When the T-Mat malfunctioned, Kelly travelled with Julian Radnor to meet Daniel Eldred. They tried to persuade him to build a rocket so they could send technicians to the Moon to repair the T-Mat. With the help of the Second Doctor, Zoe Heriot and Jamie McCrimmon, the rocket was built and launched. Kelly lost radio contact with the rocket shortly after.
The T-Mat to London became operational again and Kelly used it to travel to the Moon with a team of technicians. They were unaware that Slaar and his Ice Warriors had invaded the base. Fewsham, a prisoner of the Ice Warriors, told Kelly the accident was the fault of Harry Osgood, the former head technician, who had gone mad.
Kelly and her team repaired the T-Mat. The Ice Warriors attacked them. She was the only survivor. She escaped and rendezvoused with the Doctor, Zoe, Jamie and Phipps, the only survivor (along with Fewsham) on the Moonbase. Kelly repaired a device that ran on solar power and used it to kill an Ice Warrior. Fewsham repaired the T-Mat, allowing Kelly and the others to return to Earth.
Once there, Kelly viewed Fewsham's secret film of the Ice Warrior plan. Using this information, she developed a signal on the same frequency as that of the Ice Warriors. When deployed on a satellite, it led the Ice Warrior fleet into the Sun's orbit where they died.