The first images sent back from the Phoenix Mars Lander showed a landscape dotted with small rocks and , as well as a complex pattern of cracks and . Scientists say the evidence of cracks and troughs is exciting because it suggests that ground ice is , similar to areas of permafrost on Earth. The team's principal investigator is Peter Smith of the University of Arizona. He says some of the troughs shown in the lander's photographs appear to have been freshly .

"This is just like the active surfaces in the regions on Earth," said Peter Smith. "It implies you have an active surface, in other words the is still there and expanding and contracting with the seasons." Smith says the lander is set to transmit new photographs once a day, images of the entire area around the craft's landing zone.

The Phoenix landed with a combination of and late Sunday, ending its journey of 680 million kilometers to Mars which took nearly 300 days. The craft is expected to conduct a 90-day mission digging for signs of the raw ingredients for life in the planet's polar region.

In coming days, engineers are expected to ready the lander's equipment to begin analyzing the planet's weather and conditions.

Smith says on the lander will dig through layers of soil to study its composition and find ground ice believed to be several centimeters below the surface. He says one key hope of scientists is to find remains of life frozen in the ground ice. "We are wondering on Mars is there any indication that organic materials are preserved in this ice," he said. "And probably the organic materials would have come from and that hit the surface of Mars over the last many eons."

Smith says the Phoenix mission targeted the planet's frozen polar region because warmer conditions elsewhere on the planet would the remains of any possible organic life and make them impossible to .

The Phoenix lander joins two other NASA probes on the surface of Mars - the Spirit and Opportunity exploration - which landed in 2004.