NASA confirmed to FlightGlobal that the agency’s X-59 Quesst demonstrator has finished low-speed taxi testing, is nearly through medium-speed trials and is preparing to enter high-speed taxi runs as it moves toward a first flight planned for 2025. “The X-59 has completed low-speed taxi testing, has nearly completed medium-speed [tests] and is headed into high-speed [tests],” NASA told the aviation outlet, adding the program remains set to fly next year.

The X-59, built by Lockheed Martin’s Skunk Works for NASA, is the centerpiece of a multimillion-dollar effort to revive supersonic passenger flight over land by dramatically reducing the loud “sonic boom” that has rooted out commercial overland supersonic routes since the Concorde era. The jet’s stretched nose, careful shaping and single-engine configuration are designed to produce a low-amplitude signature—what NASA describes as a faint “thump”—that regulators might deem acceptable for flights over populated areas.

Taxi testing is a standard, incremental step before flight: engineers validate brakes, steering, landing gear, avionics and flight-control software at progressively higher speeds before committing to lift-off. High-speed taxi trials will put the X-59 close to aerodynamic departure conditions and let teams check propulsion and structural behavior under runway loads. If those runs go well, engineers will clear the aircraft for its maiden sortie, which will mark the transition to airborne envelope expansion and the start of acoustic measurement campaigns.

Beyond hardware milestones, the X-59 program is unusual for its emphasis on human response. NASA intends to pair acoustic data with surveys and social-science research as the jet overflies communities, measuring how people perceive low-amplitude supersonic sounds. Agency officials have said those paired datasets are intended to inform both the U.S. Federal Aviation Administration and the International Civil Aviation Organization as they weigh whether to relax the decades-old ban on routine supersonic flight over land.

Industry observers say the data could be decisive for a nascent commercial market in high-speed travel. Several companies are pursuing supersonic transports for business and eventually commercial service; regulatory acceptance of quieter supersonic signatures is a prerequisite for sustainable operations. But engineers and environmental advocates caution that low boom is only one piece of the puzzle. Fuel consumption and climate impacts at high altitude, certification processes and community acceptance all pose hurdles to any rapid scaling of supersonic passenger service.

The program has already weathered schedule slips and technical complexity. Developing a new aerodynamic shape optimized to minimize far-field noise, while also meeting performance and safety requirements, requires meticulous computational modeling, wind-tunnel testing and iterative flight verification. NASA’s current timeline, targeting a 2025 first flight, leaves little margin for further technical setbacks, but the agency’s public update signals confidence that major system checks are proceeding as planned.

If the X-59 delivers on its promise, it could provide regulators with the quantitative and qualitative evidence needed to reconsider long-standing overland supersonic restrictions. The program’s success—or failure—will shape not only aerospace engineering priorities but also the public debate over whether and how the era of routine overland supersonic travel should return.