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CRS-7 Launch Update

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Re: CRS-7 Launch Update

#21

Post by phkahler »

My thoughts on this. Overpressure in the LOX tank could be due to 1) failure to vent properly or 2) something heating it up.

Option 1 is based on the fact that it's constantly evaporating and needs to vent. This seems really unlikely given that it passed all test on the pad 2 minutes before. It also sounds like this was likely ruled out based on Elon's tweet about a "counter intuitive cause".

Option 2 sounds like fire or flames due to fuel leakage or something, but then realize that this is the second stage and all the action is going on 100 or more feet down in the first stage. They also have a camera on the 2nd stage engine which was shown shortly before the incident and nothing was going on in there. I wonder what the in-tank camera showed.

It seem that to get the extra energy into the tank, something must have fired up early. But if there's one thing Spacex seems to have a lot of it's data. Aside from a breech letting external air in (like the last shuttle accident), how do you get enough added energy into a tank to build pressure to the breaking point? In 2 minutes.

Re: CRS-7 Launch Update

#22

Post by rezistik »

DanielBMarkham wrote: post #15
sokrates wrote: post #14

As a non-native English speaker, I find the omissions of "the" very prominent and interesting in SpaceX speech. "shortly before first stage shutdown", "resulting in loss of mission", "139 seconds into flight", "some period of time following separation", "data to determine root cause" -- is this a general theme in engineering or journalism? I wonder what linguists have to say about this.

Not a linguist but a writer here who loves language. I'm seeing a lot of folks dropping articles. It's also becoming quite common to eliminate pronouns at the beginning of sentences, i.e., instead of "I went down to the store" you write "Went to the store" I use this purposefully to jar the reader. I have no idea what the underlying linguistic reasons are.

Implied pronouns, perhaps a trend from Facebook usage? On Facebook and Twitter you have an implied "I" that makes saying you did something redundant. This could transfer over to other formats of conversation.

Re: CRS-7 Launch Update

#23

Post by twistedpair »

kabdib wrote: post #20
colomon wrote: post #16

Earlier quoted context omitted.

Ugh, now imagining trying to debug a really sneaky bug that costs $100 million every time it triggers...

I recommend Henry S.F. Cooper's book _The Morning Star_, which is about debugging hardware failures and OS race conditions on a spacecraft orbiting Venus. (There are similar stories about debugging stuff on the various Martian rovers, but Cooper's book is a very good treatment...).

It's actually "The Evening Star"

Grab it used for $0.75 http://product.half.ebay.com/The-Evening-Star-Venus-Observed...

Re: CRS-7 Launch Update

#24

Post by alphadevx »

kabdib wrote: post #20
colomon wrote: post #16

Earlier quoted context omitted.

Ugh, now imagining trying to debug a really sneaky bug that costs $100 million every time it triggers...

I recommend Henry S.F. Cooper's book _The Morning Star_, which is about debugging hardware failures and OS race conditions on a spacecraft orbiting Venus. (There are similar stories about debugging stuff on the various Martian rovers, but Cooper's book is a very good treatment...).

I think you mean The Evening Star, marvelous book: http://amzn.to/1Hq8TcX

Re: CRS-7 Launch Update

#25

Post by drivers99 »

sokrates wrote: post #14

As a non-native English speaker, I find the omissions of "the" very prominent and interesting in SpaceX speech. "shortly before first stage shutdown", "resulting in loss of mission", "139 seconds into flight", "some period of time following separation", "data to determine root cause" -- is this a general theme in engineering or journalism? I wonder what linguists have to say about this.

"First stage shutdown". "Loss of mission". "Flight". I'm not sure what the term for it is, but these seem to refer to generalized phases/states of flight that the mission can be in. The use of "the" would refer to specific instances of the noun that the speaker has reason to believe the listener would know about. [1]

They almost feel like "uncountable" nouns, but I'm not sure. "Flight" can be countable, but as a generalized state/phase, I think it wouldn't be. It doesn't sound strange to me (a native speaker).

It would not be wrong to use "the" for many/all of these cases, but it would have changed the meaning, somewhat.

[1] http://www.edufind.com/english-grammar/definite-article/

Re: CRS-7 Launch Update

#26

Post by tomswartz07 »

sokrates wrote: post #14

As a non-native English speaker, I find the omissions of "the" very prominent and interesting in SpaceX speech. "shortly before first stage shutdown", "resulting in loss of mission", "139 seconds into flight", "some period of time following separation", "data to determine root cause" -- is this a general theme in engineering or journalism? I wonder what linguists have to say about this.

This is a common trend in scientific writing. [1]

It's considered standard to write in formal, passive, third-person tone. [2]

During undergrad, I was constantly drilled to make my writings as concise as possible.

[1] http://www2.aje.com/en/education/other-resources/articles/ed... [2] http://writingcenter.unc.edu/handouts/passive-voice/

Re: CRS-7 Launch Update

#27

Post by grkvlt »

sokrates wrote: post #14

As a non-native English speaker, I find the omissions of "the" very prominent and interesting in SpaceX speech. "shortly before first stage shutdown", "resulting in loss of mission", "139 seconds into flight", "some period of time following separation", "data to determine root cause" -- is this a general theme in engineering or journalism? I wonder what linguists have to say about this.

Indicative of shared Russian heritage of spaceflight? ;)

Re: CRS-7 Launch Update

#28

Post by VeejayRampay »

sokrates wrote: post #14

As a non-native English speaker, I find the omissions of "the" very prominent and interesting in SpaceX speech. "shortly before first stage shutdown", "resulting in loss of mission", "139 seconds into flight", "some period of time following separation", "data to determine root cause" -- is this a general theme in engineering or journalism? I wonder what linguists have to say about this.

I see it like I see git commit messages. You need to convey as much information as possible in as few words as possible. Dropping articles that don't add anything to the context is a way to keep it sweet, short and punchy I guess.

Re: CRS-7 Launch Update

#29

Post by JshWright »

phkahler wrote: post #21

My thoughts on this. Overpressure in the LOX tank could be due to 1) failure to vent properly or 2) something heating it up. Option 1 is based on the fact that it's constantly evaporating and needs to vent. This seems really unlikely given that it passed all test on the pad 2 minutes before. It also sounds like this was likely ruled out based on Elon's tweet about a "counter intuitive cause". Option 2 sounds like fir…

There are plenty of other scenarios...

The IDA is the heaviest thing they have ever carried in the trunk, AFAIK. Maybe its mounting bracket failed and it impacted the top of the second stage, buckling the LOX tank. A suddenly induced crack allowed some LOX to escape (the initial 'puff'), and the suddenly reduced pressure allowed the rest of the LOX to boil off and the tank to BLEVE, causing the catastrophic failure of the second stage.

Obviously this is a completely theoretical scenario, but it's one of many I could dream up...

EDIT: While is is a fairly technical discussion, I realize I got a little heavy handed with the acronyms there...

  IDA: https://en.wikipedia.org/wiki/International_Docking_Adapter
  LOX: https://en.wikipedia.org/wiki/Liquid_oxygen
  BLEVE: https://en.wikipedia.org/wiki/Boiling_liquid_expanding_vapor_explosion

Re: CRS-7 Launch Update

#30

Post by rwhitman »

beltex wrote: post #12

"Cause still unknown after several thousand engineering-hours of review. Now parsing data with a hex editor to recover final milliseconds." 4:09 AM - 29 Jun 2015 https://twitter.com/elonmusk/status/615431934345216001

After watching the press conference yesterday I got the sense that Musk's tweets aren't particularly helpful for SpaceX press relations
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