Bizarre microbes flourish in the most punishing environments on Earth from the bonedry Atacama Desert in Chile to the boiling hot springs of Yellowstone National Park to the sunless sea bottom vents in the Pacific. Could such exotic life emerge in the frigid arctic plains of Mars? Nasa's Phoenix spacecraft could soon find out. Since plopping down near the Martian north pole a month ago, the three-legged lander has been busy poking its long arm into the sticky soil and collecting scoopfuls to bake in a test oven and peer at under a microscope.