A failed strut caused the SpaceX rocket explosion | Hacker News Reader

A failed strut caused the SpaceX rocket explosion

theverge.com

54 pointsbtmills14 comments

"The SpaceX explosion on June 28th was caused by a failed strut in the rocket's upper stage liquid oxygen tank, SpaceX chief executive officer Elon Musk said today. The strut was one of several hundred used to hold together the helium pressure vessels in the tank......"

Goes from saying Oxygen tank to helium tank... wait what? is the helium tank inside the oxygen tank?

It's a liquid oxygen tank with a helium pressure vessel in the liquid oxygen tank. Nowhere does it say helium tank.

It seems like you are drawing a distinction between "tank" and "pressure vessel", could you explain what the difference is?

A pressure vessel does a bit more than a tank. While a tank may house liquids/gasses, it typically does not regulate or maintain a certain amount of pressure that is different from the natural, ambient pressure.

Anyways - perhaps it was my misreading or an edit after-the-fact by the parent (can posts even be edited on HN after responded to? I haven't tested or taken particular notice of it), they seemed to be confused that the statement switched from talking about an oxygen tank and then a helium tank (as if both were the same tank) and were confused about which gas the tank contained, when in fact there are 2 containers and not 1 with the gas being mixed up. I was simply clarifying that. There is a helium pressure vessel and an oxygen tank - not an oxygen tank that is later called a helium tank.

I don't remember seeing the question appended at the end when I responded:

>is the helium tank inside the oxygen tank?

Yep. Here's a photo from inside the LOX tank during a previous flight:

http://i.szoter.com/741dc2bcf5762a48.jpg

The two arrows point to the struts holding down a helium tank.

Elon Musk has played KSP. He should've known you can never have enough struts... ;)

The /r/spacex automoderator was set to report KSP references... https://www.reddit.com/r/spacex/comments/3dyvta/rspacex_crs7...

I'd find it very interesting to know how they diagnose a problem like to such a specific cause this when most of your physical evidence has disintegrated.

They had 0.893 seconds of data, some of which was from the accelerometers surrounding the LOX tank exterior.

That accelerometer data allowed them to acoustically triangulate the sound of the strut breaking. I think they even know which one.

Why isn't this on the front page with 24 points in an hour? I know HN cares about this news.

A reddit thread made the front page instead. Because we all come here to read reddit.

To be fair, the reddit thread is much better than any press article including this one. However that doesn't explain why this one didn't rise up since it was posted hours earlier and had plenty of votes. I've seen other The Verge articles fail to reach the front page before. I suspect The Verge links get a pretty severe ranking penalty automatically applied. I don't know why, though.

When something like this gets a lot of votes, I always imagine that the mods will notice and then link something better, like http://www.spacex.com/news/2015/07/20/crs-7-investigation-up...

If I wanted to read a reddit thread, I know where to find it.

All the articles submitted seemed to be falling off the "new" page with 4 or 5 points and seemed to be the only things on "new" getting upvotes.

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