Repurposed communications satellites could help save humanity from an asteroid impact.

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What do you do if you discover a big rock on a collision course with Earth and have very little time to take action?

Large satellites used for TV broadcasting could be quickly and easily repurposed as asteroid deflectors if a space rock were to threaten Earth, according to a study by the European aerospace company Airbus.

The study, part of a mission concept called Fast Kinetic Deflection (FastKD), was commissioned by the European Space Agency (ESA), as part of its effort to prepare for an apocalyptic scenario that will certainly happen one day (even though that day might be in a very distant future).

Telecommunication satellites that sit in the so-called geostationary orbit at the altitude of 22,000 miles (36,000 kilometers) circle Earth at a speed that matches the rotation of the planet, thus appearing permanently suspended above a certain region. These satellites are usually very large, like a small bus. They might weigh 4 to 6 tons, which would give them enough force to affect the trajectory of an approaching space rock.

Still, as Albert Falke, who led the FastKD study at Airbus, told Space.com, it would require maybe 10 such spacecraft hitting a 1,000-foot-wide (300 meters) asteroid within a short period of time to sufficiently change its trajectory to avoid the planet.

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