Imagine yourself taking an early morning walk in Tulsa, Oklahoma only to see a "big bright light, like a fire ? in the sky. The object continues to get bigger as it approaches overhead. A few minutes later, you feel a gentle tap on your shoulder. You look around only to find a light piece of charred metal, about the size of your hand. You've been hit! Impossible you say?

Just ask Lottie Williams of Tulsa, Oklahoma about her early morning walk on January 22, 1997. The metal mesh-like fragment which hit her came from a rocket that had been used to put a satellite into orbit for the U.S. Air Force in 1996. After nine months in space, a fuel tank from the rocket crashed into an empty field in Texas. The fragment which hit Williams on the shoulder came from that particular fuel tank. Fortunately, she was not injured.

An average of one space object reenters the Earth's atmosphere every day and this number is likely to increase. As early as 1961, nearly four years after Sputnik I, the U.S. Air Force had already discovered and tracked approximately 60 objects. By 1966, the number of objects tracked had risen to over 1,300. Today, United States Space Command tracks and catalogues over 8,900 man-made objects larger than ten (10) centimeters diameter which orbit the Earth in a 200 mile-deep sphere of space. Of these objects, approximately 23% are inactive satellites, 10% are burned out rocket stages, 62% are fragments, and only 5% are active satellites.

In other words, thousands of satellites, fragments and debris have gone out of control and are in orbit around the Earth. Granted, some of today's newer satellites have propulsion systems designed to keep them in proper orbit or at least direct them to a safer reentry point if needed. Without these systems, however, the laws of physics will drag all orbiting objects back into Earth's atmosphere at some point. Most of these objects will burn up on reentry and completely disintegrate. But there are several notable exceptions that have presented a real threat to life, property and the environment on Earth.

1. In April of 1964, a United States nuclear powered satellite (U.S. TRANSIT 5BN3/SNAP 9A) failed to reach orbit and was subsequently destroyed over the Indian Ocean releasing some 17,000 curies of plutonium-238 into the upper atmosphere. High-altitude samples later indicated a worldwide release of radiation.

2. On July 11, 1979, the 77-ton U.S. Skylab space station, despite efforts by NASA, left orbit and re-entered over a large footprint encompassing parts of Australia and the Indian Ocean. Some 500 pieces of metal were spewed over a 400,000 square mile remote area of Australia, with some pieces weighing up to 4,000 pounds. Nobody was injured. But the U.S. State Department received a $400 fine for littering from the authorities in the town of Esperance, Australia.

3. On March 23, 2001, the highly successful Mir space station was retired and brought down from orbit. It was the largest man-made object to ever reenter Earth's atmosphere. The 140-ton Mir broke apart over a remote part of the South Pacific during a controlled reentry. The debris footprint of over 300,000 square miles was well removed from all shipping lanes and populated areas.

4. On February 7, 1991, the 40-ton Soviet Salyut 7 space station deteriorated over South America, creating an impressive light show for Argentina. Unfortunately, debris rained over Capitan Bermudez, Argentina. At approximately 1:00 a.m. local time the sky was lit up with hundreds of incandescent chunks and pieces traveling from Southwest to Northeast. At dawn the inhabitants discovered numerous metal fragments, which seemed to have fallen in distinct groups at various locations in the city. Fortunately, there was no loss of life or property damage.

5. On January 24, 1978, Cosmos 954, a nuclear powered Soviet satellite used for maritime observation, reentered over northern Canada. While most of the satellite's several tons burned upon reentry, at least 65 kilograms of radioactive material and other physical debris were scattered over a remote wilderness area the approximate size of Austria or 124,000 square miles. Over 60 radioactive sites were identified. Again, no loss of life but the Canadian government worked until mid-October 1978 to complete the clean-up at a cost of six million Canadian dollars.

6. On June 4, 2000, the 17-ton Compton Gamma Ray Observatory (CGRO) reentered over the northwestern coast of South America in a controlled reentry. The debris was scattered over a 2,500 mile ellipse which extended from the southeastern tip of Hawaii to the northwestern coast of South America. The CGRO was the heaviest spacecraft ever launched by NASA.

7. In November of 1960, fragments from a U.S. satellite damaged property and killed one cow on a farm in Cuba.

8. In May of 1968, a U.S. nuclear powered satellite reentered and crashed into the Santa Barbara Channel, California where the nuclear power source was retrieved intact at a depth of 100 meters.

9. Five Japanese sailors were injured when their vessel was struck by parts of a Soviet satellite on June 5, 1965. It is unclear whether they were struck by the fragments themselves or suffered injury by some other means.

10. In November of 1964, over 40 fragments from a U.S. Agena-Atlas rocket fell onto Brazil, Cuba, Mexico and Peru.

To find out more about upcoming satellite and debris reentries that may be happening at a city near you, check out the website for The Aerospace Corporation, www.reentrynews.com They even provide a map of where they expect the upcoming reentry to occur as well as the approximate time. In any event, keep an eye out above. The sky is really falling.