 Kelly and his crew delivered the pressurized module for Kibo to the ISS . The module is the largest component of the Kibo laboratory and the station 's largest habitable module . Discovery also delivered Kibo 's Remote Manipulator System . Perhaps the most important part they delivered was a replacement part for the station 's toilet . The single toilet on the ISS had been malfunctioning for a week , creating a potentially serious problem for the crew . When Kelly first entered the station , he joked , " You looking for a plumber ? " , referring to the broken toilet . 
