NASA has cleared the X-59 Quiet SuperSonic Technology (QueSST) aircraft for final assembly and integration of its systems following a project review.

The assembly is the last programmatic hurdle for the QueSST aircraft before NASA meets again in 2020 to approve the first flight in 2021. The first flight would keep with NASA’s schedule from 2018 to roll out the new supersonic aircraft in the next three years.

The X-59 is designed to reduce the loudness of a sonic boom from reaching the ground, turning it into a gentle thump, if any noise at all. The goal is to be able to fly the aircraft over select U.S. communities to generate data from sensors and people on the ground in order to gauge public perception. This data will then help NASA determine rules to enable commercial supersonic air travel over land.

Lockheed Martin is overseeing the construction of the X-59 under a $247.5 million contract with three main work areas actively set up for building the aircraft’s main fuselage, wing and empennage. Final assembly and integration of the X-59’s systems (including the cockpit) is targeted for late 2020.