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SpaceX says Crew Dragon capsule exploded due to exotic titanium fire

Crew Dragon tests its SuperDraco-powered launch abort system in 2015. (SpaceX)

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SpaceX has announced via an official update and conference call the preliminary results of a failure investigation convened immediately after Crew Dragon capsule C201 exploded in the midst of an April 20th static fire test.

Hosted by SpaceX Vice President of Mission Assurance Hans Koenigsmann and NASA Commercial Crew Program manager Kathy Lueders, the call provided some minor additional insight beyond a fairly extensive press release issued just prior. According to the preliminary results from SpaceX’s failure investigation, Crew Dragon’s explosion was unrelated to the spacecraft’s propellant tanks, Draco maneuvering thrusters, or SuperDraco abort engines. Rather, the cause lies in a more exotic and unanticipated chemical/material interaction between a plumbing valve, liquid oxidizer, and a helium-based pressurization system.

When metal burns

According to Hans Koenigsmann, SpaceX is approximately 80% of the way through what is known as the fault tree, essentially meaning that the failure investigation is 80% complete. That additional 20% could certainly throw some curveballs but the SpaceX executive was fairly confident that the results presented on July 15th would be representative of the final conclusion.

The ultimate (likely) cause of Crew Dragon’s extremely energetic and destructive explosion centers around the spacecraft’s extensive SuperDraco/Draco plumbing and its associated pressurization system, which uses helium to keep the pressure-fed engines, propellant tanks, and feed lines around 2400 psi (16.5 megapascals). Necessarily, this method of pressurization means that there is direct contact between the pressurant (helium) and the oxidizer/fuel, thus requiring some sort of valve preventing the pressurized fluid from flowing into the pressurization system.

A detailed view of some of the Draco and SuperDraco-related plumbing used on Crew Dragon – in this case, the capsule that will now fly SpaceX’s In-Flight Abort test. (Pauline Acalin, August 2018)

During flight-proven Crew Dragon capsule C201’s April 20th static fire testing, that is reportedly exactly what happened. Over the course of ground testing, a “check valve” separating the pressurization system and oxidizer leaked what SpaceX described as a “slug” of nitrogen tetroxide oxidizer (NTO) into the helium pressurization lines. Around T-100 milliseconds to a planned ignition of the vehicle’s 8 SuperDraco abort engines, the pressurization system rapidly “initialized” (i.e. quickly pressurized the oxidizer and fuel to operational pressures, ~2400 psi).

To do this, helium is rapidly pushed through a check valve – designed with low-molecular-mass helium in mind – to physically pressurize the propellant systems. Unintentionally, the NTO that leaked ‘upstream’ through that valve effectively was taken along for the ride with the high-pressure burst of helium. In essence, picture that you crash your car, only to discover that your nice, fluffy airbag has accidentally been replaced with a bag of sand, and you might be able to visualize the unintended forces Dragon’s check valve (the metaphorical airbag) was subjected to when a “slug” of dense oxidizer was rammed into it at high speed.

Crew Dragon C201 displays its heat shield after the spacecraft’s first orbital-velocity Earth reentry, March 8th. (NASA/Cory Huston)

In itself, this sort of failure mode is not hugely surprising and SpaceX may have even been aware of some sort of check valve leak(s) and accepted what it believed to be a minor risk in order to continue the test and perhaps examine Dragon’s performance under suboptimal conditions. What SpaceX says it did not realize was just how energetic the reaction between the NTO and the check valve could be. SpaceX’s understanding is that the high-speed slug of dense NTO was traveling so fast and at such a high pressure that, by impacting the titanium check valve, it quite literally broke the valve and may have chemically ignited the metal, thus introducing a slug of burning NTO into the liberated NTO system itself – effectively a match tossed into a powder keg.

It’s unclear if the ignition came from a chemical reaction between titanium (a technically flammable metal similar to magnesium) and NTO, or if the source came from the titanium valve being smashed apart, perhaps quite literally creating a spark as metal debris violently interacted. Either way, the solution – as SpaceX perceives it – is the same: instead of a mechanical check valve (simple but still not 100% passive), the barrier between pressurant and oxidizer (as well as fuel, most likely) will be replaced with something known as a burst disk. According to Koenigsmann, only a handful (~4) of those valves exist and thus need to be replaced by burst disks, a relatively fast and easy fix.

Burst disks are single-use and inherently unreusable, but they are also completely passive and simply do not leak until subjected to a specific amount of pressure. Because they are single-use, they can’t be directly tested prior to flight, limiting some of the in-principle reliability for the sake of an extremely leak-proof barrier.

A test of one of Crew Dragon’s four ‘powerpacks’, featuring two SuperDracos and three Dracos. (SpaceX)

Ultimately, both Koenigsmann and Lueders went out of their way to avoid answering any questions about SpaceX’s Crew Dragon upcoming test and launch schedule and what sort of delays the explosion will ultimately incur. Both individuals were nevertheless upbeat and by the sound of it, delays to Crew Dragon will be far less severe relative to delays caused by a pressure vessel or engine failure. For the time being, NASA has published a tentative target of mid-November 2019 for Crew Dragon’s first crewed launch to the International Space Station, while Lueders and Koenigsmann expressed hope in a 2019 launch but refused to give a specific estimate of the odds of that occurring.

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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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Tesla posts Optimus’ most impressive video demonstration yet

The humanoid robot was able to complete all the tasks through a single neural network.

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Credit: Tesla Optimus/X

When Elon Musk spoke with CNBC’s David Faber in an interview at Giga Texas, he reiterated the idea that Optimus will be one of Tesla’s biggest products. Seemingly to highlight the CEO’s point, the official Tesla Optimus account on social media platform X shared what could very well be the most impressive demonstration of the humanoid robot’s capabilities to date.

Optimus’ Newest Demonstration

In its recent video demonstration, the Tesla Optimus team featured the humanoid robot performing a variety of tasks. These include household chores such as throwing the trash, using a broom and a vacuum cleaner, tearing a paper towel, stirring a pot of food, opening a cabinet, and closing a curtain, among others. The video also featured Optimus picking up a Model X fore link and placing it on a dolly.

What was most notable in the Tesla Optimus team’s demonstration was the fact that the humanoid robot was able to complete all the tasks through a single neural network. The robot’s actions were also learned directly from Optimus being fed data from first-person videos of humans performing similar tasks. This system should pave the way for Optimus to learn and refine new skills quickly and reliably.

Tesla VP for Optimus Shares Insight

In a follow-up post on X, Tesla Vice President of Optimus (Tesla Bot) Milan Kovac stated that one of the team’s goals is to have Optimus learn straight from internet videos of humans performing tasks, including footage captured in third person or by random cameras.

“We recently had a significant breakthrough along that journey, and can now transfer a big chunk of the learning directly from human videos to the bots (1st person views for now). This allows us to bootstrap new tasks much faster compared to teleoperated bot data alone (heavier operationally).

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“Many new skills are emerging through this process, are called for via natural language (voice/text), and are run by a single neural network on the bot (multi-tasking). Next: expand to 3rd person video transfer (aka random internet), and push reliability via self-play (RL) in the real-, and/or synthetic- (sim / world models) world,” Kovac wrote in his post on X.

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Starship Flight 9 nears as SpaceX’s Starbase becomes a Texan City

SpaceX’s launch site is officially incorporated as Starbase, TX. Starship Flight 9 could launch on May 27, 2025. 

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(Credit: Jenny Hautmann/Wikimedia Commons)

SpaceX’s Starbase is officially incorporated as a city in Texas, aligning with preparations for Starship Flight 9. The newly formed city in Cameron County serves as the heart of SpaceX’s Starship program.

Starbase City spans 1.5 square miles, encompassing SpaceX’s launch facility and company-owned land. A near-unanimous vote by residents, who were mostly SpaceX employees, led to its incorporation. SpaceX’s Vice President of Test and Launch, Bobby Peden, was elected mayor of Starbase. The new Texas city also has two SpaceX employees as commissioners. All Starbase officials will serve two-year terms unless extended to four by voters.

As the new city takes shape, SpaceX is preparing for the Starship Flight 9 launch, which is tentatively scheduled for May 27, 2025, at 6:30 PM CDT from Starbase, Texas.

SpaceX secured Federal Aviation Administration (FAA) approval for up to 25 annual Starship and Super Heavy launches from the site. However, the FAA emphasized that “there are other licensing requirements still to be completed,” including policy, safety, and environmental reviews.

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On May 15, the FAA noted SpaceX updated its launch license for Flight 9, but added: “SpaceX may not launch until the FAA either closes the Starship Flight 8 mishap investigation or makes a return to flight determination. The FAA is reviewing the mishap report SpaceX submitted on May 14.”

Proposed Texas legislation could empower Starbase officials to close local highways and restrict Boca Chica Beach access during launches. Cameron County Judge Eddie Trevino, Jr., opposes the Texas legislation, insisting beach access remain under county control. This tension highlights the balance between SpaceX’s ambitions and local interests.

Starbase’s incorporation strengthens SpaceX’s operational base as it gears up for Starship Flight 9, a critical step in its mission to revolutionize space travel. With growing infrastructure and regulatory hurdles in focus, Starbase is poised to become a cornerstone of SpaceX’s vision, blending community development with cutting-edge aerospace innovation.

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The Boring Company accelerates Vegas Loop expansion plans

The Boring Company clears fire safety delays, paving the way to accelerating its Vegas Loop expansion plans.

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Credit: The Boring Company/X

After overcoming fire safety hurdles, the Boring Company is accelerating its Vegas Loop expansion. The project’s progress signals a transformative boost for Sin City’s transportation and tourism.

Elon Musk’s tunneling company, along with The Las Vegas Convention and Visitors Authority (LVCVA) and Clark County, resolved fire safety concerns that delayed new stations.

“It’s new. It’s taken a little time to figure out what the standard should be,” said Steve Hill, LVCVA President and CEO, during last week’s board meeting. “We’ve gotten there. We’re excited about that. We’re ready to expand further, faster, than we have.”

Last month, the company submitted permits for tunnel extensions connecting Encore to a parcel of land owned by Wynn and Caesars Palace. The three tunnels are valued at $600,000 based on country records.

Plans for a Tropicana Loop are also advancing, linking UNLV to MGM Grand, T-Mobile Arena, Allegiant Stadium, Mandalay Bay, and the upcoming Athletics’ ballpark. Downtown extensions from the convention center to the Strat, Fremont Street Experience, and Circa’s Garage Mahal are also in the permitting process.

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“Those are all in process,” Hill noted. “We’ve got machines that are available to be put in the ground. I think we’ve reached a framework for how these projects are going to work and how they’ll be permitted from a safety standpoint, as well as a building standpoint.”

The Boring Company has six boring machines, with three currently active in Las Vegas. Last week, TBC announced that it successfully mined continuously in a Zero-People-in-Tunnel (ZPIT) configuration, enabling it to build more tunnels faster, safer, and at a more affordable rate.

Tunneling under Paradise Road is underway as The Boring Company works on the University Center Loop. The University Center Loop is expected to connect to the Las Vegas Convention Center within two months, linking to the Westgate tunnel. The full Vegas Loop will span 104 stations and 68 miles. Even though The Boring Company’s tunnel network in Las Vegas isn’t nearly finished, it has already become a key attraction in the city.

“It’s such a great attraction for shows that are looking at this building (convention center) and we’re going to be connected to everybody in town,” Hill said. “It’s a real difference-maker.”

A few Vegas Loop stations are already operational, including those connected to Resorts World, Westgate, Encore, and all the Las Vegas Convention Center Loop stations. The Downtown Loop, which connects to the downtown area, and the Riviera Station, the hub that leads to Resorts World with Westgate destinations, are also operational.

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As The Boring Company accelerates the Vegas Loop, its tunnels are poised to redefine mobility and tourism in Las Vegas, blending cutting-edge technology with practical urban solutions.

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