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SpaceX’s Starship Raptor Vacuum engine plans laid out by CEO Elon Musk
Elon Musk says that SpaceX Starship engine upgrades are on track to begin static fire tests of a Raptor Vacuum variant as few as a “couple months” from now.
Designed to enable more efficient performance in thin atmosphere or vacuum, Musk admitted that the first version(s) of Raptor Vacuum (RVac) will likely be a compromise between efficiency and speed of development. Nevertheless, the faster SpaceX can prepare Raptor Vacuum for flight, the easier it will be for Starship to begin serious (sub)orbital flight tests.
As it turns out, SpaceX’s first and only official render of Raptor – published in September 2016 – showed the engine’s vacuum-optimized variant. In the years since, CEO Elon Musk has vacillated between keeping the vacuum engines as a central Starship feature and simply replacing them with regular sea level Raptors to expedite the spacecraft’s debut. The 2016 and 2017 vehicles featured a mixture of vacuum and sea-level engines, whereas Musk revealed a vehicle with sea-level engines only in 2018.
Perhaps less than a month after Musk’s September 2018 presentation, the SpaceX CEO made the decision to radically redesign the vehicle – newly christened Starship and Super Heavy – by moving from a carbon composite aerostructure to stainless steel. At first, the seven SL Raptors remained a part of the design, but Musk took to Twitter in 2019 to indicate that SpaceX had changed gears again and had reprioritized Raptor Vacuum development.
This came as a bit of surprise and it should go without saying that there’s a significant chance that Musk/SpaceX will oscillate in the opposite direction once again before Raptor Vacuum is actually ready for flight. This time, though, Musk has sketched out a development schedule and strategy that suggests SpaceX is much more serious this time.
Most notably, Musk claims that the first Raptor Vacuum prototype could be ready for static fire testing just a “couple months” from now, an immensely ambitious schedule for any large liquid rocket engine development program. Nevertheless, Musk did indicate that the “V1.0” Raptor Vacuum design would be significantly compromised and “suboptimal”, an intentional decision to prioritize the engine’s “speed of development”.
Even then, Musk believes that the first variant – featuring a shortened bell nozzle – could still be up to 12% more efficient than sea level Raptors and thus already 70-80% of the way to the physical limit of methane-oxygen rocket efficiency.
On a positive note, shrinking V1.0 Raptor Vacuum’s nozzle a bit from its nominal length will likely mean that SpaceX can static fire fully-integrated engines at its McGregor, TX test facilities, critical for speedy development. If not, the company has experience with alternatives through Merlin Vacuum, which can only be tested on the ground with its lengthy nozzle detached. This method just makes it dramatically harder to optimize a vacuum nozzle design, as full-scale, flight-like testing is nearly impossible if a given vacuum engine can’t be tested on the ground with said nozzle installed.
Vacuum engines need such large and unwieldy nozzles in order to make them as efficient as possible. In a very simplistic sense, a rocket engine nozzle directs the flow of superheated, ultrafast gases in order to squeeze as much momentum transfer as possible out of available propellant. The lower the pressure of the surrounding atmosphere is, the more those gases will expand immediately after leaving the nozzle – giant vacuum nozzles simply try to harness the additional momentum available from that extra expansion. This is why rocket exhausts appear to spread and thin out as launch vehicles reach higher and higher altitudes.
In this sense, the perfect theoretical vacuum nozzle is quite literally infinitely long. The job of vacuum rocket engineers is to find the perfect balance between that impractical theoretical perfection and the limits of real-world materials and dynamics. In theory, SpaceX’s sea-level Raptor engines have already been designed to operate in vacuum conditions, while the engine’s closed-cycle design and regeneratively (i.e. propellant) cooled nozzle should apply well to a vacuum design.
If SpaceX is lucky, there will be few roadblocks in the way of simply lengthening a SL Raptor-style nozzle and calling it a day, in which case it would be impressive but not all that surprising if SpaceX is actually able to begin RVac testing before the end of 2019. Once a rough V1.0 engine is in place, the process of optimizing efficiency can be done slowly and methodically, all while exploiting an unprecedented wealth of data from flight and orbit-tested Raptor Vacuum engines.
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Tesla Full Self-Driving (Supervised) has taken yet another significant step forward in Europe. On May 29, Estonia became the third European Union country to approve the advanced driver-assistance technology, following approvals in the Netherlands and Lithuania.
Tesla Europe announced the news on X, confirming the expansion has continued across the continent that, at one time, seemed to be taking its sweet old time giving any approval to the FSD suite.
FSD Supervised now approved in Estonia🇪🇪. Rollout will begin soon pic.twitter.com/y5a64qlp5m
— Tesla Europe, Middle East & Africa (@teslaeurope) May 29, 2026
Estonia’s Transport Administration (Transpordiamet) granted the approval by recognizing the type certification issued by the Dutch vehicle authority RDW. This mutual recognition mechanism, enabled by EU regulations, allows other member states to fast-track deployment without repeating extensive local testing.
The Estonian authority noted that Tesla’s FSD had undergone rigorous evaluation on European roads for approximately 18 months before the initial Dutch approval in April 2026.
FSD Supervised remains classified as a Level 2 advanced driver-assistance system (ADAS). Drivers must maintain full attention, keep their hands on the wheel, and stay ready to intervene at any moment.
The system assists with tasks such as automatic lane changes, navigation through city streets, and responding to traffic objects, but it does not constitute full autonomy. Estonian officials emphasized this distinction, underscoring that safety responsibility lies entirely with the driver.
The rapid progression across the Baltic region highlights Tesla’s strategic approach to European expansion. The Netherlands provided the foundational type approval in April, unlocking doors for neighboring countries.
Lithuania followed swiftly in mid-May, with rollout beginning shortly thereafter. Estonia’s decision, coming just days later, demonstrates how smaller, digitally progressive nations are accelerating adoption.
Tesla owners in Estonia can expect an over-the-air software update in the coming weeks, bringing the latest FSD capabilities to compatible vehicles
This expansion builds on Tesla’s global momentum. FSD Supervised is now available in 11 countries worldwide, including the United States, Canada, Australia, and South Korea. In Europe, the approvals signal growing regulatory confidence in Tesla’s vision-based AI approach, which relies on cameras and neural networks rather than lidar or radar-heavy alternatives used by some competitors.
For Tesla, these European milestones are more than symbolic. They validate years of data collection and software iteration while opening new revenue streams through FSD subscriptions and purchases.
As the company continues refining its AI models with real-world miles from diverse driving environments, including Estonia’s variable winter conditions, the dataset grows richer, potentially benefiting global users.
Elon Musk has firmly denied recent media reports suggesting that SpaceX has reduced its target valuation for an upcoming initial public offering.
The denial came directly from the SpaceX and Tesla frontman on his social media platform X, where he responded with a single word, “False,” to a post from ZeroHedge that cited Bloomberg sources.
This swift rebuttal underscores Musk’s ongoing effort to manage speculation surrounding one of the most anticipated market debuts in recent history.
False
— Elon Musk (@elonmusk) May 29, 2026
According to the disputed reports, SpaceX had lowered its IPO valuation goal to at least $1.8 trillion from previous ambitions exceeding $2 trillion.
The claims emerged amid growing anticipation for the company’s confidential S-1 filing, which positions it for a potential public listing as early as June.
Some had pointed to strong revenue growth, particularly from the Starlink satellite internet service, which contributed heavily to the firm’s 2025 figures of $18.7 billion. Yet challenges persist in other areas, including substantial investments and losses tied to ambitious projects like Starship development and artificial intelligence initiatives, which plan to make life multiplanetary eventually.
Musk’s response highlights a pattern in which he actively counters what he views as inaccurate portrayals of his companies’ trajectories.
SpaceX, already valued privately at extraordinary levels, stands as a cornerstone of Musk’s empire alongside Tesla and xAI. The entrepreneur has long emphasized the transformative potential of reusable rockets and global broadband access, factors that fuel investor enthusiasm despite operational hurdles.
By rejecting the valuation downgrade narrative, Musk signals confidence in SpaceX’s fundamentals and its readiness for public markets on terms favorable to its long-term vision. People have been waiting a very long time to invest in SpaceX, and the valuation, as well as the introductory share price, is not going to need adjusting.
They’ll have plenty of suitors.
This episode reflects broader dynamics in the technology sector, where rumors often swirl around high-profile entities. Musk’s direct engagement with media narratives serves to maintain transparency and control the narrative around his ventures.
As SpaceX prepares for greater scrutiny in public markets, the founder’s denial reinforces optimism about its prospects. Supporters argue that the company’s innovative edge positions it for enduring success, far beyond short-term valuation debates. With the denial now public, attention turns to forthcoming regulatory filings that could provide clearer insights into SpaceX’s strategy and financial health.
The coming weeks promise to reveal more about how SpaceX will transition into a publicly traded powerhouse.
Tesla’s dreams of operating a fully autonomous ride-hailing platform just took a massive step toward reality, as two separate events have indicated the company is perhaps closer than ever to achieving self-driving as a product.
On Thursday, Tesla was granted authorization by the State of Texas to operate driverless vehicles in a commercial manner. On May 28, Senate Bill 2807, passed by the 89th Texas Legislature, took effect after being passed back on September 1, 2025.
The bill establishes a statewide regulatory framework requiring authorization from the Texas Department of Motor Vehicles for companies to operate automated vehicles commercially on Texas roads.
This covers driverless, or SAE Level 4+, operations for passenger transport, meaning Robotaxi, or freight.
Tesla and other companies can self-certify their vehicles and tech as long as they:
- Operate in compliance with Texas traffic laws
- Maintain proper registration, title, and insurance
- Use compliant automated driving systems
- Record onboard activity and handle system failures and glitches safely.
The new authorization, which was first reported by James Stephenson on X, allows companies to utilize their own processes to determine if their vehicles are ready to operate without drivers.
🚨BREAKING:
Tesla has been authorized by the State of Texas to operate driverless vehicles commercially under the new law that took effect today, May 28th, 2026. Tesla has officially self-certified the software running on its robotaxis as Level 4. $TSLA pic.twitter.com/KSJdsvlaW5— James Stephenson (@ICannot_Enough) May 28, 2026
It is a rule that expedites the entire approval process, keeping agencies out of a usually long, lengthy, and frustrating task that is essential to technological advancements. It essentially means Tesla can launch commercial Robotaxi operations at this point.
On the very same day, Tesla continued the momentum as CEO Elon Musk shared a video of Cybercab units autonomously driving off the property at Gigafactory Texas. This is a major step in the story of the Cybercab.
Mass production of the Cybercab started at Giga Texas in April, and it is already heading out of the factory on its own.
Cybercab driving itself out of the GigaTexas factory pic.twitter.com/EwAMVVDjYy
— Elon Musk (@elonmusk) May 28, 2026
These two major events mark a drastic step forward in Tesla’s progress toward Cybercab and the permissions it needs to operate a self-driving ride-hailing service. Tesla is now able to operate autonomously under Texas law by self-certifying, and with the potentially imminent rollout of Cybercab, Tesla’s autonomous dreams are starting to take serious shape.
Tesla Full Self-Driving expansion in Europe continues with new addition
Elon Musk strikes down reports on SpaceX IPO rumors
