Fri. Mar 24th, 2023
Engineers test the RL-10 engine at NASA Lewis (now Glenn) Research Center's Propulsion Systems Laboratory.

Engineers test the RL-10 engine at NASA Lewis (now Glenn) Research Center’s Propulsion Systems Laboratory.


NASA is making good progress developing the core stage of its Space Launch System rocket, as designated by Congress in 2010. At the request of lawmakers, the agency is using legacy hardware, such as the space shuttle’s main engines, to advance this core stage. thrusters and solid rocket boosters to give it an initial kick off the launch pad.

Meanwhile, the agency has not yet found an architecture for the massive rocket’s upper stage, which is used to propel payloads beyond low Earth orbit into deep space. For at least the first unmanned flight in 2018, NASA will use an intermediate stage. But Congress has urged the agency to settle on a new, permanent upper stage, dubbed the “Exploration Upper Stage,” in time for the second launch of the SLS rocket in 2022 or 2023.

According to an insider website,, the agency had considered nine proposals for the upper stage, but has now opted for an architecture that uses four RL-10 engines as it moves forward. The RL-10 engine, a workhorse developed in the late 1950s and first flown in 1963, runs on liquid hydrogen/liquid oxygen fuel.

In documents explaining the decision, NASA says it prefers the RL-10 engine because it is reliable, has undergone long-term testing and is the fastest to integrate into a flight-ready upper stage for a rocket that has been in development for six years. . NASA’s decision comes at the same time other companies, such as XCOR and Blue Origin, have developed modern, more versatile upper stage engines. NASA also spent more than $1 billion over the past decade on its own powerful upper stage engine, the J2X, before shelving that project in 2014.

The RL1 engine is being manufactured by Aerojet Rocketdyne, a veteran NASA contractor who also received $1.16 billion to restart production of the space shuttle’s main engines used to power the SLS core stage. While the space shuttle reused those engines on multiple flights, they will now be flown once on the expendable SLS rocket.

By akfire1

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