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Forum:Exploration: Asteroids, Moon and Mars
Topic:[SLS] RS-25 (SSME) engine tests (Stennis A-1)
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Above: This is the first of eight tests for the development engine, which will provide NASA engineers with critical data on the engine controller unit and inlet pressure conditions.

The engine controller unit, the "brain" of the engine, allows communication between the vehicle and the engine, relaying commands to the engine and transmitting data back to the vehicle. The controller also provides closed-loop management of the engine by regulating the thrust and fuel mixture ratio while monitoring the engine's health and status. The new controller will use updated hardware and software configured to operate with the new SLS avionics architecture.

"This first hot-fire test of the RS-25 engine represents a significant effort on behalf of Stennis Space Center's A-1 test team," said Ronald Rigney, RS-25 project manager at Stennis. "Our technicians and engineers have been working diligently to design, modify and activate an extremely complex and capable facility in support of RS-25 engine testing."

Testing will resume in April after upgrades are completed on the high pressure industrial water system, which provides cool water for the test facility during a hot fire test. Eight tests, totaling 3,500 seconds, are planned for the current development engine. Another development engine later will undergo 10 tests, totaling 4,500 seconds. The second test series includes the first test of new flight controllers, known as green running.

Above: A close-up view from the test stand.

The first flight test of the SLS will feature a configuration for a 70-metric-ton (77-ton) lift capacity and carry an uncrewed Orion spacecraft beyond low-Earth orbit to test the performance of the integrated system. As the SLS is upgraded, it will provide an unprecedented lift capability of 130 metric tons (143 tons) to enable missions even farther into our solar system.

Robert PearlmanNASA release
Some Assembly Required: The Newest RS-25 Joins the Space Launch System Family

NASA's Space Launch System, America's new deep space exploration rocket, has a new addition to the family with the completed assembly of RS-25 Engine 2063. The RS-25 engine will power the core stage of the SLS, the launch vehicle that will take humans and cargo on deep space missions, including to an asteroid and ultimately to Mars.

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.

While SLS is designed for deep space exploration far beyond Earth. It's also designed to take advantage of the investments the nation has already made in space exploration, including the RS-25.

Fourteen of the 16 RS-25 engines in the SLS inventory are veterans of numerous space shuttle missions, where they were commonly referred to as Space Shuttle Main Engines, or SSME. Engine 2063 is one of two additional "rookie" engines without previous shuttle flight experience. Engine 2063 will undergo acceptance testing to verify it is acceptable for flight, checking out the completed system. It does include some previously flown hardware, including the four turbopumps which have flown on several shuttle missions.

"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.

Four RS-25 liquid propellant engines will power the SLS for the eight-minute climb to orbit with the help of two solid propellant boosters – both flight qualified components of the Space Shuttle Program and now essential to SLS's unmatched payload capability.

"Completion of this engine is a significant accomplishment, considering it's been nearly five years since the last RS-25 was assembled," said Jim Paulsen, vice president of Program Execution Advanced Space & Launch Programs Aerojet Rocketdyne. "It's been a great opportunity for the team's SSME veterans to get reacquainted with this engine. For new members of the team, it's been an invaluable introduction to this dependable engine."

Four previously-flown RS-25s will be attached to the first SLS core stage and test fired together as a stage before being approved for the first SLS launch planned for 2018.

The SLS team began test firing one of the development engines with a new controller earlier this year to make sure it can meet the different performance and environmental conditions required by the SLS. The entire flight engine inventory will be upgraded with new state-of-the-art engine controllers, insulation and other details.

"There is nothing in the world that compares to this engine," added Paulsen. "It is great that we are able to adapt this advanced engine for what will be the world's most powerful rocket to usher in a new space age."

After the first four flights, NASA will start using brand new RS-25 engines. These "next generation" engines will be more affordable by utilizing components made with the latest 21st century electronics, cost saving manufacturing techniques and more cost effective materials.

"The RS-25 is still one of the most advanced engines in the world," said Philip Benefield, himself an SSME veteran now part of the team adapting the RS-25 to SLS. "It's an interesting challenge to put together a new SLS engine team of shuttle veterans and new engineers, much like the RS-25 incorporates veteran shuttle engine hardware and new hardware to meet new requirements."

For one of those new engineers, working on the RS-25 is the high point of a life-long interest in space exploration.

"Ever since I was in the third grade when I fell in love with the space program, I have always had the desire to work on a project that would take people further into space than ever before," said Esteban Barajas, a mechanical design engineer at Aerojet Rocketdyne.

"Now, being able to bring the space shuttle main engines roaring back to life with the many talented engineers who originally designed and built them is an incredible opportunity. As a young engineer, the experience has truly been invaluable."

Robert PearlmanNASA photo release
Steamy Summer Begins for SLS with RS-25 Test

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.

Robert PearlmanNASA release
We have Ignition: NASA Space Launch System RS-25 Engine Fires Up for Third Test in Series

Ladies and gentlemen, we've started our engine. An RS-25 engine fired up for 500 seconds June 11 at NASA's Stennis Space Center near Bay St. Louis, Mississippi.

Four RS-25 engines will power NASA's new rocket, the Space Launch System, at speeds of 17,500 mph -- 73 times faster than the top speeds of an Indianapolis 500 race car -- to send astronauts on future missions beyond Earth's orbit, including to an asteroid and ultimately to Mars.

This is the third firing of an RS-25 development engine on the A-1 test stand at Stennis. The first RS-25 test in this series was conducted Jan. 9, and the second was May 28. Four more tests are planned for the current development engine.

"While we are using proven space shuttle hardware with these engines, SLS will have different performance requirements," said Steve Wofford, manager of the SLS Liquid Engines Office at NASA's Marshall Space Flight Center in Huntsville, Alabama. The Marshall Center manages the SLS Program for the agency. "That's why we are testing them again. This is a whole new ballgame -- we need way more power for these engines to be able to go farther than ever before when it comes to human exploration. And we believe the modifications we've made to these engines can do just that."

The first flight test of the SLS -- designated as Exploration Mission 1 -- will feature a configuration for a 70-metric-ton (77-ton) lift capacity and carry an uncrewed Orion spacecraft beyond low-Earth orbit to test the performance of the integrated system.

"We have several objectives that will be accomplished during this test series, which will provide critical data on the new engine controller unit, materials and engine propellant inlet pressure conditions," Wofford added.

The new engine controller unit, the "brain" of the engine, allows communication between the vehicle and the engine, relaying commands to the engine and transmitting data back to the vehicle. The controller also provides closed-loop management of the engine by regulating the thrust and fuel mixture ratio while monitoring the engine's health and status. The controller will use updated hardware and software configured to operate with the new SLS vehicle avionics architecture.

The test series will show how the RS-25 engines will perform with colder liquid oxygen temperatures; greater inlet pressure due to the taller SLS core stage liquid oxygen tank and higher vehicle acceleration; and more nozzle heating due to the four-engine configuration and its position in-plane with the SLS booster exhaust nozzles. New ablative insulation and heaters also will be tested during the series. Aerojet Rocketdyne of Sacramento, California, is the prime contractor for the RS-25 engine work.

Robert PearlmanNASA release
Longest SLS Engine Test Yet Heats Up Summer Sky

South Mississippi was hotter than usual on June 25 when the fire and heat produced by the longest test firing yet of a Space Launch System (SLS) RS-25 rocket engine at NASA's John C. Stennis Space Center combined with already climbing summer temperatures.

Engineers conducted a 650-second test of a RS-25 developmental engine as part of its preparation for a return to deep-space missions aboard the new Space Launch System rocket. NASA is designing the SLS to carry humans deeper into space than ever before, to such destinations as an asteroid and Mars. The core stage of the new vehicle will be powered by four RS-25 engines, former space shuttles main engines operated at slightly higher power levels to provide the additional thrust needed to power the SLS.

The main goal of the series is to test the engine under simulated temperature, pressure and other changes required by the SLS design. The series also supports the development of a new controller, or "brain," for the engine. The controller monitors the engine status and communicates the programmed performance needs.

The first test in the series was in January. Testing resumed in May after scheduled work was completed on the high-pressure industrial water system that provides the tens of thousands of gallons of water needed during an engine test. Thursday's test firing, the fourth in the series, expands on the performance objectives of the first two firings, allowing engineers to better understand the engine under a range of operating conditions.

Three additional tests are scheduled in July and August before the initial series is completed.

Robert PearlmanNASA video release
Pedal to the Metal – RS-25 Engine Revs Up Again

In auto racing parlance, NASA engineers put the "pedal to the metal" during a July 17 test of its Space Launch System (SLS) RS-25 rocket engine at Stennis Space Center.

During a 535-second test, operators ran the RS-25 through a series of power levels, including a period of firing at 109 percent of the engine's rated power. Data collected on performance of the engine at the various power levels will aid in adapting the former space shuttle engines to the new SLS vehicle mission requirements, including development of an all-new engine controller and software.

Two additional tests of the RS-25 engine are planned before the current test series concludes by early September and a new test series begins on four engines for a future flight.

Robert PearlmanNASA release
Countdown to Deep Space Continues with Latest RS-25 Test

NASA's countdown to deep space continued Thursday (Aug. 13) with a 535-second test of its Space Launch System (SLS) RS-25 rocket engine to collect engine performance data at NASA's Stennis Space Center near Bay St. Louis, Mississippi. SLS will launch astronauts in the Orion spacecraft on missions to deep space and eventually on the journey to Mars.

Operators on the A-1 Test Stand at Stennis are conducting the test series to qualify an all-new engine controller and put the upgraded former space shuttle main engines through the rigorous temperature and pressure conditions they will experience during a SLS mission.

One final test of this RS-25 developmental engine is planned in this series; testing of flight engines begins later this fall.

More than 1,200 people, including elected officials and community leaders, media and social media representatives, and NASA and contractor employees and family members viewed the test. Guests saw Stennis facilities and test stands, the Aerojet Rocketdyne engine assembly facility, and the Pegasus barge that will transport the SLS core stage from NASA's Michoud Assembly Facility in New Orleans to Stennis for testing then to Kennedy Space Center in Florida for launch.

An initial 70-metric-ton (77-ton) SLS configuration will use four RS-25 engines for the core stage, along with two five-segment solid rocket boosters, providing more lift to orbit than any current launch vehicle. The core stage for the first SLS and Orion integrated flight — Exploration Mission-1 — also will be tested at Stennis. That test will involve simultaneous firing of the four RS-25 engines just as during an actual launch.

The RS-25 engine gives SLS a proven, high performance, affordable main propulsion system for deep space exploration. It is one of the most experienced large rocket engines in the world, with more than a million seconds of ground test and flight operations time. Aerojet Rocketdyne of Sacramento, California, is the prime contractor for the RS-25 engine work.

Robert PearlmanNASA release
NASA Concludes Series of Engine Tests for Next-Gen Rocket

NASA has completed the first developmental test series on the RS-25 engines that will power the agency's new Space Launch System (SLS) rocket on missions deeper into space than ever before.

The test series wrapped up Thursday with a seventh hot fire test of a developmental RS-25 engine on the A-1 Test Stand at NASA's Stennis Space Center in Bay St. Louis, Mississippi. The test ran for a full-duration 535 seconds.

"The completion of this test series is an important step in getting SLS ready for the journey to Mars," said Steve Wofford, engines manager at NASA's Marshall Space Flight Center in Huntsville, Alabama, where the SLS Program is managed for the agency. "The RS-25 engine gives SLS a proven, high performance, affordable main propulsion system. It is one of the most experienced large rocket engines in the world, with more than a million seconds of ground test and flight operations time."

The series was designed to collect valuable data on performance of the RS-25 engine, a former space shuttle main engine operating at higher thrust levels in order to provide the power needed for the SLS vehicle. Of particular interest is data that will aid in development of a new engine controller, or "brain," to monitor engine status and communicate programmed performance needs.

"These are extremely reliable engines. We are testing them again because we want to ensure that the engine performs as required with a new engine controller, higher propellant inlet pressures and lower temperatures that are part of the SLS design. We also want to mitigate any risks on the ground before flight," Wofford said.

Four RS-25 engines will help power the SLS core stage during launch. Firing simultaneously at 109 percent of its operating level, the engines will provide approximately 2 million pounds of thrust. The engines will operate in conjunction with a pair of five-segment solid rocket boosters for a total of 8.4 million pounds of thrust to lift the initial 70-metric-ton (77-ton) SLS off the launch pad. The SLS eventually will evolve to a 130-metric-ton (143-ton) configuration that will enable missions to such deep space destinations as an asteroid and Mars.

Testing of RS-25 flight engines for the initial SLS missions will begin at Stennis this fall. In addition to testing RS-25 flight engines, Stennis operators will employ their collective expertise to test the SLS core stage. The B-2 Test Stand at Stennis is being renovated to conduct tests on the SLS flight core stage prior to its first uncrewed mission. That testing will involve installing the flight stage on the stand and firing its four RS-25 engines simultaneously, just as during an actual launch.

"What a great time to be at Stennis," Center Director Rick Gilbrech said. "When it comes to powering the future of the deep space exploration program for this country, this is the front lines, where we enable those missions to fly."

The developmental tests began with a Jan. 9 hot fire and resumed in May after scheduled work was completed on the high-pressure industrial water system that provides the thousands of gallons of water needed during an engine test. Aerojet Rocketdyne of Sacramento, California, is the prime contractor for the RS-25 engine work.

"This was a great test series for Stennis," said Ronnie Rigney, RS-25 project manager at Stennis. "Our teams built up a lot of history with space shuttle main engines and were able to use that expertise to meet very challenging test specifications for the RS-25. The testing done here will help ensure the engines perform as needed during actual SLS missions."

See here for discussion of RS-25 engine use for the Space Launch System.

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