Diagram by NASA indicating location of pump on the S1 Truss.
Saturday's eight-hour spacewalk ended in difficulties. While working on disconnecting the fourth of four coolant cables in the broken ammonia pump, a leak developed which sprayed ammonia over the astronaut's suit. Extra time was required to clean off the toxic ammonia as the astronauts retreated to the station airlock.
With this setback, a second and third spacewalk are planned to work on the problem. The next EVA will take place Wednesday beginning at 4 am MDT. The objective is to complete the removal of the failed pump and prepare the replacement for its transfer. The installation of the new pump is scheduled for Sunday.