Space station

A space station is generally a large spacecraft made up of many smaller modules that are docked together in space. A space station is usually constructed in space, but smaller ones can be launched with a single rocket. These won't be able to reach the size of the ones that are built in space.

Uses

Space stations are often used as refueling stations. By, for example, first constructing a small station in Mun orbit and docking a refuelling ship to it, a lander can dock to the station and take some fuel from the refueling ship for landing and return.

It is also possible to leave a few Kerbals in a space station. The PPD-10 Hitchhiker Storage Container is especially useful for this purpose, as it can hold four Kerbals and its ladders are ideally arranged to stack multiple on top of each other.

Finally, space stations can also be used for scientific measuring using the various sensors. By placing a station on an eccentric orbit, measurements at different altitudes can be taken. This can however often be done with just a small ship and should only be a station's secondary purpose.