ON MAY 25, NASA's Phoenix Lander will touch down near the north pole… of Mars. On board is a lidar, adapted by Dr. Thomas J. Duck and a team of scientists at Dalhousie University, in Halifax, that will help measure Martian weather. Lidar (light direction and ranging) is similar in principle to radar and sonar. For 20 years, Dr. Duck has been working with lidar systems on Earth, especially in the Arctic, studying the earth's own atmosphere. Saltscapes talked to the scientist about Star Trek, Martian dust devils and the air quality in Halifax.

Q Is there someone from your childhood who led you to science?
A My dad is a scientist. His area of expertise was biomechanics, the physics of human movement. In Grade 8, a teacher, Dan McConnachie, was very big on music and science, and they've been passions in my life ever since.

Q Did you play astronaut as a kid?
A Not that I remember. We went to the Kennedy Space Centre, and I vividly remember seeing all the rockets there… I had a wonderful opportunity to see one of the Apollo capsules first-hand.

Q Were you a Star Trek fan?
A Of course. The original series is a classic. The whole sense of exploration is just wonderful. There were some tremendously creative ideas. Isn't it amazing that our cell phones now are just like the communicators they used?

Q When you think that you spend your days imagining what it's like on Mars, the scientific imagination seems truly childlike.
A It's something we need to do more. We need to dream. To some extent people have forgotten to dream. There are so many wonderful things that we can do if we just put our minds to them and give them our best try. Going to Mars is one of those things.

Q What do you use the lidar for?
A Here on Earth we use lidars to measure pollution, ozone, clouds. Carbon dioxide is important for climate-the whole greenhouse effect. On Mars, we're interested in dust, which warms up the atmosphere.

Q If Mars has weather, does it have storms?
A It has tremendous storms. In order to land people on Mars, we need to get a grip on these storms and dust devils, little tornado-like things that whip across its plains all the time. The storms are enormous. They cover half the planet. They can last several months.

Q Why is the Phoenix mission statement "follow the water"?
A Water is critical for life. We think Mars has a water cycle much like Earth. Instead of having big oceans, it's got this great big icecap. Mars is similar to Earth in a lot of respects. And yet today, it looks completely different. We're interested in understanding why Mars has had this particular fate.

Q What particular fate?
A You look at Earth and it's got lots of big, thick clouds. It's got oceans, it's got all this life. Mars is pretty desolate, pretty barren. People have wondered for a long time, where's the water? We think water might be carried away by the solar wind. The Earth has a magnetic field that deflects the solar wind. Mars doesn't. The magnetic field disappeared four billion years ago.

Q What's next for you?
A The Arctic is going to consume a lot of my time. The changes we're seeing in the Arctic... it's breathtaking. Breathtaking. We also have a laser radar project right here in Dalhousie's Dunn Building. We look at pollution transport and forest fire smoke.

Q What's the air quality like in Halifax?
A It's pretty good. Forest fire smoke from distant places passes over Halifax during the summer fairly regularly. Last summer, we saw smoke plumes from Quebec, the Northwest Territories, Idaho, Utah and Mongolia.

Q Do your kids have any interest in space?
A Oh, they certainly do. My little boy-he's five-is already known in his class for knowing things about rockets. One kid was heard to say, "He knows things that an eight-year old knows."