Space Shuttle Engines Start Hot Fire Tests For New Space Launch System

It lives! The RS-25 rocket engines from the space shuttle have been repurposed for the Space Launch System, NASA's rocket for deep space exploration. The engines hot fired for the first time since 2009 in this 500-second burn.

The RS-25 engine during a 500-second test fire at NASA's Stennis Space Center on January 9, 2014. Image credit: NASA


While based on the engines that powered the space shuttles, the RS-25 has undergone modifications in the past decade to meet the different requirements of the Space Launch System (SLS). The engines will be exposed to colder liquid oxygen temperatures; the taller core stage liquid oxygen tank and acceleration means the engines will be exposed to greater inlet pressure; and the four-engine configuration will lead to greater nozzle heating. The upgrades also include a new engine controller to relay commands to the engine, transmit data back to the vehicle, and manage the engine by regulating the thrust and fuel mixture ratio.

RS-25 rocket engine firing completely unrelated to the current tests. Image Credit: Aerojet Rocketdyne

The 500-second test provided data on the engine controller unit and inlet pressure conditions. You can watch the entire eight-and-a-half minute test here:

Why are we sticking with the RS-25 instead of inventing something new just for the SLS? It's efficient, has a track record for success, the production capacity already exists, and NASA knows how to run it through tests. NASA currently has 16 RS-25 engines, with another two development engines for ground-testing.


The 500-second test fire is the first in an eight-test sequence. After the testing pad's liquid cooling system is upgraded, the engines will go through tests totally 3,500 seconds. After that, another test sequence will start up with a second development engine, running through ten tests totalling 4,500 seconds. The second test sequence will also involve green running, tests of the new flight controllers.


We knew this day was coming, but it's still pretty awesome to see these Daleks-in-disguise roaring back to life in a hot fire for the first time since the space shuttle main engine tests in 2009. Five of the engines will be used to power the SLS, the massive rocket intended for human deep space missions with the Orion spacecraft.


Concept art of the SLS lifting Orion for a deep space mission. Image credit: NASA

When the whole system eventually reaches integrated testing (currently planned for 2018), the SLS will be used to boost an uncrewed Orion spacecraft beyond low-Earth orbit. At that stage, it should have a 70 metric ton lift capacity, but the current plan is to eventually upgrade it to a 130 metric ton lift capacity to effectively launch deep space missions.


Need more exhilarating rocketry goodness? Check out this gloriously remastered video from the Space Shuttle's booster rockets. Learn more about the Space Launch System here.

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