The X-59 QueSST has resumed flight testing after maintenance and software upgrades, entering an envelope expansion phase where it is progressively flying higher, faster, and farther. So far, it has completed nine flights, reaching about 43,000 feet and just under Mach 1, with a total of 10 flight hours.

Developed by NASA and Lockheed Martin Skunk Works, the aircraft is now being tested across a wider performance range as it moves toward eventual supersonic speeds of Mach 1.4 and 55,000 feet. The goal is to validate low-boom technology that could enable quieter supersonic flight over land, potentially paving the way for future commercial supersonic travel.