Comets and meteors are easy to spot at night as they streak across the sky. But finding them after they crash is a persistent challenge. Scientific field teams often spend days on end searching for the remains of meteorites, with only vague estimates of their likely landing sites. Sometimes they come up empty.
Now, they’re turning to drones for assistance.
Currently, a six-person team on a meteorite-hunting expedition can search about 200,000 square meters per day, according to Seamus Anderson, a planetary scientist at Curtin University in Perth, Australia.
That may sound like a lot, but field teams may have to search an area of a few million square meters, he says. As a result, searching can be “quite slow,” often lasting as long as 300 days, Anderson notes.
How fast can drones perform the same work? On average, it takes just 12 days.
Anderson’s drone team found its first meteorite in western Australia early last year. Since then they’ve found four more. “It’s exciting and challenging work,” he says.
The drone search actually starts with the reporting of a meteorite fall by ground-based sensors. Then Anderson’s team drives a jeep or van to the reported site with a drone and computer equipment aboard, plus food and camping equipment. Once there, they launch a drone at an altitude of about 20 meters. In a typical search, the aircraft will collect over 10,000 images of landscape, which are divided digitally into 100 million or so smaller sections or “tiles” and then fed into a machine learning algorithm that can identify meteorites based on their size, shape and other features.
The identification process is far from perfect. A typical search turns up false positives, including kangaroos and piles of feces. Some 50,000 images might have to be sorted visually a time-consuming process
For those images that still seem promising, Anderson and his team send out a second, smaller drone that flies about a meter off the ground to verify whether the identified item is indeed a meteorite.
Anderson says he hopes to refine the algorithm he currently uses to cut down on the number of false positives and to reduce the overall drone search time.
And his team is setting its sights on another locale: Antarctica, a veritable hotbed of meteorite sleuthing.
Anderson says his team’s meteorite hunting in Antarctica may be made far easier because meteorites will be more visible against the landscape’s starkly white background. In addition, ice flows on the continent tend to concentrate meteorites in “stranding zones” – about 600 total.
But there are downsides, too. The continent’s extreme cold makes drone flying problematic, as batteries and electronic equipment tend to fare poorly in frigid temperatures. And the region is even more remote than the Australian outback, complicating search logistics.
“It’s an entirely different beast,” Anderson says.