Russian engineers prepared late on Thursday to cast the Mir space station into fiery oblivion, a spectacular coda to a 15-year voyage that set a raft of records but often flirted with disaster.
Mir's last full day in space was spent soaking up the precious solar energy it needs to ensure a controlled plunge into a remote corner of the Pacific Ocean, in theory well away from inhabited areas and shipping lanes.
Officials said the 136-tonne craft would splash down between New Zealand and Chile on Friday between 0620 GMT and 0630 GMT, discounting Russian media reports that Mir was falling faster than planned.
Vladimir Solovyov, the first commander on board Mir who is now mission control flight commander, appeared relaxed, saying: "Everything is going normally. The station is behaving itself."
Solovyov and top officials had spent the day at mission control outside Moscow poring over contingency plans. The private NTV television station said in the event of an emergency engineers would have no time to produce plans off the cuff.
Ground control will first use Mir's recharged guidance systems to manoeuvre the craft into position before firing its motors to abruptly slow the giant structure, currently cruising at about 28,800 km (18,000 miles) per hour.
That will force the station to lower its orbit until it can no longer resist the pull of Earth's gravity.
Nikolai Ivanov, a senior flight control official, said the worst-case scenario would be if the engines of the Progress cargo vessel docked with Mir failed to restart on time.
"In that case (Mir) will be gliding (powerless), which we can't control, and we haven't even considered that situation," he told NTV.
Tons of debris from the biggest man-made object to re-enter the atmosphere will hurtle down at speeds fast enough to crash through two metres (six feet) of reinforced concrete.
Airlines plan to alter the flight times of up to six trans-Pacific flights to avoid the splashdown, but New Zealand officials said they were powerless to make 26 tuna boats move out of the drop zone.
$200 MILLION INSURANCE POLICY
Russian television said experts expected Mir to hit its designated area well away from shipping routes and populated areas, even if there were minor mishaps on the way.
Nevertheless, Moscow has taken out a $200 million insurance policy in case plans go awry. Russian firms have reinsured the space perils with Lloyd's of London, the world's biggest insurance market, where underwriters said the risks were unique.
In Fiji, local radio said fishermen were already preparing to set out to sea to collect floating bits of Mir's remains.
Elsewhere, however, Pacific island states braced for trouble.
Job Esau, of the National Disaster Management Office in Vanuatu, a tropical paradise of 182,000 people, said the authorities were considering declaring "a state of emergency".
In Nauru - little more than a large mountain of phosphate, or bird droppings - authorities issued a warning to residents not to touch any "contaminated objects" and told ships to stay out of the area.
Residents in other islands in the Pacific, such as on Chile's Easter Island, have said they were on guard.
Chile on Wednesday complained that Russia was using the ocean as a dump.
"We want people to know about the danger that debris from space can pose to the environment," Foreign Minister Soledad Alvear said.
Early on Friday, flight engineers will fire a first engine burst at 0033 GMT, a second at 0200 and a final one at 0500. Mir's solar panels and antennae will burn up first as it re-enters Earth's atmosphere.
A swirling cloud containing 20-40 tonnes of super-heated metal expected to survive re-entry temperatures of around 1,500 degrees Celsius (2,730 degrees Fahrenheit), will streak across the sky like a giant fireball, space officials said.
Vladimir Lobachyov, ground control chief, told Interfax news agency Mir would disappear from radar screens around the world during the last 40 minutes of its life as neither Russia nor any other country had facilities to monitor its final descent.
"It depends on God, because he is the only one who can see the station, commented Viktor Blagov, deputy flight controller.
A Russian-U.S. expedition in the South Pacific has lined up two aircraft to fly to a point southeast of Tonga where they hoped to see Mir streaking across the sky like a fireball after re-entry. Newspapers have reported that the expedition is charging passengers $10,000 a head.
THE FINAL COUNTDOWN
Lobachyov said that once engineers pushed Mir out of orbit, technicians would calculate the final splashdown zone and report it to some 60 foreign envoys due to gather at ground control.
The pride of the Soviet space programme on launch in 1986, Mir has outlived its intended life span three times over and set records envied by the better-funded U.S. space programme.
Despite angry protests by leftist politicians, officials have said there is no point in keeping a craft whose crews had spent 80 percent of their time on repairs in recent years.
Deputy Prime Minister Ilya Klebanov, who oversees the cash-strapped space industry, said Russia would not be able to afford another national space station in the foreseeable future.