NASA administrator Michael Griffin expects to launch three, not the planned five, Space Shuttle flights this year, pushing the delivery of key International Space Station partners' orbital modules into 2008.

The original 2007 Space Shuttle launch manifest's five missions included delivery of the European Space Agency's Columbus laboratory and the Japan Aerospace Exploration Agency's Kibo experimental module.

This year was to see Space Shuttle Atlantis's mission STS-117 during the first quarter, and then missions Endeavour/STS-118, Atlantis/STS-122, along with the Columbus and Kibo flights STS-123 and STS-124 during the remainder of the year.

However, the postponement of the STS-117 launch to no earlier than 8 June, because of hailstorm damage to Atlantis's external tank, has pushed STS-118 to August and STS-122 to the fourth quarter. STS-118 will deliver a truss segment and STS-120 will connect the Italian-made Node 2 module, named Harmony, to ISS.

Node 2 will enable the connection of the Columbus and Kibo modules to the ISS and allow the station's crew complement to expand to six. Despite the delays Griffin is upbeat on meeting the ISS assembly schedule, expected to be complete in 2010, even if 2008 also had only three missions.

"I don't think the assembly sequence is in jeopardy. We're thinking three missions [for this year] and if everything goes really well maybe we will have four," said Griffin at the US Space Foundation's National Space Symposium event, held in Colorado Springs last week.

The fourth mission would be STS-122 to deliver the Columbus module to the station and would probably occur in December.

Source: Flight International