WASHINGTON (AP) — It's as big as a bus and weighs 6 tons, but officials probably will never be able to pinpoint exactly where a massive NASA satellite plummeted to Earth.NASA space junk scientists believe that all — or nearly all — of the parts of their 20-year-old dead satellite safely plunged into the Pacific Ocean, likely missing land. But if their estimates are off, by only five minutes or so, fiery pieces could have fallen on parts of northwestern North America.No injuries or damage have been reported on land, which NASA officials said was a good indication the satellite went into the ocean.That doesn't necessarily mean it all fell into the sea. Some debris could have fallen over areas such as Portland, Ore.; Seattle; Calgary, Alberta; and Saskatoon, Saskatchewan, said Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics."Pieces are falling off of this flaming fire ball, and some of it has enough momentum to go hundreds of miles," he said.Speculation was rampant on sites such as Twitter.