Ground engineers, meanwhile, worked feverishly to power up at least one more of the stations three command-and-control computers, all of which inexplicably crashed Wednesday, delaying both of the storage jobs.

NASA wants to finish that work and come to grips with the root cause of the crucial computer failure before Tito and the Soyuz crew are given a green light to take off Saturday on a 10-day round trip to the international outpost.

"Were working with the Russians, and nothing has been decided," said NASA lead station flight director John Curry. "But we have a meeting with them again [Friday] morning to talk status and whether we would like to delay that flight."

Located in the stations U.S. Destiny laboratory, the computers are crucial to sending commands to outpost systems and beaming data on the health of those systems back to Earth.

The root cause of their failure remains a mystery.

One of the machines, however, was coaxed back into operation Thursday. A so-called "Mighty Mouse" software program loaded in a linked computer in the stations U.S. Unity module automatically turned power to the computer off and on, essentially rebooting it.

Like the cartoon character, the program was designed "to save the day" during any case in which all three of the command-and-control computers shut down.

Ground controllers, meanwhile, were taking a cautious approach to an effort aimed at bringing at least one of the other two failed computers back to life. The engineers wanted to make certain that their troubleshooting doesnt end up disabling all three computers again.

At the same time, engineers want to have at least two of the computers on-line before a shuttle robot-arm operator tries to stow the Italian moving van back in the shuttles cargo bay.

At least one of the main station-control computers is needed to send commands to release latches and bolts holding the cargo carrier to the stations Unity Module.

But NASA flight directors want to have a backup computer up and running when that operation takes place, and the same criteria will apply when it comes to the other undone storage job.

During what will be a space first, station flight engineers will use the outposts new Canadian robot arm to hand its pallet-like launch mount to a shuttle robot-arm operator, which then will place the 1.5-ton crane carrier in Endeavours cargo bay.

The tricky operation will mark the first time a pair of robot arms -- and robot-arm operators -- have worked together to hand off cargo in space.

Curry said the joint crews could perform the job with just a single computer. "But thats probably not the smartest thing in the world to do if we can help it," he added.

"Wed rather do it with redundancy, especially given the fact that each of these three boxes has had something happen that we dont understand," Curry said. "We really dont want to get into the middle of this and be stuck."

What remains to be seen is whether all the work can be done in time for the shuttle and its crew to depart the station as scheduled about 12:30 p.m. EDT (16:30 GMT) Saturday.

The Soyuz crew and Tito the American millionaire who is paying the Russians an estimated $18 million for a round trip to the station are scheduled to blast off from Baikonur Cosmodrome in Kazakhstan about 3:30 a.m. EDT (07:30 GMT) that same day.

The launch would lead to a Soyuz arrival at the station about 4 a.m. EDT (08:00 GMT) Monday.

Station flight directors, however, want to figure out the cause of the computer problem and have both a prime and backup unit operating before Endeavour departs the outpost.

The reason: Shuttle command and communications links have played a key role in maintaining near-constant contact with the station during computer troubleshooting.

If all three computers crashed again while no shuttle was docked to the complex, flight directors would have only sporadic contact with the outpost as it passed over widespread Russian ground stations.

At the same time, flight directors want to maintain at least a 16-hour gap between the shuttle departure and the Soyuz arrival to give the station crew ample time to prepare for new visitors.

And neither NASA nor the Russians are comfortable with attempting a Soyuz docking while the shuttle still is at the station. The bug-shaped ship would have to pass perilously close to Endeavours tail -- about 20 feet (6 meters) -- to get to its berthing port.

U.S. and Russian project managers, consequently, will give serious consideration to delaying the Soyuz flight until the computer problem can be solved and the shuttle crew can finish its work. And Curry said the Russians are willing to postpone the flight if necessary.

"Weve been working with them long enough to where they are very receptive when we have a serious problem like this and vice versa," Curry said. "And so if we have a problem where we are not able to undock the shuttle prior to the planned [Soyuz] docking time, then they will delay the launch."

A final decision on the issue is expected after U.S. and Russian station managers tag up during a transoceanic teleconference Friday. Until then, the shuttle and its crew remain scheduled to land here at NASAs Kennedy Space Center at 10 a.m. EDT (14:00 GMT) Monday.