Canadian researchers chart path of Rosetta's comet

When the European Space Agency's comet-chasing Rosetta mission came to an end last month, the astronomers involved made it clear that the research into the data gathered during the 12-year journey had just begun.

Now a team of Canadian researchers is charting the history of Rosetta's comet 67P/Churyumov-Gerasimenko — a distant, icy rock home to complex organic molecules that provide clues about the origin of life on Earth. 

"We're putting together the pieces of the puzzle of this really, really interesting comet," Paul Wiegert, a professor at Western University's Centre for Planetary Science & Space Exploration in London, Ont., told CBC News.

• How Rosetta helped us understand where we came from
• Rosetta boldly went where no one has gone before

The Rosetta spacecraft orbited 67P and dropped a lander onto its surface — both historic firsts. The goal was to gather as much data as possible about the comet before it moved too far from the sun for Rosetta's solar power to function. 

It provided a treasure trove of data for astronomers, who are interested in comets because they function as time capsules — ancient and pristine snapshots into the very beginnings of the solar system.

Comets could even be the key to our existence, as astronomers suspect they may have delivered the water and organic molecules needed to sustain life to Earth. 

"Everything we learn about comets — where they came from, how they moved through the solar system over time — tells us about how we came to be," Wiegert said. 

The far reaches of the solar system 

Planets are so big their orbits don't change much over time, but smaller objects like comets have more complicated trajectories.

"The reason that we did this was really to ask the question: where was this comet in the past? It hasn't always been on the orbit it is now," Wiegert said.

Using statistical analysis and scientific computing, Wiegert and co-author Mattia Galiazzo have learned that 67P is relatively new to the inner regions of the solar system.

It arrived about 10,000 years ago, most likely from the Kuiper belt, a region beyond Neptune's orbit where there is a large accumulation of asteroids, comets and other space bodies

"Over the course of the last million years or so the comet has moved inwards closer to the sun," Wiegert said. "Its birthplace is quite different from the location it finds itself in right now."

This suggests the comet is made up of primordial material — minerals that existed in their current form since before Earth was formed.

And Wiegert said they've just scratched the surface.

"We have only traced the history of the comet back partway," he said. "So there's still further to go. There's always more to do"

The findings are being presented today at the European Planetary Science Congress in Pasadena, Calif.