News
SpaceX Starship passed “cryo proof” test for the first time and here’s what’s next
Elon Musk says a SpaceX Starship prototype has passed a critical “cryo proof” test for the first time, opening the door for the rocket to move on to even bigger tests.
Late on April 26th, SpaceX’s South Texas team (and possibly a console team in California) readied the fourth full-scale Starship prototype (SN4) for its second major test. Known as a cryogenic proof test, it began less than 24 hours after the rocket completed a room-temperature gas pressure test to check for leaks and verify that the pressure vessel was sound. Musk quickly confirmed that Starship SN4 passed through that “ambient proof test” without issue.
For the cryo proof test, room-temperature nitrogen gas was replaced with ultra-cold liquid nitrogen, serving as a chemically neutral (i.e. non-explosive) simulant for Starship’s liquid oxygen and methane propellant. After a few hours of partial loading and offloading cycles meant to ensure that Starship’s valves and propellant supply hardware was working as intended, SpaceX controllers fully filled the rocket with some ~1000 metric tons (2.2 million lb) of liquid nitrogen. Once full, a hydraulic ram setup was activated to exert forces akin to Raptor engines operating at full thrust. After several prior failures, Starship SN4 thus became the first to survive the ordeal and graduate into the next stage of testing.
According to CEO Elon Musk, that next step will be a static fire test with a lone Raptor engine installed. Able to produce at least 200 metric tons of thrust (~450,000 lbf) at full throttle, Raptor is an exceptionally efficient methalox (methane/oxygen) rocket engine designed by SpaceX to power Starship and its Super Heavy booster. Methane and oxygen was chosen in large part because of the relative potential ease of its extraction and refinement on Mars.
-->Per Musk, that static fire could occur within the next six or so days, meaning that SpaceX will likely install a functional Raptor engine on a full-scale Starship for the first time ever within the next day or two. Before a static fire can be performed, though, another significant test or two will have to be completed.
Known as a wet dress rehearsal (WDR), the first of those tests will be similar to April 26th’s cryo proof but with the neutral liquid nitrogen placed by real liquid oxygen and methane propellant. This is much riskier than the cryo proof in the sense that if a tank failure were to occur or a fire to accidentally start, 1000+ tons of highly-pressurized propellant could easily create a massive explosion and fireball, destroying or damaging much of the surrounding pad equipment. The WDR could potentially be rolled into another Raptor engine test that would verify its preburner performance.
To operate, Raptors first take liquid oxygen and liquid methane into separate parts of the engine and rapidly heat them to turn them into high temperature gas. Those preburners then send that hot gas to separate turbopumps that spin up and allow the engines to keep supplying themselves with large quantities of propellant, followed by the process of actually igniting the engine itself with a complex series of blowtorches.
If the preburner and turbopump spin-up test is successful, SpaceX can then move on to the actual static fire. Featuring a single Raptor engine, Starship SN4 will hopefully become the first full-scale rocket to safely operate a flight-grade engine since SpaceX began full-scale tests in November 2019. If successful, that static fire could pave the way for Starship SN4 to perform a Starhopper-style 150m (500 ft) hop test as early as May 2020 – a hop that would be powered by a single Raptor engine according to Musk.
Starship SN5 will reportedly be the first ship to both have a nosecone installed and three Raptor engines installed if SN4 has a very successful few weeks and that new ship is perhaps just 5-10 days from being fully assembled. In short, things are about to get very busy and very exciting at SpaceX’s South Texas Starship factory and launch pad.
-->
Elon Musk
SpaceX’s Starship program is already bouncing back from Booster 18 fiasco
Just over a week since Booster 18 met its untimely end, SpaceX is now busy stacking Booster 19, and at a very rapid pace, too.
SpaceX is already bouncing back from the fiasco that it experienced during Starship Booster 18’s initial tests earlier this month.
Just over a week since Booster 18 met its untimely end, SpaceX is now busy stacking Booster 19, and at a very rapid pace, too.
Starship V3 Booster 19 is rising
As per Starbase watchers on X, SpaceX rolled out the fourth aft section of Booster 19 to Starbase’s MegaBay this weekend, stacking it to reach 15 rings tall with just a few sections remaining. This marks the fastest booster assembly to date at four sections in five days. This is quite impressive, and it bodes well for SpaceX’s Starship V3 program, which is expected to be a notable step up from the V2 program, which was retired after a flawless Flight 11.
Starship watcher TankWatchers noted the tempo on X, stating, “During the night the A4 section of Booster 19 rolled out to the MegaBay. With 4 sections in just 5 days, this is shaping up to be the fastest booster stack ever.” Fellow Starbase watcher TestFlight echoed the same sentiments. “Booster 19 is now 15 rings tall, with 3 aft sections remaining!” the space enthusiast wrote.
Aggressive targets despite Booster 18 fiasco
SpaceX’s V3 program encountered a speed bump earlier this month when Booster 18, just one day after rolling out into the factory, experienced a major anomaly during gas system pressure testing at SpaceX’s Massey facility in Starbase, Texas. While no propellant was loaded, no engines were installed, and no one was injured in the incident, the unexpected end of Booster 18 sparked speculation that the Starship V3 program could face delays.
-->Despite the Booster 18 fiasco, however, SpaceX announced that “Starship’s twelfth flight test remains targeted for the first quarter of 2026.” Elon Musk shared a similar timeline on X earlier this year, with the CEO stating that “ V3 is a massive upgrade from the current V2 and should be through production and testing by end of year, with heavy flight activity next year.”
Considering that Booster 19 seems to be moving through its production phases quickly, perhaps SpaceX’s Q1 2026 target for Flight 12 might indeed be more than feasible.
News
Elon Musk makes a key Tesla Optimus detail official
“Since we are naming the singular, we will also name the plural, so Optimi it is,” Musk wrote on X.
Tesla CEO Elon Musk just made a key detail about Optimus official. In a post on X, the CEO clarified some key wording about Optimus, which should help the media and the public become more familiar with the humanoid robot.
Elon Musk makes Optimus’ plural term official
Elon Musk posted a number of Optimus-related posts on X this weekend. On Saturday, he stated that Optimus would be the Von Neumann probe, a machine that could eventually be capable of replicating itself. This capability, it seems, would be the key to Tesla achieving Elon Musk’s ambitious Optimus production targets.
Amidst the conversations about Optimus on X, a user of the social media platform asked the CEO what the plural term for the humanoid robot will be. As per Musk, Tesla will be setting the plural term for Optimus since the company also decided on the robot’s singular term. “Since we are naming the singular, we will also name the plural, so Optimi it is,” Musk wrote in his reply on X.
This makes it official. For media outlets such as Teslarati, numerous Optimus bots are now called Optimi. It rolls off the tongue pretty well, too.
Optimi will be a common sight worldwide
While Musk’s comment may seem pretty mundane to some, it is actually very important. Optimus is intended to be Tesla’s highest volume product, with the CEO estimating that the humanoid robot could eventually see annual production rates in the hundreds of millions, perhaps even more. Since Optimi will be a very common sight worldwide, it is good that people can now get used to terms describing the humanoid robot.
-->During the Tesla 2025 Annual Shareholder Meeting, Musk stated that the humanoid robot will see “the fastest production ramp of any product of any large complex manufactured product ever,” starting with a one-million-Optimi-per-year production line at the Fremont Factory. Giga Texas would get an even bigger Optimus production line, which should be capable of producing tens of millions of Optimi per year.
News
Tesla is improving Giga Berlin’s free “Giga Train” service for employees
With this initiative, Tesla aims to boost the number of Gigafactory Berlin employees commuting by rail while keeping the shuttle free for all riders.
Tesla will expand its factory shuttle service in Germany beginning January 4, adding direct rail trips from Berlin Ostbahnhof to Giga Berlin-Brandenburg in Grünheide.
With this initiative, Tesla aims to boost the number of Gigafactory Berlin employees commuting by rail while keeping the shuttle free for all riders.
New shuttle route
As noted in a report from rbb24, the updated service, which will start January 4, will run between the Berlin Ostbahnhof East Station and the Erkner Station at the Gigafactory Berlin complex. Tesla stated that the timetable mirrors shift changes for the facility’s employees, and similar to before, the service will be completely free. The train will offer six direct trips per day as well.
“The service includes six daily trips, which also cover our shift times. The trains will run between Berlin Ostbahnhof (with a stop at Ostkreuz) and Erkner station to the Gigafactory,” Tesla Germany stated.
Even with construction continuing at Fangschleuse and Köpenick stations, the company said the route has been optimized to maintain a predictable 35-minute travel time. The update follows earlier phases of Tesla’s “Giga Train” program, which initially connected Erkner to the factory grounds before expanding to Berlin-Lichtenberg.
-->Tesla pushes for majority rail commuting
Tesla began production at Grünheide in March 2022, and the factory’s workforce has since grown to around 11,500 employees, with an estimated 60% commuting from Berlin. The facility produces the Model Y, Tesla’s best-selling vehicle, for both Germany and other territories.
The company has repeatedly emphasized its goal of having more than half its staff use public transportation rather than cars, positioning the shuttle as a key part of that initiative. In keeping with the factory’s sustainability focus, Tesla continues to allow even non-employees to ride the shuttle free of charge, making it a broader mobility option for the area.
SpaceX’s Starship program is already bouncing back from Booster 18 fiasco
Elon Musk makes a key Tesla Optimus detail official
