The most reliable, safest, and highest-performing upper-stage engine in the world.
The remarkable RL10 has accumulated one of the most impressive lists of accomplishments in the history of space propulsion. Created in 1959, after Pratt & Whitney harnessed high-energy liquid hydrogen as fuel for aerospace propulsion, the RL10 has helped place numerous military, government and commercial satellites into orbit, and powered space-probe missions to nearly every planet in our solar system. Some of its notable interplanetary missions include the Surveyor Lunar Lander, Viking Mars Lander and the Voyager Outer Planets Fly-By, while its heritage includes supporting MILSTAR, EUTELSAT, TDRS ECHOSTAR, INTELSAT, GALAXY, DSCSIII, and JCSAT satellites.
Today, the RL10 continues its legacy as the industry workhorse, with two separate models supporting the latest versions of United Launch Alliance's (ULA) launch vehicles. The RL10A-4-2 powers the upper stage of the Atlas V, and the RL10B-2 powers the upper stage of the Delta IV.
The RL10B-2 also features the world's largest carbon-carbon extendible nozzle. This high-expansion ratio nozzle enables the RL10B-2 to achieve a remarkable 465.5 seconds of specific impulse and lift payloads of up to 30,000 lbs.