
Crew Dragon Docks with ISS - Kaibeezy
https://spacenews.com/crew-dragon-docks-with-iss-2/
======
bane
SpaceX runs basically as a giant R&D program that also happens to accomplish
useful things as byproducts of its approach (with the miracle of insurance to
cover costs if things get explody). Every flight is data for incremental
improvement.

If you think of all SpaceX has ever done was try to get to this point, with
somewhere around 80 flights on the Falcon 9, but for a variety of mission
buyers (NASA, USAF, Commercial Sat companies, SpaceX itself!), somewhere
around $5b (~$60m a launch) has been spent getting an entirely new, ground-up
manned space program up and running to include launch vehicle with a majority
re-usability. But along the way, numerous satellites and other stuff ended up
in space as well. This allowed NASA to also split the R&D bill with multiple
"partners".

To put this into context, the Mercury program ran about $2.25b in today's
dollars, Gemini ran $7.3b ($723m per mission!).

The Space Shuttle program had a lifetime cost of $209b ($1.5b per flight!!!)
If you think the Shuttle program is not comparable, the F9Heavy program, a
derivative of this other work, can put up more mass than the Shuttle, managed
to split much of the development costs with the Falcon 9, can land most of its
mass, and has a per flight cost of $90m.

We now have the capability to put up another ISS _today_ , resupply it, and
staff it, at a fraction of the cost, all with launch equipment made by a
single company that started a decade ago as a side project for a guy who was
trying to make electric cars after making money on the internet.

This is a ridiculous bargain and Spacex isn't even close to done yet.

~~~
7thaccount
Incredibly impressive, but you have to take into account both more modern
technology, as well as the fact that they were able to build off the shoulders
of giants. It is still amazing of course, but I doubt they could've done the
same thing during the era of the mercury program, so not really apples to
apples comparison.

~~~
pfdietz
Guidance systems are vastly less expensive now, and can take advantage of
things like MEMs, fiber laser gyros, and GPS (and, of course, modern computing
power).

The tanks on Falcon are welded using Friction Stir Welding, which was invented
in the early 1990s.

The landing algorithm for the first stage uses convex optimization algorithms
based on interior point methods, which were not available in the 1960s.

However, something very much like an expendable F9 could probably have been
built in the 1980s. Simply evolving the Saturn 1B (which was cheaper, per lb
of payload to orbit, than the Saturn V) could have easily beaten the Shuttle's
economic performance.

~~~
jes
I had not heard of Friction Stir Welding previously. Video that demonstrates
the technique is here:

[https://www.youtube.com/watch?v=aNbQH8XBgxQ](https://www.youtube.com/watch?v=aNbQH8XBgxQ)

~~~
725686
Smarter Every Day has a very interesting video[1] inside the factory of United
Launch Alliance in which, among a lot of other things, shows the friction stir
welding used in their Atlas Rocket[2]:

[1] [https://youtu.be/o0fG_lnVhHw](https://youtu.be/o0fG_lnVhHw)

[2] [https://youtu.be/o0fG_lnVhHw?t=1933](https://youtu.be/o0fG_lnVhHw?t=1933)

~~~
jes
This is a great video. Thank you for sharing it.

------
flixic
You can try docking yourself at [https://iss-sim.spacex.com](https://iss-
sim.spacex.com)

~~~
ericol
Took me 3 tries to do it; my bad was not carefully reading the instructions.

~~~
cbhl
First three times I tried doing it by eye and ended up hopelessly lost. Needed
to pull out my trigonometry to figure out how to line up the capsule to get
the Y/Z aligned...

~~~
yellowapple
I got it on the first try, but only because I've got 600+ hours of Kerbal
Space Program under my belt (where docking is much harder when you consider
that docking in KSP entails actually getting to the target and doing it with
imbalanced RCS thrusters that I placed on the craft willy-nilly; SpaceX's
online docking sim was a breeze in comparison).

Trick was to get rotation aligned first, then worry about translation. And
yeah, might as well ignore visual; just went by the numbers.

~~~
mortehu
If you do rotation then translation, you're either going to waste fuel or
time. Just aim for the target and get within 20 meters before doing any of
that, and the amount of translation you'll have to do is minimal. It's like
traveling on the hypotenuse instead of the other two sides of a right
triangle.

~~~
yellowapple
Rotating before translating should have little to no impact on fuel
consumption. You still have to do the same amount of translation no matter how
the craft is oriented. That means the same amount of energy, and thus the same
amount of fuel. It took a _little_ bit more time, but at the timeframes
typical of orbital docking it's negligible.

In my first-try-success attempt, I was doing _all_ translations at once, not
something silly like lining up the numbers one at a time (that won't work well
anyway, due to the differences in orbit between yourself and the docking
target). That is: moving toward the ISS while simultaneously moving up/down
and left/right to line up, and thus moving along the hypotenuse.

And by the way, this seems to be the exact approach Crew Dragon _Endeavour_
took, judging by what I saw in the livestream early Sunday morning. They were
already lined up rotationally before starting the final docking approach.

~~~
mortehu
Yes, you're right. You can of course travel on the hypotenuse even if you're
not oriented along it. I was probably stuck in some fixed front wheel
thinking. I would think it's a lot easier to get the the proportion of lateral
speed exactly right if you're aimed along the hypotenuse though.

~~~
yellowapple
True. Still, if you wanted to get really exact about it, you could surely work
it out mathematically (i.e. by making sure your velocity components are
proportional to your distance components).

So for example, with the simulator loaded up in a tab right now, after lining
up the rotation, I'm seeing:

    
    
        X | 200.0 m
        Y | 12.0 m
        Z | 30.0 m
    

So if I then apply an X thrust of 20 m/s, Y thrust of 1.2 m/s, and Z thrust of
3.0 m/s, then I should travel along the hypotenuse and reach the docking port
in 10 seconds. Likewise, a thrust of X=2,Y=0.12,Z=0.3 would get me there in
100 seconds (and X=200,Y=12,Z=30 would get me there in an insane single
second). Of course, some corrections will be necessary along the way to
account for small differences between my orbit and the target orbit (which is
more relevant the longer it takes for you to get to the target), and the
velocity change ain't instantaneous so I'll need to adjust for that, too
(making 10s or 1s runs kinda implausible with the current interface, unless
perhaps I do some kind of browser-level scripting to click the buttons and
read the numbers).

Crucially, this makes it feasible for a computer to do automatically (though
automated docking tends to stop shy of actually docking from what I
understand, instead using CanadArm to grab the craft and put it on the dock).

You're right that aiming along the hypotenuse makes this a little bit easier
to eyeball, but it also makes it a bit harder in other respects since now
you'll have to adjust both rotation _and_ translation along the way to stay
along that slightly-curving hypotenuse.

------
hinkley
I recall Elon was hoping to get an order of magnitude reduction in cost per
launch, but Wikipedia claims it costs $160 million per launch versus the Soyuz
price of $76 million per astronaut. That would “only” be a 3x reduction with a
crew of seven, but they’ve configured for a crew of four, which is a hair
under 2x.

I wonder how reuse affects the math, and what they’ll be able to do to lower
those prices further. Obviously the optics on getting a domestic launch for
half the price makes it an easy sale for Congress, but we were all hoping for
more. An order of magnitude reduction might have gotten us 20x as many
launches.

~~~
danpalmer
Worth noting that Dragon also carries tons of cargo, whereas the Soyuz
“sticker price” is for just a seat.

~~~
avian
> Dragon also carries tons of cargo

Does it? I seem to remember reading somewhere that the "trunk" section will be
mostly empty on crewed vehicles.

It makes sense. We've seen that Dragon aborts with the trunk attached for
aerodynamic reasons. It seems likely that hauling a bunch of cargo together
with an escaping crewed capsule isn't feasible.

You could also see that during the Demo-2 launch stream when the Dragon
separated from the upper stage. There was a short segment where camera from
the stage showed the underside of the Dragon and you could see that it was
mostly just empty space inside.

~~~
hinkley
The color commentary yesterday suggested that a bit of cargo could be where
the other 3 passengers should be, so he might be right.

------
elliekelly
From NASA's Mission Updates:

> The Crew Dragon arrived at the station’s Harmony port, docking at 10:16 a.m.
> EDT while the spacecraft were flying about 262 miles above the northern
> border of China and Mongolia.

It's hard for me to wrap my brain around this. They seem so far away but 262
miles above earth is about the distance from NYC to DC which doesn't seem far
at all.

~~~
jandrese
There is a fantastic what if that talks about this.

[https://what-if.xkcd.com/58/](https://what-if.xkcd.com/58/)

~~~
bobwaycott
You’re right. That was fantastic. Hadn’t seen that one before. Thank you.

------
swimfar
SpaceX Live Stream:
[https://www.youtube.com/watch?v=bIZsnKGV8TE](https://www.youtube.com/watch?v=bIZsnKGV8TE)

Docking begins to occur around 3:10PM GMT in the video. This link may send you
to that point:
[https://www.youtube.com/watch?v=bIZsnKGV8TE&t=695m0s](https://www.youtube.com/watch?v=bIZsnKGV8TE&t=695m0s)

Is there an easy way to link to a specific time in live videos? I had to
manually play around with the time to find the right point.

------
orisho
They mentioned something about the suit pressure for one of them being lower
than expected and asked them to check for "white teeth" on 3 zippers, which
they reported seeing on all 3. Can anyone explain what that is?

~~~
scrumbledober
Sounds like when the zippers are fully closed the white teeth of the zipper
should be covered by the seal around the zipper. If any teeth are visible the
seal is not complete.

~~~
hinkley
Or perhaps the seal is behind the zipper and high contrast.

------
haunter
Currently they have problems with the voice between ISS and Dragon. There is a
huge interference and they can't read it. Funny enough we the viewers hear it
loud and clear

~~~
moftz
I'm sure an easy workaround would be to use Houston as a relay rather than
direct communication.

~~~
haunter
Yep that's what they are doing now

------
205guy
Am I the only one who can hear the Blue Danube Waltz just thinking about
Dragon docking at the ISS?

[https://youtu.be/0ZoSYsNADtY?t=210](https://youtu.be/0ZoSYsNADtY?t=210)

------
cletus
So when seeing this I had two questions, one of which I've found the answer
to, one of which still remains a mystery.

1\. Why only two astronauts? and

2\. How much is Crew Dragon costing?

For (1), it's stated [1] that Crew Dragon has a capacity of seven astronauts
but only 4 for NASA? How does that work? Does that mean the NASA configuration
only has 4 seats? I found this [2] saying seats 1 and 4 were empty.

Why not 4 astronauts? The answer seems to be that this is technically a test
flight (Crew Demo-2). Passing this will fully certify Dragon. I guess it's
better to risk 2 astronauts than 4. It probably also depends how many people
you want to have on the ISS.

As for (2), I found this [3], which states the cost at $55m per astronaut.
This seems... high? A full complement of 4 would cost $210m. Falcon 9 launches
cost a fraction of that. Even Falcon Heavy is ~$90m.

For some reason I thought SpaceX was enabling sending up 7 astronauts for
<$100m.

Compared to Soyuz [4], which cost NASA $80m/astronaut, that's a saving but not
as much as I would've thought.

[1]:
[https://en.wikipedia.org/wiki/Dragon_2](https://en.wikipedia.org/wiki/Dragon_2)

[2]: [https://blogs.nasa.gov/commercialcrew/2020/05/30/all-
aboard-...](https://blogs.nasa.gov/commercialcrew/2020/05/30/all-aboard-
astronauts-ingress-crew-dragon/)

[3]: [https://www.space.com/spacex-boeing-commercial-crew-seat-
pri...](https://www.space.com/spacex-boeing-commercial-crew-seat-prices.html)

[4]: [https://www.wired.com/story/spacex-launched-two-
astronauts-c...](https://www.wired.com/story/spacex-launched-two-astronauts-
changing-spaceflight-forever/)

~~~
InTheArena
Edited - wrong number of seats for the next mission.

NASA asked SpaceX to change the configuration of the capsule to only support 4
astronauts for two reasons. The first is that they wanted a more mellow Load
profile on the passengers in the case of a high-altitude (almost orbit) abort,
so they wanted the seats in a different position. The first design had the
seats fixed, and the screen pivoting down above them. This design has the
seats pivoting, and the screen fixed. It also drops the maximum crew from 7 to
4. I’m not sure if SpaceX will use the larger configuration for their own
private configurations.

The other reason is that seven is a lot, and NASA doesn’t plan on sending that
many up on a single mission.

Seats 1 and four are empty on this mission. For future missions that only have
three they will remove the extra seat. That said, the capsule seems amazingly
spacious, for being a capsule.

As far as costing, the contract was written similar to how NASA pays the
Russians (though that number is upwards of 87 million per seat right now).
SpaceX itself owns the rockets and the spacecraft - not NASA. Think of it as a
airline seat.

Finally, the vast majority of cost at this point are not the hardware - but
rather the cost of complying with NASA’s testing. Everyone was assuming that
NASA would do what they did with commercial cargo, and simply expect the cargo
to show up with a minimal number of design reviews. With commercial crew, NASA
took a much more proactive approach which led to a complete redesign of the
capsule (SpaceX’s original plan was simply to reuse cargo), plus many many
many design reviews.

Finally SpaceX has full pricing control right now. SpaceX is running some
pretty massive margins (from what I have heard) on everything - but they are
flushing all of that money into the goal of getting starship and spaceship and
their insane next generation engine up, as well as starlink. They have
deliberately only lowered their costs below their competitors, soaking margin
for a while.

~~~
_Microft
Crew-1 is flying four astronauts.

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

------
ape4
Watching now.. they were unable to get the "hard line" voice working. VOIP?

~~~
yellowapple
Considering how long the ISS has been up there, it could be POTS or something
similarly-analog. Dragon→ISS was clear, but ISS→Dragon was not, making me
think that maybe there's some wire or connector in the latter direction that's
shoddy (and that'd be more common for analog/POTS than digital/VOIP, where
such garbling would be bidirectional and/or nothing would be heard on either
end).

Then again, I ain't exactly a space telecom engineer, so what do I know? ;)

They've since switched back to RF, so apparently it ain't the end of the
world.

~~~
ape4
Makes sense. They just fixed the hard line

~~~
yellowapple
Was that the hardline or did they reroute through RF and/or "Big Loop"? I
heard the loud and clear (and earlier about the cameras possibly interfering)
but missed if that loud and clear was through the hardline.

~~~
ape4
Sorry dont know. Did hear mention of big loop

------
neals
Did Doug bump his head on the way in?

~~~
war1025
Came here hoping to find an answer to this. It looked like it was bothering
him quite a bit

~~~
neals
Apparently, space is hard...

~~~
olex
Station hatches sure as hell are. Looks like it happened during the hug
session, while still mostly inside the hatch.

------
Kaibeezy
“flew exactly like the simulators”

~~~
gpm
They did complain about the thermal camera cutting out as the thrusters fired
in real life and not in the simulator at one point. Was that fixed in the
later test?

~~~
bkanber
I thought what I heard is that the thermal cameras did cut out even in the
sim, but that on-ship they cut out differently. My assumption is that this is
something that gets fixed on the ground.

------
JoeAltmaier
What's with the gradient shadow? The space station shadow crossed the module,
and it was blurry. I thought shadows in space were knife-sharp. The nose-cone
shadow was.

Its not the stream resolution, is it? Other knife-sharp features were visible.

Maybe the space station is fuzzy? Maybe the module material blurs shadows?
What am I missing?

~~~
teraflop
Shadows in space aren't, in general, any sharper than on Earth. The "penumbra"
of a shadow -- the blurry, partially-shaded region -- is basically a simple
geometric effect, caused by the light source being partially obscured. The
penumbra's size is approximately equal to the product of the light source's
angular size and the distance from the shadow-casting object to the
illuminated surface. (Diffraction has some effect as well, but only on very
small scales that aren't particularly relevant here.)

The sun has almost exactly the same apparent angular size from either Earth's
surface or LEO, because it's almost exactly the same distance away. But since
that angular size is only about half a degree, shadows observed _at short
distances_ appear fairly sharp, either on Earth or in space.

What you may be thinking of is that, in many cases, shadows are _darker_ in
space, because the _sky_ is dark, even in broad daylight. There's no
atmospheric scattering to provide indirect, ambient illumination of regions
that are shaded from direct sunlight. But there can still be indirect lighting
from other surfaces.

For example, in photos of Apollo astronauts on the moon, shaded regions of the
astronauts' spacesuits are still fairly-well illuminated by light bouncing off
the lunar surface. But shadowed regions of the surface itself appear almost
pitch-black, because the only thing they can "see" is the dark sky.

------
MobileVet
Hatch opening scheduled for approximately 12:30pm EDT

Edit: time slipping

------
jari_mustonen
We are a small step closer inhabiting Mars.

When we will, it will be the most important event in the five billion years
history of our solar system. In other words, we are witnessing some pretty
cool stuff.

~~~
godzillabrennus
Elon Musk will have cities on planets names after him for generations to come.

The legacy he leaves will be greater than that of Ghengis Kahn, Ceasar, or
Alexander the Great.

~~~
tnli
Elonville, Musktown?

~~~
gfodor
I put like 90% liklihood we'll have a nation state named "Musk" on Mars in 50
years.

~~~
red2awn
A nation in 50 years sounds like an Elon timescale. More likely a small
settlement of <100 people for research and exploration.

------
mchusma
I was surprised they slept on the trip. I assume they took turns.

~~~
toomuchtodo
Autopilot :)

~~~
Kaibeezy
Right? It’s basically a Tesla.

~~~
TeMPOraL
Yeah. Except autopilot is easier in space than on the road, because it doesn't
have to take into account the multitudes of vehicles (and pedestrians) without
an autopilot, just zooming around.

~~~
yellowapple
I mean, not yet. Someday, though...

------
hansoolo
Why is it such a big deal this time? Don't the Russians fly to ISS all the
time?

~~~
djhworld
Few reasons, it's been 9 years since the last crewed spacecraft took off from
American soil.

Second reason is this is the first time the spacecraft has been built and run
by a commercial company (spacex)

~~~
hansoolo
For me (as a European) it is mainly exceptional because of the SpaceX effort.
It just appeared to me as if it was something America was proud of, because
they invented space flight or something, which they didn't. It's just never
"celebrated" anywhere when the Russians fly to space over and over.

~~~
s_y_n_t_a_x
America is proud because SpaceX is an American company that has made this
possible while being commercially viable.

It's a testament to American capitalism. It's something to be very proud of.

It's the next step in the space age. This paves the way for many more
companies and ventures.

------
hartator
Do we have a link to rewatch both the launch and the docking?

------
OctaviusCrassus
Unbelievable what Elon Musk has been able to create for humanity. So grateful
for him and this administration. Looking forward to see more free market
ingenuity

~~~
stevens32
Free market doesn't seem correct here since the government is the customer.

~~~
OctaviusCrassus
Govt is 100% funded from the free market

~~~
stevens32
> In a free market, the laws and forces of supply and demand are free from any
> intervention by a government or other authority and from all forms of
> economic privilege, monopolies and artificial scarcities

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

------
kthxbye123
Very impressive - only sixty years after the Communists put a man into space,
the private sector has managed to catch up.

------
jtdev
How much AI/ML do you think is running on the software associated with this
launch and docking? I suspect there’s a great deal of very explicit, well
tested code, but very little AI/ML.

~~~
moftz
Very little in terms of what you would consider AI or ML. It's a lot of trig
and control theory. You do a lot of the math beforehand to figure out the
script the craft will follow to reach the ISS. Once it gets close, you either
use manual controls or let autopilot do the docking. The autopilot is
basically looking some dots on a camera and firing the thrusters to make the
dots line up right. It's more like a dumb PID controller than an AI. The
autopilot isn't learning anything or somehow making connections that weren't
already programmed. This is all stuff NASA figured out how to do in the 60s so
it's nothing novel except for the mission and the hardware the math is done
on.

~~~
landa
What you wrote is what I would have _guessed_. Are you also guessing or do you
know for sure? It sounds right, but I'm very curious about the actual answer
to this question.

~~~
NikolaeVarius
No one is putting non deterministic code anywhere near one of the most
expensive objects ever produced

------
_ah
I am so excited by this achievement, and offer hearty congratulations to
SpaceX and NASA.

That said, I think that everyone anticipating a dramatic reduction in orbital
cost needs to temper their enthusiasm a bit. UAL was expensive, as many other
have previously noted, because it was a political jobs program. The _existence
of UAL_ gave the necessary cover for Musk & Co to envision radically more
efficient designs.

However, that was then. As SpaceX continues to succeed, it will be harder to
justify continued funding of UAL at the previous levels. Costs will be cut.
People will cheer. And then, a well-meaning congressperson or two (with their
eye on re-election) will introduce a rider onto the next funding bill: "Yes we
want these great launch capabilities, but at least $1B must be spent within
the state of Alabama" (or whatever).

This will work for a little while, but then more members of congress will jump
on the gravy train. In order for SpaceX to maintain their launch contracts
they will need to perform more and more work in distributed places. This will
result in reduced organizational efficiency and increased launch cost.

The big opportunity here is commercial launch. If SpaceX can grow their
civilian and international order book enough, they become less beholden to the
US Govt and can push back on make-work contract requirements. But if not... I
await their inevitable induction into UAL v2.

~~~
sgtnoodle
I think your last paragraph is the most likely. SpaceX will simply not accept
a government contract that works against their interests since they are a
private entity. If starlink pans out, government contracts won't be such an
important source of revenue long term.

