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From September 27th to the 29th, the University of Toronto is presenting the first annual Toronto Science Festival (TSF), a three-day celebration of science that explores the theme of Life in the Universe. ()

On Saturday, September 28th, planetary scientist Jim Bell will take his TSF audience on a tour of Mars as seen by Mars rover cameras. (.)

Bell has worked on numerous NASA robotic space missions, and is a key scientist for imaging systems on the Mars Spirit, Opportunity and Curiosity rovers. He is also an author and educator, and in 2011 received the Carl Sagan Medal for Excellence in Public Communication from the American Astronomical Society.

Anyone who has seen spectacular Mars rover photographs might ask whether you consider yourself a scientist, an explorer or a nature photographer. Which is it?

Well, first and foremost, I consider myself a scientist, in that I'm interested in testing hypotheses about the past history of Mars and other worlds, and what they might tell us about the past history of our own planet. However, to be a Mars mission scientist these days is also to be an explorer, because none of us knows just what we'll discover. And to be a Mars imaging scientist is also to be a nature photographer, because the Red Planet presents us with one of the most lovely, barren, evocative desert landscapes in the entire Solar System. (See end of article for video from the NASA rover.)

A Toronto Science Festival panel will focus on the extreme environments in which we’ve found life. Do you think we will find life of any kind on Mars?

Honestly, I don't know. No one knows. But to me, it's a question of depth. The uppermost surface of Mars—which we image and explore from orbiters, landers and rovers—has been bathed in intense solar ultraviolet radiation for billions of years, and thus is unlikely to harbor any surviving organic molecules.

But if we could dig deeply—metres, tens, hundreds of metres—the subsurface is protected from radiation, and there's ice and potentially water down there. And it's warmer. Right now, we can't say with certainty that there isn't life in the deep Martian subsurface. And that's exciting!

Would you volunteer for a one-way trip to live in a colony on Mars, as thousands have?

Not me. Don't get me wrong, I'd love to visit Mars! But I want to come back. There's this romantic, sort of “old American West" feeling about going to Mars. But the reality of Mars makes the old American West look like a tropical paradise. There's no oxygen, little to no water, frigid temperatures, fine-grained dust everywhere, no food, no easy way home.

Mars will be the most barren, inhospitable, violent, unforgiving frontier that humans have ever encountered. We can survive it—we have the technology! But it will be incredibly hard, and, as in the old American West, many people will lose their lives in the struggle to tame that frontier. Me—I want to visit, then come back to our real tropical paradise, our perfect-for-us world, and share the stories of our adventures on the Red Planet!

There are many Solar System exploration missions being planned. In your view, what is the single most important?

I don't think there's a single most important mission, but I do believe there's a single most important theme: searching for evidence of past, present or future habitability. Where are the places besides Earth where the ingredients for life may have all come together at some point in the history of the Solar System? Where are the environments that could support life today?

And where are the places that humans can go in the future to live and begin to establish ourselves as an interplanetary, and eventually interstellar, species? I think these are the most important questions that motivate our exploration of the Solar System today.

The Toronto Science Festival is about celebrating science. Why is this important to you?

Science is the best way we've come up with to explore our world and the worlds around us, and events like the Toronto Science Festival provide remarkable and exciting opportunities to engage the public in the joy and adventure of science.

Read the interviews with other TSF key note speakers, and .