
Docking standard for the International Space Station - forza
http://internationaldockingstandard.com/
======
smithian
This is not actually the interface that is used on the Dragon. This is a
docking mechanism, which allows autonomous connections between two spacecraft.
The Dragon uses the Common Berthing Mechanism (CBM) which requires assistance
from a manipulator arm to mate the two spacecraft.

One of the reasons the CBM was chosen for the resupply ships (including
Dragon) is that the CBM has a larger inside diameter and so larger pieces of
equipment (such as standard equipment racks) can be delivered through it,
while the docking connectors cannot pass them.

~~~
forza
Correct. But the manned Dragon spacecraft, cleverly named DragonRider, will
use this interface.

------
unwind
Clearly, section 3.2.1 is the most important part:

 _All dimensions are in millimeters. All angular dimensions are in degrees_

Implementors in non-metric countries, take note. Nothing is more annoying than
arriving at a place where you might want to use your docking interface, only
to find out it doesn't work. :)

~~~
dexen
_> Nothing is more annoying than arriving at a place (...) to find out it
doesn't work. :)_

Which has sort-of happened already in history of space exploration, when Mars
Climate Orbiter mis-handled Mars orbitial insertion and was lost. The problem
was traced down to mis-match of measurement units used in software (Newtons
vs. Pound-force).

[http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_f...](http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure)

~~~
drzaiusapelord
Yep happened once in 50 years of space travel.

Ugh, we get it, everyone thinks they're being cute and its a way to mock US
units. Yes, yes, this isn't getting incredibly tiresome.

~~~
wallflower
The most famous smallest but most significant human error was Mariner I:

"The error had occurred when a symbol was being transcribed by hand in the
specification for the guidance program. The writer missed the superscript bar
(or overline) in [the formula] by which was meant "the nth smoothed value of
the time derivative of a radius R". Without the smoothing function indicated
by the bar, the program treated normal minor variations of velocity as if they
were serious, causing spurious corrections that sent the rocket off course. It
was then destroyed by the Range Safety Officer."

<http://en.wikipedia.org/wiki/Mariner_1>

------
fasteddie31003
Is it just me or does this docking design look overly complex and easily
damaged by a docking miss? I am partial to designs with as few moving parts as
possible. Maybe I am nieve to the needs of space docking too.

~~~
smackfu
Actually, this is intentionally a low impact design, to avoid the following
problems with the old "ram into each other" method:

* require substantial force and velocity for docking alignment and capture

* create critical operations

* affect structure fatigue life

* disturb zero-g environments

* difficult for small mass vehicles to use

* support a limited range of vehicle performance capabilities

So the miss you're thinking of isn't really where this is used. Also, this is
an androgynous design (it can dock to itself) which makes things more complex.

(From this PDF:
[http://dockingstandard.nasa.gov/Meetings/TIM_%28Nov-17-2010%...](http://dockingstandard.nasa.gov/Meetings/TIM_%28Nov-17-2010%29/NDS_TIM_presentation.pdf)
)

------
qntm
> Vehicles using this interface may include light vehicles in the range of
> 5-8K kg, and medium vehicles in the range of 8-25K kg. These vehicles will
> dock to each other, to large space complexes in the range of 100-375K kg,
> and to large earth departure stages in the range of 33-170K kg.

I've never seen "K kg" stand for metric tonnes before. Two Ks of different
cases both standing for "kilo-" therefore meaning "kilokilogram"? At first I
thought "five kilograms is quite small for a spaceship" and then I had to re-
read it. To say nothing of the fact that "K" means Kelvin, not kilo-.

On the other hand, what are the other options? "Mg" for "megagram"?

~~~
Someone
There are (several) guidelines that abolish certain abbreviations because
misinterpretation can kill, for example
<http://www.ismp.org/Tools/errorproneabbreviations.pdf>

I cannot find a guideline w.r.t. Mg, but it can easily be confused with
milligram and microgram. That may be the reason to use this weird construct
('ton' seems a better term, but it is ambiguous, too)

~~~
qntm
"Ton" would be ambiguous, but "tonne" is unambiguously the metric tonne (1000
kilograms).

------
harichinnan
Mating Interface Definition.. Androgynous Docking System.. Soft
Capturing..Hard Capturing.. Someone in NASA was watching porn when they wrote
this.

~~~
klickverbot
Definitely: »The IDSS docking interface is fully androgynous about one axis,
meaning the interface configuration is capable of mating to an identical
configuration«

~~~
excuse-me
Is that an official Nasa chat-up line ?

------
jallmann
That's refreshing -- we're sending things into space from a readable 31-page
spec (with pictures!). RFC authors, take note.

~~~
jimktrains2
31-page spec for the door;)

------
gklitt
It'll be fun watching the Dragon docking live while following along with this
document.

------
jluxenberg
I think this is the protocol that Dragon is following on the current mission:

[http://spacecraft.ssl.umd.edu/design_lib/SSP50235.ISSvehicle...](http://spacecraft.ssl.umd.edu/design_lib/SSP50235.ISSvehicleIDD.pdf)

------
nilaykumar
We're living the future, guys.

------
sharkweek
I don't want to be the immature one here -- but I can't help but feel there is
a "yo momma" joke in there somewhere

