Spacing

Within various habitat-based societies, the dead must be disposed of somehow. On a planet, you can just bury them, there's space enough. This is not the case on a habitat. Instead, they just toss them offboard.
Of course, it's never that crude. The dead are often mounted in pods, capable of dodging debris and other stations. These are sent to the planet below, or the dead of space.
Skejon, for example, was spaced by Quaken after his death. While Quaken never practiced this tradition, Skejon did, having lived 70 years on the Ad Astra Per Aspera, and it being his home and birth(build?)place.

History

Originally done purely out of necessity, first on interstellar spaceflights, which could take several decades. From there, the practice evolved and changed into what it is now. Of course, it's subtly different everywhere you go.

Execution

The actual ceremony varies drastically depending on the culture of the station. Some may hold a funeral ceremony remembering the dead together, while others might have some individual ritual or procession in private. Varies. The unifying factor here is the spacing part. Often in a pod, the body is sent somewhere out of the way. Depending on the location of the station, this might be dead space, a sun, or a planet's atmosphere.