A Russian cargo vessel blasts off for the Mir space station on Wednesday on a mission to prevent the accident-prone orbiter from making a catastrophic crash landing back on Earth.
Russia decided in November to ditch the space station in the Pacific Ocean, saying corrosion and age had taken the shine off the jewel in its space crown and made Mir a safety hazard.
But a series of technical glitches have bedevilled preparations for its demise in early March and sparked fears of an uncontrolled re-entry into the Earth's atmosphere.
Ground controllers were forced to postpone the current flight last week after a sudden power failure knocked out Mir's navigation system, making docking impossible.
The glitch bore uncanny echoes of a December 25 power outage that cut all links between Mir and ground control, the worst communications breakdown in its 15-year history.
Although contact was restored after 24 hours, unnerved space chiefs later admitted that they feared at one stage they would never regain control of the 130-tonne craft.
Moscow has already failed to control the re-entry of a major space craft. In 1986, the Soviet Union abandoned its Salyut-7 station after wiring malfunctions. Its remains fell harmlessly on Argentina and Chile in 1991.
Wednesday's Progress craft, scheduled for a 0428 GMT lift off, will ferry fuel to Mir. Space engineers will be able to use the craft to nudge Mir out of orbit late next month and launch its descent.
CARRYING EXTRA SUPPLIES
The Progress will also carry extra oxygen supplies in case an emergency crew has to be dispatched from Earth to prepare the station manually for its demise, space officials have said.
Russian officials say they will need up to three days to ensure Mir is facing the right way for Progress to dock, a procedure scheduled for January 27.
If all goes to plan, most of Mir will burn up on re-entry, the remainder falling into the Pacific Ocean some 1,500-2,000 km (900-1,200 miles) off Australia.
However, Russian space officials concede that returning such a large structure to Earth is not an exact science, and warn some debris might strike land.
Fragments weighing as much as 700 kg (1,500 pounds) could strike Earth with enough force to smash through reinforced concrete two metres (six feet) thick, Russia's space chief Yury Koptev warned last November.
Mir's space marathon began on February 20, 1986, and the craft proceeded to set a host of endurance records that were the envy of the better-funded U.S. space programme.
But in recent years Mir has lost its aura due to a string of mishaps, including an almost catastrophic collision with a cargo vessel, an onboard fire and a string of main computer failures.
When a private consortium failed to find enough cash to keep Mir aloft, the government signed its death warrant, heralding the end of a piece of space history.
Moscow will now focus its limited financial resources for space exploration on the $60 billion International Space Station (ISS), a 16-nation venture which will build on Mir's legacy.