John Spray is passionate about his job. His recent work involves understanding the geology of Mars, in particular by studying impact craters on the Red Planet and on Earth. He is the director of the Planetary and Space Science Centre of the University of New Brunswick in Fredericton. He is member of a team of scientists who discovered a series of craters in Europe and North America—two of them in Canada—forming a chain and indicating that an asteroid might have collided with Earth 214 million years ago. For him, "the sky is the limit."
Gathering pieces of information and shaping them into exciting theories is like a crime investigation. "It is important to obtain the information carefully and then to use it to build the bigger picture, which typically involves recognizing Nature's patterns," explains Spray. "Sometimes it is easy to ignore negative evidence too, which, like Sherlock Holmes, I'm aware of."
The clues he found led him to formulate a new hypothesis concerning the impact craters he studied: "I was collaborating with a colleague in the U.K. who dates the formation of rocks. We worked together on a crater in France, called Rochechouart. We determined it to be 214 millions years old. I realized that this was the same age as the Manicouagan crater in Quebec, as well as the St. Martin Lake impact crater in Manitoba. This led me to consider that several asteroid or comet fragments had hit Earth at the same time."
But then, if the answers can be found on Earth, why study the geology of Mars? Spray has an opinion on that. "Mars is a neat planet because it has had a rich and varied geological history. We now know that it was wet in the past, that rivers flowed and that lakes, and perhaps even oceans, covered parts of its surface. Something happened to the planet that caused it to dry out and freeze up. This is one of the big scientific puzzles."
John Spray is Director of the Planetary and Space Science Centre. "The Centre is unique because it is the only NASA Planetary Image Facility in Canada. This means we have data and images for many of the past missions, which is an incentive to carry out further work. The centre provides a focus for undergraduate and graduate as well as post-doctoral students, to work together to study other planet and meteorite materials, as well as analogue geology on Earth. "And if he'd found an amazing and accessible crater, what would he do? "Send graduate students there as soon as possible!"
Among the clues he collects to build theories are rocks. "Some forestry workers brought a huge rock of several hundred kilograms to the university. They even needed an excavator to load it into the truck from the woods. The men were convinced that it was a meteorite and were hoping that I would buy it for many thousands of dollars and they were anticipating their early retirement! I had to diplomatically tell them that it was just a regular igneous rock. This particular boulder was green and black. It was out of place because glaciers had moved it. One day, I hope someone will bring a real meteorite into my lab. That will be very exciting!"