The first return to flight (RTF) mission for the Shuttle fleet, due to take place during a March/April 2005 launch window, will be delayed again, this time by six weeks, according to NASA administrator Sean O'Keefe.

The hurricanes that closed NASA's Kennedy Space Center in Florida for about nine days during September and damaged several facilities, are said to be the cause of the delay. O'Keefe estimates that this will mean a total of three Shuttle flights in 2005, but denies this threatens the assembly sequence of the International Space Station (ISS).

Speaking at the International Astronautical Congress in Vancouver last week, O'Keefe said: "It's a six-week delay to mid-May. I don't see it impacting on the [assembly sequence]."

So far two RTF flights are due to go to the ISS in 2005; STS 114/Discovery and STS 121/Atlantis.

The US space agency estimates at least 25 flights are needed to complete the ISS, but is expected to retire its Shuttle fleet in 2010. With five years of operation remaining, the completion of the ISS would require at least five flights a year.

The first RTF flight has already been delayed once from September. The decision to again put back the RTF was made by NASA's Space Flight Leadership Council on 1 October. It determined the March/April 2005 window was no longer achievable.

Source: Flight International