NASA says its defunct bus-sized satellite fell to Earth overnight off the U.S. West Coast and likely didn't cause any injuries or damage.

The aging Upper Atmospheric Research Satellite first penetrated Earth's atmosphere somewhere over the Pacific Ocean between 11:23 p.m. ET Friday and 1:09 a.m. ET Saturday, according to NASA and the U.S. Air Force's Joint Space Operations Center.

The precise re-entry time and location of any debris impacts are still being determined, the agency said in a statement mid-Saturday.

"NASA is not aware of any reports of injury or property damage," the agency said.

NASA spokesman Steve Cole said that since the plummet began over the ocean and given the lack of any reports of people being hit, agency officials have "a good feeling that no one was hurt."

Most of the satellite is believed to have burned up. Meanwhile on Saturday, the RCMP was shooting down unconfirmed reports and video published on Twitter of debris seen over Okotoks, a town south of Calgary.

RCMP Sgt. Patrick Webb says the video was likely a hoax, adding police have heard nothing about falling debris in the area.

"If that video is real, I will buy you a cup of coffee," Webb said in an interview with The Canadian Press.

NASA's calculations had predicted that the former climate research satellite would fall over an 800-kilometre area.

The UARS, weighing 5.44 tonnes, was NASA's biggest spacecraft to tumble out of orbit, uncontrolled, in 32 years.

Some 26 pieces of the satellite — 550 kilograms of heavy metal — were expected to rain down. The biggest surviving chunk was expected to weigh no more than 135 kilograms, according to NASA.

Satellite decommissioned in 2005

UARS was launched aboard space shuttle Discovery in 1991. NASA decommissioned the satellite in 2005, after moving it into a lower orbit that cut its life short by two decades.

Bits of space junk re-enter the atmosphere virtually every day. No injuries have ever been reported from it.

UARS carried some Canadian technology, which has now gone up in flames.

Robert Dick, who teaches astronomy at Ottawa's Carleton University, designed some of the equipment on board the doomed machine.

He worked on a camera — part of a $40-million Canadian research instrument called the Wind Imaging Interferometer or WINDII.

The instument allowed scientists to measure movements of certain types of molecules in the upper atmosphere.

"The reason for building it was to get data, and it did that very, very well," Dick told CBC News.

Dick has worked on other satellites that are still circling the Earth. He says the ones in high orbit will stay up there pretty much forever.

With files from The Associated Press and The Canadian Press