"The catch for all this is that I won't be able to directly see [the cargo carrier]," the Australian-born astronaut said in a preflight interview.

"So you have to sort of keep your wits about you...to make sure that what your seeing -- and what you think is happening - - is indeed what is happening, so that it comes in smoothly and evenly and settles in at all four points simultaneously."

Look for the shuttle loadmaster to disconnect Leonardo from its docking port on the side of the station's U.S. Unity module about 12:52 a.m. EST (05:52 GMT) Sunday.

A slow-motion move then will unfold over the following hour before the carrier is berthed in Discovery's cargo bay about 2 a.m. EST (07:00 GMT).

About as big as a large U-Haul truck, the shuttle-launched module was packed with almost five tons of supplies and equipment for the station's second expedition crew, which includes incoming commander Yuri Usachev and American flight engineers Susan Helms and Jim Voss.

That trio is replacing inaugural station skipper Bill Shepherd and two Russian cosmonauts, Yuri Gidzenko and Sergei Krikalev, who are nearing the end of a four-and-a-half-month "shakedown cruise" aboard the outpost.

Thomas and three other shuttle astronauts -- Discovery commander Jim Wetherbee, pilot Jim Kelly and mission specialist Paul Richards -- spent the better part of the past week unloading the Italian-built moving van.

An effort to refill it with surplus station equipment and trash fell behind schedule Friday, prompting NASA mission managers to extend Discovery's stay at the station by a day.

The repacking of Leonardo largely was wrapped up early Saturday. Tallied up, the astronauts loaded it up with 1,644 pounds (740 kilograms) of dirty laundry, dead batteries, empty food containers, surplus gear and other garbage.

The astronauts and cosmonauts will close Leonardo's wide hatch about 10:02 p.m. EST Saturday (03:02 GMT Sunday) before powering down its various systems.

The new station crew will hate to see the expansive module go.

"We'd like for you to leave it on orbit with us," incoming station flight engineer Voss told Italian Space Agency officials during a space-to-ground chat.

"We could use the space, and we would really like to have all the places to put the [station science and systems] racks and other cargo that we need to store up here."

One of three identical pressurized modules built by Italy at an estimated cost $450 million, Leonardo is ill equipped, however, to make lengthy stays in space. Many of its systems do not feature the back-ups required for extended orbital missions.

NASA and the Italian Space Agency, however, are discussing the possibility of modifying one of the three moving vans to replace an American-made station crew module.

NASA officials last month ordered work stopped on the orbital dormitory as part of an effort to absorb an estimated $4 billion station cost overrun.

The Discovery crew, meanwhile, hauled the 118-ton station into a higher orbit Saturday, putting the outpost in position for a planned link-up with shuttle Endeavour next month.

An international crew aboard that ship is to ferry a Canadian-built robot arm and another supply-filled Italian moving van to the station after a launch now scheduled for April 19.

The 58-minute, 15-second firing of Discovery's steering thrusters boosted the station by about 2.3 miles (3.7 kilometers). Three such orbit-raising maneuvers have been carried out during the past week. Total increase in the station's altitude: 8.4 miles (13.5 kilometers).

Discovery now is scheduled to depart the station about 11:30 p.m. EST Sunday (04:30 GMT Monday). A formal farewell and command handover ceremony is scheduled to take place three hours before the two ships part.

With Shepherd and his Russian crewmates in tow, Discovery remains scheduled to land here at Kennedy Space Center at 12:55 a.m. EST Tuesday (05:55 GMT) Wednesday.