The crater is home to anorthosite, a rock common on the moon but rare on Earth
The Mistastin Lake Impact Crater, in northern Labrador, is considered to be one of the best places on Earth for astronauts to learn about the moon's geology. A pair of astronauts spent two weeks in September at the crater as part of a rigorous training program to prepare them for a potential trip to the lunar surface.
"A lot of the people that we actually met, en route either in Newfoundland, on the plane or up in Goose Bay in Labrador, were very surprised," said geologist Gordon Osinski, who led a field team of geologists, as well as Canadian astronaut Joshua Kutryk and NASA astronaut Matthew Dominic, on an expedition to the crater.
"It's quite fascinating to see people's reactions when I would say, you know, the best impact crater analogue site for the moon, this kind of unique site is on their doorstep."
Osinski is the director of Western University's Institute for Earth and Space Exploration. The goals of the expedition were to do some field research on the area's unique rocks, and to give the astronauts a crash course in field geology.
"I was really excited," said Kutryk."We're both [from] F-18 test pilot backgrounds, and so all of this — science, impact cratering, the geological history of our solar system and the Earth — these are all things that are, for people like Matt and I, are very, very new."
Learning which rocks to grab — and which to leave behind
The 28-kilometer wide Mistastin crater — called Kamestastin by the local Innu people — was formed 36 million years ago when an asteroid struck Earth. The impact is believed to have heated the rock in the area up to 2,370 C, and left behind some of the best-preserved impact melt rocks on the planet.
The type of rock in the area, anorthosite, is common on the moon, but incredibly rare here.
"It's one of only two craters on the Earth that has any significant amount of this type of rock," said Cassandra Marion, the base camp manager of the expedition, and science advisor at the Canada Aviation and Space Museum. "We're just really lucky... that this type of rock was impacted there."
During the expedition, the astronauts spent their days hiking along the crater's 50-metre high ledge, learning about how to identify and sample rocks, which will be a key part of any upcoming lunar mission.
"One of the major reasons we're sending astronauts to the moon and not just robots is that they will be doing geology, they will be collecting samples," said Osinski. "And so the astronauts are training their eyes to get used to hopefully collecting these samples on the surface of the moon in the future."
Battling bears and bugs, while discovering a mysterious green gas
The team hiked up to 20 kilometres a day, while keeping an eye out for black bears, swatting away hordes of black flies, and dealing with Mistastin's challenging terrain.
"It's not a vacation spot," said Marion. "It's quite the challenging environment at times, with the winds and waves. Some days it's like summer, and some days it's like winter."
Kutryk said he faced a "steep learning curve" but by the end of the expedition, was thrilled to be making discoveries of his own, including an accidental finding that even stumped the professional geologists.
"I don't even know why we did it. We took [a rock] and we cracked it open," said Kutryk. And inside, they found what "literally looked like a little green ball of ancient gas that had basically been preserved inside of this melt rock for millions and millions of years."
Osinski said that the rock is currently being studied at his lab at Western University. "We don't actually know what this is.... I'd never seen anything like this in any of the previous rocks that I'd seen at Mistastin," he said.
For Kutryk, this expedition was not only a fun experience, it's a reminder that he could potentially be a part of a future lunar mission.
"It adds a reality to it. It makes me realize that humans are going to the moon. We don't know who that will be, but we're all going to be very excited and I think feeling very fortunate to be a part of that," he said.
Expedition members Cassandra Marion, Matthew Dominic, Joshua Kutryk, and Gordon Osinski on site at the Mistastin Lake Impact Crater. (Submitted by Cassandra Marion)
The initial asteroid strike heated the rock up to 2,370 C. Here, a team member points out impact melt rock, which looks similar to volcanic rock from a lava flow, but in this case the rock was melted by the impact of the strike. (Gordon Osinski)
The view from the Twin Otter plane that the team needed to get to the site. Their journey took three days, the same amount of time it took the Apollo astronauts to get to the moon. (Gordon Osinski)
