A 6.3-ton NASA science satellite, decommissioned in 2005, is expected to plunge into Earth's atmosphere later this month, breaking up in a shower of debris. Experts said today they expect 26 components, the largest weighing more than 330 pounds, to survive re-entry heating to hit the surface somewhere between 57 degrees north and south latitude.
But a NASA space debris expert said the threat to the public is minimal and that statistically, the odds are good the debris will land in an ocean or some other sparsely populated area.
"We looked at those 26 pieces and how big they are and we've looked at the fact they can hit anywhere in the world between 57 north and 57 south and we looked at what the population density of the world is," said Nick Johnson, chief scientist with NASA's Orbital Debris Program at the Johnson Space Center in Houston.
"Numerically, it comes out to a chance of 1 in 3,200 that one person anywhere in the world might be struck by a piece of debris. Those are obviously very, very low odds that anybody's going to be impacted by this debris."
The centerpiece of a $750 million mission, the Upper Atmosphere Research Satellite, or UARS, was launched from the shuttle Discovery in September 1991. The solar-powered satellite was designed to address a wide variety of atmospheric questions, including the depletion of Earth's ozone layer 15 to 30 miles up, a trend blamed on the release of man-made chemicals called chlorofluorocarbons, or CFCs, used in refrigerants, foam products, and various solvents.
The long-lived satellite was decommissioned in 2005 and one side of its orbit was lowered using the last of its fuel to hasten re-entry. No more fuel is available for maneuvering and the satellite's re-entry will be "uncontrolled."… Read more