In 1973, the United States banned most airplane flights faster than the speed of sound—about 1,225 kilometers (761 miles) per hour. That’s because aircraft moving at supersonic speeds create a deafening BOOM! To make supersonic flight less disruptive, NASA has developed a new, experimental jet, called the X-59. It’s designed to produce a quieter THUMP as it zooms overhead. This past June, the X-59 reached a major milestone during a test flight in California: It flew at supersonic speeds for the first time!
As an aircraft flies, it produces pressure waves that ripple through the air. When a craft goes faster than the speed of sound, these waves compress into massive shockwaves called sonic booms. To people on the ground, sonic booms sound like loud explosions. The X-59’s long, thin design is meant to prevent pressure waves from merging, creating a softer sound like “someone shutting a car door across the street,” says Gautam Shah, an aeronautical engineer at NASA.