In search of other life in the universe
The Kepler Space Telescope arose out of the U.S., but it was Canadian researcher Jason Rowe who discovered a planet that is the same size as Earth, and, more significantly, one on which water may be able to remain liquid.
Rowe, now an Assistant Professor at Bishop’s University and the Canada Research Chair in Exoplanet Astrophysics, was working on the Kepler team as a post-doctoral fellow at the National Aeronautics and Space Administration’s Ames Research Center in California when he made the discovery, one of several he cites when talking about the high points of his career so far.
Rowe’s life’s work has been to discover and characterize extrasolar planets (also called exoplanets), which are planets that are in orbit around a distant star in distant solar systems. So far, his work has contributed to the discovery of “probably 4,000 to 5,000 such planets,” he says. After their discovery, characterizing them means looking at their size, mass, atmosphere and how much light they receive from their host stars.
“We’re asking questions such as: ‘Does this planet have characteristics similar to Mercury, Jupiter, or Neptune, or are they more like the Earth?” he explains.
To do his work, Rowe uses space telescopes, in particular, the NASA Kepler Space Telescope, a one-meter telescope with a camera attached to it. Kepler is responsible for watching 200,000 stars continuously.
“The technique for finding planets is to watch them transit their host star. If you look at a star and the orbital plane is oriented such that the planet passes between you and the host star — the planet will block a little bit of light,” he says. “The odds of that happening depend on how close the planet is to its host star. If the planet is very close, there’s a 10 percent chance of finding it. If it’s much further from its host star, the chances are slimmer.”
From the 200,000 stars on Kepler’s radar, researchers have found 2,000 planets.
“So when you use the probabilities of transit occurring, it tells you that every single star likely has a planet orbiting around it,” Rowe says.
It’s a lot to contemplate, but getting to those “aha” moments requires lots of computation. Kepler, which has computers on board that collect transmissions and send them back to Earth, produces an enormous amount of data. And people such as Rowe and his many colleagues and students do most of the heavy-duty computation on Earth.
To do this math and analysis, he and his team use Canada’s advanced research computing (ARC) platform. This ARC platform is coordinated collectively by Compute Canada and its regional partners (ACENET, Calcul Québec, Compute Ontario, WestGrid) and member institutions for researchers across Canada.
“Behind the scenes, the infrastructure that’s provided by Compute Canada is used to analyze observations from Kepler, discover planets and then characterize them,” Rowe said. “Then those numbers determine which ones we follow up on to determine masses.”
Asked if he has come up with any creative names for the planets he’s discovered, Rowe admits the naming protocols are somewhat boring.
“We call them Kepler Objects of Interest, or KOI,” he said. “When we find something interesting, we give it a KOI number, so the first one is KOI 10.01, then KOI 10.02. They’re quite boring, but coming up with names can be quite challenging when there are thousands. In some ways, numbers are easier to remember. If you ask me what KOI 314.03, I could tell you about it, but if we gave it a name, I’d probably forget.”
He doesn’t forget the goals of his research, however. The first is to determine how common planets are.
“We’re the first generation of humans who know that there are more planets in the Milky Way galaxy than there are stars. It’s only been in the last decade that we’ve actually known that. When I grew up, the only planets we knew about were the ones in our solar system. Now we can say there are billions.”
He’s also looking for planets that are similar to Earth, and determining how common they are and what their masses, atmospheres and evolutionary histories look like.
All this information feeds the ultimate goal — what he refers to as “the big big question” mankind is trying to answer, which is “Are we alone in the universe?”
Rowe doesn’t think we’ll discover signs of intelligent life necessarily, but he does envision discovering biology on planets that alter the chemical makeup of the atmosphere of that planet, similar to the effect plants and animals have on Earth.
“We know life develops on a planet, so it’s natural to go seeking other planets to see if there’s life on these planets. We think we can do that by analyzing the atmosphere that we see. That’s my ultimate goal.”
For the first time in history, humanity is in a position to make observations that may directly detect life outside the solar system.
“We’re going to have to get lucky for that to work, but it’s our first chance to look and see if life is in out there in the galaxy.”