If and when we ever get an asteroid mining industry off the ground, one of the most important decisions to be made in the structure of any asteroid mining mission would be how to get the resources back to where all of our other infrastructure is—somewhere around the Earth.

That decision typically will focus on one of two propulsion methodologies—chemical rockets, such as those we already use to get us into space in the first place, or solar sails, which, while slower and unable to get us into orbit, don't require any fuel. So which propulsion methodology is better for these future missions? A study by researchers at the University of Glasgow looked at those two scenarios and came out with a clear-cut answer—solar sails.

When answering these types of theoretical questions, it is essential to impose limits on the answers. For example, billions of asteroids exist in the solar system, so it's more realistic to only look at those known as near-Earth asteroids (NEAs).