Sub-Commander Raiker was the First Officer on board the prisoner transport ship, London, which transported exiled criminals to the planet Cygnus Alpha.
While crossing over to the Liberator from the London via a airlock tube, Raiker fired on and wounded Blake, who was trying to close a door to seal the Liberator. The door closed automatically when the Liberator pulled away and Sub Commander Raiker was blown into space. (A: Space Fall)