After nearly two weeks of testing and preparation, NASA's Phoenix lander on Friday began its first day of science operations at Mars' north pole. The Lander's robotic arm delivered a cup of soil to an oven that will search for evidence that the Red Planet was once habitable.

The scoop, taken from a spot next to the lander dubbed Baby Bear, then paused over one of the eight tiny ovens attached to the Thermal and Evolved-Gas Analyzer, known as TEGA, to make sure the material doesn't spill over and contaminate other instruments.

Engineers on Earth were planning to send the command to dump the material late Friday, beginning the weekslong process of analyzing the Martian soil chemistry.

Over the three-month life of the $420-million mission managed by the Jet Propulsion Laboratory in La Canada Flintridge, Calif., Phoenix will dig down to the ice layer and deliver samples to scientific instruments that will test for organic compounds that could indicate Mars once might have been, or still might be, home to rudimentary life forms

Organic compounds contain carbon, often in combination with hydrogen, nitrogen and oxygen. Carbon is important because it is one of a few elements that can build long and complex molecules necessary to make living organisms.

Since the 756-pound, 7-foot-tall Phoenix lander touched down May 25, scientists have been doing test digs in preparation for science operations. Said JPL's robotic arm expert, Matt Robinson: "Our pre-season has been five years long. You can imagine we're raring to go."

A picture of the soil in the scoop showed familiar reddish-brown dirt, with an inch-sized clump containing whitish streaks that some scientists think could be ice.

Most researchers, however, believe it's salt. The skeptics say such small amounts of ice would evaporate quickly when exposed to the sun through sublimation, a process that converts the ice directly to a gas, skipping the liquid water phase.

Even if the ice has not shown itself, scientists are confident that they landed in the right place. Pictures of the lumpy landscape around the lander show ridges bordered by trenches that are characteristic of permafrost regions at Earth's poles. And the soil also is clumpy, easily forming clods, which can result from the presence of water.

Each of the eight ovens is about an inch long, with an opening about the size of a pencil lead. "These are very small ovens but powerful," Peter Smith, the lead scientist on the mission from the University of Arizona, said during a media briefing Friday.

TEGA will gradually heat the samples, finally reaching 1,000 degrees Fahrenheit, to study the gases given off in a mass spectrometer.