The first space shuttle launch after the Columbia tragedy is postponed to March 2005 at the earliest, officials at the US space agency NASA said Friday.

"We changed the launch planning date to March 6 to April 18 of 2005," William Readdy, NASA's associate administrator for Space Flight, told reporters.

Readdy also said that Discovery, one of the three remaining US shuttles, was chosen as the vehicle for the return to flight mission.

The US shuttle fleet has remained grounded since Columbia broke up on Feb. 1, 2003, killing all the seven astronauts on board. NASA had been planning to resume the shuttle flight in September or October this year.

A group of NASA senior officials made the decision to delay the resumption of flight because more time is needed for new safety measures, including "research, analyze and test a larger area of the space shuttle's external fuel tank for potential foam insulation loss," the space agency said in a statement.

Investigations found that the loss of Columbia was directly caused by a piece of insulating foam which broke away from the shuttle's external tank, creating a hole in the shuttle's left wing and letting in hot gases while the shuttle was re-entering the earth's atmosphere.

NASA officials also decided that once Discovery is on the return of flight mission early next year, a second shuttle will be on standby in case a rescue mission is needed.
 
(Xinhua News Agency February 21, 2004)