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SpaceX’s orbital Starship prototype gets frosty during first successful ‘cryoproof’

Starship S20 lets off some steam with a vent 200+ feet long during its first cryoproof test. (NASASpaceflight - bocachicagal)

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For the first time, SpaceX has put the first orbital-class Starship – a prototype known as Ship 20 (S20) – through a routine cryogenic proof test, filling the rocket with several hundred tons of liquid nitrogen to simulate its explosive propellant.

While it’s impossible to jump to conclusions before members of the public can return to the pad to take photos or CEO Elon Musk takes to Twitter to discuss the results, Ship 20’s first ‘cryoproof’ appears to have been largely successful [Edit: Musk has confirmed that the test went well]. Relative to the almost three-dozen cryoproofs SpaceX has completed with more than a dozen other Starship, booster, and test tank prototypes over the last two years, though, Ship 20’s first major test still has some oddities.

Historically, every cryoproof of a full Starship prototype has been visually unique and virtually impossible to predict. Without any direct insight from SpaceX or Elon on the objectives, plan, or timeline of tests, the process of watching tests (via unofficial webcams, of course) and attempting to interpret why certain things look the way they do or what’s going on at any given moment is a bit trying to interpret eroded hieroglyphics.

At the most basic level, cryogenic tanking tests – whether with Starship, Super Heavy, or test tanks and liquid oxygen (LOx)/methane (LCH4) propellant or neutral liquid nitrogen (LN2) – are fairly simple. The vehicle is attached to pad systems, powered on, and partially or fully loaded with cryogenic fluids. Once the desired test objectives are achieved or attempted, the vehicle is then detanked (drained of propellant or LN2).

Thanks to the fact that they’re incredibly cold (-160 to -200C; -260 to -330F), the LOx/LCH4 or LN2 Starships are filled with quickly chill the thin steel tanks containing them. With no insulation to speak of, that supercooled steel then freezes water vapor out of the humid South Texas air, creating a layer of frost/ice that generally follows the level of the cryogenic liquids in Starship’s tanks. Throughout that process, those cryogenic liquids inevitably come into contact with ambient-temperature Starship tanks and plumbing (white-hot in comparison) and warm up, boiling off into gas as a result.

A gaseous chemical is far less dense than its liquid form, meaning that the pressure inside Starship’s fixed tanks can rapidly become unmanageable after even a small amount of boiloff. To maintain the correct tank pressures, Starship – like all other rockets – occasionally vents off the gas that forms. And thus, the two main methods of interpreting the hieroglyphics that are cryoproof tests: frost levels and venting.

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Compared to earlier prototypes, Starship S20’s first cryoproof has been… unusual. Most notably, SpaceX began loading the rocket with liquid nitrogen around 8pm CDT. Its LOx (bottom) and CH4 (top) tanks were then slowly filled to around 30-50% of their full volume over the next hour. However, rather than detanking, SpaceX then partially drained the methane tank but filled the LOx tank further before leaving the LOx tank more or less fully filled for more than two hours, occasionally topping it off with fresh liquid nitrogen.

Several giant vents almost four hours after testing began tricked even the most experienced of ‘Tank Watchers.’

Then, almost four hours after LN2 loading began, Starship performed several massive vents. Ordinarily, given the hours of testing prior, those vents would have assuredly been detank vents – effectively depressurizing Starship’s tanks as they’re drained of fluid. However, those vents instead coincided with the rapid loading of one or several hundred more tons of LN2, seemingly topping off Starship S20 in the process. Around that point, it’s possible that SpaceX began the pressure testing portion of Ship 20’s cryoproof, (mostly) closing the rocket’s vents and allowing the pressure to gradually increase to flight levels (and maybe even higher).

Many, many months ago, when SpaceX was deep into cryoproofing the first full-size Starship prototypes, Musk revealed an operating pressure goal of 6 bar (~90 psi). Ships were eventually successfully tested above 8 bar (~115 psi), giving Starship a healthy ~30% safety margin. As the first orbital-class Starship prototype, Ship 20 likely needs to hit those tank pressures more so than any ship before it to have a shot at surviving its orbital launch debut and orbital-velocity reentry attempt.

Starship S20’s first (aborted) cryogenic proof test attempt, September 27th. (NASASpaceflight – bocachicagal)
A demonstration of the kind of forces and pressures involved with SpaceX’s building-sized Starship SN1 prototype in February 2020.

Beyond the basics of cryoproofing, Starship S20 also marked a crucial step forward on September 29th/30th, becoming the first ship to complete a cryoproof test with a full heat shield installed. While it’s impossible to judge exactly how well S20’s ~15,000-tile heat shield performed, views from public webcams showed no obvious signs of tiles shattering and falling off as Starship repeatedly cooled and warmed – contracting and expanding as a result. Additionally, still in contact with the air, the steel tank skin under a majority of Ship 20’s tiles would have likely covered itself in a layer of frost and ice, but the heat shield appeared to handle that invisible change without issue.

It’s possible that dozens or hundreds of tiles bumped together and chipped or cracked in a manner too subtle to be visible on LabPadre or NASASpaceflight webcasts, but that can only be confirmed or denied when the road reopens and local photographers can capture higher-resolution views of Starship. For now, it appears that Ship 20’s first cryoproof was highly successful, hopefully opening the door for Raptor installation and static fire testing in the near future. Stay tuned for more!

Update: As is almost tradition by now, SpaceX CEO Elon Musk didn’t take long to tweet about the results of Starship S20’s first cryoproof, confirming that the “proof was good!”

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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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Why Elon Musk’s target date for buying an Optimus robot is harder than it sounds

Musk says China’s magnet export ban cost Optimus months, and robot hands remain shockingly hard.

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Concept rendering of Tesla Optimus in mass production

Elon Musk says China’s export curbs on magnets used in electric motors set back Tesla’s Optimus program by two to three months, and that the robot’s hands remain the hardest part of the project. He made the comments Saturday during a live interview with Tesla Owners Silicon Valley at the X Takeover event at Giga Texas, in front of roughly 2,000 attendees. The Optimus discussion begins around the 49 minute mark of the stream.

On the hands, Musk was blunt and noted that a general purpose humanoid needs fine motor skills that are “incredibly difficult to get right. Shockingly difficult,” he said in the interview. He pointed to a problem he says no one has demonstrated yet: “One of the hardest things also generally is to do precision and force at the same time,” such as driving a small self tapping screw into wood. Touch sensors add another layer, since it is “actually kind of hard to get touch sensors that elastically deform and can handle high cycle life and it won’t just break after a few thousand cycles.”

He also took aim at rival robot videos. “Any complicated looking robot demo, it’s a canned demo. It’s not real,” Musk said, adding that real AI means showing a robot something it has never seen and watching it still cope, the way FSD handles a city it has never driven.

Musk expects the Optimus ramp to be slower than a new vehicle production ramp. “The initial part of that S curve of production ramp is going to be very slow at the beginning,” Musk said, partly because “unlike cars, there’s no pre existing supply chain for robot stuff.” That echoes his July reply on X that Optimus production “will be extremely slow at first, as everything is new.”

The magnet disclosure puts a number on a problem Musk first raised in 2025. He said China “prevented the export of magnets for use in electric motors” and that it “set back the Optimus program by like two or three months.” Then he added: “We had robots with no arms.” Tesla’s fix is to bring the supply chain home. “You’ve got to be able to make all the parts domestically,” he said. Teslarati reported in April 2025 that Musk tied the issue to permanent magnets in the arm actuators, where motors have to be as small as possible.

Tesla Optimus V3 hand and arm details revealed in new patents

Production is moving regardless, with a reported internal goal of more than 1,000 a week by the end of 2026. Teslarati recently covered how Tesla is certifying supply partners in China for Optimus parts, while the company’s hand design has been the subject of new patent filings.

Musk has said he wants Optimus available to the public by late 2027, though Tesla has not confirmed that date or published updated production figures.

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Investor's Corner

Elon Musk drops a Thanksgiving hint about Starship’s biggest test yet

Elon Musk says Starship Flight 15 will try to catch the ship itself, a first.

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Elon Musk says SpaceX’s next Starship flight will try something nobody has done before, by catching the ship itself. Speaking to roughly 2,000 people at the X Takeover event at Giga Texas on Saturday, Musk said Flight 15 is about four to six weeks away and “probably launches a little bit before Thanksgiving, is my guess.”

That is a slip from earlier reporting, which had pointed to a launch as early as October 19. Musk explained why the date keeps moving. “We’re making a bunch of improvements to the rocket between every flight,” he said, adding that there are often hundreds, sometimes thousands, of small changes. This time the list is short, “but some of them take a fair bit of work and we’ve got to go inside the tank to make some of these changes.”

“We’re going to try to catch the ship, which is a super big deal,” Musk said. “If we do so, that’ll be the first time that there’s been full recovery of an orbital class rocket.” SpaceX has already caught the Super Heavy booster with the tower’s mechanical arms, and has talked about catching the ship since late 2025, but the upper stage has never been caught.

Musk also laid out what comes after. “The next big milestone would be to refly both the booster and the ship,” he said, describing a Flight 16 where “all parts of an orbital rocket are reflown.”

The reason SpaceX wants this comes down to cost and cadence. Every Starship ship so far has ended its flight in the ocean, and SpaceX expects most of those water landings to end in fireballs. A ship that returns to Starbase intact can be inspected and flown again. SpaceX’s IPO filing, says Starship V3 is designed to deliver 100 metric tons to orbit in a fully reusable configuration, that SpaceX aims to cut the cost to reach orbit by 99% or more versus the historical average, and that tower catches should allow “multiple launches per day.”

The payoff goes beyond cheaper launches. The next generation Starlink V3 satellites are too large for Falcon 9 and can only fly on Starship, which can carry up to 60 per flight. Flight 14 on September 28 deployed the first 26 of them after Starship reached orbit despite an early engine shutdown, as Teslarati reported. Musk blamed engine computer software, and said the heat shield “was extremely robust,” which he claimed in August had solved Starship’s biggest challenge.

NASA’s Moon plans depend on the same capability. NASA’s inspector general has described a lander mission that needs a propellant depot in low Earth orbit and more than 10 tanker flights, with SpaceX targeting one tanker launch every six days. That schedule only works if ships and boosters come back fast and fly again. Also, ship to ship propellant transfer has not been attempted yet.

One interesting hurdle yet to be explored is bringing the ship back to the launch site, with reentry over land, which will undoubtedly come with a lot of aviation safety reviews.

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Lifestyle

Tesla’s mirrorless Cybercab will give riders a visibility upgrade

Tesla engineer confirms Cybercab update letting riders pull up rear and repeater cameras on demand.

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Tesla Cybercab camera visibility for passengers (Credit: Dan Burkland via X)
Tesla Cybercab camera visibility for passengers (Credit: Dan Burkland via X)

Tesla is working on a Cybercab update that would let passengers pull up the vehicle’s rear and side cameras on demand, and the request came straight from a rider.

The exchange played out on X late Friday. Cybercab rider Dan Burkland shared photos of the two-seater’s cabin screen after an evening ride, praised the UI team’s work, and left one request: let riders open the rear and repeater cameras whenever they want, “especially for peace of mind.” Tesla UI software engineer Evan (@CarCoder) answered with two words: “In development.”

The idea fits a pattern Teslarati has tracked since public rides began. Days after paid Cybercab service opened in Austin, Tesla sent riders a survey that asked them to rate the touchscreen, the app and the cabin, and to pick the features they wanted most. We reported on that survey in September, and a camera view is the kind of small software change Tesla can push quickly if riders keep asking.

It also speaks to something unique about the vehicle. With no steering wheel, no pedals and no driver, passengers have no mirror to check and no way to see behind them. The hardware is clearly built for camera awareness, from the repeater cameras to the rear camera. Letting a passenger look through those same cameras would give a nervous first time rider a way to confirm what is around the car.

The timing matters because the fleet is growing fast. Tesla’s Robotaxi account said on Saturday that more than 300 Cybercabs are now serving Austin, an eightfold increase in 30 days, and Tesla AI chief Ashok Elluswamy named Dallas as the next city. More cars and more cities mean more people riding in a driverless vehicle for the first time, which is exactly when small trust features carry weight.

For now, the feature is confirmed only as in development. If Tesla follows its usual pattern with Cybercab software, riders could see it appear in a point release without any announcement, and Teslarati will watch for it.

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