
SpaceX Has Pinpointed the Problem That Caused the Falcon9 to Crash Land - 51Cards
http://www.businessinsider.com/spacex-problem-falcon9-crash-landing-2015-1
======
Animats
If running out of stored hydraulic pressure is the only problem they had,
that's good. That's easy to fix, although it means some weight penalty.

What SpaceX did was a low-cost test. They were paid for a shipment to the ISS,
which was successful. The test of the booster recovery system didn't cost them
a launch. They didn't expend a booster just for this.

~~~
InclinedPlane
Indeed. They attempted to recycle a garbage rocket after it had been used
already.

This crash into the ocean thing. That happens on literally _every single other
rocket launch in history_ , it's not abnormal, it's just not usually filmed or
even thought about much.

~~~
Shivetya
which makes me curious, how many boosters are crashed into the ocean and what
are the rules regarding them? From toxins to salvage. I know we have dumped
far worse into the ocean, its littered with munitions for instance.

~~~
logfromblammo
First stage rockets likely break into pieces upon hitting the water and sink
to the ocean floor. Higher stages burn up in the atmosphere.

Debris from a successful launch are usually not worth worrying about. Failed
launches, on the other hand, could contain unburned propellants, hypergolic
fuels, radioactive or toxic payloads, and may come down as a blazing fireball
on top of something that otherwise would have expected no more than a speck of
metal oxides.

~~~
toomuchtodo
> and may come down as a blazing fireball on top of something that otherwise
> would have expected no more than a speck of metal oxides.

Not if range safety is doing their job.

~~~
logfromblammo
I recall seeing a video of a solid rocket booster that destroyed several cars
in a parking lot with flaming chunks of partially burned propellant.

Range safety cannot reasonably be expected to protect everywhere that a rocket
could possibly reach. In the worst case scenario, it must intentionally
destroy the vehicle if it may stray outside the protected area such that the
debris remain within it.

If you work on a launch complex, make sure you have good insurance.

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tommoose
The news on a radio station in my area commented on this, saying something
like:

"...just like you recycle your milk bottles, cardboard etc. a company has
tried to /recycle/ a rocket and it blew up...haha"

It made me sad since I knew it was SpaceEx, understood the complexity of what
they're attempting and they reduced it to comparing it to throwing an empty
beer bottle in a bucket.

I am relieved to see that SpaceEx is viewing it largely as a success/excellent
learning experience; in my opinion they are by far the most exciting thing in
science/technology at the moment.

~~~
InclinedPlane
One of the annoying aspects of coverage of SpaceX's attempts, although
fortunately it's fairly rare, is the desire to make fun of "eggheads" when
they "fail" because it makes people feel superior.

Nevertheless, this work is one of the most important things going on in human
civilization right now. That may seem like a bit of hyperbole, but go back and
look at things like the invention of the transistor or the internet. Nobody
perceived fully how impactful either of those things would be though they've
transformed the lives of billions and spawned trillions of dollars in economic
activity. If reusing rockets becomes feasible, and there's every reason to
believe it will be, then it will lower the costs of spaceflight by one to two
orders of magnitude right off the bat. And that will vastly accelerate our
investment, colonization, and exploration of space and kickstart a positive
feedback loop of growth in activities in space (from infrastructure like GPS
and commsats to human presence) spurring investment in improving space and
launch systems which then increases activity levels (due to increasing
capabilities and lower costs) which then spurs improvements, and so on.
Ultimately culminating in mankind becoming not just a multi-planet species but
a space faring civilization no longer confined to either the Earth or even
this Solar System. And all of that will have grown from the tiny kernel of
spaceflight activities in the present, with SpaceX's activities being
particularly relevant for that future.

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gdi2290
crashed photos were released on twitter here
[https://twitter.com/elonmusk/status/555981841476227072](https://twitter.com/elonmusk/status/555981841476227072)

~~~
ohaal
Gif:
[http://img.gfx.no/1477/1477615/spacex2.gif](http://img.gfx.no/1477/1477615/spacex2.gif)
(source, norwegian article: [http://www.tek.no/artikler/se-spacex-raketten-
kraesjlande-pa...](http://www.tek.no/artikler/se-spacex-raketten-kraesjlande-
pa-dronelekteren/166947))

~~~
mikeyouse
Which they lifted out of a reddit thread;

[http://www.reddit.com/r/spacex/comments/2sm3q7/anglecorrecte...](http://www.reddit.com/r/spacex/comments/2sm3q7/anglecorrected_gif_for_barge_crashlanding/)

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tsotha
>Although the rocket's landing did not go according to plan, the other half of
the launch mission was a success.

Describing the first stage landing as "half" the mission is disingenuous. The
mission was the ISS resupply, and even if the first stage landed properly if
the resupply failed it would have meant a 100% mission failure.

~~~
teraflop
So you're complaining that they're being disingenuous by describing their
mission as a partial success instead of a complete success? Really?

~~~
cldellow
I disliked that element of the reporting too. Your use of "they" is funny, too
--SpaceX and NASA would say that CRS-5 was a complete success from the point
of view of the mission.

The reporter's not being disingenuous, she's just...not using words correctly.
The mission was to keep the ISS astronauts supplied and alive. The mission
succeeded. The tests around rocket reuse were not part of the mission.

~~~
SapphireSun
True, but one is transformative and the other is more mundane. The issue is
that to make progress in rocketry (the mission) you have to get other people
to pay for it (making it ostensibly their mission).

Not to knock the ISS in any way, it's just that any of the big players could
have done this resupply run afaik.

~~~
jpgvm
SpaceX also does them cheaper and with a higher max cargo due to Dragon being
a more advanced vehicle than most, it can also return significant cargo from
the ISS.

So no, the other big players currently aren't on the same level as SpaceX when
it comes to ISS missions.

~~~
tsotha
The Dragon capsule is a bit less capable than one would like in that it can't
actually dock. That's what makes the Soyuz necessary and NASA's whatever-
they're-calling-it-this-week capsule necessary.

Technically the Dragon is "berthing", in that the space station's arm is
what's actually bringing the two craft together, and any failure in that arm
would render Dragon unable to connect or disconnect from the station.

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duffyt
Hydraulic systems are usually closed, can anyone explain why hydraulic fluid
is expendable in this case?

~~~
garindra
From one of his tweets:

> Hydraulics are usually closed, but that adds mass vs short acting open
> systems. F9 fins only work for 4 mins. We were ~10% off.

[https://twitter.com/elonmusk/status/554023312033341440](https://twitter.com/elonmusk/status/554023312033341440)

~~~
fit2rule
Is there a chance someone could explain this - how does not being able to move
the fins (with hydraulics) translate into a hard landing - were they just
_off_ the target landing spot because the fins couldn't be used to fine-tune
the descent to within a meter of the target landing zone, and thus they
'missed' the barge by a few meters, or is something else at play?

EDIT: never mind - I've learned that they have a steering function, as well as
drag inducing function, and they ran out of hydraulic fluid required to induce
more drag, which would thus slow the rocket down. Leaving my comment here in
case anyone else is curious.

~~~
marvin
People on /r/spacex have theorized (with the aid of comments from Musk) that
running out of hydraulic fluid caused the grid fins to get stuck in an extreme
position, which forced the rocket off course. Cold gas thrusters and gimbaling
of the engine tried to correct this, but the end result was that the rocket
had insufficient control authority to achieve a controlled landing.

~~~
StavrosK
How is the rocket going to achieve a controlled landing with no thrust? It
seems to me that it would crash into the pad anyway. Or was it that they did
have thrust, they were just unable to steer because of the lost pressure?

~~~
fit2rule
Yes I think you've got it right - they had thrust from the rocket motors, but
they ran out of hydraulic fluid required to use the fans to induce more drag,
so the rocket came down hard.

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dtparr
They just posted a video on vine:

[http://vine.co/v/OjqeYWWpVWK](http://vine.co/v/OjqeYWWpVWK)

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nhayden
>Most of the rocket was left behind, but some of the debris was recovered and
returned along with the ship

I don't get how this is ok. Why is it acceptable to leave thousands of pounds
of scrap and chemicals in the ocean?

~~~
mzs
You mean like in most every other launch? If this works that will end, I'll
cut them a little slack.

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phkahler
I still don't understand. Those waffle irons are not needed at low speed. They
did grasshopper landing without them right? Or perhaps they interfere if they
are present and not working correctly? Either way, why did the rocket hit
"hard" as Elon said? Rocket velocity shouldn't have anything to do with the
waffles right?

I've been thinking someone forgot to include the height of the GPS in some
code somewhere, and this whole hydraulic issue while true, is a handy way to
not publicly disclose a simple mistake. Don't wanna look like the mars probe
that crashed due to unit conversion issues...

So really, how does the hydralic issue affect the impact velocity?

~~~
icandownvote
First, "hard" landing doesn't necessarily mean "high speed". It's a generic
term for unsuccessful landing. It could be incorrect attitude landing (e.g.
tilted) or anything else. In this case it looks like it was exactly that:
landed tilted or with significant horizontal speed. If it was high vertical
speed, we would've seen big scrapes on the platform's surface, and there's
none.

Contrary to popular belief, the fins are _extremely_ effective even at low
speeds. First, they have enormous surface area. Secondly, they have huge
momentum around the center of mass, which is at the very bottom of the rocket
when it's empty. So, even a small force generated by the fins generates huge
momentum and can help position the rocket in the desired attitude.

It looks like the control system was commanding the fins to move and was
expecting the attitude to change, but they didn't move anymore. Perhaps at the
very end of the flight the gimbals on the engine didn't have enough authority
to orient the rocket vertically and/or arrest its horizontal speed.

I think it's amazing achievement for the very first attempt. Congrats SpaceX
and I'm jealous like hell for what you've been able to achieve.

~~~
toomuchtodo
> I think it's amazing achievement for the very first attempt.

People don't understand this enough. They took the stage of a rocket _from
supersonic speeds to a tiny barge in the ocean_. Even though they didn't
complete the objective, they were successful in showing that the theory holds
up.

~~~
51Cards
On top of what you've said I don't think enough people get the scale of this
task. This is decelerating, balancing, and maneuvering a 14 story tall object,
from supersonic speed at the edge of space, onto a tiny barge in the ocean.
It's mind boggling when you look at the scope of what they are pulling off.

~~~
ChuckMcM
Like dropping a drinking straw off the top of the empire state building and
having it land in a glass of soda on the sidewalk a block away.

~~~
StavrosK
Except there's no glass, it just lands vertically on a coaster on the
sidewalk.

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jccooper
Elon Musk has published a few photos of the almost-landing on Twitter. See:

[https://twitter.com/elonmusk/status/555978267165859840](https://twitter.com/elonmusk/status/555978267165859840)

and following.

~~~
51Cards
"full RUD (rapid unscheduled disassembly)" Love the term.

Edit: apparently comes from KSP.

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AYBABTME
When they recover their first 1st-stage, I'm curious what they will do with
it. Use it on a self-funded test launch, or use it on a customer's launch, or
just leave it there and look at it?

~~~
lmm
Probably each of those in some order. The first few recoveries will just be
for taking apart and analysing, but at some point they'll be launching them; I
believe they're already asking around for a customer willing to launch
something (at a heavy discount) on a second-hand rocket, but I wouldn't be
surprised if the very first reuse launch was self-funded.

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xophe
>> The tank filled with hydraulic fluid that powered the fins enabling them to
rotate and steer, ran out of fluid before landing.

Nit, but this is the most difficult sentence I've had to parse all year.

~~~
Lost_BiomedE
Bad news for me. I usually write like this:

The tank filled with hydraulic fluid, powering the fins and enabling them to
rotate and steer, ran out of fluid before landing.

Hopefully the above reads more clearly. It is how I parsed it on first read.

~~~
pjc50
Not everything needs to be a single sentence. "The tank of hydraulic fluid ran
out before landing. This tank powered the fins that steer the rocket.
Therefore the rocket could no longer be steered."

Or there's the ablative: "The tank of hydraulic fluid having been emptied, the
fins could no longer steer the rocket."

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Florin_Andrei
Great news (and a well-written article with plenty of relevant photos).

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jccooper
Not really new news; all this stuff has been known for days. But not a bad
summary if you haven't been watching closely.

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javiramos
SpaceX <3

