On the Phoenix Mission’s 152nd Sol (a Martian day) the lander has fallen silent and mission engineers have been unable to communicate with it for over a week. This was expected as the Martian sunlight is less and less as the season changes. The sun is simply not providing enough energy to replenish its solar batteries. There is an outside chance that communications might resume again, but it would be a fleeting opportunity at best.
In all, the mission prooved the existence of water-ice in the Martian subsurface; we saw (with our own eyes) Martian ice melting; it was the first time an atomic force microscope was used outside the bonds of Earth; the discovery that Martian soil may not be that different from the Earth’s and that growing plants in it may not be at all difficult; Phoenix found trace amounts of salt which could be nutrients for life; and finally calcium carbonate which suggests a past existence of liquid water on the surface of an anchient Mars.
And who could forget this image. Not too shabby.