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SpaceX sends “radically redesigned” Starship engine to Texas for hot-fire tests

As of September 2017, subscale Raptor engines had been cumulatively fired for more than 1200 seconds in just 12 months of testing. (SpaceX)

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8 years ago

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SpaceX has shipped one of the first of a group of Starship engines known as Raptor, described last month by CEO Elon Musk as “radically redesigned”. A culmination of more than 24 months of prototype testing, the first flight-worthy Raptor could be ignited for the first time as early as February.

According to Musk, three of these redesigned Raptors will power the first full-scale BFR prototype, a Starship (upper stage) test article meant to conduct relatively low-altitude, low-velocity hop tests over the southern tip of Texas. Those tests could also begin next month, although a debut sometime in March or April is increasingly likely.

Effectively designed on a blank slate, Raptor began full-scale component-level tests in 2014 at NASA’s Mississippi-based Stennis Space Center, evolving from main injector development to oxygen preburner hot-fires in 2015. Soon after Raptor’s prototype preburner design was validated at Stennis, SpaceX moved testing to its privately-owned and operated facilities in McGregor, Texas, where Raptor static fire testing has remained since.

Just days before CEO Elon Musk was scheduled to reveal SpaceX’s next-generation rocket (BFR, formerly known as the Interplanetary Transport System or ITS) in September 2016, he announced in a tweet that propulsion engineers and technicians had successful hot-fired an integrated Raptor prototype – albeit subscale – for the first time ever. Just 12 months later, Musk once again took to the stage to announce an update to BFR’s design, while also revealing that prototype Raptor engines had already completed more than 1200 seconds (20 minutes) of cumulative hot-fire tests, an extremely aggressive and encouraging rate of progress for such a new engine.

Although Raptor undoubtedly borrows heavily from much of the same expertise that designed Merlin 1 and operated and improved it for years, that is roughly where the similarities between Raptor and M1D end. M1D, powered by refined kerosene (RP-1) and liquid oxygen, uses a combustion cycle (gas-generator) that is relatively simple and reliable at the cost of engine efficiency, although SpaceX propulsion expertise still managed to give M1D the highest thrust-to-weight ratio of any liquid rocket engine ever flown. Still, measured by ISP (instantaneous specific impulse), M1D’s inefficient kerolox gas-generator cycle ultimately means that the engine simply can’t compete with the performance of engines with more efficient propellants and combustion cycles.

While SpaceX’s Falcon 9 and Heavy rockets – powered by Merlin 1D and Merlin Vacuum – are more than adequate in and around Earth orbit, a far more efficient engine was needed for the company to enable the sort of interplanetary colonization Musk had in mind when he created SpaceX. Raptor was the answer. Ultimately settling on liquid methane and oxygen (methalox) as the propellant and a full-flow staged-combustion (FFSC) cycle, Raptor was designed to be extraordinarily reliable and efficient in order to safely power a spacecraft (BFS/Starship) meant to ferry dozens or hundreds of people to and from Mars.

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An excellent NASASpaceflight article explores the engine’s journey from a blank sheet to integrated static-fire tests and offers a deeper explanation of the technical details.

Raptor enters a new era

For all the extensive and invaluable testing SpaceX has done with a series of prototype Raptor engines, the engines tested were subscale versions with around 30% the thrust of the c. 2016 Raptor and around 40-50% of the updated c. 2017 iteration, producing almost the same amount of thrust as Merlin 1D (914 kN to Raptor’s ~1000 kN). In September 2018, Musk described Raptor as an “approximately…200-ton (~2000 kN) thrust engine” that would eventually operate with a chamber pressure as high as 300 bar (an extraordinary ~4400 psi), requiring at least one of the FFSC engine’s two preburners (used to power separate turbopumps) to operate at a truly terrifying ~810 bar (nearly 12,000 psi).

Conveniently stood beside a Merlin 1D engine also ready for hot-fire acceptance testing, the Raptor engine spotted departing SpaceX’s Hawthorne, CA factory last week was reportedly immense in person, towering over an M1D engine. Raptor also featured a mass of spaghetti-like plumbing (complexity necessary for its advanced combustion cycle), with a significant fraction of the metallic pipes and tubes displaying mirror-like finishes. Most notable was an obvious secondary preburner/turbopump stack and the lack of any exhaust port, whereas M1D relies on a single turbopump and exhausts the gases used to power it. Raptor’s full-flow staged-combustion cycle uses separate oxygen and methane preburners to power separate turbopumps, significantly improving mass flow rate and smoothing out combustion mixing.

 

Unlike all previous hot-fired Raptors, those shipping now to McGregor, Texas are expected to be the first completed engines with a finalized design, arrived at only after a period of extensive testing and iterative improvement. They also appear to be full-scale, meaning that the test bays dedicated to Raptor will likely need to be upgraded (if they haven’t been already) to support a two- or threefold increase in maximum thrust.

SpaceX’s Starship hopper will need three finalized engines, meaning that the Raptor now in McGregor, Texas may not have been the first to arrive. Nevertheless, the shipment of full-scale hardware is always an extremely encouraging milestone for any advanced technology development program, while also foreshadowing the first imminent static-fires of the “radcally redesigned” rocket engine. With hardware now at the test site before January is out, a February test debut – one month behind a January debut teased by Elon Musk last December – is not out of the question.

Check out Teslarati’s newsletters for prompt updates, on-the-ground perspectives, and unique glimpses of SpaceX’s rocket launch and recovery processes!

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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 Full Self-Driving becomes main pillar of new Referral Program

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4 hours ago

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October 30, 2026

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Credit: Tesla

Tesla Full Self-Driving is now the centerpiece of the company’s newly revised Referral Program, which launched on October 29.

Instead of referring people to purchase vehicles and the referrer receiving $250 in Tesla Credit, the new program now incentivizes Full Self-Driving subscriptions.

If a Tesla owner is on an FSD trial and uses a referral code to subscribe to Full Self-Driving, the person whose Referral Link was used will receive one month of FSD (Supervised). Their code can be utilized 12 times per year, with January 1 marking the reset date.

Realistically, this means that if your Referral Code is used by 12 Tesla owners on an FSD trial, you will receive a full year of FSD for free.

The previous program made it pretty difficult to get referrals; buying a vehicle is obviously a much larger financial strain than subscribing to Full Self-Driving for a month.

Of course, the previous Referral Program also offered a tangible benefit: $250 in credits you could use on Service, Supercharging, or anything in the Tesla Shop. It truly could pay for someone’s travel for a year. It recently bought me a new backpack and a T-shirt.

However, this new program is much more attainable for those who do not have a massive online presence of a slew of friends in the Tesla community who will use the code and max out subscriptions for vehicle purchases.

The Full Self-Driving suite will now be the keystone of the Referral Program, which makes it more inclusive and more fun for everyone with an awesome benefit.

It also gives the impression that Tesla is truly focused on FSD subscriptions, something that saw a tremendous increase in volume in Q3, as 75 percent of deliveries for the quarter came with an FSD subscription attached.

Full Self-Driving data is so instrumental to the suite’s improvement that this kind of program benefits Tesla as much as it does the consumer.

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Tesla made napping in a Robotaxi easier with its latest update

Tesla’s quiet mode reaches Model Y Robotaxis, blacking out the screen for riders wanting rest.

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15 hours ago

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October 29, 2026

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Tesla’s quiet mode, the setting that blacks out the screen for riders who want to rest, has moved beyond the Cybercab. A video posted Thursday by Spencer (@scotsrule08) shows the feature running in a Model Y Robotaxi on a night ride that appears to be in Dallas.

The rider taps a small crescent moon icon in the bottom right corner of the map screen. The map, media player, app shortcuts and Grok prompt disappear, leaving a dark display with “Arriving soon,” the destination and a line reading “Tap display to exit quiet mode.” Controls a passenger may still need, including Pull Over, cabin temperature, volume and Support, stay visible. One tap anywhere brings the full map back.

Quiet mode first showed up in the Cybercab last week, which Teslarati reported alongside a new rear camera view. Tesla has been trimming cabin noise in other ways too. On October 25, Spencer reported that Robotaxi turn signals now chime for the first four blinks and then go silent. Tesla has not published release notes for either change.

Elon Musk has been pitching this use for more than a decade. In October 2014, he said that “maybe five or six years from now I think we’ll be able to achieve true autonomous driving where you could literally get in the car, go to sleep and wake up at your destination,”

By 2017 he was setting a higher bar. Speaking at TED, Musk said the hard part was not making self-driving work 99.9 percent of the time, “because, like, if a car crashes one in a thousand times, then you’re probably still not going to be comfortable falling asleep. You shouldn’t be, certainly.”

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Owners asked for something similar in their own cars. In December 2019, a Tesla owner requested a Nap Mode that would keep the climate running and wake the occupant with an alarm, and Musk answered “Ok,” as Teslarati covered at the time.

The line returned when the Cybercab was unveiled at the We, Robot event in October 2024. “We’ll move from supervised Full Self-Driving to unsupervised Full Self-Driving, where you can fall asleep and wake up at your destination,” Musk said. On Tesla’s first quarter earnings call in April 2025, he called it the deciding measure: “The acid test is, can you go to sleep in your car and wake up in your destination and I’m confident that will be available in many cities in the US by the end of this year,”

Tesla has run driverless Model Y rides in Dallas and Houston since April, so a passenger dozing off on the way home is now a realistic use of the button. Tesla is also offering new riders a free first trip in both cities, according to an in-app screen shared by tracker Ethan McKanna, and said on its third quarter call that Cybercab rides would launch in Dallas next month.

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FCC green lights SpaceX’s move to a showdown with Verizon and AT&T

The FCC advanced plans opening 482 MHz to satellite phone service, boosting SpaceX’s Starlink Mobile.

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1 day ago

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October 29, 2026

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A hand holds a smartphone displaying the Starlink Mobile app interface showing a strong “Connected – Direct to Cell” signal, with a Starlink satellite beaming connectivity signals down to Earth from orbit. The background features the planet’s night side glowing with city lights against the curve of the atmosphere, set above a scenic twilight landscape.

The Federal Communications Commission voted Thursday to move forward with a proposal that would open an additional 482 MHz of spectrum to satellite service beamed directly to ordinary phones, a step that could widen the road for SpaceX’s Starlink Mobile to compete with the country’s largest wireless carriers.

The commission adopted the notice of proposed rulemaking at its October open meeting in Washington, Reuters reported. The proposal would raise the number of bands eligible for Supplemental Coverage from Space from five to 13, according to the FCC fact sheet. Commissioners also advanced a companion item proposing an auction of 25 MHz in the 1675 to 1695 MHz and 2020 to 2025 MHz bands, which could be used for terrestrial service, direct to device service or both.

Thursday’s vote does not hand any spectrum to SpaceX. It opens a public comment period, and final rules will come later. Under the draft, comments would be due 60 days after the notice is published in the Federal Register. The FCC had not released the adopted text at the time of writing, so it is not yet clear whether any bands were changed before the vote.

That question is where the fight now moves. AT&T, Verizon and T-Mobile, through industry group CTIA, asked the FCC to drop the 2.5 GHz and 3.45 GHz bands, which make up 290 MHz of the 482 MHz on the table, as Teslarati reported ahead of the vote. T-Mobile argued satellite interference could wipe out up to 96% of a cell site’s uplink coverage area. SpaceX asked the commission to go the other way and add the 902 to 928 MHz band.

The rule change that matters most to SpaceX may be a structural one. Today, a satellite operator must lease spectrum from every carrier holding co-channel licenses across an entire region such as the contiguous United States. The proposal would replace that with a certification that the operator has coexistence agreements covering only the areas it plans to serve, or that it holds the terrestrial licenses itself.

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SpaceX has spent this year building that second path. It bought EchoStar’s AWS-4 and H-block licenses in a deal worth roughly $17 billion, and earlier this month agreed to acquire Grain Management’s nationwide 800 MHz portfolio, which the company said would pave the way for Starlink to become a major US mobile carrier. The FCC approved SpaceX’s purchase of three unused AWS-3 licenses from Tristar on October 21, and cleared its plan for 15,000 next generation direct to cell satellites on October 6.

The regulator has not always sided with SpaceX. In April, the FCC dismissed a SpaceX petition seeking access to Mobile Satellite Service spectrum held by incumbents, and it rejected 2.5 GHz for satellite coverage when it first adopted the framework in 2024.

The carriers are also building their own defenses. In May, the three companies agreed in principle to form a joint venture pooling spectrum for satellite service, and T-Mobile remains SpaceX’s US launch partner for Starlink Mobile even as it leads the push to keep satellites out of 2.5 GHz. SpaceX President Gwynne Shotwell has said service on SpaceX’s own airwaves is targeted for early 2028.

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