Actually, the downrigger guesses are close, but not quite. It's a 'travelling bobber'. I had one as a kid. You'd tie the rod end to the top eye, hang the baited end off the bottom eye, and cast it as far as you could. Then, by pulling quickly on the line, it would dive under water, then travel several feet farther out as it rose back to the surface. You could work it out quite a ways into a lake that way, or under trees and overhangs that would otherwise snag your casts.

I love this:
"The official spoke on condition of anonymity because the information is classified as secret."
Ummm...I guess that means the information about his identity is secret?? Sure can't be the Secret info he just gave out about the satellite!