Docking Port

**Parts Expansion Required**

*Some or all of the parts and/or features on this page require the **Parts Expansion** in-app purchase.*

## Docking Ports

* Small
* Medium
* Large

### Mass (t)

Currently:0.19t (small)
0.4t (medium)
0.6t (large)
Formerly:
0.25t (small)
0.3t (medium)
0.35t (large)

**Docking ports** are parts that are used to connect two spacecraft together. There are a total of three variants of the part, differing in size. The three ports have sizes of 2×1, 4×1 and 6×1 units. These three ports all function identically.

When two spacecraft are docked via the ports, they can both be controlled as one. The physics view camera is positioned in the two spacecrafts' center of mass. Fuel transfer can occur between the two spacecrafts' fuel tanks.

Docking ports have a small "magnetic force" towards another port in order to make the docking process easier. This force can be exploited to create a reactionless engine.

They were introduced in the 1.3 update and all were included in the Expansion. As of 1.5, the smallest port is free, while the other two are available in the Parts Expansion.

All docking ports can connect to one another, regardless of size, but must have their magnets aligned.

## One-way ports

Single docking ports can be placed in blueprints, physically connected to a non-port part in front of them, and will attach it to the part they're joined onto, until they decouple when pressed (similarly to Separators), but will remain on the craft their base is attached to. This can be used, for instance, if a spacecraft has used a parachute or landing legs in landing, but won't need them in escaping the atmosphere, but will need a docking port anyway for a later rendezvous, to decouple the unnecessary part without additional mass and size. Small docking ports can also be used as interstages instead of separators (rotated to be attached to the used stage and undocking from the remaining spacecraft), but only when there's time to stop and wait for them to fall away with reduced force, so they're not recommended in ascents (in case the used stage isn't out of the way before the rocket accelerates into it).

## Alternatives to Docking Ports before version 1.4

For those who use legacy versions of the game, there are a number of alternatives. They include:

* Use rotated Landing Legs to hold onto other spacecraft
* Use extended Solar Panel or landing legs to lock the rocket inside a bay.

None of the alternatives function properly when time warping as physics is disabled during the process, causing objects to clip into each other, and then overlapping or separating when you disable Time Warp.

## Trivia

* Any docking port can connect to another docking port, regardless of size.
* In real life, there are many varieties of docking ports, some even have complicated structures. Some can be even opened for astronauts to pass from one spacecraft to another.
* A docking port can fit through the top of a capsule.
* There is a bug when two docking ports align, they **do not dock**. This was changed to happen less often in the 1.5.2.5 update.
* If a docking port is clipped with another object that its magnet is stuck, it cannot dock with anything.
* The small docking port's size actually has the size of 1.9 units.
* Docking ports can be used as payload adapters, since it has a small separation force; however, in some cases, the payload will attract to the payload adapter.
* There is another variation of the docking port hidden in the game files and accessible with Blueprint Editing, however it crashes most devices when activated.
* There was a glitch where if done right you could use the magnets in the docking ports to have a rocket go fast without using any fuel. This was patched in 1.5.3 or 1.5.2.5