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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.

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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 ‘Killer’ heads to the graveyard as AFEELA taps out

SHM has officially discontinued development of its highly anticipated AFEELA electric vehicles. On March 25, the joint venture between Sony and Honda announced it would halt the AFEELA 1 luxury sedan and a planned SUV model.

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Credit: AFEELA/X

There have been many Tesla “Killers” over the years, all of which have either failed to dethrone the automaker from its dominance in the United States, or even make it to the market altogether.

The Sony Honda Mobility (SHM) project, known as AFEELA, is the latest to make it to the grave, as the company announced its intentions to abandon the project earlier this week, Bloomberg reported.

SHM has officially discontinued development of its highly anticipated AFEELA electric vehicles. On March 25, the joint venture between Sony and Honda announced it would halt the AFEELA 1 luxury sedan and a planned SUV model.

The decision follows Honda’s March 12 reassessment of its electrification strategy, which scrapped several upcoming EV programs amid slowing demand, high costs, and shifting market conditions.

SHM stated that it could no longer rely on key Honda technologies and manufacturing assets, leaving “no viable path forward.” Reservation fees for early buyers in California are being fully refunded, and the joint venture’s future is now under review.

Launched with fanfare in 2022, the AFEELA was positioned as a tech-forward premium EV blending Honda’s engineering reliability with Sony’s entertainment and AI expertise.

Prototypes featured advanced autonomous driving systems, immersive in-cabin displays, and even PlayStation integration, earning it early media labels as a potential “Tesla Killer.”

No more “Tesla Killers:” It’s becoming increasingly difficult to distinguish the “EV market” from the mainstream auto segment

Priced around $90,000, the sedan was slated for limited production at Honda’s Ohio plant with deliveries targeted for late 2026. Industry watchers saw it as a serious challenger to Tesla’s dominance in software, connectivity, and premium appeal.

Yet, like many ambitious EV projects, it fell victim to broader industry headwinds: softening consumer demand, persistent high interest rates, and intense competition from established players.

The AFEELA joins a long list of vehicles once hyped as “Tesla Killers” that failed to deliver. In the late 2010s, Fisker’s second act, the Ocean SUV, promised stylish design and solid-state battery tech but collapsed into bankruptcy in 2024 after production delays, quality issues, and financial shortfalls.

Faraday Future poured billions into the FF 91 luxury sedan, touting it as a hyper-tech rival with unmatched performance and features; the company delivered fewer than 100 vehicles before fading into obscurity.

Lordstown Motors’ Endurance electric pickup generated massive pre-order buzz and Wall Street excitement but imploded after exaggerated range claims, a factory sale, and eventual bankruptcy.

Even Lucid Motors’ Air sedan, frequently called a Tesla slayer for its superior range and luxury, has struggled with sluggish sales and missed growth targets despite strong reviews.

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Rivian’s R1T and R1S trucks enjoyed similar early acclaim and a blockbuster IPO, yet production ramp-up challenges and profitability woes have prevented it from dethroning Tesla.

The AFEELA’s quiet demise underscores a harsh reality in the EV sector. While Tesla’s first-mover advantage in software, charging infrastructure, and brand loyalty remains formidable, legacy automakers and tech newcomers alike continue to underestimate the complexities of scaling affordable, desirable electric vehicles.

As market realities force tough choices, the graveyard of “Tesla Killers” grows longer, another reminder that innovation alone is rarely enough to topple an established leader.

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TIME honors SpaceX’s Gwynne Shotwell: From employee No. 7 to world’s most valuable company

Time Magazine honors Gwynne Shotwell as SpaceX reaches a $1.25 trillion valuation and eyes its IPO.

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TIME Magazine has put SpaceX President and COO Gwynne Shotwell on its cover, and the timing could not be more fitting. Published today, the profile of Shotwell arrives at a moment when the company she has quietly run for more than two decades stands at the center of the most consequential developments in aerospace, artificial intelligence, and the future of human civilization.

Shotwell joined SpaceX in 2002 as its seventh employee and has never stopped expanding her role. She oversees day-to-day operations across multiple executive teams spanning Falcon, Starlink, Starship, and now xAI following SpaceX’s February 2026 merger with Elon Musk’s artificial intelligence company, a deal that made SpaceX the world’s most valuable private company at a reported valuation of $1.25 trillion. A highly anticipated IPO is expected in the second quarter of 2026.

Will Tesla join the fold? Predicting a triple merger with SpaceX and xAI

Her track record is historic. She oversaw the first landing of an orbital rocket’s first stage, the first reuse and re-landing of an orbital booster, and the first private crewed launch to Earth orbit in May 2020. She built the Falcon launch manifest from nothing to more than 170 contracted missions representing over $20 billion in business. Under her operational leadership, SpaceX completed 96 successful missions in 2023 alone and has now flown more than 20 crewed Falcon 9 missions. Starlink, which she championed as a financial pillar of the company long before it was a mainstream topic, now connects tens of millions of users worldwide and provided a critical communications lifeline to Ukraine following the 2022 invasion.

Elon Musk has never been shy about what Shotwell means to him and to SpaceX. When she shared her vision for worldwide internet connectivity through Starlink, Musk responded on X with a simple statement, “Gwynne is awesome.” It is a sentiment that has been echoed across the industry. NASA Administrator Bill Nelson once said of Musk: “One of the most important decisions he made, as a matter of fact, is he picked a president named Gwynne Shotwell. She runs SpaceX. She is excellent.”


Now, with Starship targeting its first crewed lunar landing under the Artemis program by 2028, an xAI integration underway, and a pending IPO that could reshape capital markets, Shotwell’s mandate has never been larger. She told Time that 18 Starships are already in various stages of construction at Starbase. “By 2028,” she said, gesturing across the factory floor, “these should be long gone. They better have flown by then.” If Shotwell’s history at SpaceX is any guide, they will.

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SpaceX’s IPO might arrive sooner than you think

Musk has hinted for years that an eventual public offering was inevitable, though he has stressed the need to maintain operational focus. Insiders have told outlets that the CEO is pushing for a significant retail investor allocation, reportedly more than 20 percent of shares, and tighter lock-up periods to limit early selling pressure.

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Credit: SpaceX | X

Elon Musk’s SpaceX is on the verge of one of the most anticipated Initial Public Offerings (IPO) in history.

However, a new report from The Information indicates the rocket and satellite giant is aiming to file its IPO prospectus with U.S. regulators as soon as this week, or early next week at the latest.

People familiar with the plans told The Information that advisers involved in the process expect the IPO could raise more than 75 billion dollars, potentially making it the largest stock market debut ever and eclipsing Saudi Aramco’s 29.4 billion dollar offering in 2019.

The filing would mark the formal start of what has long been rumored: SpaceX’s transition from a closely held private powerhouse to a publicly traded company.

The timing aligns with earlier signals.

In late February, Bloomberg reported that SpaceX was targeting a confidential IPO filing in March and a possible public listing in June, with a valuation north of 1.75 trillion dollars. At the time, the company’s private valuation hovered around 1.25 trillion dollars.

SpaceX considering confidential IPO filing this March: report

Starlink, SpaceX’s satellite internet constellation, has been the primary driver of that surge, now serving millions of customers worldwide and generating steady revenue. Recent Starship test flights and a record pace of Falcon launches have further bolstered investor confidence.

Musk has hinted for years that an eventual public offering was inevitable, though he has stressed the need to maintain operational focus. Insiders have told outlets that the CEO is pushing for a significant retail investor allocation, reportedly more than 20 percent of shares, and tighter lock-up periods to limit early selling pressure.

A June listing would give SpaceX immediate access to public capital markets at a moment when demand for space-related stocks remains high. It would also allow early employees and long-time investors to cash out portions of their stakes while giving everyday shareholders a chance to own a piece of the company behind reusable rockets, global broadband, and NASA contracts.

Of course, nothing is certain until the SEC filing appears. Market conditions, regulatory reviews, and Musk’s own schedule could still shift timelines.

Yet the latest word from The Information suggests the window has opened. If the filing lands this week, SpaceX’s roadshow could begin in earnest within weeks, setting the stage for what many analysts already call the IPO of the decade.

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