Los Angeles Bizarre microbes flourish in the most punishing environments on Earth from the bone-dry 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.
There hasn't been a eureka moment yet. But Phoenix turned up a promising lead last week when it uncovered what scientists believe are ice flecks in one trench and an icy layer in another.
Scientists hope experiments by the lander will reveal whether the ice has ever melted and whether there are any organic, or carbon-containing, compounds.
"We're looking for the basic ingredients that would allow life to prosper in this environment," chief scientist Peter Smith of the University of Arizona in Tucson has said in describing the mission's goal.
The discovery of extreme life forms, known as extre-mophiles, in unexpected nooks and crannies of the Earth in recent years has helped inform scientists in their search for extraterrestrial life.
"It's very suggestive that there are lots of worlds that may support life that at first glance may look like fourth-rate real estate," said Seth Shostak, an astronomer at the SETI Institute, a nonprofit dedicated to the search for extraterrestrial intelligence.
While the possibility for ET seems to grow with new extremophile discoveries on Earth, the truth is there's no evidence that life ever evolved on Mars or if it even exists today.
But if there were past or present life on the red planet - a big if - scientists speculate it likely would be similar to some extreme life on Earth - microscopic and hardy, capable of withstanding colder-than-Antarctica temperatures and low pressures.