The Aala were androids which looked like blond humanoids. They were sustained by power and radiation and acted as the servants to the One, a sentient ship created by the people of Andromeda before they became extinct.
The One was psychologically unable to cope with defiance and violence, so when the First Doctor refused to go along with its plan, it malfunctioned. As the Aalas were sustained by the One, they were shut down by the malfunction, allowing the Doctor to escape. (PROSE: Doctor Who and the Invasion from Space)