The US space shuttle Endeavour was set Wednesday to make its fourth launch attempt in a week, after delays due to technical problems and bad weather.
The launch is scheduled to take place at 5:19 pm (2219 GMT) from Kennedy Space Center, with a 70-80 percent chance of favorable weather conditions, according to NASA officials.
The shuttle is to bring the fourth long-term crew — Russian commander Yuri Onufrienko and Americans Carl Walz and Dan Bursch — to the International Space Station and will return December 15 with the current crew members, who have been on the station since August.
Endeavour will also carry the Italian Raffaello module, laden with 3.5 tonnes of equipment, food, supplies and materials for scientific experiments.
It will be the first US space shuttle launched since attacks September 11 when hijacked airliners left around 3,500 people dead and missing in New York, Washington and Pennsylvania, under heavy security.
If the launch is again delayed, it will be rescheduled for Thursday, the last chance for lift-off this week, due to military actions set for the coming days at the site and NASA’s obligations to give the crew ample rest time.
The National Aeronautics and Space Administration (NASA) pushed back the launch twice due to problems with the docking of a Russian cargo ship at the ISS, rectified Monday by a spacewalk completed by two Russian cosmonauts.
NASA officials then called off Tuesday’s launch due to bad weather above the launch pad.
Technical experts later found two metal barriers on the access ramp to the shuttle that should have been removed, as they could interfere with the launch. An emergency team was rushed to the site to sort out the problem.
Officials have ordered all air traffic within a 55-kilometer (34-mile) radius of the launch pad to be frozen through late Wednesday, while F-15 Eagles and AH-64 Apache attack helicopters have been deployed nearby.
If the launch goes according to schedule, Endeavour should reach the ISS at 1915 GMT Friday, and is to return to Florida on December 16.
