NASA's X-59, an experimental supersonic aircraft developed in partnership with Lockheed Martin, has broken the sound barrier for the first time. The test represents an important step toward "quiet supersonic" flight, in which a craft surpasses Mach 1 — the speed of sound — with a small thump rather than a deafening crash.

On June 5, test pilot Jim "Clue" Less flew the craft from Edwards Air Force Base in California for an 81-minute round trip, NASA announced in a statement. During that time, the X-59 reached a speed of Mach 1.1 ‪—‬ 713 mph (1,147 km/h) ‪—‬ at an altitude of 43,400 feet (13,200 meters).