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NASA says its derelict Upper Atmosphere Research Satellite is expected to make its final fiery plunge sometime on Friday afternoon ET and notes that "the satellite will not be passing over North America during that time period."

This afternoon's update suggests that Americans are not at any risk for injuries or property damage due to satellite debris. It also means they'll miss out on the fireworks.

For two weeks, experts on orbital debris have been telling people that the 20-year-old, bus-sized spacecraft would soon fall through the atmosphere and drop about two dozen pieces of debris on Earth — but until today, there was too much uncertainty to say exactly which day that would happen. In the morning update, NASA narrowed the time frame down to Friday. The forecast was refined further at 6:35 p.m. ET. But NASA said it couldn't yet be any more precise about UARS' zero hour than to say it'll be Friday afternoon, Eastern Daylight Time.
"It is still too early to predict the time and location of re-entry with any more certainty, but predictions will become more refined in the next 24 to 48 hours," NASA said

The six-ton satellite's orbit is limited to between 57 degrees north latitude and 57 degrees south, spanning the width of the world between northern Canada and the tip of South America. In the past, Nicholas Johnson, the head of NASA's Orbital Debris Program Office, has estimated that the chances that any of the UARS debris would hit anybody were 1 in 3,200 — which translates into a 1-in-20 trillion risk for any particular person.

[link to cosmiclog.msnbc.msn.com]