
SpaceX Dragon CRS-6 Launch Webcast - chomp
http://www.nasa.gov/multimedia/nasatv/
======
michaelmcmillan

        T+17m: Not a successful landing today.
    

That sucks. Source:
[http://www.reddit.com/r/spacex/comments/32jnyd/rspacex_crs6_...](http://www.reddit.com/r/spacex/comments/32jnyd/rspacex_crs6_official_launch_discussion_updates/)

Edit: "Looks like Falcon landed fine, but excess lateral velocity caused it to
tip over post landing" @elonmusk

~~~
ChuckMcM
I'm a big fan of arrestor lines around the sides. Basically as the stage
lands, stand up four outrigger arms with a cable going through them from the
corners of the barge. If it falls over then catch it and lower it gently. But
easy to armchair, hard to do! That they have arrived exactly where the barge
is (or would have been) 3 times now is pretty awesome in itself.

~~~
andygates
Very easy to armchair -- but it's a fifteen story beer can, so you need a huge
arrestor system, and it's pretty fragile except up its axis.

The ultimate goal is to land on a flat pad, so adding stuff now moves away
from that goal.

~~~
ChuckMcM
I love the beer can analogy. Agreed it is a really interesting problem. Which
I don't doubt SpaceX will solve. I was not impressed with the ULA "lets just
catch the engines with a helicopter" idea.

Can't wait to see the recovered barge video.

------
icpmacdo
"Ascent successful. Dragon enroute to Space Station. Rocket landed on
droneship, but too hard for survival."

[https://twitter.com/elonmusk/status/588076749562318849](https://twitter.com/elonmusk/status/588076749562318849)

~~~
cygx
Not totally unexpected:

 _Odds of rocket landing successfully today are still less than 50%._ [1]

[1]
[https://twitter.com/elonmusk/status/587704139225759744](https://twitter.com/elonmusk/status/587704139225759744)

~~~
smackfu
I think Musk said he just made up the original 50% odds.

~~~
baq
the original, yes. now they've got experience and say they've got 80% odds for
landing one first stage by the end of the year.

~~~
tsotha
How can that make sense? Until they actually get a successful landing they
can't be sure they don't have a problem that causes a failure 100% of the
time.

~~~
smeyer
Presumably they've tried to estimate that probability and factored it into the
20% probability of not succeeding. (I don't know though, since I haven't seen
the calculation.)

~~~
tsotha
Still... you can't assign a probability to something that is, by definition,
unknown.

    
    
      "This is just a complete guess..." <-- reasonable
      "Bayesian analysis tells us..."    <-- smells of ass

~~~
TeMPOraL
But you shouldn't also pretend you have _zero_ information. They hit the barge
last time, engineering principles are sound, so those two things alone give
you an estimate of "quite likely". Yes, 80% is kind of arbitrary, but it tells
you the same story as "quite likely" with an added benefit of being able to
plug it into some math that will yield you better results than going with just
words.

See "If It’s Worth Doing, It’s Worth Doing With Made-Up Statistics":
[http://slatestarcodex.com/2013/05/02/if-its-worth-doing-
its-...](http://slatestarcodex.com/2013/05/02/if-its-worth-doing-its-worth-
doing-with-made-up-statistics/).

~~~
tsotha
>But you shouldn't also pretend you have zero information.

If you've _never_ done something before you really have no idea if it's going
to work, and in rocket launch everything that occurs after the last failure is
a complete unknown in terms of failure modes.

Now, if he'd made successful flyback stages before, or it was a relatively
routine thing for the industry he _might_ have a good enough feel to assign a
ballpark number. But that's not the situation.

In the link you provided he uses computer failure as an example, where a
person who is familiar with computers does have some information - I've owned
my current rig for three years and it's never failed. If you told me you
thought it has a 50% chance of failure next month I can pretty confidently say
that's an overestimate.

But it's useless to pull numbers out of the air for something as complicated
as SpaceX is trying to do.

~~~
FeepingCreature
If you have an expectation, you have a probability. Not a numeric one, but a
probability nonetheless.

Nobody has ever landed a rocket before. But we don't expect the rocket to turn
into an alarm clock or suddenly develop antigravity. In fact, we have quite
reasonable expectations on what behaviors the rocket will exhibit. We might,
for instance, expect the rocket to crash more than we expect it to land. What
else does that say rather than p(crash) > p(land)?

(Of course, this may well come down to "probability as ratio" vs. "probability
as anticipation", which is probably a matter of preference.)

------
rvdm
Such good motivation to want to be an even better programmer / engineer /
scientist.

So inspiring what mankind is capable of when we work together.

~~~
lutorm
You guys know we are looking for software people, right?

[http://www.spacex.com/careers](http://www.spacex.com/careers)

~~~
VieElm
You guys regularly fire some portion (3% to 5%) of your employees every year
yes? I love what you're doing and I'd love to be part of it, but the press
doesn't make it out like a great place to be an employee. It makes sense I
guess, given the risk involved in launching rockets, but this kind of work
environment is probably not for everyone.

[http://www.latimes.com/business/la-fi-spacex-employees-
lawsu...](http://www.latimes.com/business/la-fi-spacex-employees-
lawsuit-20140811-story.html)

~~~
nine_k
Being fired for low performance is okay — if you feel you're continually
perform poorly, you should start to look for another job well ahead of this
moment. California is not a particularly saturated market for software
developers.

Not following the legally required procedure is bad, though.

~~~
justin66
> Being fired for low performance is okay

The problem is that companies following the "fire at least 10% every year in
every department" Jack Welch philosophy tend to let some good people go. It's
a management philosophy that just assumes that there's no such thing as a
really good team, full of worthwhile players.

Its an attitude that works better in professional sports, where hyper-
competitiveness is more often an asset than a liability. The knock-on effects
of a bunch of coworkers trying to outdo one another to make the cut seem as
though they'd make for a crappy work environment, which I believe is what
VieElm was talking about.

~~~
lutorm
It's not appropriate for me to comment on company HR policy. All I'm going to
say is that my impression of the atmosphere on the software team is not at all
"a bunch of coworkers trying to outdo one another to make the cut".

~~~
justin66
lutorm, I should have put a disclaimer in there. I know nothing about SpaceX
policy and so I wasn't trying to cast any aspersions. (and frankly, the 3%
figure VieElm mentioned sounds more like attrition than Neutron Jack policy)

------
ggonweb
Looks like Falcon landed fine, but excess lateral velocity caused it to tip
over post landing -@elonmusk

[https://twitter.com/elonmusk/status/588082574183903232](https://twitter.com/elonmusk/status/588082574183903232)

~~~
david-given
Scott Manley did precisely this in KSP the other day, trying to replicate the
barge landing:

[https://www.youtube.com/watch?v=C9I55o8hQgs](https://www.youtube.com/watch?v=C9I55o8hQgs)

Admittedly, he also replicated all the other possible failure modes too. Turns
out landing on barges is hard.

~~~
swamp40
I wonder how much of the rocket is steel?

Perhaps a barge full of Tesla batteries and electromagnets could grab and hold
it as it comes in?

~~~
Already__Taken
If that's the idea then just land it into a big sunken tube filled with
netting.

------
sylvinus
Incredible photo of S1 almost landing on the barge!
[http://livestream.com/spacex/events/3959775/images/83962965](http://livestream.com/spacex/events/3959775/images/83962965)

------
delibes
That stage 2 engine nozzle really glows hot! Looks hot enough to melt, but
holding together impressively. Also, the exhaust into the vacuum looks like a
messy grey cloud, not the bright cone I might have expected. Very cool. Or
hot.

~~~
dandelany
> That stage 2 engine nozzle really glows hot!

Yes! Amazingly, although the nozzle looks just like a bell-shaped piece of
sheet metal, it in fact uses "regenerative cooling" which means the nozzle is
full of small pipes which wind back and forth like a radiator. The rocket fuel
is passed through these pipes before combustion, resulting in a heat exchange
which is doubly beneficial, keeping the nozzle (relatively) cool and also
heating up the rocket fuel so it combusts more efficiently.

> the exhaust into the vacuum looks like a messy grey cloud, not the bright
> cone I might have expected

Yep, since there is no atmospheric pressure squeezing it into a cone shape,
the exhaust just kind of flies everywhere!

~~~
erobbins
I thought the 2nd stage engine's nozzle extension was radiatively cooled?
First stage engines are regen for sure.

~~~
Crito
Merlin 1C Vacuum had a regeneratively cooled combustion chamber but
radiatively cooled expansion nozzle. I'm not sure if Merlin 1D Vacuum differs
from this though.

------
mladenkovacevic
After this I'm gonna go watch Interstellar for the 3rd time then play some
Elite: Dangerous.

------
Cshelton
"Stage 1 has been saved"!!!

Edit: Apparently it's not what I hoped,
[http://www.reddit.com/r/spacex/comments/2swnth/how_well_does...](http://www.reddit.com/r/spacex/comments/2swnth/how_well_does_the_fts_work_on_an_empty_or_nearly/)

'saved' and 'safed' are pretty similar on stream...

~~~
bowmessage
I heard "Stage 1 FTS has been saved" and shortly after, "Stage 2 FTS has been
saved".

Not sure what FTS means but hopefully its capture was a success!

~~~
eck
FTS means flight termination system. Meaning the thing that blows it up if it
goes off course and is going to crash into people. They were saying "safed"
not "saved", meaning, no longer armed.

~~~
bowmessage
Ah, thanks for the clarification. That makes more sense!

------
ggonweb
Ascent successful. Dragon enroute to Space Station. Rocket landed on
droneship, but too hard for survival. - @elonmusk

[https://twitter.com/elonmusk/status/588076749562318849](https://twitter.com/elonmusk/status/588076749562318849)

------
rebelidealist
Stupid question but why can't the rocket drop horizontally from a close
altitude to a soft floating area? Do they really need it to land vertically?

~~~
cryptoz
SpaceX is preparing the technology to land on Mars. While this particular
rocket will not go to Mars, the next iteration will. There are no soft
floating areas on Mars, therefore that solution will not work. This is also
the reason there are no parachutes, etc. Vertical rocket landings work on
Earth, Mars, the moon, pretty much all surfaces in the accessible solar
system. So having a rocket that can land vertically, refuel, and take off
again is important for space travel, and that's the primary goal here. You can
think of the Falcon 9 rocket and its tests to be like a revenue-generating
prototype, so they're testing a bunch of future technology when they do these
landings.

------
fit2rule
I have an idea for how to improve the landing of the rocket stage: instead of
fold-out landing-legs, why not fold-out _wings_? Or, a combination of both -
legs with wing-like features - they function as wings until close to touch-
down and then feather to support the rocket laterally upon landing?

~~~
david-given
They'd be on the wrong end of the rocket. The centre of mass is close to the
engines, but not that close; the landing legs have to go at the bottom for
obvious reasons, but any aerodynamic surfaces have to go near the vehicle's
stern, as it moves through the air. Since it's descending vertically, this
means the top. This is what the pop-out grid fins way up are for.

Fun fact: if the F9 first stage had traditional fins at the bottom, they
wouldn't be able to do this. The vehicle would tumble in the upper atmosphere
and end up either nosediving into the ground or breaking up.

Don't believe me? Go get the KSP demo and try it for yourself! The demo is
pretty ancient, but it is free:
[https://kerbalspaceprogram.com/demo.php](https://kerbalspaceprogram.com/demo.php)

~~~
fit2rule
I believe you and I understand the problem (I make planes for fun, so know a
little bit about aerodynamics and CG) .. but what I think is that the wings
could indeed be mounted to the rocket higher up the frame, over the legs - so
when the legs deploy at the bottom, the wings deploy as well over the top -
they'd be part of the same leg structure, only extended all the way to the top
of the rocket body. Actually they'd need to be rotors, a kind of mini-wing, to
spin the rocket body on descent, for drag .. like maple seed wings that flip
out in the last stage of the flight envelope.

Well of course all this sounds easy, but KISS principles apply I suppose.
Still, I could see this happening at some point in the future ..

------
delibes
I never watched one of these before ... T+13 shows Dragon deploying solar
panels (really should to be called 'wings' I think). I think a second stage
camera shows the Dragon with a some fairing panel spinning away from it. This
is amazing!

~~~
david-given
They also have a camera _inside the liquid oxygen tank_. You can see it drain
away as the second stage engine runs... and then it cuts off. What do you
think happens to the remaining fuel? What happens is that it's _awesome_.

[https://www.youtube.com/watch?v=u656se4e34M](https://www.youtube.com/watch?v=u656se4e34M)

And here's extended video of the last section (I think from a different
launch):

[https://www.youtube.com/watch?v=8HZrrHI34x4](https://www.youtube.com/watch?v=8HZrrHI34x4)

------
bobcostas55
Could someone explain why it's (apparently) so much harder to land on a barge
than it is to dock with the ISS?

~~~
sounds
Just wild guesses here but anyone who has played Kerbal Space Program knows
that while docking is no piece of cake, it happens slowly and you can back off
and try again until you run out of fuel.

Landing on a moving target shouldn't be that hard except you get (almost) zero
weight budget, you're relying on atmospheric braking which means intense heat,
and at the end you're hoping the engine doesn't malfunction.

In case it wasn't clear there, the real challenge here is using something that
wasn't designed for landing - it was designed for liftoff - to do the landing.

Musk is probably just happy it hit the barge, and tried to slow down some.
We'll find out later if it:

a) ran out of fuel

b) misjudged the position and velocity of the barge at the moment of impact

c) landed at the intended speed because there were technical concerns that
kept it from landing any slower

d) something else entirely

But keep in mind, the stage landed on the barge. That means it can be
salvaged! Pretty cool, if you ask me.

~~~
david-given
In addition, even _one_ engine on the F9 first stage, throttled down to its
minimum, generates way too much thrust for the vehicle to do a gentle landing.
They have to do a suicide burn --- they fall towards the launchpad unpowered
and then at the last possible moment light up the engine, and hope that when
they come to a halt they've landed. There is no margin for error.

KSP doesn't really have an equivalent, but you can compare it to trying to
land on the moon using a solid rocket fuel engine. (The difference with SpaceX
is that at least they can turn it off.)

~~~
TeMPOraL
> _KSP doesn 't really have an equivalent, but you can compare it to trying to
> land on the moon using a solid rocket fuel engine. (The difference with
> SpaceX is that at least they can turn it off.)_

Minmus suicide burn with a Mainsail could probably compare.

------
ColinWright
"Official Rumour" is that the first stage hit the drone ship but did not land
well.

[https://twitter.com/sarahcruddas/status/588076036207812609](https://twitter.com/sarahcruddas/status/588076036207812609)

------
jerf
Will we also see the attempt to land the rocket in this stream?

~~~
grecy
At about +1:30 I heard "Recovery platform has acquisition signal"

and then:

"Stage separation confirmed. Good luck stage 1"

and "We have stage 1 boostback startup" then a little while later "stage 1
boostback shutdown" (sounded good)

"stage one entry burn has started" then "stage one entry shutdown"

"stage one is transonic"

"stage one landing burn has started"

"LOS of stage one"

(From reddit: waiting for stage one confirm..... Waiting for tweet from Musk)

officially waiting for word from the landing ship... webcast over.

(From reddit: "We falcon punched the barge" )

(From reddit: "Rumors that the Falcon 9 booster landed on the drone ship, but
not softly. At this point, who knows.")

(From reddit: Not a successful landing today.)

Musk Tweet: "Ascent successful. Dragon enroute to Space Station. Rocket landed
on droneship, but too hard for survival."

[https://twitter.com/elonmusk/status/588076749562318849](https://twitter.com/elonmusk/status/588076749562318849)

~~~
Cshelton
If it's successful I hope they'll show a quick replay for stage 1. Probably
reasons why they don't want to show it live...

~~~
mikeash
From what I understand, the reason they don't show it live is because they
don't have enough bandwidth to transmit live video from the barge. They get a
frame every second or two, and lots of telemetry, but not video.

~~~
ufmace
Which is probably because they don't want to show it live. If they wanted to,
I'm sure they could find a way to get enough bandwidth to it.

Their PR is very well-run, and not only will they not show a live video for
something that they aren't sure is going to go right, they'll also have a
plausible technical excuse for why they can't do it.

Not that I have anything against running your PR well, just admiring it.

~~~
mikeash
I don't buy it. I'm sure Musk (and many others) would like nothing more than
to watch the event live. Just having the stream doesn't mean they'd have to
show it to anybody. It could be kept private. The fact that they don't have a
stream at all means it must be pretty hard. Certainly it can be solved, but
it's hard or expensive enough that other things take priority.

(Note that the seeming ease with which they send live video back from the
rocket during the launch tells us nothing. It's relatively easy to receive
high-bandwidth data from a rocket above the horizon to a tracking station with
a big dish that it can point at the rocket.)

------
spikels
Rocket landed on droneship, but too hard for survival.

[https://mobile.twitter.com/elonmusk/status/58807674956231884...](https://mobile.twitter.com/elonmusk/status/588076749562318849)

------
spikels
Pics of landing - landed on target then fell over

[https://mobile.twitter.com/elonmusk/status/58808257418390323...](https://mobile.twitter.com/elonmusk/status/588082574183903232)

------
ColinWright
T-3 minutes ...

Weather is 60% "go" ... Lightning and clouds still a concern

Schedule:

    
    
                    PDT      ET     GMT     BST
        * Webcast: 12:50   15:55   19:50   10:50
        * Liftoff: 13:10   16:10   20:10   21:10

------
Flockster
Alternative Stream from SpaceX:
[http://www.spacex.com/webcast/](http://www.spacex.com/webcast/)

~~~
exDM69
[https://www.youtube.com/watch?v=csVpa25iqH0](https://www.youtube.com/watch?v=csVpa25iqH0)
official YouTube mirror for SpaceX webcast.

~~~
Flockster
Unfortunately it is not viewable in Germany because of copyright problems.

------
51Cards
@elonmusk - "Looks like Falcon landed fine, but excess lateral velocity caused
it to tip over post landing"

------
PLenz
Looks like we'll have to find out if Stage 1 makes it on twitter. Webcast is
ending.

------
jjar
When is the launch scheduled for? Also, do you think it'll go ahead this time?

~~~
mezeek
4.10 Eastern. Weather looks better than it did yesterday.

------
grey-area
@PlanetaryRsrcs: Go for launch!! T minus 1 minute 30 #A3R!!

------
jkrejci
well at least it didnt blow up. ¯\\_(ツ)_/¯

