion engine like Raptor, getting from the supercool liquid oxygen and methane propellant to 200+ tons of thrust is quite literally staged, meaning that the ignition doesn’t happen all at once. Rather, the preburners – essentially their own, unique combustion chambers – ignite an oxygen- or methane-rich mixture, the burning of which produces the gas and pressure that powers the turbines that bring fuel into the main combustion chamber. That fuel then ignites, producing thrust as they exit the engine’s bell-shaped nozzle.

The first obvious test occurred around 7:30pm CT, July 14th. (LabPadre)
The second obvious test followed around 8:50 pm CT. (LabPadre)

Although the fireworks are so subtle that they are easily missed, the conditions inside the preburner – hidden away from view – are actually far more intense than the iconic blue, purple, and pink flame that exists Raptor’s nozzle. This is because the preburners have to nurture the conditions necessary for the pumps they power to fuel the main combustion chamber. Much like hot water will cool while traveling through pipes, the superheated gaseous propellant that Raptor ignites to produce thrust will also cool (and thus lose pressure) as it travels from Raptor’s preburner to the main combustion chamber.

Thus, if the head pressure produced in the preburners is too low, Raptor’s thrust will be (roughly speaking) proportionally limited at best. At worst, low pressure in the preburners can completely prevent Raptor from starting and running stably and can even trigger a “hard start” or shutdown that could damage or destroy the engine. As such, to preburners fundamentally have to operate at higher chamber pressures (and thus higher temperatures) than the main combustion chamber (the big firey bit at the end). According to Elon Musk, Raptor’s oxygen preburner has the worst of it, operating at pressures as high or higher than 800 bar (11,600 psi, 80 megapascals).

Coincidentally, this is roughly equivalent to the pressure at the bottom of the Pacific Ocean.

Starhopper and Raptor seen on the afternoon of July 14th, preparing for an evening of testing. (NASASpaceflight – bocachicagal)

In short, preburner testing is no less critical than full-on static fire testing with an engine like Raptor. July 14th’s test was also made doubly efficient due to the fact that preburner testing requires liquid propellant, which effectively makes the whole test a wet dress rehearsal (WDR) even before any engine ignition or partial ignition is involved. Per SpaceX moving from propellant loading to preburner/turbine testing, Starhopper is almost certainly healthy and operating as expected, an excellent sign that the ungainly vessel may be ready for a static fire of Raptor as early as 2pm CT, July 15th.

The memes, oh, the memes.

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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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8 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:

“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.

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

Elon Musk teases huge merger: ‘Trending towards convergence’

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

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10 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.

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.”

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.

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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Elon Musk

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.

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12 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.

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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