

News
SpaceX’s path to refueling Starships in space is clearer than it seems
Perhaps the single biggest mystery of SpaceX’s Starship program is how exactly the company plans to refuel the largest spacecraft ever built after they reach orbit.
First revealed in September 2016 as the Interplanetary Transport System (ITS), SpaceX has radically redesigned its next-generation rocket several times over the last half-decade. Several crucial aspects have nevertheless persisted. Five years later, Starship (formerly ITS and BFR) is still a two-stage rocket powered by Raptor engines that burn a fuel-rich mixture of liquid methane (LCH4) and liquid oxygen (LOx). Despite being significantly scaled back from ITS, Starship will be about the same height (120 m or 390 ft) and is still on track to be the tallest, heaviest, and most powerful rocket ever launched by a large margin.
Building off of years of growing expertise from dozens of Falcon 9 and Falcon Heavy launches, the most important fundamental design goal of Starship is full and rapid reusability – propellant being the only thing intentionally ‘expended’ during launches. However, like BFR and ITS before it, the overarching purpose of Starship is to support SpaceX’s founding goal of making humanity multiplanetary and building a self-sustaining city on Mars. For Starship to have even a chance of accomplishing that monumental feat, SpaceX will not only have to build the most easily and rapidly reusable rocket and spacecraft in history, but it will also have to master orbital refueling.
The reuse/refuel equation
In the context of SpaceX’s goals of expanding humanity to Mars, a mastery of reusability and orbital refueling are mutually inclusive. Without both, neither alone will enable the creation of a sustainable city on Mars. A Starship launch system that can be fully reused on a weekly or even daily basis but can’t be rapidly and easily refueled in space simply doesn’t have the performance needed to affordably build, supply, and populate a city on another planet (or Moon). A Starship launch system that can be easily refueled but is not rapidly and fully reusable could allow for some degree of interplanetary transport and the creation of a minimal human outpost on Mars, but it would probably be one or two magnitudes more difficult, risky, and expensive to operate and would require a huge fleet of ships and boosters from the start.
The question of how SpaceX will make Starship the world’s most rapidly, fully, and cheaply reusable rocket is a hard one, but it’s not all that difficult to extrapolate from where the company is today. Currently, the turnaround record (time between two flights) for Falcon boosters is two launches in less than four weeks (27 days). SpaceX’s orbital-class reuse is also making strides and the company recently flew the same orbital Crew Dragon capsule twice in just 137 days (less than five months) – fast approaching turnarounds similar to NASA’s Space Shuttle average, the only other reusable orbital spacecraft in history.


While Dragon and Falcon 9 are far smaller than Starship and Super Heavy, Dragon is only partially reusable and requires significant refurbishment after recovery and Falcon 9 boosters are fairly complex. Starship, on the other hand, should effectively serve as a fully reusable all-in-one Falcon upper stage, Dragon capsule, Dragon trunk, and fairing, making it far more complex but potentially far more reusable. To an extent, Super Heavy should also be mechanically simpler than Falcon boosters (no deployable legs or fins; no structural composite-metal joints; no dedicated maneuvering thrusters) and its clean-burning Raptor engines should be easier to reuse than Falcon’s Merlins. Put simply, there are precedents set and evidence provided by Falcon rockets and NASA’s Space Shuttle that suggest SpaceX will be able to solve the reusability half of the equation.
What about refueling?
The other half of that equation, however, could not be more different. The sum total of SpaceX’s official discussions of orbital refueling can be summed up in a sentence included verbatim in CEO Elon Musk’s 2017, 2018, and 2019 Starship presentations: “propellant settled by milli G acceleration using control thrusters.”
On the face of it, that simple phrase doesn’t reveal much. However, with a few grains of salt, hints from what the company’s CEO has and hasn’t said, and context from the history of research into orbital propellant transfer, it’s possible to paint a fairly detailed picture of the exact mechanisms SpaceX will likely use to refill Starships in space. The cornerstone, somewhat ironically, is a 2006 paper – written by seven Lockheed Martin employees and a NASA engineer – titled “Settled Cryogenic Propellant Transfer.” Aside from the obvious corollaries just from the title alone, the paper focuses on what the authors argue is the simplest possible route to large-scale orbital propellant transfer.
In orbit, under microgravity conditions, the propellant inside a spacecraft’s tanks is effectively detached from the structure. If a spacecraft applies thrust, that propellant will stay still until it splashes against its tank walls – the most basic Newtonian principle that objects at rest tend to stay at rest. If, say, a spacecraft thrusts in one direction and opens a hatch or valve on the tank in the opposite direction of that thrust, the propellant inside it – attempting to stay at rest – will naturally escape out of that opening. Thus, if a spacecraft in need of fuel docks with a tanker, their tanks are connected and opened, and the tanker attempts to accelerate away from the receiving ship, the propellant in the tanker’s tanks will effectively be pushed into the second ship as it tries to stay at rest.
The principles behind such a ‘settled propellant transfer’ are fairly simple and intuitive. The crucial question is how much acceleration the process requires and how expensive that continuous acceleration ends up being. According to Kutter et al’s 2006 paper, the answer is surprising: assuming a 100 metric ton (~220,000 lb) spacecraft pair accelerates at 0.0001G (one ten-thousandth of Earth gravity) to transfer propellant, they would need to consume just 45 kg (100 lb) of hydrogen and oxygen propellant per hour to maintain that acceleration.
In the most extreme hypothetical refueling scenario (i.e. a completely full tanker refueling a ship with a full cargo bay), two docked Starships would weigh closer to 1600 tons (~3.5M lb) and the “Milli G” acceleration SpaceX has repeatedly mentioned in presentation slides would be ten times greater than the maximum acceleration analyzed by Kutter et al. Still, according to their paper, that propellant cost scales linearly both with the required acceleration and with the mass of the system. Roughly speaking, using the same assumptions, that means that the thrusting Starship would theoretically consume just over 7 tons (half a percent) of its methane and oxygen propellant per hour to maintain milli-G acceleration.
With large enough pipes (on the order of 20-50 cm or 8-20 in) connecting each Starship’s tanks, SpaceX should have no trouble transferring 1000+ tons of propellant in a handful of hours. Ultimately, that means that settled propellant transfer even at the scale of Starship should incur a performance ‘tax’ of no more than 20-50 tons of propellant per refueling. All transfers leading up to the worst-case 1600-ton scenario should also be substantially more efficient. Overall, that means that fully refueling an orbiting Starship or depot with ~1200 tons of propellant – requiring anywhere from 8 to 14+ tanker launches – should be surprisingly efficient, with perhaps 80% or more of the propellant launched remaining usable by the end of the process.
A step further, Kutter et al note the amount of acceleration required is so small that a hypothetical spacecraft could potentially use ullage gas vents to achieve it, meaning that custom-designed settling thrusters might not even be needed. Coincidentally or not, SpaceX (or CEO Elon Musk) has recently decided to use strategically located ullage vents to replace purpose-built maneuvering thrusters on Starship’s Super Heavy booster. If SpaceX adds similar capabilities to Starship, it’s quite possible that the combination of cryogenic propellant naturally boiling into gas as it warms and the ullage vents used to relieve that added pressure could produce enough thrust to transfer large volumes of propellant.
Last but not least, writing more than a decade and a half ago, the only technological barrier Kutter et al could foresee to large-scale settled propellant transfer wasn’t even related to refueling but, rather, to the ability to autonomously rendezvous and dock in orbit. In 2006, while Russia was already routinely using autonomous docking and rendezvous technology on its Soyuz and Progress spacecraft, the US had never demonstrated the technology on its own. Jump to today and SpaceX Dragon spacecraft have autonomously rendezvoused with the International Space Station twenty seven times in nine years and completed ten autonomous dockings – all without issue – since 2019.

Even though SpaceX and its executives have never detailed their approach to refueling (or refilling, per Musk’s preferred term) Starships in space, there is a clear path established by decades of NASA and industry research. What little evidence is available suggests that that path is the same one SpaceX has chosen to travel. Ultimately, the key takeaway from that research and SpaceX’s apparent use of it should be this: while a relatively inefficient process, SpaceX has effectively already solved the last remaining technical hurdle for settled propellant transfer and should be able to easily refuel Starships in orbit with little to no major development required.
There’s a good chance that minor to moderate problems will be discovered and need to be solved once SpaceX begins to test refueling in orbit but crucially, there are no obvious showstoppers standing between SpaceX and the start of those flight tests. Aside from the obvious (preparing a new rocket for its first flight tests), the only major refueling problem SpaceX arguably needs to solve is the umbilical ports and docking mechanisms that will enable propellant transfer. SpaceX will also need to settle on a location for those ports/mechanisms and decide whether to implement ullage vent ‘thrusters’, cold gas thrusters like those on Falcon and current Starship prototypes, or more efficient hot-gas thrusters derived from Raptors. At the end of the day, though, those are all solved problems and just a matter of complex but routine systems engineering that SpaceX is an expert at.
Elon Musk
Elon Musk is now a remote DOGE worker: White House Chief of Staff
The Tesla and SpaceX CEO Elon Musk is no longer working from the West Wing.

In a conversation with the New York Post, White House Chief of Staff Susie Wiles stated that Tesla and SpaceX CEO Elon Musk is no longer working from the West Wing.
As per the Chief of Staff, Musk is still working for DOGE—as a remote worker, at least.
Remote Musk
In her conversation with the publication, Wiles stated that she still talks with Musk. And while the CEO is now working remotely, his contributions still have the same net effect.
“Instead of meeting with him in person, I’m talking to him on the phone, but it’s the same net effect,” Wiles stated, adding that “it really doesn’t matter much” that the CEO “hasn’t been here physically.” She also noted that Musk’s team will not be leaving.
“He’s not out of it altogether. He’s just not physically present as much as he was. The people that are doing this work are here doing good things and paying attention to the details. He’ll be stepping back a little, but he’s certainly not abandoning it. And his people are definitely not,” Wiles stated.
Back to Tesla
Musk has been a frequent presence in the White House during the Trump administration’s first 100 days in office. But during the Q1 2025 Tesla earnings call, Musk stated that he would be spending substantially less time with DOGE and substantially more time with Tesla. Musk did emphasize, however, that DOGE’s work is extremely valuable and critical.
“I think I’ll continue to spend a day or two per week on government matters for as long as the President would like me to do so and as long as it is useful. But starting next month, I’ll be allocating probably more of my time to Tesla and now that the major work of establishing the Department of Government Efficiency is done,” Musk stated.
Elon Musk
Tariff reprieve might be ‘Tesla-friendly,’ but it’s also an encouragement to others
Tesla stands to benefit from the tariff reprieve, but it has some work cut out for it as well.

After Secretary of Commerce Howard Lutnick made adjustments to the automotive tariff program that was initially announced, many quickly pointed to the reprieve as “Tesla-friendly.”
While that may be the case right now, it was also a nudge of encouragement to other companies, Tesla included, to source parts from the U.S. in an effort to strengthen domestic manufacturing. Many companies are close, and it will only take a handful of improvements to save themselves from tariffs on their cars as well.
Yesterday, Sec. Lutnick confirmed that cars manufactured with at least 85 percent of domestic content will face zero tariffs. Additionally, U.S. automakers would receive credit up to 15 percent of the value of vehicles to offset the cost of imported parts.
Big Tesla win? Sec Lutnick says cars with 85% domestic content will face zero tariffs
“This is ‘finish your cars in America and you win’,” Lutnick said.
Many were quick to point out that only three vehicles currently qualify for this zero-tariff threshold: all three are Teslas.
However, according to Kelley Blue Book’s most recent study that revealed who makes the most American cars, there are a lot of vehicles that are extremely close to also qualifying for these tariff reductions.
Tesla has three vehicles that are within five percent, while Ford, Honda, Jeep, Chevrolet, GMC, and Volkswagen have many within just ten percent of the threshold.
Tesla completely dominates Kogod School’s 2024 Made in America Auto Index
It is within reach for many.
Right now, it is easy to see why some people might think this is a benefit for Tesla and Tesla only.
But it’s not, because Tesla has its Cybertruck, Model S, and Model X just a few percentage points outside of that 85 percent cutoff. They, too, will feel the effects of the broader strategy that the Trump administration is using to prioritize domestic manufacturing and employment. More building in America means more jobs for Americans.

Credit: Tesla
However, other companies that are very close to the 85 percent cutoff are only a few components away from also saving themselves the hassle of the tariffs.
Ford has the following vehicles within just five percent of the 85 percent threshold:
- Ford Mustang GT automatic (80%)
- Ford Mustang GT 5.0 (80%)
- Ford Mustang GT Coupe Premium (80%)
Honda has several within ten percent:
- Honda Passport All-Wheel-Drive (76.5%)
- Honda Passport Trailsport (76.5)
Jeep has two cars:
- Jeep Wrangler Rubicon (76%)
- Jeep Wrangler Sahara (76%)
Volkswagen has one with the ID.4 AWD 82-kWh (75.5%). GMC has two at 75.5% with the Canyon AT4 Crew Cab 4WD and the Canyon Denali Crew Cab 4WD.
Chevrolet has several:
- Chevrolet Colorado 2.7-liter (75.5%)
- Chevrolet Colorado LT Crew Cab 2WD 2.7-liter (75.5%)
- Chevrolet Colorado Z71 Crew Cab 4WD 2.7-liter (75.5%)
These companies are close to reaching the 85% threshold, but adjustments need to be made to work toward that number.
Anything from seats to fabric to glass can be swapped out for American-made products, making these cars more domestically sourced and thus qualifying them for the zero-tariff boundary.
Frank DuBois of American University said that manufacturers like to see stability in their relationships with suppliers and major trade partners. He said that Trump’s tariff plan could cause “a period of real instability,” but it will only be temporary.
Now is the time to push American manufacturing forward, solidifying a future with more U.S.-made vehicles and creating more domestic jobs. Tesla will also need to scramble to make adjustments to its vehicles that are below 85%.
News
Tesla Cybertruck RWD production in full swing at Giga Texas
Videos of several freshly produced Cybertruck LR RWD units were shared on social media platform X.

It appears that Tesla is indeed ramping the production of the Cybertruck Long Range Rear Wheel Drive (LR RWD), the most affordable variant of the brutalist all-electric pickup truck.
Videos of several freshly produced Cybertruck LR RWD units were shared on social media platform X.
Giga Texas Footage
As per longtime Tesla watcher Joe Tegtmeyer, Giga, Texas, was a hotbed of activity when he conducted his recent drone flyover. Apart from what seemed to be Cybercab castings being gathered in the complex, a good number of Cybertruck LR RWD units could also be seen in the facility’s staging area. The Cybertruck LR RWD units are quite easy to spot since they are not equipped with the motorized tonneau cover that is standard on the Cybertruck AWD and Cyberbeast.
The presence of the Cybertruck LR RWD units in Giga Texas’ staging area suggests that Tesla is ramping the production of the base all-electric pickup truck. This bodes well for the vehicle, which is still premium priced despite missing a good number of features that are standard in the Cybertruck AWD and Cyberbeast.
Cybertruck Long Range RWD Specs
The Cybertruck LR RWD is priced at $69,990 before incentives, making it $10,000 more affordable than the Cybertruck AWD. For its price, the Cybertruck Long Range RWD offers a range of 350 miles per charge if equipped with its 18” standard Wheels. It can also add up to 147 miles of range in 15 minutes using a Tesla Supercharger.
Much of the cost-cutting measures taken by Tesla are evident in the cabin of the Cybertruck LR RWD. This could be seen in its textile seats, standard console, seven-speaker audio system with no active noise cancellation, and lack of a 9.4” second-row display. It is also missing the motorized tonneau cover, the 2x 120V and 1x 240V power outlets on the bed, and the 2x 120V power outlets in the cabin. It is also equipped with an adaptive coil spring suspension instead of the adaptive air suspension in the Cybertruck AWD and Cyberbeast.
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