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SpaceX’s thin-skinned Starship ‘test tank’ passes first trial

Elon Musk says that SpaceX's first 3mm-thick Starship test tank passed its first major trial. (LabPadre)

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CEO Elon Musk says that a new thin-skinned Starship ‘test tank’ just passed its first trial, taking advantage of delays to Starship SN9’s planned high-altitude launch debut.

Delayed by a lack of FAA approval for unknown reasons, Starship SN9’s 12.5-kilometer (7.8 mi) launch debut (virtually identical to SN8’s 12.5 km launch last month) is in limbo pending an “FAA review” according to Musk. SpaceX thus found itself with at least 24 hours of guaranteed inactivity for Starship SN9, time the company rapidly chose to fill with crane transportation and, more importantly, the first Starship ‘test tank’ stress test in months.

Known as Starship SN7.2, SpaceX’s latest ‘test tank’ is the third to carry the SN7 moniker and appears to have been built primarily to test refinements to the rocket’s structural design. Following test tanks SN7.0 and SN7.1, both used to qualify the use of a new steel alloy on an otherwise unchanged design, SN7.2 – likely built out of the same alloy – is instead focused on determining if SpaceX can begin trimming the margins of an increasingly mature technology.

Starship test tank SN7.0 and SN7.1. (NASASpaceflight – bocachicagal)
SN7.2. (NASASpaceflight – bocachicagal)

Curiously, SN7.2 is a sort of fusion of its predecessors: combining the stout stature of SN7.0 with SN7.1’s use of an aft thrust dome, but without SN7.1’s Starship-style skirt (the three rings at its bottom). Welded directly to its black test stand, it’s unclear why SpaceX chose to give SN7.2 a thrust dome, given that the thrust of Raptor engines can only be simulated with hydraulic rams if the tank is installed on one of two Starship launch mounts.

Regardless, whether SpaceX actually tests that aspect of SN7.2, the tank’s most important task is determining if future Starships (and perhaps Super Heavy boosters) can be built out of thinner, lighter steel rings. Its domes appear to be identical to past ships but writing on the exterior of the tank strongly implied that its three rings were built out of 3mm steel rather than the 4mm sheets that have made up every Starship built in the last 12 months.

SpaceX began loading the thin-skinned tank with liquid nitrogen (used to simulate cryogenic propellant without the risk of an explosion) around 9am CST and spent around three hours performing an “initial pressure test.” It’s unclear what that test entailed but it most likely involved raising the tank’s internal pressure to levels achieved by SN7.0 and SN7.1 Musk has previously said that that 6 bar was the bare minimum necessary for orbital flight, translating to 7.5-8.5 bar to achieve an industry-standard safety margin of 25-40%.

That SN7.2 survived that initial pressure test bodes well for the significant mass reductions SpaceX will need to optimize Starships for efficient orbital flight, potentially shaving 5-10 metric tons off the dry mass of future ships. For orbital rocket stages, every single kilogram of mass reduction translates to an extra kilogram of cargo capacity, whereas boost stages (i.e. Super Heavy) offer far more lenient ratios on the order to 10:1, meaning that adding 5-10 kilograms of rocket hardware reduces maximum payload capacity by just ~1 kg.

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Depending on when SpaceX is allowed to launch Starship SN9, the company’s next test could involve pressurizing SN7.2 until it bursts, determining if the tank’s thinner skin substantially impacts its performance as a pressure vessel.

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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Verizon, AT&T and T-Mobile are trying to shut Starlink out before FCC vote

AT&T, Verizon and T-Mobile want 290 MHz cut from an FCC satellite plan before Thursday.

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Starlink D2D direct to device vs Verizon, AT&T (Concept render by Grok)

AT&T, Verizon and T-Mobile are asking the Federal Communications Commission to pull nearly 300 MHz of spectrum out of a proposal that would let satellite companies like SpaceX offer cell service directly to ordinary phones. The request lands one day before the agency votes on it.

The FCC will vote Thursday, October 29, on a notice of proposed rulemaking that would make an additional 482 MHz available for direct to device service, expanding the number of eligible bands from five to 13, according to the FCC fact sheet. It would also scrap the rule requiring a satellite operator to lease spectrum from carriers, replacing it with a certification that the operator has coexistence agreements in place or holds the terrestrial license itself.

That second path matters for SpaceX. As Teslarati reported earlier this month, SpaceX agreed to buy Grain Management’s nationwide 800 MHz portfolio to turn Starlink Mobile into a full US carrier, adding to the spectrum it already bought from EchoStar.

The carriers want two bands removed, 2.5 GHz and 3.45 GHz, which make up 290 MHz of the 482 MHz on the table. Through industry group CTIA, they argued that about 300 million users depend on those bands and that satellite operations in them are not technically feasible. T-Mobile, which calls 2.5 GHz the foundation of its Ultra Capacity 5G network, said in its own filing that satellite interference could wipe out up to 96% of a cell site’s uplink coverage area and cut uplink speeds by 88% to 99%.

Executives from all three carriers met with FCC staff on October 20, and T-Mobile CEO Srini Gopalan met separately with FCC Chairman Brendan Carr. T-Mobile’s role stands out because it is still SpaceX’s US launch partner for Starlink Mobile. The three carriers have also teamed up on their own satellite joint venture to pool spectrum, a move widely seen as a response to Starlink.

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SpaceX is asking for the opposite. In an October 23 filing after meetings with FCC staff and commissioners’ offices, the company asked regulators to add the 902 to 928 MHz band to the proposal. “Doing so now saves time later,” SpaceX wrote. The company also asked the FCC to modernize interference rules and align satellite deployment requirements with those for terrestrial cell networks, saying the goal is to let satellite and ground networks work together so Americans stay connected wherever they are.

The carriers have not been shy about how they view SpaceX as a competitor. On Verizon’s third quarter earnings call Monday, its chief executive said Starlink Mobile “just can’t compete with a terrestrial network” and estimated SpaceX would need four to six years and $300 billion to $500 billion to build a full US carrier network.

Thursday’s vote will not settle which bands survive. Adopting the notice opens a public comment period, with final rules to come later in the proceeding. The FCC already considered and rejected 2.5 GHz for satellite coverage once, in 2024. SpaceX also is not the only satellite player watching: the FCC approved Amazon’s $11.6 billion acquisition of Globalstar on October 27, giving its planned direct to device fleet its own mobile satellite spectrum.

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Tesla Semi catches fire in California: what we know

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Credit: KTVU

A Tesla Semi caught fire in Hayward, California, which caused both directions of traffic to shut down for hours before being completely reopened early on Wednesday, the California Highway Patrol said.

The fire occurred just after 5:30 local time in Hayward on Tuesday, as the Semi caught fire in the southbound lanes of I-880 before CHP officials made the decision to shut down both lanes of traffic due to potential risks from hazardous chemical smoke.

There were no injuries reported.

The cause of the fire is currently unknown, as neither Tesla nor the CHP have not determined a cause.

However, some images taken before the Semi was completely destroyed by the fire seem to indicate this might have been an older unit, as it appears to be one of the designs that Tesla shipped as part of its pilot program, before revising it and starting mass production just a month ago.

At the time of publication, CHP had not returned our request for a comment for additional details, including the Semi involved and any potential collaboration on an investigation between the CHP and Tesla. We will update this story when we hear back from them.

The southbound lanes were reopened at 3:30 a.m. on Wednesday, with the northbound lanes opening last night a few hours after the fire began. The CHP did state that the lithium batteries were “incredibly difficult to extinguish,” according to NBC Bay Area.

The truck’s driver said that the Semi caught fire, but he did not have an explanation.

An estimated 5,000 to 7,000 semi-truck and large commercial vehicle fires occur on U.S. roadways every year.

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Tesla’s ‘Emergency Drive Away’ function gets its first use in the real world

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Credit: Tesla

Tesla’s launch of the “Emergency Drive Away” function a few months back offered owners a safe option to evacuate an area if they were in reasonable danger. The function finally got its first use in the real world, but it appears it was by mistake.

A video shared by u/Joshalander in the r/TeslaLounge subreddit recorded the instance from his vehicle and said the incident took place in Austin this past weekend during the city’s F1 Race.

“Was charging around 6 AM this past Sunday in Austin before heading to the F1 race and heard a pop. Looked over and saw the new emergency drive-away feature in action. Genuinely felt bad for the dude when he got out and realized what happened, since he looked exhausted and only seemed to half-read the prompts.”

Emergency Drive Away unlatches the Supercharger connector from the vehicle, but still causes damage to both the car and the Supercharger. Tesla has said that it will cost up to $25,000 in repairs to have everything fixed back to normal.

Additionally, the company said that if it were not used in an emergency situation, the driver of the vehicle who activated the Emergency Drive Away feature would be responsible for all repair costs.

Tesla constitutes the following situations as reasonable justifications for activating the feature:

  • You face an immediate threat to your life or personal safety.
  • You must leave the area immediately.
  • Exiting the vehicle is unsafe.
  • Unplugging the charge connector would unreasonably delay your departure or expose you to a risk to your personal safety.

After using the feature, Tesla requires the driver to schedule Service so the car can be inspected.

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