NASA has awarded a nearly quarter-billion dollar contract to Lockheed Martin for the development of a supersonic jet plane that can break the sound barrier without causing an ear-splitting boom.

The contract, valued at $247.5 million, dictates that Lockheed’s Palmdale, Calif.-based Skunk Works division will build an experimental aircraft, known within the aeronautics industry as an X-plane, that produces sound only “as loud as a car door closing…instead of a sonic boom,” NASA said in a Tuesday news release. The specifications call for a plane that cruises as high as 55,000 feet and reaches a speed of about 940 miles per hour. (For reference, the speed of sound is about 767.3 miles per hour.)

NASA and Lockheed said the plane, a so-called low-boom flight demonstrator, will aim to provide regulators with useful data to inform their decision-making as they consider implementing new rules regarding supersonic flights. The United States’ Federal Aviation Administration (FAA) has banned supersonic flights over land by commercial and private aircraft since 1973.

Lockheed said in a Tuesday news release that the project “will help NASA establish an acceptable commercial supersonic noise standard to overturn current regulations.” The company is set to deliver a prototype of the jet for testing to NASA by the end of 2021.

NASA said in a Tuesday blog post that it plans to fly the aircraft over four to six yet-to-be-selected U.S. cities, collect data, and deliver findings to the FAA as well as the International Civil Aviation Organization, a standards-setting United Nations agency, by 2025.

The to-be-realized plane, whose designs build on an earlier 2016 contract between NASA and Lockheed, is intended to fit a single pilot in its cockpit.