The newly described aerobraking maneuver allows the X-37B spaceplane to change its orbit by using the Earth’s atmospheric drag—the friction caused by molecules in the atmosphere. Normally, spacecrafts have to fire their thrusters to achieve a shift in orbit, which uses up propellant and thus can only be done a limited number of times, per Space.com’s Brett Tingley.

“When we aerobrake, we utilize atmospheric drag to effectively step down our apogee”—the farthest point from Earth in the orbit—“one pass at a time, until we get to the orbital regime that we want to be in,” John Ealy, a Boeing engineer, says in a video released by the company. “When we do this, we save enormous amounts of propellant, and that’s really why aerobraking is important.”