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SpaceX’s first orbital Starship rocket engine is almost ready for testing

Elon Musk says that SpaceX could be just a month away from testing the first Raptor Vacuum (RaptorVac) engine, three of which are pictured burning in this Starship render. (SpaceX)

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CEO Elon Musk says that SpaceX is “about a month away” from testing a rocket engine that will be essential for Starship and its Super Heavy booster to reach their full potential.

Known as Raptor Vacuum, the engine – as its name suggests – is a variant of the base Raptor engine optimized for maximum performance and efficiency in the vacuum of space. Although Starship could technically still function and likely reach orbit with only sea level-optimized Raptors installed, it would likely significantly limit the amount of payload it could carry into Earth orbit and would especially harm the ship’s performance to higher orbits and other planets.

Back in May 2019, Musk revealed that SpaceX had shifted gears again, forgoing a plan to begin orbital Starship flight operations with only sea level Raptors, gradually designing and phasing in RaptorVac engines much further down the road. Instead, SpaceX restarted (relatively) urgent work on the vacuum variant and Musk hinted that it would “aspirationally” be ready to support launches in the near term. A few weeks shy of a year later, Musk says that Raptor Vacuum testing could begin as early as June 2020.

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)

For a variety of reasons, even if based directly off of an existing design, vacuum-optimized engines are typically much more complex than a comparable sea level variant. While efficiency is always relatively important for rocket engine design, it becomes even more paramount when dealing with vacuum rocketry, as the entire point of a dedicated vacuum-optimized engine is to eke as much efficiency as possible out of a launch vehicle’s orbital stage(s).

A visual comparison of Merlin 1D (optimized for sea level) and Merlin Vacuum. (SpaceX)

For example, even from a purely visual perspective, Merlin Vacuum (MVac) is substantially different when compared to the Merlin 1D engine it’s based on. Due to a number of major and largely unknown differences, the engines’ shared components are largely invisible. It’s unclear how similar they are but it’s safe to say that they share at least ~50% commonality. Obviously, the most apparent part of the difference between a vacuum-optimized engine and an atmosphere-optimized engine is the bell nozzle: MVac has a nozzle that is dramatically larger than M1D.

Raptor will be no different, with the sea-level variant featuring a nozzle about 1m (3.2 ft) in diameter, whereas RaptorVac’s bell will have a diameter closer to 2.5m (~8 ft). With SpaceX’s apparent May 2019 pivot back to working on RaptorVac now, the company has been working on a dedicated vacuum variant of the high-performance methane-oxygen engine for at least a full year. Now, perhaps beginning as early as June or July, Musk suggests that the first RaptorVac engine (SN0? SN1?) is almost ready to commence static fire testing.

A Falcon 9 upper stage’s vacuum nozzle glows white hot during an orbital MVac burn. (SpaceX)
SpaceX technicians wrench on a Merlin Vacuum D (MVacD) engine. (SpaceX)
Raptor performs a static fire test in McGregor, Texas. (SpaceX)

The nature of that testing is a bit of a mystery. While it will almost certainly occur at SpaceX’s McGregor, Texas test and development facilities, it’s unclear if Raptor Vacuum’s first static fire test campaign will be attempted with the engine’s extended nozzle installed. Back in October 2019, Musk suggested that yes, Raptor Vacuum version 1.0 would have a nozzle small enough to operate at sea level without destroying itself or its test facilities. With Merlin Vacuum engines, SpaceX performs acceptance tests in Texas but only without their nozzle extensions installed. If Musk’s October 2019 comments remain true, that may not be the case for RaptorVac.

Either way, it will be thoroughly interesting to note the differences between RaptorVac and its sea level-optimized predecessor if or when Elon Musk or SpaceX releases photos of their newest engine as it nears its first major tests. Simultaneously, SpaceX is also readying a sea-level Raptor for its inaugural static fire test while attached to a full-scale Starship prototype, while the first test with three Raptor engines installed could be attempted just a few weeks from now.

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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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Elon Musk

Tesla Roadster owners to get “Flying Stunt Mode” and looping track access

Musk says Roadster owners can command the unveiling stunts autonomously, with a Texas looping track.

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Elon Musk says owners of the new Tesla Roadster will be able to ask the car to perform the stunts Tesla showed at its unveiling, with the car doing the driving itself. Musk made the comment Saturday in a reply on X to tech blogger Robert Scoble, and he added a promise of a looping track at Tesla’s Texas headquarters.

Scoble had argued that the person in the Roadster is not really driving it. In his description, the driver operates a computer that tells another computer what to do, with steering, braking and acceleration all handled by wire. Musk answered, “True. You will be able to ask the Roadster to perform any of the tricks shown autonomously, as it will be sentient. Also, we will have a wild looping track (crazier even than Hot Wheels) at our Texas HQ where you can test out your Roadster.”

At the October 15 event outside Waco, the car drove up a curved ramp until it was upside down, flew off on cold gas thrusters, flipped and landed. It also hovered over a Cybercab, Cybertruck, Semi, Model Y and Model 3 while moving. As we noted in our breakdown of the three Roadster configurations, Musk said at the event that the car “literally is just going to puff itself up” to perform the maneuvers whenever an owner wants. Saturday’s reply adds that the car would run them on its own.

Tesla has described some of the hardware that would make that possible. The Roadster uses steer by wire with a yoke, and its cold gas thrusters rely on electric actuators for small adjustments in flight. A fan system under the car creates suction, which Tesla says is strong enough to hold it upside down, a setup we covered in our look at the Roadster’s fan system and thrusters.

Musk did not say when an autonomous stunt feature might arrive, how it would work, or what he means by sentient. He also gave no size, location or opening date for the Texas track. Production is planned for Giga Texas in 2027 or 2028, and Tesla says the car is not approved for public road use. The Rocket version, the one built to fly, is invite only.

The comment follows a week of Musk teasing the event, including his claim that the demo would be a banger, which we covered before the stream. Tesla reports third quarter earnings on October 21, and shareholders can submit and vote on questions through the Say portal until 4 p.m. EDT on October 20, according to our earnings Q&A preview. A question about autonomous Roadster stunts and the Texas track would be a quick way to get specifics from management.

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Elon Musk

How to use Grok Bot to block spam calls and texts

Musk told users to ask Grok Bot to scrub their phone numbers from spam lists.

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Elon Musk has a new use case for Grok Bot, and it is the spam call. On Thursday he replied to an X user named Arash with a short instruction: “Ask your @Grok @Bot to remove your phone number from spam call & text lists!” Arash had said he got tired of the calls, had an AI bot find his number on listing sites and file removal requests, and packaged the process as a free skill for others.

The skill is called Spam-Call Scrubber, which is described to find a phone number on people search sites and data brokers, submits the opt outs, completes the confirmation emails those sites send back, and rechecks on a schedule the user picks. Using it requires the Grok Bot app. The pitch is time saved, since most broker opt outs sit behind separate forms on separate sites.



Musk said Grok Bot now gives each bot its own email address, and that it can detect scam emails. On Thursday he also said SpaceX would make users whole if the bot botches a purchase or leaks a card, then told users to shop away from Amazon after the retailer blocked the agent, as Teslarati reported. The terms of service we reviewed at the time put responsibility for what an agent does on the user.

For Tesla owners, Grok Bot is not just a phone app. Tesla brought Grok Bot into its vehicles on September 22, and we argued earlier this week that the Cybercab’s real advantage may be the errands it runs during a ride. Every Cybercab and the rest of the Model Y Robotaxi fleet has it enabled. The more routine tasks like this one become, the more a rider has reason to hand over something personal in the back seat.

The new Spam-Call Scrubber skill can be downloaded for free and works on sites that honor removal requests, while noting that listings can reappear, and illegal robocallers do not check any registry. Whether Spam-Call Scrubber cuts anyone’s call volume is something the first wave of users will find out, and Musk’s endorsement guarantees that wave is coming.

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Investor's Corner

Tesla’s flying Roadster just revealed something bigger than the car

Analysts say the Roadster demo puts a Tesla and SpaceX merger back on the table.

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Tesla’s new Roadster, upside down and trailing cold gas thruster smoke, flips over a lineup of Tesla vehicles at the Roadster unveiling near Waco, Texas on October 15, 2026. (Image: Tesla)
Tesla’s new Roadster, upside down and trailing cold gas thruster smoke, flips over a lineup of Tesla vehicles at the Roadster unveiling near Waco, Texas on October 15, 2026. (Image: Tesla)

The Roadster unveiling near Waco ended Thursday night, and by Friday morning much of the investor reaction had less to do with the car than with who owns the rocket technology inside it.

Wedbush analyst Dan Ives said the event “puts the Tesla/SpaceX relationship on the table in a tangible way,” pointing to the propulsion, pressure vessel and control hardware sitting on a Tesla product. Gene Munster of Deepwater Asset Management called the demo “a ridiculous display of engineering” with “no commercial value” beyond embarrassing traditional automakers, though he said it showed Musk wants the two companies together.

The more specific forecast came a day earlier from Barclays. Analyst Dan Levy told clients a deal could be announced before Tesla’s annual meeting, which must happen by December 6, and that an announcement in late October or early November could make shareholder approval harder. Barclays expects SpaceX to be the buyer in an all stock deal, with Tesla holders receiving SpaceX shares at a premium, based on market values of roughly $2.1 trillion for SpaceX and $1.5 trillion for Tesla. If nothing lands around the meeting, the bank still sees an announcement within 6 to 12 months.

The Roadster demo just added more weight to merger speculations. Tesla’s demo used cold gas thrusters and pressure tanks of the kind SpaceX uses on Falcon 9, and Musk described the car as a collaboration between Tesla and SpaceX engineers, as we mentioned in our breakdown of the three Roadster configurations.


Musk has not publicly addressed a deal since the event, as far as we have seen. His most direct answer remains the one he gave at the All In Summit, when he said that with so much collaboration, “who can imagine what action one might take” without ruling anything out. Ives has held to a 2027 timeline since his March note, and Musk pushed back on the China piece of the speculation when ARK floated a year end announcement in August.

The next test is Tesla’s third quarter earnings call on October 21. However, we recall in July that Musk told analysts, “we can’t talk about combining companies and that kind of thing on an earnings call,” so a clear answer wouldn’t be expected.

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