Stage Set for Mir’s Fiery Plunge as Man’s Largest Space Derelict

From his modest El Segundo office decorated with burnt and twisted metal, William Ailor has led a quiet and somewhat obscure career tracking trash floating in space.

But in the last few weeks, Ailor’s telephone has been ringing off the hook, as government officials and reporters from as far as Japan and England have clamored for his expertise on the return to Earth of the Russian space station Mir.

On Thursday, if all goes according to plan, Russian officials hope to bring down Mir--the largest piece of trash to fall from space--somewhere over the South Pacific, about 1,500 miles east of Australia.

“It’s the Super Bowl of space debris,” Ailor said. “This is a big one. This is a very exciting time for us.”

Resembling a massive dragonfly with solar panels and a collection of laboratories and living quarters, the Mir will be the largest man-made object to plummet from orbit. It is nearly double the mass of the 78-ton U.S. Skylab, which fell out of control in 1979, scattering debris over Australia.

Most of the 15-year-old space station is expected to burn up in the atmosphere, but Russian officials estimate that 1,500 fragments, weighing up to 27 tons, could reach the Earth’s surface.

Although the chance of a chunk clobbering anybody is considered almost zero, 600-pound pieces of space debris have pounded the Earth several times in recent years. And the prospect of a human collision has triggered growing fears in Japan, which postponed a high-level defense summit in Washington next week.

Mir’s deorbit is expected to yield a treasure trove of information for Ailor, the director of the Center for Orbital and Reentry Debris Studies. His team at Aerospace Corp., a government-funded research facility, includes two other scientists, Russell Patera and Wayne Hallman.

The Mir descent should also provide invaluable insight for NASA officials who in future decades will have to bring down the biggest spacecraft in orbit, the 500-ton International Space Station.

As space gets crowded with rockets and satellites--about 2,700 are in orbit and 1,000 more are expected to go up in the next decade--more attention is being paid to the risks of collision, analysts said.

But for now, the idea of a bus-size chunk of metal falling to Earth has ignited a host of theories and worries among residents in countries that will be in Mir’s deorbiting path.

Ailor and others say there should be very little to worry about. Based on previous experience, most space objects are destroyed during reentry, and no one has ever been hurt.

An average of 100 man-made pieces larger than a basketball hit the ground each year, Ailor said. But in the four decades since the first man-made objects were blasted into space, there have been no reported injuries from falling debris.

There was, however, one case of an individual getting struck by space rubbish without being injured. Lottie Williams of Tulsa, Okla., reported that she was hit by a small wire-mesh piece of debris from a falling Delta second-stage rocket in 1997. Williams has claimed that it was a message from God and has refused to turn the glove-like piece over to government officials. Williams’ story is immortalized in a display case at Aerospace headquarters.

In short, Ailor said, the chances that an individual will be hit and injured by a piece of debris is less than one in 1 trillion--significantly less likely than getting struck by lightning, a risk of one in 1.4 million.

The statistics are staggering considering that 600-pound rocket fuel tanks that were supposed to burn up in reentry have fallen to Earth virtually intact--twice in recent years, one in Texas and another in South Africa.

Japan isn’t taking any chances. Despite assurances by Russia that the Mir poses no threat to Japan, a public safety official said Friday that the government may urge people to stay indoors to avoid being hit by debris.

Not assuaged, Japan has sent six experts to Russia to monitor the deorbit, and Japan’s Defense Agency Chief Toshitsugu Saito postponed a meeting with Defense Secretary Donald H. Rumsfeld in Washington next week. Russia’s last-minute decision to take out a $200-million insurance policy on the Mir deorbit didn’t help matters.

And what are the chances of Mir remnants hitting Japan?

“It’s [as] zero as you can get,” he said.

But all bets are off if Russian officials cannot control the Mir and maneuver it for deorbit, Ailor said. A Progress cargo ship with fuel and thrusters was attached to the Mir in January to guide the Mir. But if the engines fail or controls are lost because of faulty batteries, as has happened before, the Mir would begin what Ailor calls a natural, or uncontrolled, reentry. In that scenario, Mir could “fall anywhere.”

“Everything has to happen precisely right for it to come down where they want it to,” Ailor said.

The footprint, or where Mir remnants are expected to fall under a controlled entry, is a 124-mile-wide swath stretching 3,728 miles across a remote area of the Pacific. With an uncontrolled entry, that footprint could be anywhere across 80% of the Earth’s surface, Ailor said.

But if all goes according to plan--and few doubt that it won’t--the flimsy elements of the Mir, such as its solar panels and antennas, should begin breaking off because of friction and disintegrate as the craft approaches an altitude of about 54 to 56 miles above Earth.

When the Mir descends to about 48 miles, there should be a “catastrophic” breakup in which most elements of the craft are destroyed, Ailor said. Whatever pieces survive “the wall”--so called because most debris disintegrate at that point--will likely make their way to Earth.

Besides spacesuits and other small items stored in lockers deep within the Mir, 50 beach-ball size titanium spheres could rain down on the ocean, Ailor said.

Ailor should know. He has collected space junk and has studied the pieces to find out why some pieces make it through the atmosphere. He has one of the largest collections, including rocket fuel tanks and satellite fragments. He covets a 600-pound fuel tank that fell in South Africa but has not been able to persuade a museum there to give it up.

The Mir reentry will be tracked by Air Force radars, providing data that Ailor’s group can research in future years.

“It will be spectacular,” he said.

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Mir Space Station

Plans call for Russia’s Mir space station to be brought back to Earth on Thursday. A look at the history of the station:

Feb. 20, 1986, the Soviet Union announces the launch of its new space station, Mir, a 20-ton core module with six docking ports for transport craft.

March 13, 1986, the first Mir crew, Leonid Kizim and Vladimir Solovev, opens the station.

On March 31, 1987, Mir’s second component, the Kvant-1 module, arrives.

In December 1988, French astronaut Jean-Loup Chretien conducts the first non-U.S. and non-Russian spacewalk.

In December 1989, the Kvant-2 module docks with Mir.

On Feb. 1, 1990, during a spacewalk, Alexander Serebrov tests an experimental flying armchair.

On June 10, the Kristall module, carrying materials-processing equipment, docks with Mir.

On July 17, cosmonauts accidentally damage the hatch of the air lock while repairing a docked Soyuz spacecraft.

In December 1991, Soviet Union collapses.

In March, Russian cosmonaut Valery Polyakov returns from Mir after a 438-day mission, the longest human spaceflight.

Norman Thagard is the first American astronaut to visit Mir.

On June 1, the Spektr module docks with Mir.

1996

NASA astronaut Shannon Lucid sets a U.S. record for long-duration spaceflight with a 188-day mission on Mir.

On April 26, 1996, Priroda module docks to complete the space station.

During a docking maneuver on June 25, 1997, the 7-ton unmanned supply craft Progress rams Mir, causing a complete loss of pressure in the Spektr module. The crew, including American astronaut Michael Foale, severs cables leading to the leaking module and seals its hatch before pressure inside the station falls dangerously low.

On Aug. 28, 1999, Mir is abandoned due to a lack of government funding.

On March 22, 2000, Mir begins deorbit.

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The final path

A look at the Mir deorbit plan received by the United Nations:

Possible area of debris

About 1,500 fragments weighing in total up to 27.5 tons are expected to fall over an ocean area 120 miles wide by 3,600 miles long. Some remaining pieces could weigh up to 1,500 pounds.

Sources: Space.com, Associated Press

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More Inside

Life in Space: Launched in 1986, Russia’s Mir space station grew into a complex of six modules, A6