Served it's duty well beyond expectations, now will stand a monument to mankind's first babysteps into the solar system, for a long long time. Maybe a tourist stop one day..

Well, they're quite possibly already here and have been for a looong time. If a space traveling species exist, and made it here already, they'd definitely be able to conceal themselves from us. Or, they evolved before us here on earth and like to experiment on monkeys and poof here we are. Or a combo of 1 and 2.