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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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Cybertruck

Tesla confirms date when new Cybertruck trim will go up in price

Tesla has officially revealed that this price will only be available until February 28, as the company has placed a banner atop the Design Configurator on its website reflecting this.

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Credit: Tesla

Tesla has confirmed the date when its newest Cybertruck trim level will increase in price, after CEO Elon Musk noted that the All-Wheel-Drive configuration of the all-electric pickup would only be priced at its near-bargain level for ten days.

Last week, Tesla launched the All-Wheel-Drive configuration of the Cybertruck. Priced at $59,990, the Cybertruck featured many excellent features and has seemingly brought some demand to the pickup, which has been underwhelming in terms of sales figures over the past couple of years.

Tesla launches new Cybertruck trim with more features than ever for a low price

When Tesla launched it, many fans and current owners mulled the possibility of ordering it. However,  Musk came out and said just hours after launching the pickup that Tesla would only keep it at the $59,990 price level for ten days.

What it would be priced at subsequently was totally dependent on how much demand Tesla felt for the new trim level, which is labeled as a “Dual Motor All-Wheel-Drive” configuration.

Tesla has officially revealed that this price will only be available until February 28, as the company has placed a banner atop the Design Configurator on its website reflecting this:

Many fans and owners have criticized Tesla’s decision to unveil a trim this way, and then price it at something, only to change that price a few days later based on how well it sells.

It seems the most ideal increase in price would be somewhere between $5,000 and $10,000, but it truly depends on how many orders Tesla sees for this new trim level. The next step up in configuration is the Premium All-Wheel-Drive, which is priced at $79,990.

The difference between the Dual Motor AWD Cybertruck and the Premium AWD configuration comes down to towing, interior quality, and general features. The base package is only capable of towing up to 7,500 pounds, while the Premium can handle 11,000 pounds. Additionally, the seats in the Premium build are Vegan Leather, while the base trim gets the textile seats.

It also has only 7 speakers compared to the 15 that the Premium trim has. Additionally, the base model does not have an adjustable ride height, although it does have a coil spring with an adaptive damping suspension package.

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Cybertruck

Tesla set to activate long-awaited Cybertruck feature

Tesla will officially activate the Active Noise Cancellation (ANC) feature on Cybertruck soon, as the company has officially added the feature to its list of features by trim on its website.

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Credit: Tesla

Tesla is set to activate a long-awaited Cybertruck feature, and no matter when you bought your all-electric pickup, it has the hardware capable of achieving what it is designed to do.

Tesla simply has to flip the switch, and it plans to do so in the near future.

Tesla will officially activate the Active Noise Cancellation (ANC) feature on Cybertruck soon, according to Not a Tesla App, as the company has officially added the feature to its list of features by trim on its website.

Tesla rolls out Active Road Noise Reduction for new Model S and Model X

The ANC feature suddenly appeared on the spec sheet for the Premium All-Wheel-Drive and Cyberbeast trims, which are the two configurations that have been delivered since November 2023.

However, those trims have both had the ANC disabled, and although they are found in the Model S and Model X, and are active in those vehicles, Tesla is planning to activate them.

In Tesla’s Service Toolbox, it wrote:

ANC software is not enabled on Cybertruck even though the hardware is installed.”

Tesla has utilized an ANC system in the Model S and Model X since 2021. The system uses microphones embedded in the front seat headrests to detect low-frequency road noise entering the cabin. It then generates anti-noise through phase-inverted sound waves to cancel out or reduce that noise, creating quieter zones, particularly around the vehicle’s front occupants.

The Model S and Model X utilize six microphones to achieve this noise cancellation, while the Cybertruck has just four.

Tesla Cybertruck Dual Motor AWD estimated delivery slips to early fall 2026

As previously mentioned, this will be activated through a software update, as the hardware is already available within Cybertruck and can simply be activated at Tesla’s leisure.

The delays in activating the system are likely due to Tesla Cybertruck’s unique design, which is unlike anything before. In the Model S and Model X, Tesla did not have to do too much, but the Cybertruck has heavier all-terrain tires and potentially issues from the aluminum castings that make up the vehicle’s chassis, which are probably presenting some challenges.

Unfortunately, this feature will not be available on the new Dual Motor All-Wheel-Drive configuration, which was released last week.

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Tesla Model S and X customization options begin to thin as their closure nears

Tesla’s Online Design Studio for both vehicles now shows the first color option to be listed as “Sold Out,” as Lunar Silver is officially no longer available for the Model S or Model X. This color is exclusive to these cars and not available on the Model S or Model X.

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Credit: Tesla

Tesla Model S and Model X customization options are beginning to thin for the first time as the closure of the two “sentimental” vehicles nears.

We are officially seeing the first options disappear as Tesla begins to work toward ending production of the two cars and the options that are available to those vehicles specifically.

Tesla’s Online Design Studio for both vehicles now shows the first color option to be listed as “Sold Out,” as Lunar Silver is officially no longer available for the Model S or Model X. This color is exclusive to these cars and not available on the Model S or Model X.

Tesla is making way for the Optimus humanoid robot project at the Fremont Factory, where the Model S and Model X are produced. The two cars are low-volume models and do not contribute more than a few percent to Tesla’s yearly delivery figures.

With CEO Elon Musk confirming that the Model S and Model X would officially be phased out at the end of the quarter, some of the options are being thinned out.

This is an expected move considering Tesla’s plans for the two vehicles, as it will make for an easier process of transitioning that portion of the Fremont plant to cater to Optimus manufacturing. Additionally, this is likely one of the least popular colors, and Tesla is choosing to only keep around what it is seeing routine demand for.

During the Q4 Earnings Call in January, Musk confirmed the end of the Model S and Model X:

“It is time to bring the Model S and Model X programs to an end with an honorable discharge. It is time to bring the S/X programs to an end. It’s part of our overall shift to an autonomous future.”

Fremont will now build one million Optimus units per year as production is ramped.

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