Spaceflight Insider

DARPA selects rocket engine for XS-1 experimental spaceplane


Boeing’s Phantom Express (XS-1) – An autonomous, experimental spaceplane designed to transform the future of rapid, reusable space launch for small satellites. Image & Caption Credit: Boeing

Aerojet Rocketdyne has been chosen to provide the main propulsion system for the Boeing and the U.S. Defense Advanced Research Projects Agency (DARPA) reusable Experimental Spaceplane (XS-1).

“As threats to our nation’s space systems increase, it is imperative that we have the ability to rapidly deploy replacement assets,” said Aerojet Rocketdyne CEO and President Eileen Drake via a release issued by the company. “This demonstration program is vitally important to maintaining assured access to space, which remains a top priority for our nation.”

Because of flight experience gained from NASA’s retired fleet of space shuttle orbiters, as well as the U.S. Air Force’s classified X-37B, Aerojet Rocketdyne is supplying two engines, designated AR-22, for the XS-1 program to “demonstrate reusability, a wide operating range[,] and rapid turnarounds” – according to a release issued by the company.

If everything goes as it is currently planned, the AR-22 will undergo assembly and ground testing at NASA’s John C. Stennis Space Center in Mississippi.

The XS-1s primary propulsion system is based on NASA’s Space Shuttle Main Engines (SSME) which ran off a mixture of liquid hydrogen and liquid oxygen. It is hoped that the spacecraft will be able to deliver small satellites to orbit.

“As one of the world’s most reliable rocket engines, the SSME is a smart choice to power the XS-1 launch vehicle,” Drake said. “This engine has a demonstrated track record of solid performance and proven reusability.”

The AR-22 will be assembled from components of the rocket engine that remained from early versions of the SSME that were in both Aerojet Rocketdyne and NASA’s inventories. The SSME was manufactured by Rocketdyne before they merged with Aerojet in 2013.

Video courtesy of DARPAtv



Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology,, The Mars Society and Universe Today.

Reader Comments

Vlastislav Výprachtický

Supplementary Design Phantom Ex.
For vertical start with longer range XS-1 supplement/ an sides/auxilliary accelerating engines.

⚠ Commenting Rules

Post Comment

Your email address will not be published. Required fields are marked *