ANCHORAGE, Alaska—In the wake of Viking, it seemed less likely that life could exist right now on Mars. But evidence that the planet was once warmer and wetter -- and could have harbored life billions of years ago -- has been accumulating.
One reason scientists now believe that Mars may have harbored life in its distant past is because of all the Carbon Dioxide Ice that is today locked-up at the planet's North and South Poles.
Calculations have been done showing that every once in a great while, Mars flips over wildly on its poles. This flipping takes place over a period of tens of millions of years. That's because unlike Earth, Mars does not have a relatively large moon spinning around it. The Earth's Moon -- due to gravitational tugging on the Earth's equatorial bulge -- does not allow our planet to "topple over". It keeps Earth's axis very close to a 23.5 degree inclination with respect to the sun.
But Mars, without a big moon, is free to topple over as much as 60 degrees on its axis -- like a spinning top running out of energy. When that happens, it's hypothesized, the carbon dioxide in the pole facing the sun sublimates, creating a dense, warm atmosphere.
Under such conditions, the permafrost -- believed to exist beneath much of the Martian regolith (or soil) -- would melt, creating flowing water.
On earth, wherever there is liquid water, there is life.
These theories have shaped "Curiosity" into the rover that is only capable of searching extant life. And for that, the vehicle and its mission were beautifully designed.
8 months ago -- when it launched from Florida on its 350 million mile journey -- Curiosity was aimed at a specific section at the edge of a specific crater on Mars. And after that 350 million mile journey the vehicle landed almost precisely in the middle of its touchdown ellipse.
NASA said the trajectory was so precise it was like firing a pea-shooter from Florida and hitting a dime in downtown Los Angeles. Not just ANY dime, the specific dime that you were aiming for!
Such accuracy is important because the "dime" that NASA was aiming at is Gale Crater. It's a crater has evidence of ancient flowing water. It also has evidence of clay-like soil, which is believed to have formed in the presence of ancient seas.
Curiosity is equipped to examine these promising mineral formations, and even test them for signs of organic compounds -- the compounds that make up all life on Earth.
The work that the U.A.A Students are doing is not likely to directly affect the interpretation of data fed to Earth by Curiosity. But it may be helpful for future Mars Missions -- which are designed to search more directly for life.
Cold, desiccated environments -- like the dry valleys of Antarctica, and certain parts of Alaska -- seem to contain microorganisms which have evolutionary adaptations that are very likely to be useful on Mars.
By studying these cold places on our planet, we may -- in the future -- be equipped to recognize evidence of life, or extant life on Mars.
Without studying such "Mars Analogues" on Earth, we risk sending billion-dollar-spacecraft to the Red Planet, and not recognizing what could be the most significant finding in the history of biology: the existence of microbial life beyond Earth.
Is there life on other worlds?
It's a question humanity has asked for much of the 200,000 years that modern man has roamed the earth.
You and I are lucky enough to be part of the first generation of human beings who can ask that question, and reasonably expect to receive an answer.