
Launching and landing rockets: A comparison between Blue Origin and SpaceX - kamilszybalski
http://i.imgur.com/ATkpdAX.png
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benjaminl
This graphic aptly shows the differences in complexity between the two flight
plans, but it doesn't show the biggest difference between the two rockets.
When the Falcon 9, enters space at the height of 100 km, it is traveling at
5000 km/h with 125 metric tons of payload[0]. Blue Origin's New Shepard, the
best I can tell was traveling at ~0 km/h at that height, as it reached apogee
at the height of 100.5 km and began falling back to Earth.

According to Musk[0], a first stage of a rocket is judged by the energy it can
impart to its payload at the standardized height of 100 km. Merely getting to
100 km is the easy part. The Falcon 9 is able to deliver 120 giga-joules to
its payload at the height of 100 km, while performing a return to launch site
landing. While it appears the New Shepard had ~0 joules left at 100 km.

[0] - [http://www.spacex.com/news/2015/12/21/background-tonights-
la...](http://www.spacex.com/news/2015/12/21/background-tonights-launch)

[1] - [https://www.blueorigin.com/news/news/blue-origin-makes-
histo...](https://www.blueorigin.com/news/news/blue-origin-makes-historic-
rocket-landing)

~~~
jzila
Potential energy is energy, so it's not quite correct that New Shepard had 0
joules at 100km. At 100km and 0 velocity it'll have about 1 gigajoule of
energy per metric ton of mass.

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lutefisk
Potential energy is not energy that you can give to a payload unless you want
to have it fall 100km back to earth.

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jzila
Sure, but it's energy that a rocket needs to impart nevertheless.

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gfodor
The point was that the measurement is what it can impart on a payload
(presumably one going UP.) So your point doesn't seem relevant.

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jzila
I think the point was to illustrate the difference in energy requirements for
the rocket to impart to the payload.

That said, re-reading Elon's article, he did explicitly say _kinetic_ energy
in the 120GJ figure, in which case 0 is the right number for New Shepard at
100km.

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nanofortnight
A more apt comparison is this: A single SpaceX F9 rocket can lift _three_ Blue
Origin New Shepards _into orbit_ at 200km altitude (vs merely touching space
at 100km) and then _come back to land_.

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cowkingdeluxe
Here's a size difference comparison as well:
[http://i.imgur.com/g2VIKVC.jpg](http://i.imgur.com/g2VIKVC.jpg)

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smackfu
So it turns out that guy messed up the SpaceX plot (the distance downrange was
doubled), and posted a corrected one to reddit:
[http://i.imgur.com/Z81NgAk.png](http://i.imgur.com/Z81NgAk.png)

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hiccup
Jeff Bezos: "... Welcome to the club!"
[https://twitter.com/jeffbezos/status/679116636310360067](https://twitter.com/jeffbezos/status/679116636310360067)

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kamilszybalski
The best part about that tweet is how Jeff double spaces after a period.

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fvdfogi
Why is that the best part?

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devindotcom
It's sort of a nonstandard punctuation thing, especially on Twitter, where
characters are limited and space-saving measures like single spaces after
periods are standard.

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exabrial
I'm curious, why does the falcon reverse course after having so much lateral
velocity? Why not launch somewhere in Arizona and land in Texas or Florida?

~~~
cesarb
Probably to avoid a path which goes over populated land. Launches almost
always go east to benefit from the Earth's rotation, so you want to launch
from the eastern coast if at all possible.

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bryanlarsen
It's also a great illustration why SpaceX landing on land requires
substantially more reserve fuel than a barge landing. (look at the length of
the burn at apogee)

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bobalouie1-_
For those trying to figure out the importance of who did what first please
read . [http://www.theverge.com/2015/11/24/9793220/blue-origin-vs-
sp...](http://www.theverge.com/2015/11/24/9793220/blue-origin-vs-spacex-
rocket-landing-jeff-bezos-elon-musk)

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bobalouie1-_
Please read this Trisell and others who are so concerned about who did what
first. [http://www.theverge.com/2015/11/24/9793220/blue-origin-vs-
sp...](http://www.theverge.com/2015/11/24/9793220/blue-origin-vs-spacex-
rocket-landing-jeff-bezos-elon-musk)

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Shish2k
A somewhat tangential question I've had since seeing the landing -- why are
these rockets trying to land by themselves, which seems really difficult,
compared to say getting the rocket _roughly_ in the right place and then
having a robotic arm attached to the ground reach out and grab them?

~~~
DougWebb
Two big issues with that. First, the arm would have to grab an attachment
point of some sort, so you'd be trying to position the rocket and the hand
close together and still enough to lock on. That's a much smaller and tougher
target than landing. Second, there's no way you could build a robotic arm and
grasping mechanism that's strong enough to hold the rocket once the engine
shuts down, while also being nimble enough to reach out and grab it. To even
have a chance, you'd need three arms and three attachment points, evenly
spaced around the rocket, and coordinated to all grab on at the same time.

This sort of thing works well in space when everything is just kind of
floating next to each other, and you only have to deal with very small thrusts
to make small position adjustments, and momentum when you try to move things.
(Weightless != massless) But down on the surface everything that's not solidly
on the ground is constantly accelerating towards the center of the planet, and
it takes a lot of force to counter-act that.

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anovikov
What about hard numbers? Anyone has delta-v figures for first stage ascent,
velocity both vertical and lateral components at meco, and delta-v for
boostback, entry, and landing burns?

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IshKebab
This is pretty cool. Is the first stage trajectory to scale here?

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Overtonwindow
Dear Jeff Bezos: Suck it.

Sincerely, Science

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Trisell
The problem that SpaceX has is that Blue Origin did it first. Even if the
technical challenges were larger for SpaceX then Blue Origin.

In the mind of the general public that cares, it's all the same thing. The
technicalities of a suborbital flight of a small capsule verses an orbital
flight carrying a payload is meaningless. They just saw the Blue Origin rocket
do it, and then the SpaceX rocket do it, and they looked about the same.

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joelrunyon
Nope.

SpaceX did it in 2011 w/ Grasshopper -
[https://en.wikipedia.org/wiki/Grasshopper_(rocket)](https://en.wikipedia.org/wiki/Grasshopper_\(rocket\))

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schwap
Uh, Grasshopper went < .5 miles up, Blue Origin went _into space_.

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derekp7
Too bad Blue Origin can't actually put anything into space that stays for a
while (such as 11 satellites). The only thing Blue Origin exists for is to
give millionaires a thrill ride that lasts a few minutes. BTW, this isn't
fanboyism -- I really fail to see how the suborbital rockets will advance
humanity's future in space -- whereas getting down the cost to orbit (and
remember, leo is halfway to anywhere) is what is going to open up a new future
for mankind.

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DougWebb
If the millionaire gets out and jumps at apogee, they might stay in space for
a while. But that'll use up Blue Origin's market pretty quickly.

