All moral, ethical, and political quandaries aside, one of the big problems with aerial drones is that, eventually, the things must land. It’s the age-old problem of refueling—or for smaller unmanned systems, recharging. But that all could be changing. In recent trials headed up by the Department of Defense’s blue-sky research wing, DARPA, two unmanned aircraft were able to cruise close enough to one another to allow for automated refueling.

The experiments paired two RQ-4 Global Hawk planes, which at the moment are being used almost exclusively for spying. For a good 2.5 hours, and at cruising altitudes of 48,000 feet, the giving-Hawk’s 100-foot fuel probe managed to link up to the receiving-Hawk’s port. As the capstone on a two-year research project, the trial proved incredibly successful.

Read the rest over at Motherboard.