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  • Alec Gallimore: “What you're seeing is this energetic blue-greenish plasma that comes

  • out of the thruster.

  • It really looks like science fiction.

  • In the end, we're supplying electricity through a wire and an inert gas and we turn it into

  • this beautiful plasma that's moving at tremendous velocities that's providing thrust that may

  • one day send people to Mars.”

  • Chemical rockets are the workhorses of the space age, and they've had a pretty standard

  • formula for the past 60 years.

  • Get millions of pounds of liquid or solid fuel into a rocket, light it on fire with

  • an oxidizer, and then the speed of the propellant shooting out the back gives the rocket enough

  • thrust, or kick, to get into space.

  • This works great for escaping Earth's gravity.

  • But if we want to get to Mars, chemical rockets have hit their their performance limit.

  • We need new propulsion systems that can rapidly shoot a spacecraft across interplanetary distances,

  • while using less propellant at the same time.

  • That's where the X3 comes in.

  • As part of NASA's NextStep program, the X3 is an entirely new space engine that's

  • all electric.

  • Alec Gallimore: “Electro-propulsion devices have the equivalent of 10 times the propellant

  • efficiency of a chemical system.

  • To give you an example, a chemical rocket tops out at around 40,000 mph.

  • An electric system can go over 100,000 mph and in fact, NASA is working on a project

  • to design one that can actually achieve a velocity of 500,000 mph.

  • And at that speed you cover a distance between the Earth and the Moon in about 30 minutes.”

  • Here at the University of Michigan's Plasmadynamics and Electric Propulsion lab, engineers and

  • students are working on the X3, a type of electric propulsion design called a Hall thruster.

  • Alec Gallimore: “Hall effect thrusters are really a kind of a very ingenious propulsion

  • system.

  • We take a propellant, in some cases an inert gas like xenon.

  • We put a huge amount of energy into it, creates a high temperature plasma, charged particles

  • of electrons and ions, and then we can use electromagnetic fields to shoot out the plasma

  • at very high speeds.

  • So they're very simple in design, complex though in operations and very, very efficient.”

  • Hall thrusters aren't just a thing of the future.

  • There are actually hundreds of satellites above you right now using electric propulsion

  • to stay in position.

  • But this technology hasn't been used for manned missions yet, because the amount of

  • thrust they're capable of generating is just too low, which means slower acceleration

  • and a longer trip to Mars.

  • So, we need more thrust.

  • Ben Jorns: “Traditional Hall thrusters that work in space operate between one and six

  • kilowatts.

  • Now the X-3 comes in and trying to scale Hall effect thruster technology, into a new power

  • operator machine.

  • So going from six kilowatts to 100 or 200 kilowatts.

  • And the advantage of that is if you go to higher power, you can generate higher thrust.

  • And therefore have higher acceleration.

  • Instead of using one channel, which a traditional hall thruster has three channels, so you take

  • all those engineering requirements and you multiply it by a factor of three.”

  • For these engines to be used in space one day, testing is critical, and these labs are

  • uniquely equipped for the challenge.

  • Alec Gallimore: “Sitting behind me is what's called 'The Large Vacuum Test Facility'

  • the LVTF.

  • It has one of the highest pumping speeds in the world, which means it's able to have a

  • very low pressure while it's operating a large flow rate.

  • And we use it to simulate space.

  • We have 19 cryogenic pumps, that remove all the air and all the gasses from the chamber

  • so we can have a more realistic environment to test these thrusters.

  • Students run experimental campaigns in the LVTF.

  • One student might be trying to analyze the life of a thruster.

  • Another person might be trying to understand how the electrons from the cathode make their

  • way to the channel.

  • A successful test is often when you find something unexpected that ultimately leads you to having

  • a better understanding of the device you're testing.

  • And that happens quite a bit.”

  • But the X3 is too powerful for even the LVTF, and at this point, only NASA's Glenn Research

  • facility can handle its testing at full capacity.

  • Alec Gallimore: “A typical thruster may weigh 10 pounds, this thing weighs 500 pounds.

  • So just designing and building all the components of this mega-scale thruster was a challenge

  • that we took on.

  • Last year was a blockbuster year for the X3.

  • It set records for Hall thrusters for the highest power level at over 100 kilowatts

  • of power.

  • The highest level of thrust and actually the highest amount of current being passed through

  • any type of Hall current thruster.”

  • These engineering achievements are key, because electric propulsion is going to be a central

  • part of our future in space.

  • Alec Gallimore: “NASA is working on developing a sort of a 20 year game plan.

  • The idea is that we've been in the International Space Station now for more than a decade and

  • that has been a great.

  • But the next step would be something like a space station around the Moon.

  • We would have an outpost around lunar orbit to test new technologies that would be needed

  • to have humans live in space.

  • Hall thrusters are playing a really important role in this...it's baseline is to have a

  • bank of four Hall effect thrusters around because they want to be able to move around

  • this space station and actually demonstrate the ability to use electric propulsion of

  • this kind with a human attended spacecraft.”

  • The X3 is likely two incarnations away from being flight ready, but the work happening

  • here is all about demonstrating new principles for how to design electro-propulsion engines.

  • Ultimately, future space travel will use a combination of chemical and electric propulsion

  • to travel through space.

  • And it's projects like the X3 that make a future mission to Mars even more possible.

  • For more science documentaries, check out this one right here, don't forget to subscribe

  • and keep coming back to Seeker for more videos.

Alec Gallimore: “What you're seeing is this energetic blue-greenish plasma that comes

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B1 中級

X3イオンスラスタはここにある、これはそれが火星に私たちを取得する方法です。 (The X3 Ion Thruster Is Here, This Is How It'll Get Us to Mars)

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    林宜悉 に公開 2021 年 01 月 14 日
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