"It was not a problem to exclude this tiny area that our calculations showed to be away from where debris would go down," Blagov said.

As of March 15, the deorbiting date was officially still set for early hours of March 22, but noted that this date can shift a couple of days "back or forth" depending on density of the atmosphere which constantly changes due to fluctuations of solar activity, Blagov said.

[uplink]

The "latest calculations" show that deorbiting will take place sometime between 7 p.m. on March 21 and 2 a.m. on March 22 EST (00:00-07:00 GMT; 3 a.m-10 a.m. Moscow time March 22), a source close to MCC's Mir deorbiting task force told SPACE.com. The source, who asked not to be identified, said this time period "is subject to change."

Blagov would not comment on the projected deorbit schedule.

Blagov said MCC specialists "will sit down" to calculate the exact deorbiting time only one day before the controlled descent will begin since any earlier forecast of solar activity would be too approximate. "All I can tell you is that each day [of delay] will shift the deorbiting time [back] by half an hour," Blagov said.

This means, according to Blagov, that if deorbiting is set to begin at 3.00 a.m. on March 22, a one-day delay will shift the time to 2.30 a.m. on March 23.

Yuri Grigoryev, deputy general designer of RSC Energia, the designer and builder of Mir, told SPACE.com that deorbiting could actually begin in the late hours of March 21 and end on March 22, but would not elaborate on his estimates of the planned reentry.

MCC recently decided to go with a shorter, simpler deorbit plan in an effort to minimize risks.

The newly selected scheme provides for the station to be sunk in one day, rather than three as initially planned. Under the new scenario, the controlled descent of the 15-year old scientific outpost will begin once it passes the 137-mile (220-kilometer) mark, according to the center's chief ballistics expert Nikolai Ivanov.

The latest plan also calls for the engines of the Progress cargo ship, which has been docked to Mir since January, to be fired just three times to reduce the aged station's orbital speed. The previously announced plan used four braking impulses, Ivanov said. According to Blagov, however, MCC still has the option to resort a modified version of the earlier four-impulse scheme.

The first impulse will be begin when the station is flying above Africa and end above the Caspian Sea. MCC will then wait for Mir to complete an orbit before it orders the second impulse, roughly over the same area, according to Grigoryev.

Commands for these two engine firings will be uploaded into the Progress ship's control system in advance since they both will begin before Mir enters the zone of radio communication with MCC, according to Grigoryev. However, Mir will be in radio contact with Mir when these two impulses end.

The third and final braking impulse will be executed completely within MCC's zone of radio contact, Grigoryev said. The space tracking facility in Ulan-Ude will be the last Russian outpost to "watch" Mir before it goes into a fiery dive, he said.

It will be the U.S. Army on the Kwajalein Atoll in the Marshall Islands that will be the last to track Mir as it will begin its reentry.

Both Blagov and Grigoryev insist they do not expect Mir's main computer to break down before the third impulse is completed. The station will be at an altitude somewhere between 110 and 125 miles (180 and 200 kilometers) at this time where it "can start scraping against" the denser layers of the atmosphere, according to an official at the Russian Aviation and Space Agency (Rosaviacosmos).

If Mir's digital computer breaks down, MCC has a backup plan that uses Progress' simpler, but more durable analog control system. Also Mir has its own backup control system based on the Progress ship's BUPO docking and orientation block, which can process only four basic commands.

Up to 1,500 fragments, weighing a total of some 13 to 19 tons, will survive the planned burning dash through Earth's atmosphere to splash down more than 930 miles (1,500 kilometers) away from Australia, according to Ivanov.

There is a 2-percent chance Mir will spin out of control during the deorbit sequence, according to Ivanov. Theoretically, the station can end an uncontrolled dive anywhere between 52 degrees north and 52 degrees south latitude where approximately 5 billion out of Earth's 6 billion people live, Ivanov said in a recent interview.