Using prisoners on Base Diana, Jackson planned to wipe their minds and replace them with the minds of people who were dying. However, his equipment unknowingly sent out a signal that the Talerians were able to follow back to Earth. One named Androparg managed to latch onto the signal and follow it back, reaching Base Diana as Jackson was setting up his equipment for the first tests. Androparg possessed Jackson though it took him awhile to gain full control over Jackson's body. Unlike the later possessed victims, Jackson's mind wasn't erased so his knowledge and emotions could be accessed by the Talerians though a copy of the real Jackson's mind was kept in the base data storage.
Although it took some time, Androparg eventually managed to suppress Jackson's consciousness and began using his body and equipment to begin a Talerian invasion of Earth. While Jackson's mind continued to exist within his body and was used by Androparg to successfully impersonate Jackson, the real Jackson was unable to do anything to stop the Talerian plan, seeing the world as if through windows. When the Eleventh Doctor and Amy Pond arrived, Jackson managed to regain control long enough to use the process equipment to transfer some of his own memories over to Prisoner Nine, but Androparg quickly regained control and Nurse Phillips killed Prisoner Nine before he could tell the Doctor anything.
By the time the Doctor had restored the minds of everyone else in Base Diana, Jackson's mind was very nearly gone though he continued futilely to battle with Androparg for control of his body. During a confrontation with Androparg, the Doctor was able to steal the back-up of Jackson's mind and discreetly served it to Androparg in a cup of tea. Drinking Jackson's back-up destroyed the mind of Androparg and restored Jackson to control of his body. Horrified by what he had been forced to do and remembering that the Doctor said the Talerians were vulnerable to pressure changes, Jackson used a Talerian gun to shoot out his office window, blowing Jackson into space and killing him. Before he was blown into space, Jackson witnessed the death of the Talerian leader due to his actions and in his last moments, smiled with satisfaction at what he had done. The immediate drop in pressure throughout Base Diana killed the Talerian invasion force while the Doctor and Amy were able to seal the breach. The Doctor then dismantled Jackson's equipment so that the Talerians could not use it again. (PROSE: Apollo 23)