ISS Docking
Training

Today is Step 20. It is time to dock!

The ISS is floating in space.
Our spacecraft is getting closer.
We need to connect to it.

This is called docking.
Docking means connecting two spaceships together.

First, we train underwater.
The pool feels like space.
We learn to move slowly and carefully.

Then we fly to the ISS.
10... 9... 8... 3... 2... 1...
Contact! We are connected!

Docking complete. Welcome to the ISS!

Docking with the International Space Station is one of the most precise operations in human spaceflight.

The ISS orbits Earth at approximately 7.7 kilometers per second.
A visiting spacecraft must match this velocity exactly before attempting to dock.
This process — called orbital rendezvous — can take several hours of careful maneuvering.

The docking sequence itself follows strict phases.
Soft capture occurs when the docking ring makes initial contact and probe mechanisms engage.
Hard mate follows, as 12 structural latches lock the two vehicles together permanently.
Finally, pressurization equalizes air pressure in the connecting tunnel so astronauts can safely open the hatch.

To train for this sequence, NASA uses the Neutral Buoyancy Laboratory — a pool containing 23 million liters of water.
Full-scale ISS modules are submerged inside.
Astronauts in weighted spacesuits spend up to 6 hours at a time practicing each step underwater.

During actual docking, the crew monitors translational velocity (forward/backward movement) and rotational axes — pitch, yaw, and roll — simultaneously.
Any deviation beyond a few centimeters requires an immediate thruster correction or a complete docking abort.

The precision required is extraordinary.
Yet astronauts achieve successful docking again and again — because they prepare completely, communicate constantly, and trust each other absolutely.