In 1960, the Soviet Union began the Vostok space program, a series of unmanned satellites carrying various equipment. The first such satellite was Korabl-Sputnik 1, launched in May of 1960. The West called this satellite Sputnik 4. The descent module separated from the equipment module, but did not "descend" as planned. Instead, the descent module orbited for two years, then burned up on reentry. A piece of it fell in the United States.
Two policemen in Manitowoc, Wisconsin, encountered a chunk of something that was too hot to touch. They didn't think much of it until they heard on the news that Sputnik 4 had burned up in space. They went back to retrieve the 20-pound chunk of metal. NASA analyzed it thoroughly, then offered it back to the Soviets. Meanwhile, in Manitowoc, the historic chuck of metal was memorialized in the street where it was found, on the sidewalk nearby, and in two museum exhibits that have been there for decades. Read about Manitowoc and the satellite at Amusing Planet.
(Image credit: Amy Meredith)