Space mission · United States

How much did X-59 Low-Boom Flight Demonstrator cost to build?

The X-59 is NASA's Low Boom Flight Demonstrator, a single-seat experimental supersonic aircraft built by Lockheed Martin Skunk Works for the Quesst mission to show that sonic booms can be reduced to quiet thumps acceptable over land. It is about 30.4 m long and is designed to cruise at Mach 1.4 at 55,000 ft. GAO put the project's life-cycle cost at $902.4 million in 2025 after delays; the aircraft made its first flight on 28 October 2025 and will later fly over US communities to gather public response data.

Published project estimate

$902.4 million

Cost basis: 2025

NASA’s X-59 quiet supersonic research aircraft sits on the ramp at Lockheed Martin Skunk Works in Palmdale, California during sunrise, shortly after completion of painting. With its unique design, including a 38-foot-long nose, the X-59 was built to demonstrate the ability to fly supersonic, or faster than the speed of sound, while reducing the typically loud sonic boom produced by aircraft at such speeds to a quieter sonic “thump”. The X-59 is the centerpiece of NASA’s Quesst mission, which see
NASA/Steve FreemanPublic domain

Cost record

How the cost changed

Budgets, contracts and final costs may cover different stages. Each figure keeps its own year and source.

Published project estimate

2025

$902.4 million

gao.gov

Project metrics

Key dimensions

Total lengthNASA
30.4 m

Project record

Timeline

  1. 2022

    Planned completion

    Low-Boom Flight Demonstrator original schedule baseline

  2. 28 October 2025

    Opened or launched

    NASA

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