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  • [♪ INTRO]

  • Someday, we're going to send people to Mars, and it's gonna be awesome.

  • But for now, everyone from NASA to Elon Musk

  • is still trying to figure out the best way to do it.

  • With today's rockets, a one-way trip to Mars takes somewhere around seven months,

  • but one company is developing an engine

  • that might be able to get us there in only forty days.

  • It's called the VASIMR engine, and it propels spacecraft using a jet of plasma.

  • VASIMR stands for Variable Specific Impulse Magnetoplasma Rocket,

  • and the idea behind it has actually been around since the 1970s.

  • But engineers didn't make too much progress on it until 2015,

  • when NASA gave the Ad Astra Company a grant to develop it as part of their NextSTEP program.

  • It works using a kind of electric propulsion,

  • and it's a big step up from the other engines available right now.

  • To get your rocket into space, you'd still need a chemical engine, which generates thrust

  • with a reaction that releases tons of gas, like combining hydrogen and oxygen.

  • So far, that's the only kind of engine we have

  • that's powerful enough to get a heavy rocket to space.

  • But once you're there, you can move it with all kinds of things,

  • from ions to particles of light, depending on what your mission is.

  • Right now, any spacecraft that would send people to Mars would still use a chemical engine,

  • because we mostly have the technology figured out.

  • But carrying all that fuel also adds a lot of weight.

  • So newer kinds of engines use electric propulsion, often in the form of ion thrusters,

  • which create a beam of charged atoms, or ions, to push your spacecraft around.

  • Ion engines are a lot more efficient than chemical engines,

  • but they aren't designed to handle large payloads,

  • like a bunch of humans and all the supplies they'd need for a trip to Mars.

  • So we mostly use ion thrusters for small satellites.

  • VASIMR also uses electric propulsion, but it will be way more powerful.

  • It propels the spacecraft by creating plasma,

  • in the form of a super hot jet of ions and electrons.

  • Unlike other kinds of electric propulsion, it uses radio waves to heat the plasma,

  • rather than electrodes or other electronics in ion engines.

  • Which among other things, makes the engine a lot more durable.

  • To make the plasma, it starts by pumping a gas like hydrogen or argon into a tube,

  • which is surrounded by a magnet and two couplers, a kind of device that emits radio waves.

  • Most kinds of gas will work, which makes VASIMR really versatile,

  • but hydrogen is a good choice if you want a lightweight, easy-to-find fuel.

  • Once the gas is pumped in, the first coupler strips some of the electrons off their atoms

  • and turns the gas into plasma.

  • At this point, it's already very hot, around 5500 degrees Celsius,

  • but then, the second coupler makes it even hotter.

  • It raises the plasma to 10 million degrees Celsius,

  • which isn't that far from the temperature inside the Sun.

  • A magnetic nozzle then turns that super hot plasma into a nice, controllable jet,

  • and it's shot out of the end of the engine.

  • Besides being more durable, VASIMR is great because it also has different settings,

  • like the gears on a car, which means it can generate the right amount of thrust

  • for different kinds of missions.

  • So besides getting people to Mars, it could also be scaled down

  • to send small satellites zooming around the Earth.

  • But most importantly for our future astronauts, VASIMR can be made

  • big and powerful enough to move human-sized spacecraft.

  • Ion engines just aren't ready to do that yet, partly because many tend to rely on more

  • mechanical parts than VASIMR, some of which aren't designed to work on a large scale.

  • Although engineers are working on that, too.

  • Still, there is one thing we need to figure out before VASIMR is ready to go:

  • the power supply.

  • It takes a lot of power to produce all those radio waves,

  • especially if you want an engine strong enough to push a crew of astronauts.

  • Solar panels can generate enough power to propel small satellites,

  • but we'd need something a lot stronger for a full-sized spacecraft.

  • And our best option is probably using a small nuclear reactor.

  • But because those have the potential to be really dangerous,

  • we'll want to make sure that we're extra confident in that technology

  • before we start using nuclear power to transport people through space.

  • Right now, the goal for the VASIMR team is to develop an engine

  • so it can fire for 100 consecutive hours at 100 kilowatts of power,

  • which is 10 to 100 times more power than an ion thruster has.

  • To get to Mars in 40 days, you'd still need a lot more power than that,

  • like, 2000 times more power.

  • And that's probably where a nuclear reactor would come in.

  • But for now, 100 kilowatts is a good start.

  • Ad Astra's plans with NASA are to have the engine ready

  • for the 100 kilowatt goal by the summer of 2018.

  • As of last August, they'd fired the engine for around 10 hours, so they're making progress.

  • Still, even after they meet that goal, VASIMR will need to go through

  • plenty of development and tests before we use it to go anywhere.

  • So when the first human steps on Mars, we'll probably have made it there

  • with a chemical engine, since that technology is a lot more developed.

  • But someday, our trips to Mars could be a whole lot faster.

  • Thanks for watching this episode of SciShow Space!

  • If you thought getting to Mars in 40 days sounded cool,

  • you can watch our episode on photonic propulsion,

  • where we explain how we could someday get to Mars in only three daysat least in theory.

  • But I wouldn't hold your breath.

  • [♪ OUTRO]

[♪ INTRO]

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