Spirit of exploration
As of today, NASA has officially given up attempts to contact the Mars Rover Spirit. They'll apparently still do some "passive listening," but they're pretty much saying that it's done, time to turn the lights off. Which is a little sad, but given that the thing functioned for six years instead of the 90 days it was intended to last, represents a huge and remarkable achievement. So I'm raising a virtual glass to Spirit, and I hope that one day humans will go find it and build a little monument around it.