Boeing has dropped out of an experimental suborbital spaceplane development program funded by the Defense Advanced Research Projects Agency (DARPA). The exit of Boeing all but ends the program as no other bid was still in the running for the DARPA contract.

In a statement to SpaceNews, Boeing spokesman Jerry Drelling confirmed the company’s withdrawal from the program but declined to provide the details behind Boeing’s decision.

“Following a detailed review, Boeing is ending our role in the Experimental Spaceplane (XSP) program immediately,” said Drelling. “We will now redirect our investment from XSP to other Boeing programs that span the sea, air and space domains.”







Boeing, Masten Space Systems and Northrop Grumman all received Phase 1 contracts for what was then called the XS-1 program in 2014. Following an initial design proposal submission, only Boeing was selected for both Phase 2 and Phase 3 contracts in May 2017.

The Phase 2 development period called for the construction of the first Boeing prototype. Dubbed the Phantom Express, the Boeing design was a small autonomous spaceplane 30.5 meters in length with a 19-meter wingspan. Boeing claimed the spaceplane would offer “rapid, aircraft-like access to space.”

Although it is believed a prototype of the vehicle was never completed, Boeing made significant progress alongside Aerojet Rocketdyne in the development of the AR-22 engine that would power it. The AR-22 was a variant of the Space Shuttle Main Engine and during a July 2018 test series was fired 10 separate times over a 240-hour period.

The test series displayed the potential for the engine to be utilised in a highly reusable and flexible launch system. DARPA itself cited this series of AR-22 engine tests as one of the major achievements of the program.

However, with Boeing pulling out of the program so suddenly, the fate of the AR-22 engine, the Phantom Express, and $146 million of taxpayers money awarded to the company to build the vehicle is not yet known.