NASA’s X-59 experimental aircraft has completed its 25th test flight, reaching a speed of Mach 1.2—1.2 times the speed of sound—before entering a critical phase of its mission. This phase aims to prove that supersonic flights can be quiet enough to avoid disturbing people on the ground. The X-59 is the centerpiece of NASA’s Quiet Supersonic Technology (Quesst) program, which seeks to demonstrate that commercial supersonic travel could be feasible over populated areas without the loud "sonic boom" traditionally associated with breaking the sound barrier. The X-59 has a unique design, with an elongated body and an engine mounted above the fuselage. This configuration helps spread out the shock wave created when the plane exceeds the speed of sound, resulting in a much quieter "sonic thump" rather than a loud bang. NASA hopes that data collected from these test flights will convince U.S. regulators that such quiet supersonic travel is possible. The aircraft first broke the sound barrier in June at Mach 1.1, and since then, it has been testing its performance at higher speeds and altitudes. The 25th flight, which took place on August 21 from NASA’s Armstrong Flight Research Center in Edwards, California, reached Mach 1.2 at an altitude of nearly 15 kilometers (about 49,000 feet). The flight was monitored by a fighter jet and lasted 72 minutes. Now that the X-59 has completed its initial testing phase, the Quesst team is preparing for the next and most crucial stage: acoustic validation. During this phase, ground-based instruments and other aircraft will measure the noise levels of the X-59 as it flies supersonically. Eventually, the aircraft will conduct overflights over selected American communities to gauge how the public perceives the noise. According to Larry Cliatt, who oversees this validation process, "this is the phase we have been waiting for." The data from these tests could help the Federal Aviation Administration (FAA) replace its 1973 ban on civil supersonic flights over the U.S. with a new standard based on noise levels. The push for supersonic travel is being driven by companies like Boom Supersonic, which is developing the Overture, a commercial aircraft expected to fly at Mach 1.7 with 64 to 80 passengers on board. Boom has already tested a smaller demonstrator, the XB-1, which achieved supersonic speeds without producing a noticeable boom on the ground, thanks to atmospheric refraction. NASA’s X-59, on the other hand, uses its design to disperse the shock wave into multiple quieter waves. If the FAA adopts the new acoustic standards, it could pave the way for a return of supersonic travel over the United States, potentially revolutionizing air travel. However, the timeline for implementing this change remains unclear, as the FAA has not set a specific deadline.