Friday, May 29, 2015

NASA Tests RS-25 Engine for SLS

A billowing plume of steam signals a successful 450-second test of the RS-25 rocket engine May 28 at NASA's Stennis Space Center near Bay St. Louis, Mississippi. Credit: NASA

A billowing plume of steam signals a successful 450-second test of the RS-25 rocket engine May 28 at NASA's Stennis Space Center near Bay St. Louis, Mississippi. The hotfire test was conducted on the historic A-1 Test Stand where Apollo Program rocket stages and Space Shuttle Program main engines also were tested. RS-25 engines tested on the stand will power the core stage of NASA's new rocket, the Space Launch System (SLS), which is being developed to carry humans deeper into space than ever before.

The heavy-lift SLS will be more powerful than any current rocket and will be the centerpiece of the nation's next era of space exploration, carrying humans to an asteroid and eventually to Mars. Four RS-25 engines will power the SLS vehicle at launch, firing simultaneously to generate more than 1.6 million pounds of thrust.

RS-25 engines are modified Space Shuttle Main Engines, which powered 135 successful low-Earth orbit missions. One of the objectives being evaluated in this test is the new engine controller, or "brain."

The RS-25 is unique among many engines in that it automatically runs through its cycles and programs. The controller monitors the engine conditions and communicates the performance needs. The performance specifications, such as what percentage of thrust is needed and when, are programmed into the controller before the engines are fired. For example, if the engine is required to cycle up to 90 percent thrust, the controller monitors the fuel mixture ratio and regulates the thrust accordingly. It is essential that the controller communicates clearly with the engine; the SLS will be bigger than previous rockets and fly unprecedented missions, and its engines will have to perform in new ways.

Tests at Stennis will ensure the new controller and engine are in sync and can deliver the required performance to meet the SLS requirements.

NASA engineers conducted an initial RS-25 engine test on the A-1 stand Jan. 9. Testing then was put on hold for scheduled work on the Stennis facility high-pressure industrial water system that provides the tens of thousands of gallons of water needed to cool the stand during an engine test. RS-25 testing now is set to continue through the summer.

Engine maker Aerojet Rocketdyne completed assembly of RS-25 Engine 2063 at NASA’s Stennis Space Center near Bay St. Louis, Mississippi, after approximately three months of work. The new engine becomes the 16th assembled RS-25 flight engine in inventory for SLS flights. It will be one of four RS-25s used to power Exploration Mission 2, the second SLS launch targeted for the 2021 time frame. Testing of these four engines will begin later this year as work accelerates on NASA’s newest launch vehicle.

Aerojet Rocketdyne technicians put the final touches on the 16th engine for the RS-25 program. This engine will join three others to help propel the nation’s most powerful rocket, the Space Launch System, which is currently in-development by NASA. Credits: Aerojet Rocketdyne
Aerojet Rocketdyne technicians put the final touches on the 16th engine for the RS-25 program. This engine will join three others to help propel the nation’s most powerful rocket, the Space Launch System, which is currently in-development by NASA. Credits: Aerojet Rocketdyne

"Assembly of this new engine is part of a very busy year for the RS-25 team," said Steve Wofford, manager of the SLS Liquid Engines Office at NASA’s Marshall Space Flight Center, where the SLS Program is managed for the agency. “We’re testing one engine, developing a new controller and planning to manufacture new engines in the future."

Engine 2063 joins a famous family with a proud tradition. The RS-25 is one of the most tested large rocket engine in history, with more than 3,000 starts and over a million seconds of total ground test and flight firing time over 135 missions.

Credit: NASA

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