As vast as space is, ironically the hardest part of the journey is the first 100 km or so, as we break free of the grasp of the Earth. For over a century people have floated the idea of a space elevator – which is exactly what it sounds like – but the logistics of that just aren't possible yet. Now Japan has launched a pair of satellites to test out some technologies that might help make a space elevator a reality in future.

The project is known as the Space Tethered Autonomous Robotic Satellite - Mini Elevator (STARS-Me), and it's made up of two CubeSats with a 10-m (32.8 ft) cable running between them.

The two satellites were launched on September 23 by the Japan Aerospace Exploration Agency (JAXA) onboard the cargo transporter KOUNOTORI7, to deliver them to the International Space Station.

This isn't the first time two satellites have been connected with a tether, but the difference this time is that a small robot measuring 3 x 3 x 6 cm (1.2 x 1.2 x 2.4 in) will be climbing the cable, by way of a motor that feeds the cable through it.

Ten meters is a far cry short of the roughly 36,000 km-long (22,400 mi) cable that would be needed for a full-size space elevator, but baby steps are important. The ultimate goal is to test out technologies that could one day be used in space elevators, but in the more immediate future these tethered robots could be put to work on other tasks in space, like refueling runs, inspections, or lowering equipment to the Moon's surface from orbit.

Previous space elevator concepts, including inflatable designs and ones that would be tested on the Moon first, have so far failed to get off the ground. One of the most promising projects could be that by Japanese construction company Obayashi Corp., which is involved with the STARS-Me project. This would be made up of cars climbing a cable made of carbon nanotubes, connecting an ocean-based Earth Port to a space station 36,000 km overhead. To keep the structure stable, a huge counterweight, floating in space, would be attached about 60,000 km (37,000 mi) above the space station.

Ambitious as this project is, Obayashi has given itself plenty of time to get there, with plans for it to be up and running by 2050. In the meantime, it'll be interesting to see what the STARS-Me project can achieve.