My friend Jim Oberg wrote a very cool article about a very cool event: Vanguard 1, the oldest surviving satellite still in orbit, turned 50 a few days ago. It's actually outlived most of the people who put it in orbit.
Imagine! 50 years in space. 197,000 orbits. I would love to have this satellite brought back some day; studying just the impacts it's survived would probably be very helpful in designing future spacecraft. But then, maybe we should leave it in place. 50 years is a long time, and maybe keeping it there will serve as a reminder of how far we've come, and how far we have yet to go.