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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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Elon Musk
SpaceX’s Anthropic deal has a catch, and Elon Musk just addressed it
Elon Musk says SpaceX’s Anthropic compute deal cuts both ways after Chamath floats higher prices.
Elon Musk pushed back on Sunday against the idea that SpaceX’s compute contract with Anthropic is a one way bet, after venture capitalist Chamath Palihapitiya argued the company could use a termination clause to charge the AI lab far more.
“It works both ways, of course. If compute becomes plentiful and cheap, SpaceX revenue will drop. No crying in the casino for either party,” Musk wrote on X Sunday evening, replying to a clip of Palihapitiya’s comments shared by AI commentator Rohan Paul.
On the All-In podcast released Sunday, Palihapitiya said either side can walk away from the agreement on 90 days’ notice. If data center supply tightens, he argued, SpaceX could exercise that option and bring the contract back at two to three times the current price, and Anthropic would have little choice but to accept. He called it “the kingmaking move,” according to BigGo Finance.
The clause itself is not new. SpaceX disclosed in its IPO filings in May that Anthropic would pay $1.25 billion per month for dedicated capacity at its Colossus clusters through May 2029, nearly $45 billion in total, with both companies able to terminate on 90 days’ notice, as Teslarati reported at the time. SpaceX’s later compute deals with Google and Reflection AI carry similar exit terms.
What has changed is the political backdrop. Palihapitiya’s thesis rests on incoming Democratic governors pulling tax incentives for data centers and slowing new construction. In Texas, Gov.-elect Gina Hinojosa campaigned on a moratorium on new data center approvals, and Deutsche Bank analysts warned last week that SpaceX’s Texas compute capacity could face delays. SpaceX and Tesla shares both fell after the midterm results.
A slowdown would favor companies that already own capacity. SpaceX acquired xAI in February and has been renting data centers to outside AI labs before the space is needed for Grok. At the Baron Investment Conference on Friday, Musk said SpaceX was “getting 50 billion a year for 35 billion dollar investments” and that it can bring a data center online in eight or nine months, compared to two and a half years for competitors. He also said SpaceX is tracking toward an annualized revenue rate above $100 billion in December, with a “best guess” of $500 billion by December 2027.
Musk’s reply points to the other side of the clause. Anthropic has signed large compute agreements with Amazon, Google and Microsoft, and if that capacity comes online faster than new construction slows, the AI lab would have its own leverage to renegotiate or leave. Musk has called Anthropic “obviously currently the leader in AI,” and it remains one of SpaceX’s largest compute customers.
SpaceX shares rose more than 2 percent in overnight trading late Sunday after closing Friday at $134.27, according to Stocktwits.
Elon Musk
Elon Musk spotlights the Starlink rescue that got through where no cell tower could
Elon Musk spotlighted how Starlink helped rescuers reach five people stranded in Kazakhstan’s snowy mountains.
Elon Musk put a spotlight on a mountain rescue in eastern Kazakhstan on Sunday, writing “Starlink saves lives” in response to a post describing how SpaceX’s satellite internet helped five stranded people reach emergency crews.
The post from DogeDesigner, which had been viewed more than 500,000 times by Sunday afternoon, said the group’s SUV broke down about 15 kilometers from the village of Kystau Kurchum in an area with no usable mobile network. Starlink carried their call for help and kept them in contact with rescuers, who used the connection to locate them.
The rescue itself took place in October. Local outlet YK.kz reported on October 22 that Kazakhstan’s Ministry of Emergency Situations responded to the breakdown in the Kurchum district of East Kazakhstan region and noted that the group stayed in touch through Starlink. Rescuers covered roughly 100 kilometers in a Trekol, a low pressure tire vehicle built for snow and marshland, then escorted the disabled SUV back to Kystau Kurchum. Nobody needed medical attention.
Starlink saves lives
— Elon Musk (@elonmusk) November 8, 2026
Conditions in the region were rough at the time. Kazakh broadcaster Channel 7 identified the five as hunters caught in a snow trap and said satellite communication allowed rescuers to pinpoint where they were. A spokesperson for the East Kazakhstan emergency department said a storm warning was in effect and urged residents not to leave populated areas unless necessary. The same weather stranded seven utility workers repairing power lines in the nearby Kuygan rural district, according to Tengrinews.
Kazakhstan has been one of Starlink’s more notable markets in Central Asia. Teslarati reported in 2024 that Starlink was serving 1,731 of the country’s 1,879 schools, with the country’s Education Minister saying it had set a new standard for internet service in schools.
Rescue stories like this one have followed Starlink for years, usually in places where ground networks fail or never existed in the first place. Then Florida CFO Jimmy Patronis called Starlink a “game changer” for search and rescue crews during Hurricane Milton, and SpaceX and T-Mobile switched on Starlink Direct to Cell in North Carolina to push emergency alerts to phones after Hurricane Helene.
The next target is dead zones for people who do not carry a dish at all. SpaceX is building out Starlink Mobile and earlier this week selected Qualcomm to supply core infrastructure for a planned terrestrial 5G network in the United States, which it intends to pair with its next generation satellite constellation.
Sunday’s post is at least the third time Musk has written “Starlink saves lives” on X this week, following identical posts on November 5 and November 7.
SpaceX plans to attempt what will be a defining moment in rocket reusability on Starship Flight 15.
As Elon Musk announced in a recent X post, SpaceX will attempt to catch both the Super Heavy Booster and the Starship upper stage during the upcoming orbital flight. If successful, it will mark the first time that all parts of an orbital rocket return to Earth intact, a breakthrough Musk has called essential to making life multiplanetary.
SpaceX will attempt to catch both the Super Heavy booster and Starship on the upcoming flight.
If both are successful, it will mark the first time that all parts of an orbital rocket return to Earth intact.
This is the critical breakthrough needed to make life multiplanetary.
— Elon Musk (@elonmusk) November 6, 2026
Previous flights have demonstrated the tower-catch technique with Super Heavy. SpaceX has successfully caught V1 boosters three times (on Flights 5, 7, and 8), with some even reflown. The Ship upper stage has never been caught.
Returning from orbital velocity after deploying payload makes it a significantly harder challenge due to higher energy, heat loads, and the need for precise belly-flop reentry, a flip maneuver, and a final landing burn to settle between the Mechazilla tower’s chopstick arms.
Flight 15, using Booster 22 and Ship 42 (both Block 3 vehicles), is targeted for no earlier than Friday, November 13, 2026, from Orbital Launch Pad 2 at Starbase, Texas. The 75-minute window opens at 4:45 p.m. CT, pending regulatory approval. After hot staging and separation, the booster is planned to return for a catch roughly 6 minutes and 35 seconds after liftoff.
The Ship will insert into a roughly 275 km orbit, deploy 26 advanced Starlink V3 satellites, complete about 14 orbits over more than 22 hours, and—if systems check out—perform a deorbit burn, reentry, flip, and landing burn for a tower catch at approximately T+22 hours 32 minutes.
SpaceX confirms Starship 15 launch window with massive ambitions
A simulation shown during SpaceX’s October earnings call depicted the Ship descending in a belly-flop attitude, flipping upright with a short engine burn, and being captured by the arms:
From simulation to reality
SpaceX is just ONE WEEK away from attempting its most ambitious Starship catch yet https://t.co/nHrxSX6DSz
— X Freeze (@XFreeze) November 6, 2026
Contingency splashdown zones exist in the Gulf of Mexico (booster) and Pacific (Ship) if a catch is not viable. SpaceX has stressed rigorous health checks before committing the Ship to a return-to-launch-site trajectory.
Musk has described the odds of success on this first dual-catch attempt as “more likely than not,” noting a steady stream of additional flights is already scheduled if needed. Full recovery would enable rapid inspection, refurbishment, and reflight—slashing costs and supporting the high launch cadence required for Starlink expansion, lunar missions, and eventual Mars settlement.
As Musk put it, this is “the critical breakthrough needed to make life multiplanetary.”
SpaceX’s Anthropic deal has a catch, and Elon Musk just addressed it
Elon Musk spotlights the Starlink rescue that got through where no cell tower could
