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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 to make app change for easier communication following Service

“Looking into it. After a service visit is complete, we close the in-app messaging option after 2 hours. We will change this to 24hours or more.”

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Credit: Tesla

Tesla will enhance the ability to communicate through the mobile app with Service after work has been done on your car.

One of the biggest weaknesses of Tesla’s automotive division has been Service, as Service Centers are not necessarily plentiful, and wait times, in some regions of the country, are over a month in duration.

Getting in touch with Service after a car has work done to it is also difficult. Calling showrooms in some regions has proven to be difficult to enable direct communication between the customer and the company.

If something is not resolved properly, Tesla keeps the in-app messaging option active for two hours after the service visit is complete.

However, that doesn’t resolve everything, as some issues may arise again more than two hours later. Then the issue of communication presents itself once again.

Tesla is going to extend that time frame to a day or more, according to Raj Jegannathan, Tesla’s AI/IT-Infra, Cybersecurity, IT Apps & Vehicle Service VP.

Tesla has made several changes over the past few years to attempt to improve its Service. Recently, for Collision repair, it started offering a $45-per-day loaner program with free FSD, free tolls, and free Supercharging.

It also recently started sharing local and regional leader contact information so customers have the ability to reach out when they have complaints or disagree with warranty claims, changes in estimates, or initial diagnostics.

Tesla creates clever solution to simplify and improve its Service

However, this is only available at a few showrooms and is currently a pilot program.

These improvements are aimed at resolving communication breakdown, which appears to be a problem that many owners experience.

Tesla is one of the few companies that also operates a fleet of Mobile Repair vehicles, which will perform service at your house or place of business. However, the size of it has gone down by 11 percent year over year.

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Tesla is overhauling its Full Self-Driving subscription for easier access

The subscription model is more accessible to many owners, as it is reasonably priced and offers the option to take a month off from using it if they are interested in saving money.

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Credit: Tesla

Tesla is overhauling its Full Self-Driving subscription and how it markets it to customers after several owners and fans of the company complained about the accessibility of the monthly access to its driver assistance suite.

Tesla Full Self-Driving is the automaker’s semi-autonomous driving suite, which is widely regarded as the most robust and capable on the market today. Owners can purchase the suite outright for $8,000, or they can subscribe to the program for $99 per month, an option it enabled a few years ago.

However, it is not super easy to subscribe to the subscription model, nor is it even recognized on the company’s Online Design Studio. Without some research or prior knowledge, a consumer might not even know they could pay monthly to experience Full Self-Driving.

That is set to change, according to Tesla’s AI/IT Infrastructure, Cybersecurity, IT Apps, and Vehicle Service head Raj Jegannathan, who said the company is planning to change that.

Instead of having customers only have the option to pay outright for the suite, Tesla is now planning to offer the subscription model in its Online Design Studio, making it easier to activate that option:

It will be the second major change Tesla makes to how it sells Full Self-Driving to customers, the first being videos of real-life operation of FSD in the Design Studio. Previously, the site only showed animations of Full Self-Driving’s capabilities.

Tesla added the videos of FSD handling some tricky situations, as well as general operation of the suite, to the Design Studio in recent weeks.

Tesla makes big change to encourage Full Self-Driving purchases

The subscription model is more accessible to many owners, as it is reasonably priced and offers the option to take a month off from using it if they are interested in saving money.

Many cannot justify paying for the suite outright, especially as it adds $8,000 to the cost of their car. After they experience its capabilities for themselves, they might.

Both moves appear to be an effort to increase the take rate of Full Self-Driving, particularly as autonomy takes center stage at Tesla.

With the rollout of Robotaxi and some teased capabilities of the upcoming v14 iteration of Full Self-Driving, Tesla is gearing up to continue advancing its self-driving technology.

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Tesla talks Semi ramp, Optimus, Robotaxi rollout, FSD with Wall Street firm

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Credit: Tesla

Tesla (NASDAQ: TSLA) recently talked about a variety of topics with Wall Street firm Piper Sandler, as the firm released a new note on Friday about their meeting with the company’s Investor Relations team.

According to the note from Piper Sandler, Tesla talked in detail about the Semi program, Optimus, and its potential valuation given its capabilities, the rollout of Robotaxi in Austin, and Full Self-Driving progress in the United States.

Tesla Semi Ramp

The Tesla Semi is set to enter mass production in 2026 at a dedicated factory near the company’s Gigafactory in Reno, Nevada.

The Semi has already been in pilot program testing, as Tesla has partnered with a few companies, like Frito-Lay and PepsiCo., to perform regional logistics. It has been met with excellent reviews from drivers, and it has helped give Tesla a good idea of what to expect when it makes its way to more companies in the coming years.

Piper Sandler said that it is evident Tesla is preparing for a “major ramp,” but it is keeping its expectations low:

“We’ve never expected much from this product, but we’d love to be proven wrong (Tesla is clearly prepping for a major ramp).”

Tesla Optimus and its value internally and externally

Optimus has been working in Tesla factories for some time, but its expectations as a product offering outside of the company internally have major implications.

Its role within Tesla factories, for now, is relatively low, but Optimus is still doing things to assist. By this time next year, Piper Sandler said Optimus should have bigger responsibilities:

“By this time in 2026, Optimus should be moving/staging parts within Tesla’s facilities.”

Outside of Tesla, Optimus could be a major beneficiary for companies as it could be a more affordable way to handle tedious tasks and manual labor. The firm believes that if Optimus can work 18-hour shifts, a cost of $100,000 per unit “would be justified.”

Tesla Robotaxi Expansion

The big focus of the firm with Robotaxi was Tesla’s expansion of the geofence in Austin this week. It was substantial, bringing the Robotaxi’s total service area to around 170 square miles, up from the roughly 90 square miles that rival Waymo is offering in the city.

Tesla Robotaxi geofence expansion enters Plaid Mode and includes a surprise

Tesla has doubled its geofence three times since its launch in late June, and it also revealed that its fleet of vehicles has expanded by 50 percent. It did not give a solid number of how many vehicles are operating in the fleet.

Tesla Full Self-Driving v14 launch

Tesla’s Full Self-Driving suite is set to have a fresh version, v14, rolled out in either September or October, and there are some pretty high expectations for it.

CEO Elon Musk said:

“The FSD release in about 6 weeks will be a dramatic gain with a 10X higher parameter count and many other improvements. It’s going through training & testing now. Once we confirm real-world safety of FSD 14, which we think will be amazing, the car will nag you much less.”

There is also some expectation that v14 could be the public release of what Tesla is running in Austin for Robotaxi. The firm confirmed this in their note by stating it “should enable Tesla owners to use software that is on par with Robotaxis in Austin.”

The only real hold up would be regulator skepticism, but Tesla can alleviate this with strong data.

The firm maintained its ‘Overweight’ rating and the $400 price target it holds on the stock.

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