CAPE CANAVERAL, Fla. - A dead 6-ton satellite is getting closer and closer, and is expected to smack down on Earth on Friday.

NASA's old research satellite is expected to come crashing down through the atmosphere Friday afternoon, Eastern Time. The spacecraft will not be passing over North America then, the space agency said in a statement Wednesday evening.

The predictions should become more precise by Thursday afternoon and certainly by Friday.

"It is still too early to predict the time and location of re-entry with any more certainty," NASA said.

An estimated 26 pieces -- representing approximately 544 kilograms -- are expected to survive.

NASA is anticipating a splashdown rather than a landing. Nearly three-quarters of the world is covered with water. The Aerospace Corporation in California, in fact, predicts that re-entry will occur over the Pacific late Friday afternoon, Eastern Time. But that's give or take 14 hours.

The 20-year-old Upper Atmosphere Research Satellite will be the biggest NASA spacecraft to fall uncontrolled from the sky in 32 years.

It is expected to break into more than 100 pieces as it enters the atmosphere, most of it burning up. The heaviest metal parts are expected to reach Earth, the biggest chunk weighing about 140 kilograms. The debris could be scattered over an area about 800 kilometres long.