The Endeavour's landing was a day early due to Hurricane Dean threatening Texas

The astronauts quickly finished the fourth spacewalk of the Endeavor mission last night, and closed the doors between the station and the shuttle in preparation for going out this afternoon

Hurricane Dean as photographed from the International Space Station during Saturday. May cause shutdown of control center in Houston

updating

09:00

Control Center managers in Houston gave the shuttle Endeavor on mission STS-118 the green light to detach from the International Space Station today (Sunday) at eight o'clock in the morning EST (15:00 Israel time). This decision caused the early termination of the fourth spacewalk yesterday.

The astronauts closed the gate connecting the two spacecraft on Saturday at 17:10 (00:10 on Sunday Israel time) and this allows the shuttle to detach from the station today for a possible landing on Tuesday. The early landing was considered by NASA in case Hurricane Dean threatened the Houston area. Although the ferry lands in Florida, which is outside the path of the current storm, the control is done entirely from Houston.

A landing on Tuesday would effectively be the last chance before NASA is forced to evacuate the control center and prepare for the storm. The mission managers will continue to monitor the forecasts regarding the progress of the hurricane and decide on the options before them accordingly.

Update: 00:00

 The fourth spacewalk of the Endeavor mission has ended

Install a stand for the shuttle's robotic arm extensions so that they can be used to replace the extension during future missions * The shuttle will leave the station tonight, earlier than expected and will try to land on Tuesday, before a hurricane that will cause the control center in Houston to be evacuated 

The spacewalkers continued to work on the outer part of the space station. Dave Williams and Clay Anderson started the operation at 15:17 Israel time and it lasted only about five hours instead of six and a half as planned in advance.

Williams and Anderson installed a stand for the robotic arm extension system of the shuttles arriving at the station, on the outside of the station's boulevard structure. Other tasks the two performed were installing an antenna for the station's wireless system and returning two containers with experiments into the station. Astronaut Triscoldwell was the spacewalk coordinator, as she had been for all three previous STS-118 walks.
Inside the station, the astronauts and cosmonauts continued to prepare for the closing of the hatch between the station and the Endeavor shuttle planned for tonight (17:00 PM Eastern Time - 02:00 Sunday Israel Time).

During the night, the mission managers decided to shorten the spacewalk by two hours, so that the team could close the opening between the station and the shuttle at the end of the working day on Saturday. The plan maintains the possibility for the shuttle to leave the station on Sunday and land on Tuesday. The early landing is being considered due to the event of Hurricane Dean threatening the Houston area, so it will be possible to land before the control center in Houston has to be cleared in preparation for the storm.

However, the managers are re-examining the predictions regarding the law, until the appointed time, and only then will they make the decision whether to indeed leave the station earlier.

NASA's announcement from Saturday does not mention at all the dent that was discovered in the heat shield and about which it was stated earlier this week that it does not endanger the shuttle.