The Phoenix Mars Lander is sitting at the Martian north pole, its mission complete. Designed to study the history of water on Mars and investigate potential human habitability, it touched down in May 2008. It dug trenches and examined the surface soil of Mars for months, but the Martian winter was inexorable. Eventually, the intense cold forced engineers to shut Phoenix down (as planned), and there it still sits.
The HiRISE camera on the Mars Reconnaissance Orbiter took images of Phoenix last year while its mission was still active, in June 2008. Here's that image:
Phoenix is pretty obvious! The surface there was relatively free of frost at that time. But scientists on Earth decided to get more images, this time during the winter. In July of this year they found Phoenix once again, but the picture is a little different!
First off, the green is not real; this is a false color image. So don't go thinking they found moss bogs or anything like that. What you're seeing is the same field as in the first picture, but this time its covered with carbon dioxide frost! Even Phoenix appears to have CO2 over it, making it pretty difficult to see. I imagine that if they hadn't taken the earlier picture, it would've been a lot harder to pick the lander out from the background.
Spring sprung on the northern hemisphere of Mars a couple of weeks ago, and in another few months scientists will try to contact Phoenix and see if they can wake it up after its lengthy hibernation. It's a bit of a long shot -- the mission wasn't designed for it -- but one thing we've learned about the probes we've sent to Mars is that they can be incredibly hardy: the two rovers are still operating years after the initial design lifetime. So maybe Phoenix will live again, and get back to work (expect other news sources to say it will rise from its ashes; a bad metaphor given that it's covered in frost). And if it does, images like the ones above from HiRISE will help us back here on Earth interpret what it's seeing. The more eyes we have on Mars, the better.