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SpaceX fires up Starship rocket twice in 30 hours ahead of next big tests

Starship SN4 is looking downright shiny after successfully completing multiple wet dress rehearsals and two Raptor static fire tests. (NASASpaceflight - bocachicagal)

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SpaceX has successfully fired up a full-scale Starship rocket for the second time in barely 30 hours and removed the ship’s Raptor engine to perform an additional suite of “cryo testing”.

Around 7pm CDT on May 6th, SpaceX technicians began loading the fourth full-scale Starship with liquid oxygen and methane, filling up a large portion of its massive propellant tanks. Just the latest in a line of several tests involving wet dress rehearsals (WDR) completed in the days prior, this test would soon become exceptional. About an hour and a half after work began, Starship SN4’s lone Raptor engine ignited and burned for ~3 seconds, marking the first time in history a next-generation SpaceX rocket truly came alive with one of the engines designed to take it all the way to orbit.

In line with tests performed with Starhopper – a low-fidelity, subscale tested that flew twice with Raptor – last year, it would have been business as usual if SpaceX had called it a day and moved on to something else with Starship SN4. Instead, Starship performed another WDR and fired up its Raptor engine for a second time in just 30 hours after SpaceX teams inspected the rocket and cleared it for another round. It’s unknown why two back-to-back static fires were performed but, to be clear, every step Starship SN4 takes forward is a step into uncharted territory. Already, the ship’s next steps could come as soon as Friday, May 8th.

According to CEO Elon Musk, SpaceX’s second Starship SN4 static fire test was completed successfully and actually marked the operational debut of a critical aspect of the next-generation launch vehicle and spacecraft. Known as header tanks, Starship needs two smaller secondary propellant tanks to complement its main tanks, a need driven mainly by the challenges of landing such a large and mobile spacecraft. Smaller header tanks will also make it dramatically easier for SpaceX to insulate cryogenic propellant and ensure it remains liquid over long-duration cruises in space, but safe and reliable landings are a more pressing concern for these early prototypes.

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During landing operations, the main benefits smaller header tanks offer are relative ease of pressurization (needed to safely feed Raptor engines) and a much lower risk of issues from sloshing, which can introduce bubbles and voids that can obliterate rocket engines if ingested. Impressively, per Musk, Starship SN4 completed its second static fire test using its internal liquid methane header tank – a sort of bubble attached to the bottom of the main methane tank dome.

Starship SN5’s common methane and oxygen tank dome (and spherical methane header tank) is pictured here on May 1st. (NASASpaceflight – bocachicagal)
While header tanks will be invaluable for Starships attempting to landing on other planets or Moons after weeks- or months-long coasts in space, they’re also a great help for landing on Earth. (SpaceX)

Starship’s liquid oxygen header tank is situated at the tip of the conical nose section, a part that all full-scale ships have been tested without thus far. However, the use of the fuel header tank on May 7th means that Starship SN4 already has a functional, plumbed header tank installed, verifying the partial functionality of a critical part of the next-generation launch vehicle. A second static fire will have also provided SpaceX a wealth of extra data about Raptor’s performance while installed on Starship, invaluable at such an early stage of integrated testing.

Two Starship static fires now under its belt, SpaceX removed SN4’s Raptor engine around 12 hours after its second test and returned it to storage at the company’s nearby factory facilities. According to public notices provided by Cameron County, Texas officials, SpaceX’s next Starship SN4 activity is expected to occur on May 8th with backup windows on the 9th and 10th and will involve “cryo testing”.

SpaceX removed Starship SN4’s Raptor engine after two successful back-to-back static fires. (NASASpaceflight – bocachicagal)

The most obvious conclusion is that SpaceX – having completed enough static fire testing to verify Starship SN4’s performance – now wants to really put the rocket through its paces with another cryogenic test. Completed on April 26th, the ship’s first cryogenic ‘proof’ test maxed out at around 4.9 bar (70 psi), enough for low-stress hop tests but well short of the sustained pressure needed for orbital spaceflight. While testing singular propellant tanks in the first few months of 2020, Musk revealed that SpaceX was targeting a minimum of 6 bar (~90 psi) for orbital Starship flights – ~8 bar (115 psi) with a 25% safety factor.

Pictured here on May 7th, Starship SN5 could be just days away from its final tank section stacking operation and just a week from rolling to the launch pad for proof testing. (NASASpaceflight – bocachicagal)

The company actually achieved 8.4 bar with one of its Starship test tanks, the same processes of which were used to build Starship SN4, but a full-scale ship has yet to demonstrate those pressures. Now, SpaceX already has a fifth full-scale prototype (Starship SN5) likely just a week or so away from pad readiness, meaning that Starship SN4’s potential destruction during pressure testing wouldn’t have a big impact on plans for a series of imminent flight tests. If SN4 survives pressure testing, it would likely have its Raptor engine reinstalled and move on to a 150m (500 ft) hop test.

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 already has a complete Robotaxi model, and it doesn’t depend on passenger count

That scenario was discussed during the company’s Q4 and FY 2025 earnings call, when executives explained why the majority of Robotaxi rides will only involve one or two people.

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Credit: @AdanGuajardo/X

Tesla already has the pieces in place for a full Robotaxi service that works regardless of passenger count, even if the backbone of the program is a small autonomous two-seater. 

That scenario was discussed during the company’s Q4 and FY 2025 earnings call, when executives explained why the majority of Robotaxi rides will only involve one or two people.

Two-seat Cybercabs make perfect sense

During the Q&A portion of the call, Tesla Vice President of Vehicle Engineering Lars Moravy pointed out that more than 90% of vehicle miles traveled today involve two or fewer passengers. This, the executive noted, directly informed the design of the Cybercab. 

“Autonomy and Cybercab are going to change the global market size and mix quite significantly. I think that’s quite obvious. General transportation is going to be better served by autonomy as it will be safer and cheaper. Over 90% of vehicle miles traveled are with two or fewer passengers now. This is why we designed Cybercab that way,” Moravy said. 

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Elon Musk expanded on the point, emphasizing that there is no fallback for Tesla’s bet on the Cybercab’s autonomous design. He reiterated that the autonomous two seater’s production is expected to start in April and noted that, over time, Tesla expects to produce far more Cybercabs than all of its other vehicles combined.

“Just to add to what Lars said there. The point that Lars made, which is that 90% of miles driven are with one or two passengers or one or two occupants, essentially, is a very important one… So this is clearly, there’s no fallback mechanism here. It’s like this car either drives itself or it does not drive… We would expect over time to make far more CyberCabs than all of our other vehicles combined. Given that 90% of distance driven or distance being distance traveled exactly, no longer driving, is one or two people,” Musk said. 

Tesla’s robotaxi lineup is already here

The more interesting takeaway from the Q4 and FY 2025 earnings call is the fact that Tesla does not need the Cybercab to serve every possible passenger scenario, simply because the company already has a functional Robotaxi model that scales by vehicle type.

The Cybercab will handle the bulk of the Robotaxi network’s trips, but for groups that need three or four seats, the Model Y fills that role. For higher-end or larger-family use cases, the extended-wheelbase Model Y L could cover five or six occupants, provided that Elon Musk greenlights the vehicle for North America. And for even larger groups or commercial transport, Tesla has already unveiled the Robovan, which could seat over ten people.

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Rather than forcing one vehicle to satisfy every use case, Tesla’s approach mirrors how transportation works today. Different vehicles will be used for different needs, while unifying everything under a single autonomous software and fleet platform.

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Tesla Cybercab spotted with interesting charging solution, stimulating discussion

The port is located in the rear of the vehicle and features a manual door and latch for plug-in, and the video shows an employee connecting to a Tesla Supercharger.

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Credit: What's Inside | X

Tesla Cybercab units are being tested publicly on roads throughout various areas of the United States, and a recent sighting of the vehicle’s charging port has certainly stimulated some discussions throughout the community.

The Cybercab is geared toward being a fully-autonomous vehicle, void of a steering wheel or pedals, only operating with the use of the Full Self-Driving suite. Everything from the driving itself to the charging to the cleaning is intended to be operated autonomously.

But a recent sighting of the vehicle has incited some speculation as to whether the vehicle might have some manual features, which would make sense, but let’s take a look:

The port is located in the rear of the vehicle and features a manual door and latch for plug-in, and the video shows an employee connecting to a Tesla Supercharger.

Now, it is important to remember these are prototype vehicles, and not the final product. Additionally, Tesla has said it plans to introduce wireless induction charging in the future, but it is not currently available, so these units need to have some ability to charge.

However, there are some arguments for a charging system like this, especially as the operation of the Cybercab begins after production starts, which is scheduled for April.

Wireless for Operation, Wired for Downtime

It seems ideal to use induction charging when the Cybercab is in operation. As it is for most Tesla owners taking roadtrips, Supercharging stops are only a few minutes long for the most part.

The Cybercab would benefit from more frequent Supercharging stops in between rides while it is operating a ride-sharing program.

Tesla wireless charging patent revealed ahead of Robotaxi unveiling event

However, when the vehicle rolls back to its hub for cleaning and maintenance, standard charging, where it is plugged into a charger of some kind, seems more ideal.

In the 45-minutes that the car is being cleaned and is having maintenance, it could be fully charged and ready for another full shift of rides, grabbing a few miles of range with induction charging when it’s out and about.

Induction Charging Challenges

Induction charging is still something that presents many challenges for companies that use it for anything, including things as trivial as charging cell phones.

While it is convenient, a lot of the charge is lost during heat transfer, which is something that is common with wireless charging solutions. Even in Teslas, the wireless charging mat present in its vehicles has been a common complaint among owners, so much so that the company recently included a feature to turn them off.

Production Timing and Potential Challenges

With Tesla planning to begin Cybercab production in April, the real challenge with the induction charging is whether the company can develop an effective wireless apparatus in that short time frame.

It has been in development for several years, but solving the issue with heat and energy loss is something that is not an easy task.

In the short-term, Tesla could utilize this port for normal Supercharging operation on the Cybercab. Eventually, it could be phased out as induction charging proves to be a more effective and convenient option.

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Tesla confirms that it finally solved its 4680 battery’s dry cathode process

The suggests the company has finally resolved one of the most challenging aspects of its next-generation battery cells.

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tesla 4680
Image used with permission for Teslarati. (Credit: Tom Cross)

Tesla has confirmed that it is now producing both the anode and cathode of its 4680 battery cells using a dry-electrode process, marking a key breakthrough in a technology the company has been working to industrialize for years. 

The update, disclosed in Tesla’s Q4 and FY 2025 update letter, suggests the company has finally resolved one of the most challenging aspects of its next-generation battery cells.

Dry cathode 4680 cells

In its Q4 and FY 2025 update letter, Tesla stated that it is now producing 4680 cells whose anode and cathode were produced during the dry electrode process. The confirmation addresses long-standing questions around whether Tesla could bring its dry cathode process into sustained production.

The disclosure was highlighted on X by Bonne Eggleston, Tesla’s Vice President of 4680 batteries, who wrote that “both electrodes use our dry process.”

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Tesla first introduced the dry-electrode concept during its Battery Day presentation in 2020, pitching it as a way to simplify production, reduce factory footprint, lower costs, and improve energy density. While Tesla has been producing 4680 cells for some time, the company had previously relied on more conventional approaches for parts of the process, leading to questions about whether a full dry-electrode process could even be achieved.

4680 packs for Model Y

Tesla also revealed in its Q4 and FY 2025 Update Letter that it has begun producing battery packs for certain Model Y vehicles using its in-house 4680 cells. As per Tesla: 

“We have begun to produce battery packs for certain Model Ys with our 4680 cells, unlocking an additional vector of supply to help navigate increasingly complex supply chain challenges caused by trade barriers and tariff risks.”

The timing is notable. With Tesla preparing to wind down Model S and Model X production, the Model Y and Model 3 are expected to account for an even larger share of the company’s vehicle output. Ensuring that the Model Y can be equipped with domestically produced 4680 battery packs gives Tesla greater flexibility to maintain production volumes in the United States, even as global battery supply chains face increasing complexity.

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