A five-gear space rocket engine

A five-gear space rocket engine

Summary: Georgia Tech researchers have had a brilliant idea. Rocket engines used today to launch satellites run at maximum exhaust velocity until they reach orbit. For a car, this would be analog to stay all the time in first gear. So they have designed a new space rocket which works as it has a five-gear transmission system. This space engine uses 40 percent less fuel than current ones by running on solar power while in space and by fine-tuning exhaust velocity. But as it was designed with funds from the U.S. Air Force, military applications will be ready before civilian ones.

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TOPICS: Nasa / Space
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Georgia Tech researchers have had a brilliant idea. Rocket engines used today to launch satellites run at maximum exhaust velocity until they reach orbit. For a car, this would be analog to stay all the time in first gear. So they have designed a new space rocket which works as it has a five-gear transmission system. This space engine uses 40 percent less fuel than current ones by running on solar power while in space and by fine-tuning exhaust velocity. But as it was designed with funds from the U.S. Air Force, military applications will be ready before civilian ones.

This technology has been developed by a team led by Mitchell Walker, an assistant professor in the Aerospace Engineering Department and leader of the High-Power Electric Propulsion Laboratory.

Before going further, below is a diagram showing how this new rocket engine "uses a novel electric and magnetic field design that helps better control the exhaust particles. Ground control units can then exercise this control remotely to conserve fuel" (Credit: Mitchell Walker's team, Georgia Tech). Here is a link to a larger version.

Georgia Tech's new space rocket engine

Here is how this new engine could pave the way "for deep space missions, lower launch costs and more payload in orbit."

The efficient satellite engine uses up to 40 percent less fuel by running on solar power while in space and by fine-tuning exhaust velocity. Satellites using the Georgia Tech engine to blast off can carry more payload thanks to the mass freed up by the smaller amount of fuel needed for the trip into orbit. Or, if engineers wanted to use the reduced fuel load another way, the satellite could be launched more cheaply by using a smaller launch vehicle.

And here is how the engine will shift from first to fifth gear.

The new Georgia Tech engine allows ground control units to adjust the engine’s operating gear based on the immediate propulsive need of the satellite. The engine operates in first gear to maximize acceleration during orbit transfers and then shifts to fifth gear once in the desired orbit. This allows the engine to burn at full capacity only during key moments and conserve fuel.

Finally, as Walker's lab doesn't contain many details about this military-funded project, here are some tidbits of information on how the engine works.

The Georgia Tech engine operates with an efficient ion propulsion system. Xenon (a noble gas) atoms are injected into the discharge chamber. The atoms are ionized, (electrons are stripped from their outer shell), which forms xenon ions. The light electrons are constrained by the magnetic field while the heavy ions are accelerated out into space by an electric field, propelling the satellite to high speeds.
Sources: Georgia Institute of Technology news release, via The Engineer Online, UK, February 22, 2007; and various other websites

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Topic: Nasa / Space

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9 comments
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  • ion engine?

    whats so amazing about an ion engine, they've been around since the 80's. http://en.wikipedia.org/wiki/Ion_engine
    sweklaweklfwe@...
    • Do you even read the article

      or is the point to respond as fast as you can?


      First, it's not an ion engine. It's a chemical engine. Second, the "amazing" part is instead of always operating at full power, it has different speeds that allow it to control the amount of fuel used. The overall result seems to be a rocket engine that uses 40% less fuel than other rockets.
      normalforce
      • Ok

        I apologize, it is not a chemical engine. But you did miss the point of the article. Who cares how long the engine has been around, this is a good improvement over the old design.
        normalforce
    • RE: A five-gear space rocket engine

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  • Er...

    This article doesn't make a lot of sense. I went to The Engineer and read their piece too and that didn't make sense either. I even went to the Georgia Tech site and read the original press release before I could see what was going on.

    The confusing bit is that ion engines cannot lift a satellite (or anything else) from the ground into orbit - yet this is strongly implied by your piece and the piece in The Engineer. The original press release is less misleading but still ambiguous. In fact, Mitchell's claim is that his engine can operate at different degrees of thrust as it manoeuvres in space. Using a high thrust for orbital transfers and lower thrust for other, less demanding, manoeuvres.

    In itself, this is a great advance, making ion rockets much more cost-effective and versatile. But it isn't quite what your article suggests.
    graywave
    • RE: A five-gear space rocket engine

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  • Two Engines, not Two Gears?

    My reading is that a 'normal' chemical engine is used to punt into space, then the (Xenon) ion engine is used once you reach orbit. It may be 'one engine to rule them all', but I expect that it will really turn out to be two (intertwined, but?) separate engines.
    darkonc
  • Hall Effect Thruster

    Previous commenters are correct that this is a TYPE of ion thruster.

    The are also correct that electric thrusters like this can not be used for launch. Electric thrusters don't work under atmospheric conditions, and while they are very efficient, they have very low thrust...so instead of putting out a lot of thrust for a short time (think of the space shuttle), ion thrusters put out a little thrust for lots of time (sometimes thousands of hours). So, these types of thrusters are best suited for when your craft is already in orbit. But, once out of the atmosphere and, they can be used for station-keeping, orbit transfers, and even interplanetary trajectories.

    Specifically, this is a Hall Effect Thruster (see wikipedia), and they have been around since the 50's/60's. The idea of "gears" is not new either -- all you have to do is change the strength of the electric field (apply more or less voltage) and the magnetic field (more or less current to the magnetic coils) to tailor the exhaust velocity. It is the voltage that accelerates the ionized (charged) gas.
    EQC
  • RE: A five-gear space rocket engine

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