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SpaceX's "Christmas tree" is a Raptor engine for the holidays
SpaceX CEO Elon Musk showed off a holiday-themed Raptor engine “Christmas tree” with its very own star on top. Musk noted via a tweet that the company’s Starship propulsion team is “making great progress” building, testing, and refining the Raptor engines that will one day propel the next-generation rocket to Earth orbit and beyond.
On December 13th, Musk revealed that SpaceX is preparing to ship the 17th completed Raptor engine to the company’s McGregor, Texas rocket test and development facilities, the site of several dedicated test stands for the Starship engine. Likely one of the most complex rocket engines ever designed, built, or tested, Raptor relies on an exotic combustion cycle, referring to the specifics of how engines turn their propellant into meaningful thrust.
Raptor uses what is known as full-flow staged combustion (FFSC) and is the first FFSC engine to graduate beyond ground testing and actually fly, thus far having completed two flight tests in July and August 2019 as part of SpaceX’s Starhopper test campaign. In simple terms, the FFSC cycle aims to extract as much energy from a rocket’s propellant as efficiently as possible, resulting in what is theoretically the most efficient possible chemical propulsion from a given fuel and oxidizer combination.
Due to the sheer complexity required to achieve full-flow staged combustion, the engine type is incredibly rare and only two other (once) functional examples exist – one developed by Soviet engineers in the 20th century and the other built, tested, and inexplicably scrapped by NASA in the 2000s. In fact, the Soviet RD-270 engine’s thrust-to-weight ratio is likely second only to SpaceX’s own Merlin 1D engine, an absolutely spectacular achievement for a propulsion bureau operating in the late 1960s.
RD-270 had major development challenges and would likely have taken years of additional hardware-rich (i.e. destructive trial and error) testing to produce an engine actually capable of reliable flight. Before the program was cancelled in 1970, 22 engines were tested and no single RD-270 survived to perform a fourth static fire, a testament to the immense challenge of FFSC engines.
SpaceX appears to have had a much better go of it with Raptor, although many, many engines have definitely been destroyed or irreparably damaged since the full-scale engine’s February 2019 static fire debut. SpaceX CEO Elon Musk says that the 17th completed Raptor engine is almost ready to head to McGregor, Texas to kick off development and acceptance testing.
It remains to be seen when exactly Raptor engines will be mature and reliable enough to perform the 3-10 minute burns needed to send a Starship to orbit, let alone the Moon or Mars, but Musk appears confident that SpaceX is making great progress along those lines.
Per photos and info posted by NASASpaceflight.com earlier today, Raptor engine SN15 is already installed on a recently-reactivated McGregor test stand ahead of its first rocket-related test in almost half a decade.
Formerly used to test Falcon 9 first stages before SpaceX built a new stand for Falcon 9 and Heavy, that tripod stand has been reactivated for the sole purpose of supporting vertical Raptor engine static fire testing, which Musk says will simplify and expedite development by making test conditions much more flight-like. As of now, all subscale and full-scale Raptor engine static fire testing has been performed at horizontal test stands in McGregor, apparently resulting in wear and behavior that would not likely appear if engines were tested vertically.
SpaceX has gone through the same process with its Merlin engine programs, beginning with horizontal testing (far easier and simpler) but ultimately building a number of dedicated vertical test bays to ensure that engine acceptance and development tests can be performed under more flight-like conditions.
According to NASASpaceflight, SpaceX may have already fired up Raptor SN15 on its reactivated tripod test stand earlier this week, kicking off Raptor’s first Starhopper-free vertical static fire testing. It’s now unclear where the twin horizontal Raptor test bays will fit into future engine testing given Musk’s comments. More importantly, every completed Starship and Super Heavy rocket will require several dozen new Raptor engines and every one of those engines will likely need to pass acceptance testing (including static fires) in McGregor before they can be installed on a launch vehicle.
SpaceX’s Falcon 9 rocket already requires 10 engines per new booster and upper stage, a test burden SpaceX has only managed with the help of two Merlin 1D stands and one Merlin Vacuum stand, all vertical. In other words, it’s safe to say that the reactivated tripod stand is likely just the first of several vertical Raptor test stands to come.
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Elon Musk
Tesla shows what Roadster drivers will see on screen before thruster activation
Tesla’s Roadster video reveals a fighter jet inspired cockpit with a 5,500 PSI thruster gauge.
Tesla has given future owners their clearest look yet at the cockpit of its next generation Roadster. In a 34 second video posted to X on Friday afternoon, the company walked through the car’s touchscreen with a caption: “Inspired by fighter jet cockpits, Roadster’s interface was designed around the pilot.”
The clip opens on a black screen with red graphics and a 3D wireframe of the car, which sits beside the Roadster’s squared off yoke. Tapping parts of the model brings up controls for the rear wing, including low drag and high downforce positions, along with a charging page with a charge limit bar and a small music player. A row of tabs along the bottom reads Home, Vehicle, Listen, Climate and Navigate.
Most of the video is spent in Track Mode. The dashboard shows a live circuit map, a list of session lap times, brake and motor temperatures, and pressure and temperature readouts for each tire. A setup page lets the driver pick Auto, Low Drag, High Downforce or Custom aero modes, adjust aero balance and brake balance, and switch stability and traction control off. Along the bottom, a status bar reads “Thruster · 5,500 PSI” next to a “Boost Ready” indicator.
That gauge ties the software to the hardware Tesla showed off near Waco, Texas on October 15. The Thrust and Rocket versions use cold gas thrusters fed by carbon overwrapped pressure vessels, and Tesla lists 0 to 60 mph times of under 0.9 seconds and under 0.59 seconds for them, as Teslarati detailed in its breakdown of the three Roadster configurations. The base Performance car relies on a fan and ground sealing system for grip, and the aero settings on screen match the active wings and suction setup covered in our look at how the Roadster generates downforce.
The Roadster layout is a departure from the rest of Tesla’s lineup. Instead of a map centered screen, the Roadster puts the car itself at the center of the home page, and Tesla’s Roadster page lists two smaller forward displays alongside the main touchscreen. Tesla has not said whether any of the Track Mode telemetry will make its way to the Model 3 Performance or other vehicles.
The interface could still change before deliveries. Elon Musk said at the event that Roadster production will begin in 2028, and Tesla says the flagship Rocket version is not approved for public road use. Reservations are open with a $50,000 payment, while Thrust is listed as a limited release and Rocket is invite only.
Those who want to see the car in person will get their first chance this weekend. The Roadster goes on display in the lobby of the Petersen Automotive Museum in Los Angeles from October 24 to 27, according to Sawyer Merritt, the first time the public will be able to view it up close.
Elon Musk
Tesla reveals Optimus Academy, where robots teach themselves
Tesla has begun building production quality Optimus robots in Fremont and revealed its training plan.
Tesla has started building Optimus on the high volume line it set up inside its Fremont factory, and the company says the robots coming off it are the first that meet the bar for a real product. “The bots coming off this line are the first production-quality bots that we have manufactured,” Tesla wrote in its third quarter shareholder letter, adding that it has “proven that the current manufacturing process for Optimus is suitable for a commercial product.”
The line sits in space that built the Model S and Model X until this spring. Tesla cleared the old vehicle line in 46 days, as Teslarati reported in July, to make room for robot production sized for one million units a year. On Wednesday’s earnings call, Elon Musk said most of the equipment for that capacity is already in Fremont, with output set to climb toward roughly 20,000 robots a week as the line ramps.
Musk described the ramp as a classic S curve. “The growth of Optimus is an S curve, but the initial curve is a shallow slope,” he said. The team is now refining the robot’s AI, electromechanical design, reliability and service life, and Musk expects that work to be finished by the end of next year, when Tesla plans to start delivering Optimus to outside companies for dangerous, repetitive and around the clock jobs.
The most interesting part of the call was how Tesla plans to teach the robots. Its cars send real driving data back to the AI team from millions of vehicles, but Optimus has no fleet like that yet. “A big difference with Optimus versus the cars is we don’t have this vast fleet of cars from which we can gather training data,” Musk said. Tesla’s answer is an Optimus Academy, where 10,000 to 20,000 robots will practice a wide range of tasks and feed what they learn into the next version of the model. Every unit off the Fremont line becomes a source of that training data.
Smarter hardware is on the way too. Tesla plans to put its AI5 chip into Optimus next year, and Musk said a new Optimus video should arrive within one or two months showing the robot completing tasks driven by AI rather than preprogrammed motions. He took aim at rival humanoid demos that only run scripted routines, saying those would not hold up in the real world.
The supply chain is lining up behind the program. In September, Tesla certified Tuopu, Joyson and Sanhua as mass production partners for Optimus components. A far larger Optimus factory is also rising at Giga Texas, where drone footage from Joe Tegtmeyer showed the steel frame nearing completion, and Musk has pegged that plant’s long term target at 10 million robots a year.
Tesla executives also said Optimus production costs are trending toward the expected manufacturing cost of Cybercab, a sign the robot is being engineered for volume from the start. The hands remain the toughest piece of the design, a point Musk also made at the X Takeover event earlier this month, as Teslarati covered at the time, and that is where much of the current engineering effort is focused.
Elon Musk
The Starship moon landing number NASA and Elon Musk can’t agree on
Musk disputes NASA estimate of 22 Starship launches for Moon landing, predicting 6 to 8.
Elon Musk is disputing a new NASA safety panel estimate of how many Starship launches it will take to put astronauts on the Moon, saying the real number will be less than half the panel’s figure.
On Thursday, NASA’s Aerospace Safety Advisory Panel held its quarterly public meeting. Panel member Charlie Precourt, a former NASA astronaut, flagged the fueling process for SpaceX’s lunar lander as a major risk for Artemis IV, the mission planned to land a crew on the Moon in 2028. “We need to keep our eyes on numerous required fuelings for the lander,” Precourt said, according to Ars Technica. “I think the last estimate is around 22 flights.”
Ars Technica’s Eric Berger posted the comment on X, and Musk replied. “That’s way too high,” Musk wrote. “Actual number will be more like 6 to 8.”
The disagreement comes down to a basic problem with sending a ship as large as Starship to the Moon. Starship burns nearly all of its propellant just reaching Earth orbit, so it cannot continue on to the Moon without stopping for a refill. SpaceX’s answer is a gas station in space. First, a Starship that works as a storage tank, called a depot, is launched into orbit. Then a series of tanker Starships launch one at a time, dock with the depot and pump their leftover propellant into it. Once the depot is full, the lunar lander version of Starship launches, docks, fills up and heads for the Moon.
Every tanker trip is its own full rocket launch, which is why the count matters. More launches mean more time, more cost and more chances for something to go wrong before astronauts ever leave Earth. Berger estimated that even if SpaceX reaches twice weekly Starship launches by the end of 2027, filling a depot at the panel’s number would still take roughly three months.
How many tankers are needed depends mostly on how much propellant each one can carry to orbit and how much is lost along the way. Starship’s fuel and oxygen are stored at extremely cold temperatures, and some of it slowly boils off while waiting in orbit. More is lost in each transfer. NASA appears to be working from what Starship can lift today, while Musk’s range assumes a more capable rocket.
Musk has pushed back on higher counts before. In 2021, after a government document suggested 16 launches, he called that “extremely unlikely” and said eight tankers would be the most required.
Much of the answer depends on hardware SpaceX has not finished flying. As Teslarati noted earlier this year, the company plans to carry out the refueling process with its upgraded V3 Starship, and Precourt described Artemis IV as carrying “a large number of firsts.” He also praised NASA Administrator Jared Isaacman’s team for working to clear obstacles for both SpaceX and Blue Origin, whose Blue Moon lander does not rely on orbital refueling for its first mission.
Tesla shows what Roadster drivers will see on screen before thruster activation
Tesla reveals Optimus Academy, where robots teach themselves
