But it was designed to be serviced by the shuttle, and so in 1984 the astronauts replaced some failed components and left the craft 310 miles in orbit.

During the emergency flight, astronauts installed six new gyroscopes, replaced the main computer and installed a new data recorder and radio transmitter.

He said a decision had not yet been made on whether to try to repair the existing panels or to have the astronauts replace them with redesigned ones.

Assembly of the truss, which will be as long as a football field, began last month and may be delayed if the astronauts do not replace a faulty joint on the arm.

The astronauts - with the help of two cargo flights, also paid for by MirCorp - repaired air leaks, replaced deteriorating batteries and revitalized the station's life support systems.

The three astronauts will replace the space station's escape vehicle and conduct experiments involving weightlessness during the eight-day stay.

A second step to restoring the transporter will come on Monday, when the astronauts will replace the cut cable.

After a visual inspection of the telescope, astronauts conducted repairs, replaced failed or degraded components, upgraded equipment, and installed new instruments.

In addition to installing the new instruments, astronauts replaced other existing hardware with upgrades and spares.

Replacing a Camera On the second day, the astronauts will replace the Hubble's wide-field camera, which was scheduled for replacement in 1993.