SpaceX’s Crew Dragon explosion investigation almost complete, says executive

Crew Dragon C201 is lifted off the deck of a SpaceX recovery vessel on March 10th. C201 was destroyed in an explosion on April 20th. (NASA)

Speaking at the 2019 AIAA Propulsion & Energy Forum, SpaceX Vice President of Build and Flight Reliability Hans Koenigsmann was significantly more confident that the company is just days or weeks away from wrapping up a serious Crew Dragon failure investigation.

On April 20th, flight-proven Crew Dragon capsule C201 experienced a catastrophic failure mode – largely a surprise to SpaceX – that completely destroyed the vehicle milliseconds prior to a planned static fire test. Given the obvious mortal danger such a failure would have posed to any crew aboard, SpaceX’s plans to conduct its first crewed Crew Dragon launch (Demo-2) in Q3 2019 were thrown out the window. Thankfully, Hans believes that SpaceX is just shy of concluding that investigation, “hopefully” permitting the launch of a critical abort test and Demo-2 before 2019 is out.

More specifically, Koenigsmann noted that SpaceX is currently planning to conduct a critical Crew Dragon in-flight abort (IFA) test in October or November, more or less in line with a recent report from NASASpaceflight.com that the test is targeted for November 11th, 2019. NASASpaceflight also confirmed that SpaceX still plans to fly Falcon 9 booster B1046.3 on the critical test flight, currently the only established plan to launch a thrice-flown booster, a potential first for SpaceX’s reusability program.

SpaceX’s IFA test is a continuation of the company’s suborbital Crew Dragon testing. Back in 2015, SpaceX successfully completed a pad abort test in which a low-fidelity Dragon mockup used its eight SuperDraco abort thrusters to replicate an escape from a rocket failure on the launch pad. SpaceX’s in-flight abort test will – like its namesake indicates – perform a similar test in flight, ensuring that Crew Dragon is able to safely escape from a failing Falcon 9 at Max Q, the point during launch where atmosphere-induced mechanical stress is at its peak.

In theory, demonstrating a successful pad and in-flight (Max Q) abort means that a given spacecraft is able to safely abort at all points during flight – from the pad all the way to orbit. It’s not clear if Crew Dragon is actually designed to be capable of what’s known as an “abort-to-orbit”, but the hardware is likely there if it’s needed.

Crew Dragon approaches the ISS during its orbital launch debut, March 3rd. (NASA)

On July 15th, Hans Koenigsmann and NASA Commercial Crew Program (CCP) manager Kathy Lueders went into significant detail with a preliminary Crew Dragon failure investigation update. They revealed that Crew Dragon’s April 20th explosion was traced to a likely mode, in which a “slug” of Dragon’s liquid oxidizer (nitrogen tetroxide, NTO) leaked and was subsequently smashed into a titanium valve by helium pressurized to several thousand PSI.

Said impact – effectively turning NTO into a bullet – thus created a spark in one or two ways: the titanium debris could have easily created sparks on its own, while NTO is also known to interact in violent and exotic ways with titanium under impact conditions. Either way, the fix is relatively simple (replace the valves and avoid titanium in the NTO pressurization system), but the fact that the design flaw existed in the first place serves as a much larger concern for the entirety of Crew Dragon’s joint SpaceX-NASA design and certification.

Ultimately, Hans seemed much more confident on August 19th than he was a month prior, indicating that the investigation is just shy of wrapping up. Once complete, SpaceX can complete the necessary modifications and get back on the saddle for Crew Dragon’s inaugural crewed launch and next abort test.

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"Eric Ralph : @twitter.com/13ericralph31 I write about space, among other things.."
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