
SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines - jacquesm
http://www.latimes.com/business/la-fi-spacex-falcon-heavy-core-20180212-story.html
======
code4tee
They’ll learn and move on. All told it was a very successful mission and they
got the money shot of the two other boosters landing back at the space center
+ putting the car in orbit. Very impressed with everything they’ve
accomplished and can’t wait to see what’s next.

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std_throwaway
I bet it didn't randomly lack fluid due to some stupid miscalculation. It's
probably more like: "Due to unforeseen circumstances it needed more fluid than
expected. But we adjust our numbers and next time we expect more (in the hopes
that it will be enough, which it will probably be)."

~~~
Cacti
It says right there in the article that it used up the fuel while attempting
to re-lights the engines (without success).

~~~
ceejayoz
Sure, but that system was in place for all the Falcon 9 relights as well.
Presumably there's something different about the FH - minor architectural
differences, flight profile, etc. - that caused this previously reliable
system to run out.

~~~
sehugg
The center core has a different structural design than the side boosters,
which are stock F9 stages AFAIK.

~~~
baobrien
Both of the side boosters were re-used for the Falcon Heavy launch. So stock
F9s to some extent.

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freehunter
I like hearing that the problem is something as (relatively) trivial to solve
as this. I know carrying more fuel with the rocket isn't exactly an easy thing
to do, but far easier than finding out there's something fundamentally wrong
with the design.

SpaceX is amazing and I'm glad they're doing the hard stuff.

~~~
js2
It apparently ran out of TEA-TEB ignition fluid, not fuel:

[https://space.stackexchange.com/questions/15403/why-is-
tea-t...](https://space.stackexchange.com/questions/15403/why-is-tea-teb-
chemical-ignition-used-instead-of-spark-ignition)

I can't find any info on how much TEA-TEB is carried on-board, only that it's
ground supplied for initial launch with the on-board TEA-TEB being used only
for restarts.

(I'm not even an amateur rocket scientist: I just googled all this.)

~~~
cremp
If I'm not mistaken, the SR-71 and A12 had enough TEB for 15 restarts. After
doing an aerial refueling, they had to use TEB to get back to afterburner.

~~~
mulmen
They also had to use TEB to re-light after an unstart [1]. I think 15 is
abount right but it seems like a very small margin to deal with considering
how common unstarts were.

[1]:
[https://en.wikipedia.org/wiki/Unstart](https://en.wikipedia.org/wiki/Unstart)

~~~
Already__Taken
Once they learned about that they worked around unstarts with software to
control the engine spikes to keep the shockwave inside.

~~~
mulmen
Yes, unstarts became less common but they still happened.

------
ggchappell
> about 328 feet from the floating platform

Someone doesn't understand precision.

(That's 100 meters, so "about 300 feet".)

~~~
ReverseCold
I think it's not exactly 328 feet, so it's about 328 feet.

~~~
jessriedel
Equally well could have said "about 328.084 feet".

~~~
ReverseCold
Hm, I don't know of a rule that specifies how to use the word "about".

To me at least, "about 328 feet" seems okay. It gives you more precision than
"about 300 feet" while still letting you know that it's not exactly 328 feet.

~~~
williamscales
The point is that extra precision is unwarranted. We only know that it missed
by somewhere between 50 and 149 meters, so it's not appropriate to imply that
we know it more precisely.

~~~
ReverseCold
Ah, didn't notice that. Thanks for clarifying.

------
ZeroGravitas
He also announced the 3rd drone ship's name on twitter as "A Shortfall of
Gravitas".

~~~
olympus
Going all in on the Culture ship names. I'd be happy if he just made 100(ish)
more just to name them after every ship that Iain M. Banks named. They don't
need to catch rockets, they can just link up and make a floating utopia.

~~~
stcredzero
_They don 't need to catch rockets, they can just link up and make a floating
utopia._

Well for that, you'd want to change the hull type from a barge to a spar buoy.
Given that, there's no reason why they couldn't do both.

[http://www.technip.com/sites/default/files/technip/illustrat...](http://www.technip.com/sites/default/files/technip/illustrations/page/spar_comparison_graphic_11-15-12_0.jpg)

(Permanent structures in the ocean need to be spar buoys, or some other
architecture that are largely immune to Rogue Waves.)

~~~
089723645897236
Got any more cool info on permanent ocean structures. Or large ocean structure
engineering in general?

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everdev
This is why we compare hard problems to rocket science. It's so hard to
recover from failure of even the smallest sources.

~~~
chii
but the hip programming tips these days are to move fast and break things!

a rocket certainly moves fast...

~~~
prewett
It would have broken a bunch of things if it weren't "about 328 feet" off
target, too.

When they said they lost the core, I've been envisioning a barge with a big,
round hole in the center...

~~~
ncallaway
They intentionally aim off-target, and have the final engine burn steer them
back into the landing.

If an engine relight doesn't happen, they won't hit the barge.

I think the biggest danger to the barge is a final engine relight without
enough fuel, or with a guidance and nav systems failure or error.

~~~
lb1lf
-OT, but related - for the same reason, offshore vessels set their autopilot targets say, half a mile off the oil rig/whatever they are headed for - just in case someone doesn't pay attention as they approach.

I once saw a nice enamelled sign on a bridge stating 'Whoever programs a
target on target will be promoted to figurehead prior to arrival at said
target.'

(And, in that position, being the first to regret their sloppiness. Plus, they
will somewhat soften the impact. Cough.)

~~~
ncallaway
Super interesting. Something I wouldn't have ever thought about, but makes
perfect sense.

The world is just frighteningly complex, sometimes.

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ChuckMcM
Obviously one of the things you don't want "too much of" is a pyrophoric fluid
that you need to dump before you can let people near :-). Have they ever
published their safeing procedure? I'm wondering if they recover more
volattiles than the old shuttle did after it landed.

~~~
jccooper
It doesn't have as much nasty as Shuttle. The TEA-TEB takes care of itself by
combusting when vented, but that's the only hazardous material. Shuttle had
hypergolics on board which F9 doesn't use (just kerosene, oxygen, nitrogen,
and helium.)

The rest of the passivation will mostly be purging the engines, closing
valves, and releasing pressure in the various tanks and vessels. LOX venting
might take a while as it all boils off.

~~~
baybal2
Man, TEA-TEB is a hypergolic pair

~~~
jccooper
No, it is not. It's a pyrophoric mixture. It is hypergolic with oxygen.

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dmix
> The fix, he said, was "pretty obvious."

I've said the same before many software bugs or family computer problems that
ended up being all nighters on :P

But I'm sure SpaceX will get through this,,,

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ashleyn
Perhaps some rocket scientist can explain why this seemingly-obvious error
even happened? Shouldn't it be possible to calculate the precise amount of
fuel used, and therefore required?

~~~
jccooper
They probably used a simple model (and experience) to determine the needed
amount. But the model was wrong because, well, it encountered the real world.
So they'll adjust in the future. Probably they could have analyzed the heck
out of it for years, and gotten it right, but then that would take years and
cost buckets.

~~~
aerophilic
This reminds me of a phrase: “All models are wrong; Some models are useful”.
[https://en.m.wikipedia.org/wiki/All_models_are_wrong](https://en.m.wikipedia.org/wiki/All_models_are_wrong)

~~~
philipwhiuk
Or to quote a Prussian general:

"No plan of operations extends with any certainty beyond the first contact
with the main hostile force."

------
huhtenberg
Has anyone seen any updates on how their fairing recovery attempt went?

They had the ship done and seemingly ready back in December -
[https://imgur.com/gallery/MQcEE](https://imgur.com/gallery/MQcEE)

~~~
rwmj
Isn't the fairing just a simple pair of metal casings. Why bother to recover
it?

~~~
boznz
Wonder why they dont just leave them in space, could make a good chassis or
building block for building bigger space stations

~~~
ridgeguy
The fairing doesn't get carried to orbit. It's dumped as soon as aerodynamic
loads are negligible.

Since the fairing has the same energy requirement as the payload (in
energy/kg), it's important to get rid of it the moment it's unnecessary. If
they took it to orbit (so they could leave in space), it would drastically cut
down payload mass.

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SubiculumCode
So, I wonder why the side boosters won't be used again? Was that explained.
I'm curious, but I barely have internet on this hill.

~~~
msumpter
I believe the two boosters were previously flown and were of an older
block/generation (block 3 and 4 if memory serves me) where they are focusing
on block 5 as the final revision and all future Falcon rockets would be this
same standard.
[https://en.wikipedia.org/wiki/Falcon_9#Block_5](https://en.wikipedia.org/wiki/Falcon_9#Block_5)

~~~
zrail
Whoa, so not only were the boosters landed, they were actually reused from
previous launches! That's doubly awesome.

~~~
SubiculumCode
Yeah. I'd say even more than double awesome. The falcon heavy launch was super
important for Space-X, PR and investment wise. Trusting two used rockets for
THAT launch shows real confidence in the re-usability of their rocket tech.
Bravo.

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quadyeast
Is that also why the video feed was not working? SpaceX commentators said it
was possibly due to vibration.

~~~
Stratoscope
The video feed didn't stop working, or if it did, it was only for a brief
moment.

If you watch this part of the YouTube stream, after it cuts back to the two
hosts there is a monitor at the far right center of the video that shows the
continuing camera feed of the drone ship landing pad. Only part of the monitor
is visible, but after the smoke clears over the next few minutes you can see
the empty pad:

[https://www.youtube.com/watch?v=wbSwFU6tY1c&t=30m33s](https://www.youtube.com/watch?v=wbSwFU6tY1c&t=30m33s)

You can also see the surprised reactions of the hosts during these few
minutes, and how relieved they were when John Insprucker joined them to wrap
things up. It would have been interesting to be a fly buzzing around their
earpieces to hear what the producers were telling them!

People have speculated that with everything else in the mission being so
spectacularly successful, they wanted the initial news reports to be about
that success instead of the one core that failed to land.

Knowing how the news works - "Here's what's wrong with the world today!" \- I
can sympathize with that.

~~~
0xTJ
Although I understand why they would have done that for click-bait news
outlets, it did really bother me that they were so slow in revealing what
happened. What I like about SpaceX is that they're always been very open about
their failures, even compiling that great video of their failures. Being able
to seeing the full result would have been nice, and I spent a fair bit of time
for the following hours refreshing Twitter.

~~~
Mithaldu
They weren't only slow about revealing it, they straight-up lied.

Smoke on deck clears, no core visible, deck empty. Both go "oh." and after a
pause, while looking at the empty deck: "we're waiting to hear what happens.
[...] we'll let you know as soon as we find out" and "we'll [...] know [...]
whether it's standing". All while looking at the empty pad.

They saw it didn't land, they found out immediately and didn't let "us" know.
Instead they claimed it might be possible it is standing despite seeing the
empty deck.

------
evanlivingston
I'm someone who doesn't follow a lot about current aerospace capabilities and
technologies. Can someone explain why the work SpaceX is doing is so much more
exciting than that of United Launch Alliance or Khrunichev or similar systems?

~~~
justin66
SpaceX is still the only company to land a real first-stage booster, and the
Falcon Heavy was the largest rocket (in terms of payload capacity) to fly
since the Saturn V.

~~~
Zardoz84
false! The energia and the N-1 flow before and they was more powerful that the
Falcon Heavy.

~~~
cycrutchfield
Did the N-1 rocket really "fly"?

~~~
jacquesm
It flew all the way to the scene of the crash.

~~~
philipwhiuk
Ah, the Chuck Yeager school of flying:

"If you can walk away from a landing, it's a good landing. If you use the
airplane the next day, it's an outstanding landing"

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inamberclad
That engine uses tetraethyl borane (TEB), right? Do they have to first ignite
the turbopump and then ignite the main engine?

~~~
JshWright
This is not a definitive answer (a quick googling failed to turn up a solid
source), but presumably they have to ignite both the gas generator (that
powers the turbopump) as well as the main combustion chamber. You certainly
see the green flash of TEA/TEB lighting underneath the rocket (inside the
combustion chambers) just before liftoff.

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meteor333
> Those two boosters, which were used in previous launches of SpaceX's
> workhorse Falcon 9 rocket, will not be reused again, Musk said in a post-
> launch news conference last week.

Why did SpaceX spend resources to get them to safe landing then? I presume,
they rather maintain their routine and maintain the success of landing the
booster. It would probably be expensive to change their standard procedure.

Does any know how many times a booster can be resued? What dictates its
lifetime?

~~~
kragen
The current version of the rocket is called "block 5". Those two boosters
weren't block 5 boosters. Presumably the reason to spend resources to get them
to safe landing was to learn things that will be useful in future launches;
for example, those two boosters had enough ignition fluid to land successfully
this time, but the main first stage did not.

~~~
meteor333
That make sense. In that case, wouldn't these boosters be useful in future
Falcon Heavy launches? Why can't they be resued?

~~~
jaggederest
At this point they're historic artifacts worthy of preservation. Retire them
to a museum.

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invalidusernam3
The good news is it seems like a fairly easy thing to fix going forward. Not
really an engineering problem as such, but rather a miscalculation

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drewbens
What is ignition fluid, exactly?

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anguyenhuy

      The fix, he said, was "pretty obvious."
    

I mean, it's not rocket science, is it? >_>

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vkou
This is one of the reasons why space travel will never be 'routine'.

A million and one things can go wrong, and any one of them can destroy the
spacecraft. Compare that to commercial air travel - where a number of unlikely
events have to happen, to down an airplane.

Some time ago, there was a HN discussion about traveling from continent to
continent in minutes, using a sub-orbital hop. I don't know about anyone else,
but I'll pass on being strapped to a skyscraper filled with LOX and RP-1.

~~~
mulmen
An airliner is on a building scale and carries a slightly less refined
petroleum fuel. RP-1 and Jet Fuel are both refined petroleum fuels. Rockets
only carry LOX because they go into space where there is no atmospheric oxygen
to burn the fuel.

Airliners are fully capable of turning themselves into fireballs. It doesn't
happen often because we have a lot of experience operating them. The same
safety levels are possible with rockets over time.

~~~
vkou
> An airliner is on a building scale and carries a slightly less refined
> petroleum fuel. RP-1 and Jet Fuel are both refined petroleum fuels. Rockets
> only carry LOX because they go into space where there is no atmospheric
> oxygen to burn the fuel.

That's true, but a 747 does not burn its weight in fuel in 397 seconds. A
Falcon 9 does. It's the difference between igniting a gas barbecue in your
back yard, and igniting the propane tank that feeds it. One of those things is
something I do on the 4th of July. For the other, I'd prefer to be taking
cover in a foxhole.

> Airliners are fully capable of turning themselves into fireballs. It doesn't
> happen often because we have a lot of experience operating them. The same
> safety levels are possible with rockets over time.

It's also because the possible margins for safety with airplanes are much
higher. You can engineer redundant systems, and overbuild, because you aren't
fighting the tyrrany of the rocket equation.

There is no one thing that can go wrong on a 747 that will down the aircraft.
The dozen SpaceX launch/landing failures were almost all due to 'one thing
went wrong, there went $60-100m USD.'

Incidentally, most other catastrophic launch failures (Including ones that
claimed lives) were also due to 'one particular thing went wrong, everyone
died.'

Rocket engineers aren't stupid, there's a reason that rockets don't have the
amount of rendunancy and capability for failure recovery that a commercial
airliner does.

~~~
ceejayoz
> There is no one thing that can go wrong on a 747 that will down the
> aircraft.

C'mon, that's demonstrably false.

[https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981](https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981)
involved a poorly sealing latch.

[https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123](https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123)
involved a single poorly repaired bulkhead.

[https://en.wikipedia.org/wiki/TWA_Flight_800](https://en.wikipedia.org/wiki/TWA_Flight_800)
may have been a spark in the fuel tank.

Plenty of other examples on
[https://en.wikipedia.org/wiki/Category:Airliner_accidents_an...](https://en.wikipedia.org/wiki/Category:Airliner_accidents_and_incidents_caused_by_mechanical_failure)

