A short range teleportation device that allows the transportation of individuals from ships in orbit to the planet surface, and back through the use of a remote.
In lower class ships like Lexx's Rift, there is a visible doorway of light when in use. In higher class ships, like those owned by Riley, Damian, and Claudia, the doors don't show up like Lexx's does. There's a very faint rippling effect to show where they are and that's about it. You don't actually SEE them unless you're looking for them.
They don't always drop you on dry land however. (AD Day 11, strip 3)
The remotes can be keyed to specific individuals so no one else can access the Door even if they have the remote. (AD Day 12, strip 6)