They have a TDRS satellite, I believe it is TDRS-3, that covers the ZOE to help track a few unmanned satellites and the data attained goes through the Guam TDRS station. From time to time, there are a few orbits were TDRS-3 does have some time open to receive data and comms from the shuttle.<br /><br />TDRS-3 or TDRS-ZOE as it sometimes called, main job are the few research satellites that are doing polar research. But from time to time, the time sharing will allow other spacecraft to downlink data to the Guam station, including the shuttle and ISS. It all depends again on what activities are occuring at the time. If there is an EVA, they will use TDRS-ZOE as much as possible.