"We've developed a strategy for searching for life that starts with 'follow the water,'" said NASA scientist Chris McKay, who helped design the Phoenix mission. "All life on Earth needs water to grow or reproduce, so it makes sense that when we're going to other planets, we would go where we find evidence of water."
The Phoenix Lander will not be testing the soil for Martian microbes or other simple life forms -- that will be a task for future missions. But with such a promising beginning, scientists are optimistic about what they might find in the future.
"If we find that life started on Mars and on Earth, separately," McKay said, "then we know that we're not just some sort of cosmic fluke, that life is a naturally emerging phenomenon."
Peter Smith, lead scientist on the Phoenix Mars mission, agreed that the search has just begun.
"I think of Phoenix as a stepping stone, part of the long-term search for life outside the Earth," he said. "And I wish I could be a fly on the wall for the next 500 years and watch it unfold."
It's still quite a leap from believing that life exists somewhere in the universe to believing that intelligent life has visited us here on earth. But millions have already made that leap of faith. To them, the question is, when will everyone else follow?
Theoretical physicist Michio Kaku agrees that it is time for a real investigation.
"Even if there's a grain of truth, even if there's a slightest possibility that these sightings could lead to something greater, then let's look into it," Kaku said. "That's the spirit of science."