Alien bomber

An unidentified spaceship based on the Discovery One from 2001: A Space Odyssey called Guardal Canal (a misspelling of "Guadalcanal") was designed (along with its auxiliary craft) and built as a model by a sixteen-year-old Martin Bower just after he saw that film. Around a decade later, he reused it for the series.

In "Alpha Child" the bomber is used to destroy the ships belonging to the fugitive alien Jarak (which are the auxiliary craft designed by the sixteen Bower).

In "War Games" the aliens cause the bomber to appear, perhaps using as sources the Alphan memories, to destroy Moonbase Alpha.

In "Dragon's Domain" the Guardal Canal model is in the spaceship graveyard above Ultra.

In "The Metamorph" the Guardal Canal model is in the spaceship graveyard on Psychon.

A modified version of the bomber is also featured as the Deltan battleship in "The Last Enemy" which appears (often with a command module attached and a command module separated) in both the spaceship graveyards, too.