CAPE CANAVERAL, Fla. The U.S. space shuttle Discovery is due to lift off on Thursday on a mission to take a new crew, a new module and tons of equipment to the International Space Station, even as back on earth NASA is scaling back its plans for the orbiting outpost.

Liftoff on the latest mission to the giant construction site is scheduled for Thursday at 6:42 a.m. EST (1142 GMT), just two minutes after dawn at the Kennedy Space Center on Florida's Atlantic coast.

This 12-day mission features three crews, three commanders and the space station's first temporary module -- built by Italy and named for Leonardo da Vinci. It will dock to the station while astronauts empty it of cargo, then undock and return to earth inside the shuttle.

The three commanders are: U.S. Navy Capt. James Weatherbee, the shuttle commander; Navy Capt. William Shepherd, commander of the Expedition One crew now living on the station; and Yury Usachev, a Russian civilian and commander of the next space-station crew.

Usachev and his two crew mates will ride up on the shuttle but remain on the station, while Shepherd and his inaugural station team return in Discovery after a stay of more than four months.

NASA said on Tuesday that cold weather in Florida was the most significant threat to getting the launch done on time.

Space Station Being Scaled Back

A similar chill is being felt throughout the space agency and its international partners in the wake of recent news that NASA could run $4 billion over budget on the construction phase of the program. The previous target price to build and operate the station for at least a decade was $95 billion.

In response to the overruns, the Bush administration last week pulled the plug on several key space station elements. Gone is a module that would have housed four additional astronauts, as well as an emergency escape vehicle that could have returned a seven-member crew to earth.

A propulsion module was axed and the number of shuttle missions a year cut from eight to six.

Tommy Holloway, NASA's space-station manager, said on Tuesday that it was "premature to speculate" about the space agency's response to the cuts contained in the Bush administration's budget blueprint.

Various options being floated have had astronauts sleeping in station hallways and buying Russian Soyuz spacecraft as extra evacuation vehicles.

Holloway said he had reassured international partners in Russia, Europe, Japan and Canada that NASA would live up to its commitment to launch their modules and hardware.

NASA would not complete a review of its options until May, Holloway said, but any changes would be less than those made in 1993, when the Clinton administration trimmed the budget by bringing aboard international partners.

(Reuter)