14.02.2019

Department of Geosciences Distinguished Professor Scott McLennan

As a young undergraduate student in Canada, Scott McLennan planned to spend his life studying the composition and characteristics of the Earth, and in 1987, he began teaching in Stony Brook’s Department of Geosciences, part the College of Arts and Sciences. But a decade later, McLennan was captivated by a new subject: Mars. He has now spent more than 20 years researching the Red Planet and assisting in numerous missions, and was named a Distinguished Professor in 2017. We sat down with McLennan recently to learn more about the development of Mars research and what might come next.

What got you interested in geosciences?

I started off with an interest in oceanography, but as that was a graduate discipline, I started to focus on geology in college. I enjoyed the research side of it, and we would get to go out once a week and do field work. I did my Ph.D. at the Australian National University, and my adviser was actually a planetary scientist, but I wasn’t interested at the time and chose to study geochemistry.

When did your research begin to focus on Mars?

It wasn’t until I had been here at Stony Brook for a little over 10 years, when the Pathfinder mission landed on Mars in 1997. I became very interested in that when I learned we could address questions about the sedimentary history of Mars with the mission data. I had enough training in planetary science from my Ph.D.that I felt comfortable moving into Mars research.

Why did you choose Mars over other planetary bodies?

My primary interest is in the sedimentary geology of Mars, the processes that occur on its surface. Specific conditions are required to create a sedimentary surface, so my options for research were essentially limited to either Venus or Mars. The Mars program became very active when I was getting involved, so it was a logical place to go.

Why are scientists so interested in studying Mars? What does it have to teach us?

Mars and Earth are actually very complementary places. On Earth, we have a magnificent geological record that takes us back hundreds of thousands of years, but the earliest part is either missing or transformed. But when we go to Mars, it’s the earliest history that’s best preserved. If we want to understand the origin of life here, Mars is a good place to study when it comes to the geochemistry and learning how life processes work. Even if we don’t find life on Mars, we can learn a great deal about how life works, how climate functions over long periods of time, and how a planet changes.

How has the field changed over time?

In the mid-1970s, the Viking mission was deemed a failure by many because it set out in search of life on Mars and didn’t find any. They learned a lot from that experience, but afterward the program faded — the United States didn’t land anything on Mars for more than 20 years, and people just lost interest. Scientists moved on to other things. And then the Pathfinder mission occurred and was immensely successful, which led to the reestablishment of a Mars program. The biggest successes from that were Spirit and Opportunity. Mars’ orbit allows us to go there every two years, and during that time we had a mission every chance we got.

What’s involved with assisting with these missions? What do you contribute, and how does it affect your schedule?

Everyone gathers at the jet propulsion lab in Pasadena, California, which has mission control facilities as well as research facilities where we work.  When the missions first land, we live on Mars time. On Mars, one day is 40 minutes longer than it is here on Earth. To compensate, our schedule shifts by 40 minutes each day. It’s OK for a week or two, but when you’re doing this for months at a time it becomes exhausting. It’s like shift work, but magnified. It’s especially difficult for the scientists that do this work full-time, especially if they have families who are living on Earth time. It was especially grueling for Spirit and Opportunity, since the two rovers were operating at the same time for many months.

As researchers, we’re trying to make sense of the data that’s sent to us by the rovers. But the rovers also have to be commanded every day. So we evaluate the data overnight, determine what we want the rover to do the next day, then build a command sequence and send it back up to the spacecraft. There’s a very short window where it’s possible to do this. Depending where Mars is in its orbit, it can take 10-15 minutes for it to receive the signal. Then it operates independently following those commands for the whole day.

Tell me about the current Mars mission, InSight.

InSight is different from the other missions I’ve worked with in the past. It’s a fixed lander, so it never moves. It has two cameras, but it’s primary goal is to study Marsquakes, meteoric impacts and other seismic activity. From this, we can figure out the internal structure of the planet — where the core and crust boundaries are and the composition of the planet’s insides. The other experiment involves heat flow, which studies how much heat comes out of the surface. This can teach us about how heat convection and plate tectonics work on Mars. Lastly, we’re studying the way Mars wobbles as it turns in order to learn more about the internal structure of its core — for example, if it’s solid or liquid.  

Where do you think space exploration is headed?

Mars exploration still has a lot of support, and people are very interested in going back to the moon, including in the United States, China and India. This time, the interest is in learning more about how we might live on another planetary body, as well as asteroids and moons of other planets. The Mars 2020 mission will take samples of the soil for us to study here on Earth.

Why is space exploration important? What do we have to learn from the field?

I was always taught that in science, you should seek to answer the really big questions, like the origin of life. Planetary exploration allows us to do just that. On Mars, we are beginning to learn that the conditions were appropriate for early life, so if it didn’t take place, what was it about the planets chemistry that prevented it? Or if life did exist, what happened? The answers we find will have profound sociological and philosophical consequences.

Why is Stony Brook a great place for students interested in space research?

Stony Brook has fantastic laboratory facilities, as well as our partnership with Brookhaven National Lab. We have just enough people in our department for small groups of researchers to interact and explore a diversity of interests, and beyond that, everyone is very collegial.

Quelle: Brook University