NASA's Phoenix Mars lander uncovered last week what scientists believe is ice layer some 5 centimeters below the surface of the alien rust-coloured planet, raising hope that some exotic life may emerge in the frigid arctic plains of the Red Planet.
Martian ice melts in this combination photo taken by NASA's Phoenix Mars Lander's Surface Stereo Imager on June 15 and 18, 2008, in this handout image released by NASA June 20, 2008. A trench dug by Phoenix with its robotic arm at the arctic circle of Mars shows dice-sized chunks of white material that are seen to melt away over the course of several days. The presence of water on Mars is crucial because it is a key to the question of whether life, even in the form of mere microbes, exists or has ever existed on Mars. On Earth, water is a necessary ingredient for life. (Xinhua/Reuters/NASA Photo) After 20 days of scratching its way through the Martian top soil, the Phoenix uncovered a bright white layer just two inches below the surface.
Four days after the white layer was first exposed to sunlight, photographs taken by the lander's on board camera showed the white surface had disappeared.
This proves, the scientists say, that the white layer was not salt as had been previously thought possible because it was melting.
The Robotic Arm on NASA's Phoenix Mars Lander carries a scoop of Martian soil bound for the spacecraft's microscope in handout photo released on June 13, 2008. (Xinhua/Reuters Photo) Channels and gullies seen on the Martian surface suggest the planet enjoyed a wetter past, but it is thought much of the water evaporated -- while at the poles it was trapped beneath the surface in the form of ice.
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 said in describing the mission's goal.
Most living things on Earth thrive not only in the presence of water, but also need sunlight, oxygen and organic carbon.
But the range of conditions in which life can survive has been expanded with recent discoveries of micro-organisms trapped in glaciers and rocks or living in volcanic vents and battery acid-like lakes.
These extreme conditions on Earth mirror the harsh environments found on Mars and other parts of the solar system.
Experts believe that if life once existed on Mars, it could still survive today in isolated pockets beneath the soil. Meanwhile scientists speculate it would likely be similar to some extreme life on Earth — microscopic and hardy, capable of withstanding colder-than-Antarctica temperatures and low pressures.
The presence of water ice on Mars will also make future missions to send humans to the planet easier.
NASA has plans to send astronauts to the planet after it returns humans to the Moon in 2020, and hopes eventually to establish a permanent base on the Red Planet.
Source: Xinhua\agencies
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