
SpaceX: CRS-10 Hosted webcast - manaskarekar
https://www.youtube.com/watch?v=giNhaEzv_PI
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andreasley
Gorgeous external video of the landing:
[https://www.youtube.com/watch?v=glEvogjdEVY](https://www.youtube.com/watch?v=glEvogjdEVY)

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wiremine
Watched it this morning... extremely cool. I missed why they landed on land
instead of on a barge. Anybody know?

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unspecified
The landing is all based on how much fuel is left after the primary mission is
complete: some missions require more fuel to get to their destination orbits,
others require less.

This launch was an ISS resupply, which is on the low end of fuel requirements.
So the first stage can get all the way back to its launch site.

Other launches are in the middle of the fuel range: they just follow their
ballistic path to the barge, and do not have the extra fuel to get turned all
the way back around for a return to the launch site.

A few launches are at the very high end: the upcoming Echostar mission has
such a high fuel requirement that SpaceX isn't even attempting a landing:
they're just dumping the whole stage into the ocean like we've been doing for
60 years.

SpaceX is saying that this upcoming Echostar launch will be their last
"expendable launch", ever.

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wiremine
Very helpful. Thx!

> A few launches are at the very high end: the upcoming Echostar mission has
> such a high fuel requirement that SpaceX isn't even attempting a landing:
> they're just dumping the whole stage into the ocean like we've been doing
> for 60 years... SpaceX is saying that this upcoming Echostar launch will be
> their last "expendable launch", ever.

Can I infer that they won't be doing launches that require high-end fuel
usage? Are they just giving up on those types of use cases, or do they have
another solution for those moving forward?

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zackmorris
Something to keep in mind is that for space exploration, all that really
matters is achieving low earth orbit (LEO). After that, ion engines/solar
sails/space tethers, all manner or propulsion can get us out to further
reaches. But it takes dedicated engineering to build craft powerful enough to
get through the atmosphere with only a small fraction of mass going to engine
and airframe.

The cost of fuel is generally pretty negligible compared to the cost of
spacecraft. Even 1,000,000 pounds of kerosene only costs about $500,000 ($3
per gallon at 7 pounds per gallon). I'm having trouble finding current prices
on liquid oxygen but it looks like about 15 cents per pound, so a 2.56:1
ox:fuel ratio gives $384,000 for 2,560,000 pounds of oxygen. (500,000 +
384,000)/(1,000,000 + 2,560,000) = 25 cents per pound of fuel+oxidizer
(honestly I have to saw wow here, as this is much lower than I expected). If a
shuttle launch cost $1 billion, less than $1 million went to fuel at 2017
prices (assuming that more expensive liquid hydrogen and less expensive
booster solid fuel roughly match the cost of ox-kerosene). Another way of
saying this is that the design tradeoffs of the shuttle cost 100 to 1000 times
more than other designs might have (mainly due to reusing the orbiter rather
than the first stages). A lot of people knew this in the late 70s and warned
about it, but due to political reasons NASA went with the more expensive
shuttle system and now here we are.

My guess is that from here on, SpaceX will do incremental launches, using a
rocket to carry a stage to LEO and then assemble those stages in orbit into
new rockets to go further out, landing the first stages to reuse them. This is
scalable all the way out to Mars and further, which is pretty remarkable and
obvious in hindsight. It wasn't until I considered how one would land a stage
on Mars with such a thin atmosphere that I realized why SpaceX has been so
committed to retrorocket landing.

[https://www.nyserda.ny.gov/Researchers-and-
Policymakers/Ener...](https://www.nyserda.ny.gov/Researchers-and-
Policymakers/Energy-Prices/Kerosene/Average-Kerosene-Prices)

[https://en.wikipedia.org/wiki/Oxygen#Industrial_production](https://en.wikipedia.org/wiki/Oxygen#Industrial_production)

[http://www.astronautix.com/l/loxkerosene.html](http://www.astronautix.com/l/loxkerosene.html)

[http://coolcosmos.ipac.caltech.edu/ask/268-How-much-did-
the-...](http://coolcosmos.ipac.caltech.edu/ask/268-How-much-did-the-Space-
Shuttle-weigh-)

[https://en.wikipedia.org/wiki/Hydrogen_economy#Current_hydro...](https://en.wikipedia.org/wiki/Hydrogen_economy#Current_hydrogen_market)

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greglindahl
Why are you guessing? This is SpaceX's announced plan.

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FLUX-YOU
Oh god, 30-60 FPS during the entire landing except for the 15s burn. Fucking
brilliant, SpaceX.

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manibatra
Amazing to live in times when the first stage landing back has started to feel
like routine! Great job SpaceX!

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lsaferite
Awesome. Just watched it with my 7 year old son and he had so many questions.
I love being able to pass on my love of space. :)

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imdsm
My son is 7... months old, so he doesn't really understand it yet.

I can't wait until he's getting excited about these things.

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XorNot
The landing video for that was beautiful - great footage all the way down.

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spike021
Always cool being able to watch these and understand how my dad felt during
the space race of the 1960s.

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ragebol
Recap of the landing bit:
[https://www.youtube.com/watch?v=CP0ficDsOkE](https://www.youtube.com/watch?v=CP0ficDsOkE)

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Luc
Did anyone see the debris fly past before the second return burn of the first
stage? Some ice I assume?

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nprecup
Yes! I saw it at the 36 minute mark on the video. That had me curious. I think
it was a trick of perspective, it first looked like some huge chunk of debris
that the first stage flew past, but after watching it again, it looks like a
little chunk of ice that got blown off of by the cold gas thrusters.

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Luc
Yes, that's it, a few seconds after the 36 minutes mark. I think you're right,
and it does look a lot smaller upon rewatching!

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castis
For some reason I found it really cool that it was immediately gone into the
overcast.

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detritus
I didn't! I was irritated that I couldn't see anything, so then had a quick
scoot to see if the NASA feed would show the on-board view (unlikely!) before
coming back again to miss the first stage separation!

The landing through the clouds, on the other hand, I did appreciate. Once my
irritation has subsided, anyway!

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hallmark
I recommend watching the Hosted Webcast on one device and the Technical
Webcast on another. Either mute the Technical Webcast or have it on lower
volume. They're both easily found on YouTube under SpaceX.

I did this for the previous launch, Iridium-1, and was treated to unbroken
views live from the first stage on the technical stream, while the hosts
narrated and switched views more frequently on their stream.

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detritus
Oh, that's a good idea, thanks! Next launch!

Yesterday I was stuck with just my phone though, so my 'alt-tabbing' was
particularly tortuous :)

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pbreit
I hadn't seen the landing from the rocket before. That was cool. Makes me
wonder what else in corporate america warrants employee cheering?

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mikeash
This is only the second time they've had live video all the way down. Getting
that much data back from the thing must be tough. They've been making steady
improvements, though, and it's now paying off delightfully.

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rst
Probably easier when it's coming down on land, and not offshore past the
horizon.

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Ajedi32
The last one was offshore, and had video all the way down:
[https://youtu.be/tTmbSur4fcs?t=26m4s](https://youtu.be/tTmbSur4fcs?t=26m4s)

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david-given
...and here's the technical webcast for those of you who can't stand talking
heads:

[https://www.youtube.com/watch?v=rUDLxFUMC9c](https://www.youtube.com/watch?v=rUDLxFUMC9c)

(Although they don't show the onboard footage for the takeoff, unfortunately.
Or in-tank footage, which is always cool.)

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oherrala
NASA Live can be found here:
[https://www.nasa.gov/nasalive](https://www.nasa.gov/nasalive)

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kegan
How long does it take for Dragon to reach ISS?

I should be able to see ISS tomorrow night from my location. Do you know if I
would be able to see Dragon too?

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J0-nas
In the webcast they said that if you can see is ISS you'll see it

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lutorm
Rendezvous isn't scheduled until the 22nd, so there will likely still be quite
a distance between the ISS and Dragon tomorrow. They will be in trail, while
the Earth rotates, so depending on where the ISS passes relative to you
there's a possibility the Earth might have rotated enough by the time Dragon
comes around to not see it. It's definitely worth keeping a look out though.

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sidcool
This is exhilarating! Perfect lift off, separation, landing and deployment. I
am OK with this becoming routing and boring .

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smaddali
It looked so routine, therefore so exciting.

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shripadk
Bravo! Congrats SpaceX! :)

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michaelhamel
Launch at 9:49 AM EST

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michaelhamel
Successful landing!

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CarolineW
Nailed it!

