Mission Control told Space Shuttle Endeavour's crew Wednesday that STS-118's fourth spacewalk will be moved to Saturday. The decision gives the STS-118 and Expedition 15 crew members an extra day to prepare for the spacewalk, which was added to the mission after the STS-118 crew arrived at the station

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Preparations for a possible spacewalk to repair a small ding in Endeavour's thermal protection system tiles will occupy a considerable part of today for Commander Scott Kelly and Mission Specialists Rick Mastracchio, Dave Williams and Tracy Caldwell.

Mission managers have not decided that a repair spacewalk will be needed. But to prepare for that possibility, the crew members will begin to get ready to do the repair, should managers determine that is necessary.

The managers did decide to move the flight's fourth spacewalk from Friday to Saturday. If the repair isn't done, that spacewalk will see installation of two antennas and removal of one, installation of a stowage stand for the shuttle's orbiter boom sensor system and other tasks.