CAPE CANAVERAL - NASA is poised to push back the launches of its first three 2007 shuttle flights but still intends to stage five International Space Station construction missions next year, officials said Monday.

The schedule slips--which are expected to be formally approved in November--would give the agency adequate time to deliver modified external tanks to Kennedy Space Center and complete required pre-launch work on shuttle orbiters.

Also a factor: performing station assembly work without interfering with previously scheduled missions to haul crews and cargo to the orbiting outpost.

Station crew rotation missions are scheduled for launch on Russian Soyuz spacecraft next spring and next fall. Robotic Russian space freighters also are to be launched on quarterly supply runs to the outpost.

"There are a lot of vehicles on the highway, if you will, and we have to make sure everybody is kind of following all the traffic signals to make sure that it's all integrated properly," said Kyle Herring, a spokesman for NASA's Johnson Space Center in Houston.

NASA's next shuttle mission--a flight aimed at delivering another segment of the station's central truss--remains scheduled for launch about Dec. 7.

The assembly of the outpost's metallic backbone would continue on shuttle missions scheduled for launch March 16 and June 28. Then, an American module that will serve as a gateway to international partner science labs would be launched Sept. 7.

The missions had been slated for launches on Feb. 22, June 11 and Aug. 9. The changes were requested after an all-day meeting of shuttle and station program managers.

Herring said NASA still intends to launch the European Space Agency's Columbus lab and the first section of the Japanese Kibo science complex before the end of 2007.

NASA managers did not discuss launch date changes for those flights. Recent NASA schedules reflected a Sept. 22 launch date for the European lab and a Nov. 29 target for launch of the Japanese mission.

A spring 2008 "placeholder" remains in the schedule for a potential mission to service the Hubble Space Telescope, Herring said. A decision on whether to proceed with a final flight to the flagship observatory is expected at the end of the month.

NASA needs to launch at least 14 more shuttle missions to finish the half-built station before a Sept. 30, 2010, deadline set by President Bush.

Also under consideration: Two additional flights to haul large spare parts and supplies up to the station prior to the retirement of NASA's three-orbiter shuttle fleet.

Herring said the launch schedule slips are not expected to impact the agency's ability to complete the international station by the presidential deadline.

• Complete Space Shuttle Mission Coverage
• The Great Space Quiz: Space Shuttle Countdown

Published under license from FLORIDA TODAY. Copyright © 2006 FLORIDA TODAY. No portion of this material may be reproduced in any way without the written consent of FLORIDA TODAY.