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SpaceX’s Starship Raptor Vacuum engine plans laid out by CEO Elon Musk

A 2016 render of Raptor Vacuum. Much has changed about the engine's design in the three years since, but SpaceX is still pursuing a vacuum variant. (SpaceX)

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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.

Known as the Interplanetary Transport System in 2016, the ship featured six vacuum Raptors and 3 SL engines. (SpaceX)
In 2017, Big Falcon Spaceship shrunk and changed to 4 x RVac and 3x x Raptor SL engines. (SpaceX)
In 2018, Musk decided to sidestep vacuum engines entirely, moving to 7 SL Raptors. (SpaceX)

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.

A sea-level Raptor engine is static-fired at SpaceX’s McGregor, TX test facilities. (SpaceX)

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.

A Falcon 9 upper stage’s vacuum nozzle glows white hot during an orbital MVac burn. (SpaceX)

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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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 Cybercab ownership will come with plenty of strings attached

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Credit: Tesla

Tesla’s long-promised Cybercab is finally available for personal purchase, at least for a select few in the Austin area. But it’s far from a straightforward ownership experience.

The $29,990 price tag comes with a stack of restrictions that redefine what “owning” the vehicle actually means. The two-seat, steering-wheel-free Robotaxi, previously limited to Tesla’s own fleet, now carries contractual terms that limit where it can go, how it can be used, and whether it can even move without an active paid subscription.

Opening Night of Orders

Late on November 13, Tesla announced that select customers were being invited to order a Cybercab for personal use.

Tesla Cybercab goes on sale for $29,990, slated for December deliveries

The estimated purchase price is $29,990 before taxes, paired with a non-refundable $1,000 deposit and an estimated December 2026 delivery in Austin, Texas. The first month of the required :Autonomy Subscription,” priced at $299 per month is included.

After that, the vehicle needs an active subscription to operate at all. The announcement confirmed that customer sales had begun, albeit on an invite-only basis rather than a public order page.

The Fine Print for Buyers

For those invited to order, the agreements (Cybercab Order Agreement, Terms of Use, and Autonomy Subscription Agreement) impose significant constraints. Major points include:

  • A mandatory Autonomy Subscription (currently listed at $299 per month on the order screen, first month included) is required; without it, the Cybercab will not operate.
  • Personal, non-commercial use only; ride-hailing, Robotaxi network participation, delivery, or rental requires separate written authorization or product enablement from Tesla.
  • Operation restricted to Tesla-enabled Robotaxi geofences and supported service areas, which the company can expand, shrink, or alter; the vehicle may be technologically prevented from operating outside them.
  • No unauthorized modifications (including wraps, window tint, or wheel changes) without Tesla or an authorized provider.
  • Restricted resale and transfer: written permission required, with contractual damages of at least $50,000 (or full transaction value if higher) for unauthorized sales; Tesla also reserves repurchase rights at a company-determined fair market value, with the owner covering return costs.
  • Safety or improper-use “strikeouts” (three or more) can trigger a one-week suspension of autonomous features without prorated refund.
  • Owners remain responsible for insurance, registration, charging, parking, and general cleaning; the subscription covers certain maintenance items such as tires, windshields, filters, and camera cleaning, plus limited towing.
  • Manual controls on the touchscreen allow only short-distance movement up to about 2 mph and require a valid driver’s license; they are not for public-road driving.

Why These Terms Might Exist

Tesla’s approach prioritizes control over a vehicle designed without traditional human controls and intended primarily as transport-as-a-service, something that Musk has hinted toward for some time now. Restricting commercial use and modifications could be as much of a software integrity, safety, and data collection effort as it is a safety effort.

Fleet consistency could also be in regulatory scrutiny early on in the Cybercab’s days of public operation.

The subscription model generates ongoing revenue beyond the low vehicle price and ensures the car remains connected and updatable, something that will keep the Cybercab as safe as possible as new updates roll out.

Buyback and resale limits reduce the risk of vehicles circulating outside Tesla’s operational and service ecosystem.

It apperas that personal ownership is secondary to the broader Robotaxi network strategy, as Musk has previously stated that the vast majority of Cybercabs would remain Tesla-owned.

Pickup Locations and Musk’s Pricing View

Initial deliveries are estimated for Austin, but personal vehicles are able to operate in any of Tesla’s Robotaxi geofences:

Those who have been invited to order can also have their personal Cybercab delivered to numerous locations in Texas, including:

  • Austin
  • Dallas
  • Houston
  • San Antonio
  • Fort Worth

As far as the monthly “Autonomy Subscription,” it appears Musk already wants it to be low. He acknowledged last night on X that the subscription price is too high. Along with detailing that the Cybercab will be available nationwide as regulatory approval is received, Musk said the monthly fee should match the cost of FSD and Premium Connectivity, which is about $115 per month.

The launch marks a milestone for unsupervised personal autonomous vehicles, but the fine print makes clear that buyers are purchasing a highly constrained asset whose usefulness is tightly bound to Tesla’s software, service network, and geographic approvals.

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Tesla Cybercab goes on sale for $29,990, slated for December deliveries

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Credit: Tesla

Tesla has officially put the Cybercab up for sale, revealing a bargain price and a $299 per month “Autonomy Subscription” that could hit customer hands as soon as December.

The offer requires a $299 monthly Autonomy Subscription, with the first month included in the purchase price, along with a $1,000 non-refundable order deposit. Tesla’s ordering interface shows deliveries targeted for Austin, Texas.

Tesla says that the Cybercab is making transportation more efficient, affordable and accessible than ever before, and that buyers can order their own Cybercab for personal use.

The Cybercab is Tesla’s dedicated robotaxi, a gold-finished, two-passenger vehicle without a steering wheel or pedals, designed from the outset for unsupervised autonomous operation. It has been in limited Robotaxi service in Austin since September 2026, operating alongside Tesla’s larger fleet of Model Y vehicles.

Production takes place at Gigafactory Texas, which launched earlier this year. Tesla has stated for some time that it planned to put Cybercabs on sale by the end of the year, and it looks like they will come through on that promise if everything goes according to plan.

The Autonomy Subscription is mandatory for the vehicle to operate because it is void of a steering wheel and pedals. Tesla notes that the subscription and regular vehicle maintenance are required, indicating that personal owners will depend on the company’s software and service infrastructure rather than traditional ownership models.

One month of the subscription is included with purchase and subsequent months are billed separately until canceled.

This limited personal-sales opening marks a shift from Tesla’s earlier emphasis on fleet and transport-as-a-service operations. During the Q3 2026 Earnings Call, executives indicated that the vast majority of Cybercabs would remain Tesla-owned and used for rideshare service, while still aiming to place some vehicles with customers by year-end.

Elon Musk has previously targeted a price below $30,000, which was a huge point of emphasis for the Cybercab being the central point of Tesla’s “transportation-as-a-service” model.

Availability remains restricted to invited customers rather than a public order page, and the initial deliveries are expected only in the Austin area where unsupervised Robotaxi operations are already active. Buyers will need to accept the geographic and operational constraints of current autonomous deployment, as the vehicle cannot be driven manually outside supported zones.

The move gives a small number of early buyers the chance to own Tesla’s dedicated autonomous vehicle at the long-discussed sub-$30,000 price point, while the bulk of production continues to support the company’s expanding Robotaxi network.

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SpaceX Starship Flight 15: How to watch the double catch attempt

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Credit: SpaceX

UPDATE: The FAA has granted the license for Starship Flight 15.

SpaceX is set to attempt its 15th test flight of Starship this evening from Starbase, Texas.

SpaceX is targeting Starship Flight 15 for a launch as soon as today, Friday, November 13, pending an FAA Flight License, during a 75-minute window that opens at 4:45 p.m. CT (5:45 p.m. ET) from Orbital Launch Pad 2 at Starbase, Texas. The flight remains pending final regulatory approval.

The mission, using Booster 22 and Ship 42, aims to achieve the first full recovery of an orbital launch system. Primary objectives include a tower catch of the Super Heavy booster roughly six and a half minutes after liftoff and the first-ever tower catch of a Starship upper stage after more than 22 hours in space.

SpaceX will perform Starship double catch attempt with Flight 15

Between those catches, Ship 42 is planned to enter a low Earth orbit of about 275 km, complete roughly 14 orbits, and deploy 26 next-generation Starlink V3 satellites (Starlink Group 31-2). Three of those satellites carry cameras to inspect the ship’s heat shield in orbit and help controllers decide whether the vehicle is healthy enough for a return to the tower.

Contingency ocean splashdown options exist if either stage is not cleared for catch.

To watch the attempt, check the link to the broadcast in both X posts in this article. The live webcast is scheduled to begin about 30 minutes before liftoff and is planned to continue through the ship catch the next day, with the possibility of extended onboard views during the orbital coast via Starlink.

Because the schedule is dynamic, check back here or on our social media channels for the latest updates on window timing and regulatory status. A successful dual catch would mark a major milestone toward making Starship a rapidly reusable rocket capable of frequent flights.

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