Norma Kelligan was the captain of a gas dredger that mined gas from Jupiter. Like all dredger captains, she was telepathic.
When her husband Thom and his dredger crew were killed in an accident for which the Lorannan-Ycole Corporation blamed him, Norma, as Thom's next of kin, was considered responsible to the Corporation and the victims' families. She had to work on the dredger until her debt was paid.
Norma began hearing Thom's voice inside her head. The Sixth Doctor and Evelyn Smythe helped her realise that there was a sentient entity on Jupiter that absorbed the minds and beings of those killed. Norma learned from Thom's voice that Mr Hepton from the Corporation would kill the entity and left the ship through the airlock to be with Thom. Together with the entity, they defeated Hepton. (PROSE: Jupiter)