In 1908, an asteroid is thought to have entered the earth’s atmosphere and exploded over a Siberian forest, leveling some 800 square miles of trees in what is known as the Tunguska Event. If we knew today that another asteroid were on a path to intersect with our planet, what could we do?

Massimiliano Vasile, a lecturer in aerospace engineering at the University of Glasgow, recently concluded a two-year study comparing nine asteroid-deflection methods, rating them for efficiency, complexity and launch readiness.

The best method, called “mirror bees,” entails sending a group of small satellites equipped with mirrors 30 to 100 feet wide into space to “swarm” around an asteroid and trail it, Vasile explains. The mirrors would be tilted to reflect sunlight onto the asteroid, vaporizing one spot and releasing a stream of gases that would slowly move it off course. Vasile says this method is especially appealing because it could be scaled easily: 25 to 5,000 satellites could be used, depending on the size of the rock.

The losing ideas — satellites equipped with lasers; detonating a nuclear explosion; pushing the asteroid with a spacecraft, to name a few — might still have their place. Vasile says improved technologies could make others appealing in the future. (In March, NASA released a report on “near Earth objects” that deemed the nuclear-explosion method the most effective.)