LiftPort Group has built a cable for a space elevator stretching a mile into the sky and tethered on balloons, enabling robots to scrabble some way up and down the line.

To make the cable, researchers sandwiched three carbon-fiber composite strings between four sheets of fiberglass tape, creating a mile-long cable about 5 centimeters wide and no thicker than about six sheets of paper.

The aim is to produce a functioning space elevator by 2018, with a ribbon built from ultra-strong carbon nanotube composites and to have solar-powered lifters carry 100 tons of cargo into space once a week, 50 times a year.