NASA Considers New Target Dates For Last Two Shuttle Missions

NASA is considering new target launch dates for its last two shuttle missions to give engineers more time to load up equipment for the International Space Station and avoid heavy traffic around the outpost.

The launch of Discovery and a module that will serve as a warehouse at the station would be targeted for Oct. 29 and Endeavour would be targeted for liftoff on Feb. 28. Senior shuttle program managers are expected to approve the new target dates at a meeting on July 1.

NASA is modifying an Italian cargo carrier dubbed Leonardo to take up permanent residence at the station after its delivery aboard Discovery, which will officially remain targeted for launch Sept. 16 until the change request is approved.

The cylindrical module is being outfitted with additional shielding to protect it from micrometeorite or orbital debris hits and redundancy is being added to some of its critical systems. Also known as a Multi-Purpose Logistics Module, or MPLM, Leonardo was designed for short rather than long stays at the station.

The new date will give engineers more flexibility to get all the modifications done.

Some of the cargo flying up on the mission -- including a humanoid "Robonaut" designed to do work outside the outpost -- could not be delivered to Kennedy Space Center in time to support a Sept. 15 launch.

The expected delay in the Discovery mission will bump Endeavour back behind a period of heavy traffic at the station.

A Russian Soyuz crew transport will be flying back to Earth and robotic space freighters from Russia, Europe and Japan all will be flying up to the station during December and January. The sun angle on the station during much of January and February also will be such that the outpost could not generate enough energy or dispel enough heat to support a docked shuttle mission. So Feb. 28 would be the first available target date for Endeavour.

NASA is deferring until August a decision on whether Atlantis would fly one last supply run to the station in next June. The orbiter and an external tank-solid rocket booster stack will be readied for launch on a rescue mission should Endeavour sustain critical damage on NASA's last currently scheduled shuttle mission. NASA and supporters in Congress are lobbying to launch Atlantis on an additional station outfitting mission before the shuttle fleet is retired.

In unrelated news, NASA and contractor engineers discovered a problem with a turbopump on one of Discovery's three main engines. All three will be removed so the faulty pump can be replaced. The engines then will be reinstalled. The work could have been completed in time to support a Sept. 16 launch so the problem was not a factor in the proposed launch date changes.