Just before 5:30 a.m. Saturday morning, a Delta 7925 rocket will launch from Cape Canaveral carrying an important payload for planetary exploration: the Phoenix, NASA's latest mission to Mars. If all goes well, Phoenix should land in the northern polar region of Mars in May 2008, giving scientists the first close-up views of this relatively unexplored area of the Red Planet.
In many ways Phoenix resembles the Viking landers of the 1970s, the ambitious probes that tried to determine whether or not life existed on Mars. Like the landers in Viking 1 and Viking 2, Phoenix will make a "soft" landing on Mars, firing retrorockets for a slow and controlled descent to a specific landing site. Once there, it won't relocate; Phoenix isn't a rover. Instead, like the Viking landers, it will use a robotic arm to collect and analyze samples of Martian soil.
But unlike Viking, Phoenix isn't being billed as a mission to address the question of current life on Mars. Rather, its goals are to examine the historical evidence of water on Mars and to establish and define any habitable zone where life could survive within the planet's top layers of soil and ice. It's perhaps for the best that Phoenix isn't directly searching for life like its Viking predecessors: A paper published in January hypothesized that the Viking landers accidentally killed any life they collected in their samples due to biochemical differences between Earthly organisms and putative Martian microbes.
On the Phoenix mission website, check out the snazzy animations that simulate the lander's journey.
Image: The fully assembled Phoenix Mars Lander awaits launch at Cape Canaveral. NASA/United Launch Alliance