
Anomaly Updates - yread
http://www.spacex.com/news/2016/09/01/anomaly-updates#
======
mikeytown2
3 helium tank issues in 3 years

2014
[https://en.wikipedia.org/wiki/Falcon_9_Flight_10](https://en.wikipedia.org/wiki/Falcon_9_Flight_10)
(delayed by SpaceX due to a first stage helium leak)

2015
[https://en.wikipedia.org/wiki/SpaceX_CRS-7](https://en.wikipedia.org/wiki/SpaceX_CRS-7)
(failure of a strut which secured a high-pressure helium bottle inside the
second stage's liquid oxygen tank)

2016 (a large breach in the cryogenic helium system of the second stage liquid
oxygen tank took place)

~~~
djsumdog
So these high pressure tanks must be an incredibly hard/complex problem?

~~~
mikeyouse
They're a complicated problem, but I can't help but wonder if SpaceX
underestimated the difficulty. They used to have a 3rd patty supplier for the
helium tanks but they decided to manufacture them in-house a few years ago. As
far as I know, all 3 tank problems have happened since they started producing
their own.

~~~
mikeash
The strut which failed in 2015 was outsourced. A tiny fraction of the struts
from the factory failed at well under the specificed maximum load, and one of
them ended up in that rocket.

------
simonpure
_At this stage of the investigation, preliminary review of the data and debris
suggests that a large breach in the cryogenic helium system of the second
stage liquid oxygen tank took place._

...

 _Pending the results of the investigation, we anticipate returning to flight
as early as the November timeframe._

~~~
samcheng
Note that the second-stage helium system was also the source of the previous
explosion of a SpaceX mission to the International Space Station (which blew
up during launch).

[https://en.wikipedia.org/wiki/SpaceX_CRS-7#Launch_failure](https://en.wikipedia.org/wiki/SpaceX_CRS-7#Launch_failure)

~~~
DangerousPie
But:

> Through the fault tree and data review process, we have exonerated any
> connection with last year’s CRS-7 mishap.

~~~
api
I found that puzzling too... doesn't this mean it was the _same component_ ,
though perhaps failing in a different way?

Sounds like that pressurization system needs to be taken out back and shot.

~~~
daeken
Frankly, that's how you increase your failure rate. If a system fails, you
figure out why, figure out any other failure cases that may have been missed,
and you fix them.

You don't ditch something that largely works, and replace it with something
brand new, for which you have zero data. That's how you lose rockets, cargo,
and lives.

~~~
HeyLaughingBoy
Same thing applies to software: you encounter an error, you analyze why it
happened. Then ask: what other places could have this error? Can I eliminate
this entire class of error by design or other method or do I need to fix them
all individually?

You organically end up with a more robust system that way. Don't throw out the
baby with the bathwater.

~~~
SEJeff
And then there is the "Did you turn it off and on again" school of thought.
I've had to fight against that so hard before when the correct issue is
inducing something to drop core, or fix a leaky program using valgrind.

------
ythl
I love/hate the carefully curated language.

"Three weeks ago, SpaceX experienced an anomaly at our Launch Complex 40
(LC-40) at Cape Canaveral Air Force Station. This resulted in the loss of one
of our Falcon 9 rockets and its payload."

==

"Three weeks ago, SpaceX experienced a catastrophic failure at our Launch
Complex 40 (LC-40) at Cape Canaveral Air Force Station. This resulted in a
massive explosion/fireball that completely destroyed the rocket and its
payload."

~~~
eric_h
Personally I love the euphemism they use when they blow up: "rapid unscheduled
disassembly"

~~~
drspacemonkey
No word of a lie, I do that all the time in Kerbal Space Program. I didn't
crash, the mission terminated due to unscheduled lithobraking. My rocket
design didn't explode, it had a excessive surplus oxidisation.

------
imaginenore
RELATED:

 _" just had dinner with a credible source i trust that spacex is about 99%
sure a COPV issue was the cause. 'explosion' originated in the LOX tank COPV
container that had some weird harmonics while loading LOX."_

(COPV = Composite Overwrapped Pressure Vessel, they are titanium bottles
wrapped in layers of continuously wound carbon fiber + resin)

[https://www.reddit.com/r/spacex/comments/545dju/unconfirmed_...](https://www.reddit.com/r/spacex/comments/545dju/unconfirmed_rumors_that_spacex_found_the_issue/)

~~~
vannevar
Presumably, loss of the cryogenic helium through a "large breach" would lead
to rapid warming of the liquid oxygen and equally rapid over-pressurization of
the tank. So this is consistent with the source's contention that the
explosion originated in the LOX tank, although the COPV may not be the root
cause in that case, depending on the over-pressure it was rated for.

~~~
dogma1138
The helium isn't "cryogenic" the LOX is, Oxygen is liquid at 182.9c, SpaceX
cools it down to ~-206c when they load their fuel in cryogenic mode.

Helium boils at -268.9c, basically when liquid helium meets liquid oxygen it
boils and expands to 757 times it's volume, which means boom.

~~~
vannevar
Yes, I misinterpreted the article. Here's a clearer description from
spaceflightnow.com ([https://spaceflightnow.com/2016/09/23/falcon-9-rocket-
explos...](https://spaceflightnow.com/2016/09/23/falcon-9-rocket-explosion-
traced-to-upper-stage-helium-system/)):

"The Falcon 9 rocket’s upper stage liquid oxygen tank contains several
composite helium vessels, each pressurized to about 5,500 pounds per square
inch in flight. The helium is routed through the second stage’s Merlin engine,
where the helium warms up and is injected into the rocket’s propellant tanks
to pressurize the stage as the launcher burns fuel, keeping the tanks
structurally sound."

------
imaginenore
The most interesting hypothesis I've heard is intentional sabotage, like with
a sniper rifle shot. Snipers have been known to hit human targets from 1.5
miles away. It seems like a huge rocket can get shot from a much larger
distance.

~~~
pavelrub
What is it with HN and belief in various absurd conspiracy theories? Is it an
American thing?

~~~
optforfon
I think there is a big cultural element. Not to say other cultures are immune
to conspiracy-theory thinking, but something about American exceptionalism
seems to encourage it.

~~~
jdavis703
Aren't religions (at least Abrahamic ones) just one big conspiracy theory?
People believing in some kind of series of events with little to no evidence?
If so I think people globally are apt to believe in dubious claims, aka
conspiracy theories.

