SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD (2)

[high road]

  The other thing we discovered is that we can exactly replicate what happened on the launch pad if someone shoots the rocket. We don’t think that is likely this time around, but we are definitely going to have to take precautions against that in the future. We looked at who would want to blow up a SpaceX rocket. That turned out to be a long list. I think it is unlikely this time, but it is something we need to recognize as a real possibility in the future.”

That is plain paranoia.  There always has been that threat.

Did you just contradict yourself? If the threat is real, it's not paranoia... And you've been pretty adamant about the importance of safe operations  in rocketry, so this comes across as quite a 180° turn.

In the current climate of fear for terrorism, combined with sabotage being on the list of possible (however unlikely) causes, they would never hear the end of it if they did not take measures, even if they're only symbolic.

Edit: let's hope this update stays in the update thread. Personally, I found Gwynne Shotwells comment quite obvious empty manager talk: using new words for the same things as you said last time (generally speaking, business processes encompass all processes important to the activity of the enterprise, including operational ones) to hide that you're no further than just ticking off disproven causes. Which is the kind of thing I have to parse as an update on a daily basis.

Now that they aparantly are onto something, I can say this without being purely negative.

[envy887]

How many feasible mechanisms are there for formation of solid oxygen in the COPV overwrap? Need to cool to freezing point and then extract the latent heat somehow.

Maybe they loaded the subcooled LOX too cold? That would be a ops issue, though not really a business process issue directly.

[JebK]

  The other thing we discovered is that we can exactly replicate what happened on the launch pad if someone shoots the rocket.

"Exactly replicate"? That, to me, implies that they have shot a partialy fueled upper stage and saw it explode in the same fashion, which I doubt they have done so this:

We don’t think that is likely this time around, but we are definitely going to have to take precautions against that in the future. We looked at who would want to blow up a SpaceX rocket. That turned out to be a long list. I think it is unlikely this time, but it is something we need to recognize as a real possibility in the future.”

... is a joke right?

[jpo234]

How many feasible mechanisms are there for formation of solid oxygen in the COPV overwrap? Need to cool to freezing point and then extract the latent heat somehow.

Maybe they loaded the subcooled LOX too cold? That would be a ops issue, though not really a business process issue directly.

If you fill high pressure He into an empty bottle, the He will expand. An expanding gas gets colder. An example are CO2 fire extinguishers. They are filled with high pressure CO2. On release it freezes to dry ice.

See here: http://www.fireextinguisherguide.co.uk/types-of-fire-extinguishers/co2-fire-extinguishers/

[launchwatcher]

  The other thing we discovered is that we can exactly replicate what happened on the launch pad if someone shoots the rocket.

"Exactly replicate"? That, to me, implies that they have shot a partialy fueled upper stage and saw it explode in the same fashion, which I doubt they have done ...

Elsewhere in the same reddit thread there is this comment:

Gonna be flat honest with you, we literally hired a marksman and shoot a mock-up second stage at long range.

[high road]

  The other thing we discovered is that we can exactly replicate what happened on the launch pad if someone shoots the rocket.

"Exactly replicate"? That, to me, implies that they have shot a partialy fueled upper stage and saw it explode in the same fashion, which I doubt they have done so this:

We don’t think that is likely this time around, but we are definitely going to have to take precautions against that in the future. We looked at who would want to blow up a SpaceX rocket. That turned out to be a long list. I think it is unlikely this time, but it is something we need to recognize as a real possibility in the future.”

... is a joke right?

If their test stand would have to explode as dramatically, testing failed rockets would be prohibitively expensive. They only have to replicate the milliseconds of data they got before their sensors were fried. So with the problem in the helium bottle in an oxygen tank, you don't need the other reactant that would be required for things to go boom. Or whoosh in this case.

[HMXHMX]

quoted from  https://www.reddit.com/r/spacex/comments/57balr/details_from_elons_speech_at_the_nro/

Details from Elon's speech at the NRO (self.spacex)
submitted 23 minutes ago * by Ravenous117

Addressing the anomaly:

“We are close to figuring it out. It might have been formation of solid oxygen in the carbon over-wrap of one of the bottles in the upper stage tanks. If it was liquid it would have been squeezed out but under pressure it could have ignited with the carbon. This is the leading theory right now, but it is subject to confirmation.  ...

These are my personal accounts of what I heard from Elon live and the rough transcript is from a recording of the event. I do not know much other than what I heard but I wanted to share with you guys. Enjoy.

A minor pat on my back:

http://forum.nasaspaceflight.com/index.php?topic=30981.msg1576926#msg1576926

The "solid oxygen" seems to me unlikely, but both LOX and especially GOX could, in my view, still provide an oxidizer source sufficient to act with the local fuel.

[Norm38]

“We are close to figuring it out. It might have been formation of solid oxygen in the carbon over-wrap of one of the bottles in the upper stage tanks. If it was liquid it would have been squeezed out but under pressure it could have ignited with the carbon.”

I want to understand this better.  He didn't say solid oxygen in the bottles, he said solid oxygen in the carbon over-wrap itself.  That means that LOX got into the graphite weave?  Isn't that all that space filled with epoxy resin.  Is there an outer coating of some kind?  Letting LOX penetrate the COPV structure sounds like a bad idea.

Next, they're loading sub-cooled LOX, close to the freezing point.  Then they're loading in He and compressing it.  But He is thermally opposite, correct?  As discussed here it heats up when it expands, but that means it cools when it condenses?  So as the COPVs are being loaded, they're getting colder?  And that could cause LOX to freeze around (or inside??) the carbon over-wrap?

So next, ignition:  Musk says liquid LOX would "squeeze out" but solid LOX is trapped.  So as the COPVs pressurize and compress the graphite layers, the energy source for ignition is friction?  Or some pizo-electric effect?

[MP99]

If you fill high pressure He into an empty bottle, the He will expand. An expanding gas gets colder.

The He is compressed. It will get hotter.

...and it's compressed a lot.

Cheers, Martin

[HMXHMX]

  The other thing we discovered is that we can exactly replicate what happened on the launch pad if someone shoots the rocket.

"Exactly replicate"? That, to me, implies that they have shot a partialy fueled upper stage and saw it explode in the same fashion, which I doubt they have done ...

Elsewhere in the same reddit thread there is this comment:

Gonna be flat honest with you, we literally hired a marksman and shoot a mock-up second stage at long range.

I would have been happy to shoot it for free; who would charge to perform such an experiment? 

It's the one test I wanted to conduct when we were building and testing composite LOX vessels; maybe someday...

[jpo234]

If you fill high pressure He into an empty bottle, the He will expand. An expanding gas gets colder.

The He is compressed. It will get hotter.

...and it's compressed a lot.

Cheers, Martin

Where does the He get compressed? In the compressor somewhere in the GSE. When it arrives at the bottle it expands, especially if the pressure in the bottle is still low, because it's only partially filled.

[LouScheffer]

How many feasible mechanisms are there for formation of solid oxygen in the COPV overwrap? Need to cool to freezing point and then extract the latent heat somehow.

Maybe they loaded the subcooled LOX too cold? That would be a ops issue, though not really a business process issue directly.

The only way I could see this happening is if they load really cold helium into the COPV early in the process.  This could make the COPV colder than the melting point of LOX.   Then, as the LOX level rises and contacts the tank, some portion of it solidifies within the overlap layer.

The business process part might then be deciding to load colder helium, or do it earlier in the count, without carefully testing the consequences first.  (This is of course just speculation.)

[rsdavis9]

If you fill high pressure He into an empty bottle, the He will expand. An expanding gas gets colder.

The He is compressed. It will get hotter.

...and it's compressed a lot.

Cheers, Martin

Compressed it gets colder above the Joule-Thomson inversion temperature of about 32K to 50K.

https://en.wikipedia.org/wiki/Helium#Gas_and_plasma_phases

[Norm38]

If you fill high pressure He into an empty bottle, the He will expand. An expanding gas gets colder.

The He is compressed. It will get hotter.

...and it's compressed a lot.

Cheers, Martin

Warning, Wikipedia:

Helium has a negative Joule-Thomson coefficient at normal ambient temperatures, meaning it heats up when allowed to freely expand. Only below its Joule-Thomson inversion temperature (of about 32 to 50 K at 1 atmosphere) does it cool upon free expansion.[13] Once precooled below this temperature, helium can be liquefied through expansion cooling.

The freezing point of oxygen is 54K.  Meaning that even for sub-cooled LOX, the helium in the COPVs would be above the J-T point.  But that's only at 1atm.  So what is the J-T point of He as it's compressed?
And it's been a long time since I've had chemistry.  Does the J-T inversion only apply to free expansion, or also to compression?
Do the COPVs heat up as they're filled?  Can anyone please confirm that?

[envy887]

...
So next, ignition:  Musk says liquid LOX would "squeeze out" but solid LOX is trapped.  So as the COPVs pressurize and compress the graphite layers, the energy source for ignition is friction?  Or some pizo-electric effect?

Pressure and O2 concentration are all you need to autoignite combustible materials. Typically the O2 is only under about 3 atmospheres of pressure in the LOX tank, but if it's caught as a solid in the COPV overwrap it could see a significant fraction of the 300+ atmospheres that the helium tanks operate at.

[jaufgang]

At the risk of overdoing it with copying other people's reddit posts, here's the top voted comment on that same reddit thread.  The post provides a plausible seeming explanation which I think might provide a useful contribution to this discussion

https://www.reddit.com/r/spacex/comments/57balr/details_from_elons_speech_at_the_nro/d8qies7

ergzay 136 points an hour ago*

For people who aren't understanding the "solid oxygen" comment, here's a likely scenario where this occurs:

The helium COPVs are sitting inside the oxygen tank. The oxygen tank is then filled with subcooled oxygen that's very close to oxygen's freezing temperature. The helium tanks are immersed in and covered by this liquid oxygen. The helium tanks are then begun to be filled. When you fill the tanks, initially before too much pressure builds up, the helium will be expanding from the pressure lines into the pressure vessels. This will cause an associated temperature drop from adiabatic cooling. This could cause the surface of the vessel to drop below the freezing temperature of Oxygen. There will now be tiny frozen/solid Oxygen crystals that develop in between the aluminum tank and the carbon fiber wrapping of the COPV. As the vessel is then pressurized these crystals are strongly compressed as the COPV expands by a few centimeters as it pressurizes. When you strongly compress an oxidizer and a fuel source (carbon fiber) you can cause spontaneous combustion if the pressures are high enough. This causes tank and COPV rupture and then the runaway explosion of the vehicle.

[LouScheffer]

If you fill high pressure He into an empty bottle, the He will expand. An expanding gas gets colder.

The He is compressed. It will get hotter.

...and it's compressed a lot.

Cheers, Martin

Maybe they compress the helium, then cool the compressed gas to 60K or so, then use the cooled gas that to fill the bottles.  Without doing the calculation, I'd think they have to do something like this.  If they loaded room temperature or above helium, then they would have to wait until the LOX cooled the bottle (and its contents) to cram enough helium in.  That would be a slow process, I'd think, since the gas within the bottle is not circulating.

[envy887]

At the risk of overdoing it with copying other people's reddit posts, here's the top voted comment on that same reddit thread.  The post provides a plausible seeming explanation which I think might provide a useful contribution to this discussion

https://www.reddit.com/r/spacex/comments/57balr/details_from_elons_speech_at_the_nro/d8qies7

ergzay 136 points an hour ago*

For people who aren't understanding the "solid oxygen" comment, here's a likely scenario where this occurs:

The helium COPVs are sitting inside the oxygen tank. The oxygen tank is then filled with subcooled oxygen that's very close to oxygen's freezing temperature. The helium tanks are immersed in and covered by this liquid oxygen. The helium tanks are then begun to be filled. When you fill the tanks, initially before too much pressure builds up, the helium will be expanding from the pressure lines into the pressure vessels. This will cause an associated temperature drop from adiabatic cooling. This could cause the surface of the vessel to drop below the freezing temperature of Oxygen. There will now be tiny frozen/solid Oxygen crystals that develop in between the aluminum tank and the carbon fiber wrapping of the COPV. As the vessel is then pressurized these crystals are strongly compressed as the COPV expands by a few centimeters as it pressurizes. When you strongly compress an oxidizer and a fuel source (carbon fiber) you can cause spontaneous combustion if the pressures are high enough. This causes tank and COPV rupture and then the runaway explosion of the vehicle.

As noted above, Helium doesn't adiabatically cool from expansion (at these temps, at least). Need another cooling mechanism.

[Stan-1967]

quoted from  https://www.reddit.com/r/spacex/comments/57balr/details_from_elons_speech_at_the_nro/

Details from Elon's speech at the NRO (self.spacex)
submitted 23 minutes ago * by Ravenous117

Addressing the anomaly:

“We are close to figuring it out. It might have been formation of solid oxygen in the carbon over-wrap of one of the bottles in the upper stage tanks. If it was liquid it would have been squeezed out but under pressure it could have ignited with the carbon. This is the leading theory right now, but it is subject to confirmation.  The other thing we discovered is that we can exactly replicate what happened on the launch pad if someone shoots the rocket. We don’t think that is likely this time around, but we are definitely going to have to take precautions against that in the future. We looked at who would want to blow up a SpaceX rocket. That turned out to be a long list. I think it is unlikely this time, but it is something we need to recognize as a real possibility in the future.”

bold is mine.

It is not just who may want to blow up a SpaceX rocket, but who may want to blow up the payload you have sitting on your rocket?  I think the list of suspects grows longer when considering who in the middle east may feel threatened by AMOS-6's mission to connect millions of users in that area to social media, when social media has been weaponized by the USA as a means of coordinating the overthrow of governments.  Mr. Zuckerberg is open in his support of these efforts.

[JasonAW3]

quoted from  https://www.reddit.com/r/spacex/comments/57balr/details_from_elons_speech_at_the_nro/

Details from Elon's speech at the NRO (self.spacex)
submitted 23 minutes ago * by Ravenous117

Addressing the anomaly:

“We are close to figuring it out. It might have been formation of solid oxygen in the carbon over-wrap of one of the bottles in the upper stage tanks. If it was liquid it would have been squeezed out but under pressure it could have ignited with the carbon. This is the leading theory right now, but it is subject to confirmation.  The other thing we discovered is that we can exactly replicate what happened on the launch pad if someone shoots the rocket. We don’t think that is likely this time around, but we are definitely going to have to take precautions against that in the future. We looked at who would want to blow up a SpaceX rocket. That turned out to be a long list. I think it is unlikely this time, but it is something we need to recognize as a real possibility in the future.”

bold is mine.

It is not just who may want to blow up a SpaceX rocket, but who may want to blow up the payload you have sitting on your rocket?  I think the list of suspects grows longer when considering who in the middle east may feel threatened by AMOS-6's mission to connect millions of users in that area to social media, when social media has been weaponized by the USA as a means of coordinating the overthrow of governments.  Mr. Zuckerberg is open in his support of these efforts.

Hmmm... That would open up the whole situation to people with REALLY deep pockets and access to some pretty interesting technology.