There are more than 2,000 active satellites orbiting Earth. At the end of their useful lives, many will simply burn up as they reenter the atmosphere. But some will continue circling as "zombie" satellites — neither alive nor quite dead.
"Most zombie satellites are satellites that are no longer under human control, or have failed to some degree," says Scott Tilley.
Tilley, an amateur radio operator living in Canada, has a passion for hunting them down.
Rest of the story at https://www.npr.org/2020/04/24/843493304/long-lost-u-s-military-satellite-found-by-amateur-radio-operator
