Science

Eugene

(61,938 posts) Mon Apr 22, 2019, 10:30 PM Apr 2019

Here's what we know, and what we don't, about the Crew Dragon accident

Source: Ars Technica

Here’s what we know, and what we don’t, about the Crew Dragon accident

The company undoubtedly had a busy Easter weekend.

ERIC BERGER - 4/22/2019, 9:53 AM

During a series of engine tests of SpaceX's Dragon spacecraft this past Saturday, the vehicle experienced what the company has characterized as an "anomaly." Based upon an unauthorized leaked video of the accident, the company was counting down toward a firing of the Dragon's SuperDraco thrusters when the vehicle exploded. SpaceX has not validated the video, but it is consistent with verbal accounts of the failure that have been shared with Ars.

After the accident, large dramatic clouds of orange smoke billowed above "Landing Zone 1," where SpaceX conducted Saturday's engine tests. According to one source, the orange plumes were the result of between one and two tons of nitrogen tetroxide—the oxidizer used by Dragon's SuperDraco engines—burning at the location. After a dramatic weekend, what follows is a summary of what we know, what we don't know, and where SpaceX goes from here.

What was destroyed?

The Crew Dragon capsule in question is the same one that successfully flew a demonstration mission to the International Space Station in March. The spacecraft was being prepared for a launch abort test this summer. During this test, the Dragon would have launched from Florida on a Falcon 9 booster and then fired its powerful SuperDraco engines to show that the Dragon could pull itself safely away from the rocket in case of a problem with the booster before or during flight.

Now that SpaceX has lost this capsule, it must find a substitute for this launch abort test. It is not clear whether it will fabricate a boilerplate vehicle with a SuperDraco system of eight thrusters, or re-purpose one of the Dragons it has built for crewed flights to the space station. Either way, this is a significant materiel loss for the company.

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Read more: https://arstechnica.com/science/2019/04/heres-what-we-know-and-what-we-dont-about-the-crew-dragon-accident/

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Here's what we know, and what we don't, about the Crew Dragon accident (Original Post) Eugene Apr 2019 OP

Yuck. Nitrogen tetroxide. hunter Apr 2019 #1

hunter

(38,325 posts)

1. Yuck. Nitrogen tetroxide.

Reply to Eugene (Original post)

Tue Apr 23, 2019, 10:46 AM

Apr 2019

It's very toxic.

https://en.wikipedia.org/wiki/Dinitrogen_tetroxide

There was an accident with this fuel combination on the Apollo-Soyuz mission that put U.S. astronauts in the hospital.

The only serious problem was during reentry and splashdown of the Apollo craft, during which the crew were accidentally exposed to toxic hydrazine and nitrogen tetroxide fumes, caused by unignited reaction control system (RCS) hypergolic propellants venting from the spacecraft and reentering a cabin air intake. The RCS was inadvertently left on during descent, and the toxic fumes were sucked into the spacecraft as it drew in outside air. Brand briefly lost consciousness, while Stafford retrieved emergency oxygen masks, put one on Brand, and gave one to Slayton. The three astronauts were hospitalized for two weeks in Honolulu.

It's also why, when the Space Shuttle landed, the first ground crew to arrive had to wear protective suits with integral air supplies. One of the things they were doing was checking for leaks of this toxic fuel combination.

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