And if they couldn't dock, they didn't know if they could make it back home again. "Docking was imperative," Mr Wilmore told BBC News, two months after he and Ms Williams finally made a successful return to Earth. Mr Wilmore said that the possibility they might never see Earth again "definitely went through our minds". After months of experiments aboard the space station, Ms Williams and Mr Wilmore eventually returned to Earth on 18 March. "We understand space flight is hard, human space flight is even harder."