NASA expects 26 "potentially hazardous" pieces of UARS to reach the ground, most of them made of titanium, stainless steel or beryllium, which have high melting points. These pieces of debris include batteries, wheel rims and empty fuel tanks. UARS debris is expected to range in mass from 0.6 to 158 kilograms.

Orbital Debris Management

NASA's Orbital Debris Program works to reduce the number of large debris pieces in orbit. One aim is to prevent pieces of space junk from colliding and breaking into smaller pieces as well as to keep active satellites and spacecraft safe.

NASA's Mark Matney says the space agency took steps in 2005 to decommission the Upper Atmosphere Research Satellite.

"With what fuel was left on board UARS, we lowered the orbit to a point that we actually shaved 20 years off its lifetime, off its orbit lifetime, to try to remove it from orbit a bit sooner," the scientist explains.

Finders Keepers?

NASA officials say people should call their local law enforcement agencies if they find parts of the satellite. Matney cautions that although the pieces are not toxic, they might have sharp edges. Even though it is commonly referred to as "space junk," the debris still belongs to the country that owns the craft, in this case, the United States.