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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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Tesla has officially launched public Robotaxi rides in Austin, Texas, without a Safety Monitor in the vehicle, marking the first time the company has removed anyone from the vehicle other than the rider.
The Safety Monitor has been present in Tesla Robotaxis in Austin since its launch last June, maintaining safety for passengers and other vehicles, and was placed in the passenger’s seat.
Tesla planned to remove the Safety Monitor at the end of 2025, but it was not quite ready to do so. Now, in January, riders are officially reporting that they are able to hail a ride from a Model Y Robotaxi without anyone in the vehicle:
I am in a robotaxi without safety monitor pic.twitter.com/fzHu385oIb
— TSLA99T (@Tsla99T) January 22, 2026
Tesla started testing this internally late last year and had several employees show that they were riding in the vehicle without anyone else there to intervene in case of an emergency.
Tesla has now expanded that program to the public. It is not active in the entire fleet, but there are a “few unsupervised vehicles mixed in with the broader robotaxi fleet with safety monitors,” Ashok Elluswamy said:
Robotaxi rides without any safety monitors are now publicly available in Austin.
Starting with a few unsupervised vehicles mixed in with the broader robotaxi fleet with safety monitors, and the ratio will increase over time. https://t.co/ShMpZjefwB
— Ashok Elluswamy (@aelluswamy) January 22, 2026
Tesla Robotaxi goes driverless as Musk confirms Safety Monitor removal testing
The Robotaxi program also operates in the California Bay Area, where the fleet is much larger, but Safety Monitors are placed in the driver’s seat and utilize Full Self-Driving, so it is essentially the same as an Uber driver using a Tesla with FSD.
In Austin, the removal of Safety Monitors marks a substantial achievement for Tesla moving forward. Now that it has enough confidence to remove Safety Monitors from Robotaxis altogether, there are nearly unlimited options for the company in terms of expansion.
While it is hoping to launch the ride-hailing service in more cities across the U.S. this year, this is a much larger development than expansion, at least for now, as it is the first time it is performing driverless rides in Robotaxi anywhere in the world for the public to enjoy.
Tesla has scheduled its Earnings Call for Q4 and Full Year 2025 for next Wednesday, January 28, at 5:30 p.m. EST, and investors are already preparing to get some answers from executives regarding a wide variety of topics.
The company accepts several questions from retail investors through the platform Say, which then allows shareholders to vote on the best questions.
Tesla does not answer anything regarding future product releases, but they are willing to shed light on current timelines, progress of certain projects, and other plans.
There are five questions that range over a variety of topics, including SpaceX, Full Self-Driving, Robotaxi, and Optimus, which are currently in the lead to be asked and potentially answered by Elon Musk and other Tesla executives:
- You once said: Loyalty deserves loyalty. Will long-term Tesla shareholders still be prioritized if SpaceX does an IPO?
- Our Take – With a lot of speculation regarding an incoming SpaceX IPO, Tesla investors, especially long-term ones, should be able to benefit from an early opportunity to purchase shares. This has been discussed endlessly over the past year, and we must be getting close to it.
- When is FSD going to be 100% unsupervised?
- Our Take – Musk said today that this is essentially a solved problem, and it could be available in the U.S. by the end of this year.
- What is the current bottleneck to increase Robotaxi deployment & personal use unsupervised FSD? The safety/performance of the most recent models or people to monitor robots, robotaxis, in-car, or remotely? Or something else?
- Our Take – The bottleneck seems to be based on data, which Musk said Tesla needs 10 billion miles of data to achieve unsupervised FSD. Once that happens, regulatory issues will be what hold things up from moving forward.
- Regarding Optimus, could you share the current number of units deployed in Tesla factories and actively performing production tasks? What specific roles or operations are they handling, and how has their integration impacted factory efficiency or output?
- Our Take – Optimus is going to have a larger role in factories moving forward, and later this year, they will have larger responsibilities.
- Can you please tie purchased FSD to our owner accounts vs. locked to the car? This will help us enjoy it in any Tesla we drive/buy and reward us for hanging in so long, some of us since 2017.
- Our Take – This is a good one and should get us some additional information on the FSD transfer plans and Subscription-only model that Tesla will adopt soon.
Tesla will have its Earnings Call on Wednesday, January 28.
Elon Musk shared an incredible detail about Tesla Cybercab’s potential efficiency, as the company has hinted in the past that it could be one of the most affordable vehicles to operate from a per-mile basis.
ARK Invest released a report recently that shed some light on the potential incremental cost per mile of various Robotaxis that will be available on the market in the coming years.
The Cybercab, which is detailed for the year 2030, has an exceptionally low cost of operation, which is something Tesla revealed when it unveiled the vehicle a year and a half ago at the “We, Robot” event in Los Angeles.
Musk said on numerous occasions that Tesla plans to hit the $0.20 cents per mile mark with the Cybercab, describing a “clear path” to achieving that figure and emphasizing it is the “full considered” cost, which would include energy, maintenance, cleaning, depreciation, and insurance.
Probably true
— Elon Musk (@elonmusk) January 22, 2026
ARK’s report showed that the Cybercab would be roughly half the cost of the Waymo 6th Gen Robotaxi in 2030, as that would come in at around $0.40 per mile all in. Cybercab, at scale, would be at $0.20.
Credit: ARK Invest
This would be a dramatic decrease in the cost of operation for Tesla, and the savings would then be passed on to customers who choose to utilize the ride-sharing service for their own transportation needs.
The U.S. average cost of new vehicle ownership is about $0.77 per mile, according to AAA. Meanwhile, Uber and Lyft rideshares often cost between $1 and $4 per mile, while Waymo can cost between $0.60 and $1 or more per mile, according to some estimates.
Tesla’s engineering has been the true driver of these cost efficiencies, and its focus on creating a vehicle that is as cost-effective to operate as possible is truly going to pay off as the vehicle begins to scale. Tesla wants to get the Cybercab to about 5.5-6 miles per kWh, which has been discussed with prototypes.
Additionally, fewer parts due to the umboxed manufacturing process, a lower initial cost, and eliminating the need to pay humans for their labor would also contribute to a cheaper operational cost overall. While aspirational, all of the ingredients for this to be a real goal are there.
It may take some time as Tesla needs to hammer the manufacturing processes, and Musk has said there will be growing pains early. This week, he said regarding the early production efforts:
“…initial production is always very slow and follows an S-curve. The speed of production ramp is inversely proportionate to how many new parts and steps there are. For Cybercab and Optimus, almost everything is new, so the early production rate will be agonizingly slow, but eventually end up being insanely fast.”
BREAKING: Tesla launches public Robotaxi rides in Austin with no Safety Monitor
Tesla Earnings Call: Top 5 questions investors are asking
