On the ground: dig, dig, dig

If all goes well, ground controllers on Earth expect to hear a signal from Phoenix on Mars at 7:53 p.m. EDT Sunday.

The 772-pound craft will wait 15 minutes for the dust to settle before unfurling its solar panels. Then it will hoist its weather mast and beam back the first images of its surroundings.

Over the next several sols, as days are known on Mars, it will check its instruments and stretch its robotic arm to scoop up the first soil sample. A Martian day is about 40 minutes longer than a day on Earth.

By around sol 10, Phoenix will dive into the digging phase that is expected to dominate the rest of the mission, excavating about two hours a day.

While scientists say there's a chance Phoenix could live a month or so beyond its 90-day mission to see late summer or fall, it won't survive as long as the six-wheeled rovers Spirit and Opportunity, which are still operating four years after they debuted on Mars.

That's because Phoenix's solar panels won't produce enough power to keep it alive during the Martian winter. Also unlike the rovers, Phoenix will stay in one spot.

Said Ray Arvidson of Washington University in St. Louis, the mission co-leader: "Its feet will be embedded with dry ice and the sun will be below the horizon."