sentences:  It was subsequently commissioned for scripts on 24 January 1974 and planned as the second story of Season 12.It was dropped on 17 June 1974 and replaced by Lucarotti's "The Ark in Space".Written by John Lucarotti, this script came about after "Space Station" was rejected and Lucarotti was suggested by Terrance Dicks as a replacement writer on the strength of his "Moonbase 3" script.