Phoenix sent its last message Nov. 2, before a lack of power caused it to go to sleep, permanently, it now appears.

The craft survived nearly three months longer than its expected 90-day mission but was finally done in by plunging temperatures with the approach of the Martian winter and the effects of an arctic dust storm that coated the lander's solar panels.

"We are ceasing operations and declaring an end to the mission," Phoenix project manager Barry Goldstein said Monday.

Other spacecraft orbiting Mars will continue to listen for messages for the next few weeks, Goldstein said, but he held out little hope that Phoenix would be heard from again.

Pronouncing the $475 million mission a success, Doug McCuistion, director of NASA's Mars Exploration Program, said the end should be an occasion for celebration rather than disappointment.