Launched on August 4, 2007, Phoenix landed on the Martian surface on May 25, 2008. The $420-million mission lasted much longer than the planned three months, and verified the presence of water-ice in the Martian subsurface, among other important scientific discoveries.

"Phoenix provided an important step to spur the hope that we can show Mars was once habitable and possibly supported life," said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington.

According to NASA, "additional findings include documenting a mildly alkaline soil environment unlike any found by earlier Mars missions; finding small concentrations of salts that could be nutrients for life; discovering perchlorate salt, which has implications for ice and soil properties; and finding calcium carbonate, a marker of effects of liquid water."

Phoenix's cameras also returned more than 25,000 pictures of the Martian surface.

NASA experts last received a signal from the lander on Nov. 2. and concluded that "the seasonal decline in sunshine at the robot's arctic landing site is not providing enough sunlight for the solar arrays to collect the power necessary to charge batteries that operate the lander's instrument