Exploring Mars: A Part of Human Destiny

The scoop: The Phoenix Mars Lander may be frozen into silence, but its mission isn't over. Lead scientist Peter Smith gives his take on the spacecraft's accomplishments and why exploring Mars is worth all of the trouble.

It's been a thrill sharing the Phoenix Mars Lander with the public as leader of the mission. Be it images, blog posts or "tweets" from the spacecraft, millions were given a virtual seat in our operations room. And yet our mission is not complete.

The Phoenix science team is still working through reams of spacecraft data in hopes of answering the following question: Does ice in the northern plains of the Red Planet represent a zone habitable to life? As with everything else, this will also be shared with you as the story develops.

We have placed the facts on the table for all to see: Ice two to three inches beneath the surface, an alkaline soil buffered by limestone (calcium carbonate), salts dominated by perchlorate, and a trove of weather data showing distribution of water vapor. Data in hand, we ask ourselves what to make of this evidence.

On Earth we associate carbonate formation with liquid water, perchlorates as an energy source for microbes, and salts as nutrients crucial to life. All suggest habitability on Earth, but Mars is not Earth. Carbonates we found on the Red Planet might have formed in the atmosphere and sprinkled globally with falling dust. Perhaps the ice we sampled never melted and just circulates with vapor in the atmosphere...

This uncertainty means the search for Martian truth is a time-consuming process that goes far beyond a single mission.

Phoenix investigated permafrost discovered by the Mars Odyssey orbiter in 2002 and, as the Mars Reconnaissance Orbiter now completes its primary mission, new discoveries abound to entice scientists -- most recently, the discovery of vast carbonate deposits in northern Mars. Next up is the Mars Science Laboratory (MSL). This nuclear-powered robot, which is nearing completion, is set to follow up on our collective discoveries by scouring a promising site for signatures of life.

After MSL, exploring the northern plains could not happen before 2016. Alternating between orbiters and landers might seem inefficient, but missions to Mars can launch only every 26 months, thanks to the orbits of the planets. Therefore, switching between orbiter and lander makes sense -- after all, the results from one mission can't be known before the next mission must launch.

Questions of inefficiency aside, is our continued stay on Mars justified? We stopped exploring Mars for 20 years after the Viking mission in 1976, denying an entire generation of scientists the chance to study the second most habitable planet in the solar system. Our approach to exploring the Red Planet today seems erratic, yet offers opportunities for scientists, their students, and the rest of the world to partake in the search for life.

I think questions we ask of Mars reach to the very core of our connection to the universe.

In spite of Herculean efforts, we've struggled to define life and understand its origin even on Earth. The gift of consciousness separating us from other animals bears a responsibility -- even a destiny -- as we stretch and push our knowledge and understanding toward unknown limits. This is the quiet revolution that has been taking place over the last 500 years and has completely transformed us into a paragon of civilization.

We must continue.

Peter Smith is the principal investigator for the Phoenix Mars mission and holds the Thomas R. Brown Distinguished Chair of Integrated Science at the University of Arizona. The views expressed here are the author's alone and do not represent the official position of the Discovery Channel.

Article posted December 24, 2008.

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