"Wish we could stay longer," Commander Robert Cabana said yesterday, "but we'll get safely away and leave it for somebody else to come back and add more to it." It will be spring before the next construction crew arrives.

With the flick of a switch that released the snares holding them together, space shuttle Endeavour separated from the 77-foot, 31,700-kg station and, with Pilot Rick Sturckow at the controls, slowly backed away. Flight controllers in Houston and Moscow monitored the 394-km-high action. The undocking, similar to those between space shuttles and Mir, occurred over Russian ground stations.

The winged, cylindrical station glistened in the sunlight as the shuttle circled from a distance of 450 feet for a final photo survey. Once that was done, Sturckow fired Endeavour'sthrusters and the shuttle pulled away for good.

The astronauts could still see the station from more than eight miles out and excitedly beamed down pictures. "It's the brightest new star on the horizon," Cabana said as the station grew smaller and smaller, its two components resembling the head and body of a snowman lying sideways. With Endeavour's flawless departure, NASA's lead flight director, Bob Castle, was finally ready to declare the assembly part of the 12-day mission a success.

"I'm very, very, very gratified," Castle said.