It also costs a lot of money to keep it running. So Russia is going to bring Mir down into the ocean. They will be careful that none of Mir's pieces hit places where people live. It seems that something as large as Mir hitting the Earth is very rare. But scientists who keep a check on what's flying around near planet Earth say a 135-ton object zooming in from space happens fairly often.
Military satellites record the flashes of their explosions in the upper atmosphere.
Just last year a 200-ton meteor surprised people in Canada with a loud boom and a bright fireball in the sky. The meteor blew apart high in the sky. Scientists later found some small meteorites on the ice of a nearby lake, but none were very large. But Mir will never make it that close to the ground, he says. The atmosphere is very good protection, and it breaks up meteorites and other space objects well before they can hit the Earth.