Engine - Blog Posts

Today we successfully tested one of our RS-25 engines, four of which will help power our Space Launch System (SLS) to deep space destinations, like Mars! This 500-second engine test concludes a summer of successful hot fire testing for flight controllers at our Stennis Space Center near Bay St. Louis, Mississippi.

The controller serves as the “brain” of the engine, communicating with SLS flight computers to ensure engines are performing at needed levels. The test marked another step toward the nation’s return to human deep-space exploration missions.

We launched a series of summer tests with a second flight controller unit hot fire at the end of May, then followed up with three additional tests. The flight controller tests are critical preparation for upcoming SLS flights to deep space– the uncrewed Exploration Mission-1 (EM-1), which will serve as the first flight for the new rocket carrying an uncrewed Orion spacecraft, and EM-2, which will transport a crew of astronauts aboard the Orion spacecraft. 

Each SLS rocket is powered at launch by four RS-25 engines firing simultaneously and working in conjunction with a pair of solid rocket boosters. The engines generate a combined 2 million pounds of thrust at liftoff. With the boosters, total thrust at liftoff will exceed 8 million pounds!

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Ion Propulsion…What Is It?

Ion thrusters are being designed for a wide variety of missions – from keeping communications satellites in the proper position to propelling spacecraft throughout our solar system. But, what exactly is ion propulsion and how does an ion thruster work? Great question! Let’s take a look:

Regular rocket engines: You take a gas and you heat it up, or put it under pressure, and you push it out of the rocket nozzle, and the action of the gas going out of the nozzle causes a reaction that pushes the spacecraft in the other direction.

Ion engines: Instead of heating the gas up or putting it under pressure, we give the gas xenon a little electric charge, then they’re called ions, and we use a big voltage to accelerate the xenon ions through this metal grid and we shoot them out of the engine at up to 90,000 miles per hour.

Something interesting about ion engines is that it pushes on the spacecraft as hard as a single piece of paper pushes on your hand while holding it. In the zero gravity, frictionless, environment of space, gradually the effect of this thrust builds up. Our Dawn spacecraft uses ion engines, and is the first spacecraft to orbit two objects in the asteroid belt between Mars and Jupiter.

To give you a better idea, at full throttle, it would take our Dawn spacecraft four days to accelerate from zero to sixty miles per hour. That may sounds VERY slow, but instead of thrusting for four days, if we thrust for a week or a year as Dawn already has for almost five years, you can build up fantastically high velocity.

Why use ion engines? This type of propulsion give us the maneuverability to go into orbit and after we’ve been there for awhile, we can leave orbit and go on to another destination and do the same thing.

As the commercial applications for electric propulsion grow because of its ability to extend the operational life of satellites and to reduce launch and operation costs, we are involved in work on two different ion thrusters of the future: the NASA Evolutionary Xenon Thruster (NEXT) and the Annular Engine. These new engines will help reduce mission cost and trip time, while also traveling at higher power levels.

Learn more about ion propulsion HERE.

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Space Launch System

Our Space Launch System (SLS) is an advanced launch vehicle for exploration beyond Earth’s orbit into deep space. SLS, the world’s most powerful rocket, will launch astronauts in our Orion spacecraft on missions to an asteroid and eventually to Mars!

A launch system required to carry humans faster and farther than ever before will need a powerful engine, aka the RS-25 engine. This engine makes a modern race car or jet engine look like a wind-up toy. With the ability to produce 512,000 pounds of trust, the RS-25 engine will produce 10% more thrust than the Saturn V rockets that launched astronauts on journeys to the moon!

Another consideration for using these engines for future spaceflight was that 16 of them already existed from the shuttle program. Using a high-performance engine that already existed gave us a considerable boost in developing its next rocket for space exploration.

Once ready, four RS-25 engines will power the core stage of our SLS into deep space and Mars.