
Musk says SpaceX knows what caused the latest rocket failure - collinmanderson
http://www.theverge.com/2016/11/5/13533900/elon-musk-spacex-falcon-9-failure-cause-solved
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Trisell
Seems best that they found this out at this stage instead of when they had 3
humans setting on top of it.

While the loss of the cargo is regrettable, it in no way is as damaging as the
loss of 1-3 lived would have been on SpaceX.

~~~
krastanov
I agree with the general sentiment, however SpaceX and others have said that
this particular explosion would not have harmed any astronauts. The Dragon 2
crew capsule has a launch abort system - if an explosion happens the Dragon
launches off to a safe distance using its own thrust.

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tunap
Why do they not use this continency for saving the capsule & non-living cargo,
as well? Surely the recommissioning costs would be less than full replacement
of equipment+cargo & would give working knowledge for any future "live cargo"
aborts.

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Anchor
They could, when Dragon 2 is in use for supplying ISS. But Dragons do not
carry the kinds of payloads lost in this case. The satellite is on top of the
second stage and covered by fairings. There's no craft on top of second stage,
so there is no launch escape system.

~~~
Symmetry
Well, it'll save any supplies in the cabin. I believe anything in the trunk
would still be lost.

~~~
Anchor
True, the trunk needs to be jettisoned from the craft before it lands with
parachutes.

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userbinator
_The solid oxygen that formed could have ignited with the carbon, causing the
explosion that destroyed the rocket._

This makes me wonder why the liquid oxygen wouldn't have the same effect?
Liquid oxygen is itself an extremely reactive oxidiser (search YouTube
videos.)

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endymi0n
Could it be sharp oxygen crystals penetrating the carbon fiber resin layer -
just like what happens when freezing living cells?

~~~
phkahler
>> Could it be sharp oxygen crystals penetrating the carbon fiber resin layer

Why would one keep just a layer of hardened resin between all that oxygen and
carbon? Seems like an accident waiting to happen.

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ethbro
I'm guessing the reason you don't do a lot of "Plan B" mitigation in rocketry:
weight and added complexity.

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Animats
Strange. Their previous failure (CRS-7 blowing up in flight in 2015.[1]) was
supposedly caused by a liquid helium tank support strut in the second stage
breaking in flight. The liquid helium tank is inside the liquid oxygen tank,
so a failure there overpressurizes the liquid oxygen tank.[1]

This second failure again involves a similar liquid helium tank. Not one under
flight stress, just sitting there on the pad. Similar failure, though - tank
leaks, overpressurizes liquid oxygen tank, second stage explodes.

The Saturn V had helium tanks inside the liquid oxygen tanks, but they were
compressed gaseous helium, not liquid helium. Has any other rocket design ever
put a liquid helium tank inside a liquid oxygen tank?

[1] [https://www.nasaspaceflight.com/2015/07/spacex-
falcon-9-fail...](https://www.nasaspaceflight.com/2015/07/spacex-
falcon-9-failure-investigation-focuses-update/)

~~~
JshWright
Other than the fact that they involved the He tanks, there weren't many
similarities between the events.

With CRS-7, there was acoustic evidence of the strut failing and the COPV
smacking into the tank wall. With AMOS-6, the first indication of any event
was the catastrophic failure of the COPV.

In either case, the location of the He tank isn't terribly relevant... It was
going to destroy the rocket either way.

~~~
logingone
COPV:
[https://en.wikipedia.org/wiki/Composite_overwrapped_pressure...](https://en.wikipedia.org/wiki/Composite_overwrapped_pressure_vessel)

~~~
JshWright
Ah, thanks (I assumed it was in the article...)

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caconym_
So how are they going to fix it? Will changes to the loading sequence be
enough? Otherwise, December seems a bit soon for a return to flight.

~~~
vayeate
Seems to be caused by the too-cold liquid oxygen interacting with carbon
elements. So either change how the tanks are pressurized with helium to
prevent the oxygen getting too cold, and/or somehow insulate the carbon from
the oxygen better. Neither seem like insurmountable problems.

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edblarney
I should hope so ...

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Theodores
This is a quick investigation into the 'disaster' and that contrasts with how
things normally get investigated, i.e. by big government with findings taking
years to see the light of day and with big business and other special
interests doing what they can to obfuscate truth and shift the blame onto 'the
pilot' (as is usually the way in aviation, car crashes, train crashes and
anything else that crashes).

Well done to SpaceX for getting to this explanation, I am so glad this has not
been blamed on a sniper hired by their rivals!!!

~~~
daphreak
I understand your criticism but the Columbia Accident Investigation Board
released a full report with recommendations for changes 6 months after that
accident. Not too shabby.

Right now we have a press release that is pretty thin on details from SpaceX.
Not quite comparable.

