The Electric Thruster That Could Send Humans to Mars


Thanks for CuriosityStream for supporting
this episode of SciShow Space! To learn more, go to CuriosityStream.com/space. [ intro ] When you imagine humans on their way to Mars, you probably imagine them in a spacecraft
with big, explosive, chemical engines. And that’s totally reasonable. Humans need to travel with a lot of stuff, and engines that rely on chemical combustion
are currently the only ones powerful enough to move us through space at a reasonable speed. Except, chemical engines also have a pretty
big downside. They need to carry a bunch of fuel, which makes their spacecraft super heavy. And that leads to more expensive missions
that are harder to launch. Honestly, it would be nicer if we could move
humans with a lighter, more fuel-efficient propulsion system. And the good news? We might have already found our best option. It’s a form of electric propulsion called
a Hall-effect thruster, or a Hall thruster for short. They’re thrusters that look a bit like a
bullseye and glow with an eerie, colorful light. And they could be the future of human space
exploration. Unlike some of the ideas we talk about on
this channel, Hall thrusters aren’t theoretical — or
even new. They were invented in the 1960s, and engineers have spent decades advancing
the technology. On a basic level, these thrusters work by accelerating charged
particles called ions. First, you start with a circular channel — or a few channels, depending on how big your
thruster is. Between each channel, you put some magnetic coils that generate
a magnetic field. Then, at the bottom of your channels, you add an electrically-charged plate called
an anode, which creates an electric field. And finally, you add a cathode, which is located somewhere outside the channel and can spit out a bunch of electrons. Now, you’re ready to go. When you power up the thruster, the cathode starts releasing those electrons. The particles are attracted to the anode,
so they go flying into the channel. There, they’re caught up in the magnetic
field and start zooming in circles around and around
the thruster. And that’s where the magic happens. Once the electrons are zooming around, Hall thrusters pump a bit of propellant into
the channel — usually a neutral gas like xenon. The xenon gets hit with all of those incoming
electrons, and that knocks off some of its electrons
and turns the xenon atoms into ions. The electric field inside the thruster then
pushes those xenon ions out of the channel at incredible speeds — sometimes more than a dozen kilometers per
second. And that’s what generates the thrust to
move your thruster and your spacecraft forward. Now, this basic idea of accelerating ions
isn’t unique to Hall thrusters. Every form of ion-based electric propulsion
does something like this. What makes Hall thrusters special is that they satisfy three major conditions. For one, they have among the highest thrust
of all forms of electric propulsion. There are a few reasons for this, but one is because the propellant ions are
created and accelerated in the same area. Other thrusters keep these processes separate, and there’s a limit on how many charged
particles they can cram into one spot before the electric field gets messed up. Hall thrusters also use their fuel really
efficiently. Since they accelerate their ions to such high
speeds, they generate more thrust for every molecule
of propellant they use. And finally, they can fire for a long time. Other ion thrusters have components that quickly
wear out, and while Hall thrusters do have their own
lifetime problems, engineers have found ways to solve or mitigate
many of them. So in the end, these thrusters can fire for
much longer, which means they’re a lot more practical
for spaceflight. Since the ‘60s, Hall thrusters have flown
on dozens of missions. Mostly, they’ve been used to adjust satellites’
orbits, but in the 2020s, they’ll be used on even
bigger projects, like the Psyche mission to investigate an
asteroid. But earlier, I said Hall thrusters could be
the future of human space exploration. And the thrusters we have today… well, they’re nowhere near strong enough
to push around people at a helpful speed. Because here’s the thing about Hall thrusters
— and about electric thrusters in general: Their main benefit is that they can fire for
a long time. That means though you might start off slow, you can gradually build up speed until you’re
zooming along faster than any spacecraft that uses chemical propulsion. The problem right now is that getting to those
speeds takes a long time. With our current tech, it would take years
to get people to Mars. But someday, that could change. Because there’s a Hall thruster currently
in development that could become strong enough to move humans. It’s called X3. It’s been in development since 2009, and it gets its name because it has three
channels instead of the more common two. This allows it to accelerate more ions at
once. It’s still nowhere near strong enough to
fly humans, even if we put several of them on the back
of a spacecraft. But, it has generated more thrust in a test
than any other Hall thruster. Now, engineers are working to make X3 more
reliable and increase its thrust. And if they can manage that, NASA may eventually select the thruster to
help send people to Mars. Even if this doesn’t happen, though… there’s a good chance this project will
inspire other teams to continue the work. There are a lot of electric propulsion methods
out there, and many of them are already changing spaceflight. But when it comes to flying humans around, Hall thrusters might be our best bet. At the end of the day, a lot of people just want to see humans walk
on the surface of Mars. But while that will be amazing, it’s worth remembering the engineering behind
this goal, too. It’s taking a lot of clever, creative work
to make something like this feasible. And the research being done on Hall thrusters
is a great example of that. If you want to learn more about space exploration, you can consider checking out a documentary
on CuriosityStream! CuriosityStream is a subscription streaming
service that offers more than 2,400 documentaries and nonfiction titles, including exclusive originals. They even have a whole series called Space
Probes!, including an episode about future missions
— like one that could someday visit a distant
star. You can check out this content free for 31
days if you sign up at curiositystream.com/space
and use the promo code “space.” And after that, you can get unlimited access
for just $2.99 a month. If you decide to check them out — thanks! You’re supporting SciShow along the way. [ outro ]

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100 thoughts on “The Electric Thruster That Could Send Humans to Mars

  1. Ya as you said, nothing new. Ion engines have been around a long time and this is a variation. Let us know when a real breakthrough happens.

  2. Whats wrong with both? Chemical explosive for acceleration and an ion engine for the top speed limit increase? Build a giant slingshot on the moon!

  3. its interesting too because when we see star ships from some movies or games, we often see not a large flame pushing them but a small gentle blue or red glow which looks pretty similar to what this video is all about

  4. Good video. The Martian used ion thrusters to move it's ship didn't they? Also KSP has Xenon thrusters which are Hall Effect thrusters.

  5. I want to see a Moon base that uses Railguns to fire supplies to Mars and perhaps a long track electromagnetic sled to accelerate passengers at a safe rate.

  6. The VASIMR ion drive is already running at 200 kw (though not putting out 200 kw of thrust) and has been test run in a vacuum chamber for more than two years. Putting a number of them on the upper stage of a chemical rocket capable of moving at (earth's) escape velocity could allow acceleration half way to Mars, until it was necessary to reverse thrust to slow down for entry into Mars atmosphere. Using this method it is possible to reach Mars in just 39 days according to the manufacturer of VASIMR.

  7. Any thoughts on how to create that sort of electrical energy in a portable unit? Currently, we have to heat water using coal, gas or nuclear fission to produce steam in order to turn a turbine fan to produce electricity. I think science should concentrate on that first before faking mars landings for political gain. When energy is free to all, there will be fewer deaths, less starvation, less thirst, less suffering and a better quality of life for all. That is my end-game.

  8. I don’t think people quite understand how thrust engines work. Hall engines are chemical engines. Literally everything is a “chemical”. Ion thrusters, like hall thrusters, propel a vehicle or object forward by shooting mass in the opposite direction of desire motion. This is literally the exact same way that “chemical” engines work. It’s how any motion works throughout the entire universe. So you would need to have the same amount of fuel (same amount of mass being thrown out of the engine) for hall thrusters as a “chemical” engine.

    The only way to use less fuel, is to either have a less massive rocket, or throw the fuel (just mass) out of the engine faster (more energy).

  9. The problem with ion engine is it can't move any vehicle inside earth gravity well, not even the engine itselves. Its thrust is too small to compete against earth gravity (plus friction). It means we still have to rely on chemical rockets to fling spaceship to orbit and only then we can use ion engine to deliver us to the target.

  10. Something very different came to my mind when I read that title… lol

    *teenage robot boy thrusting around the halls in between classes*

  11. 4:53 Why don"t you EVER mention the force it exerts?!?!?!?!??!!?! So instead of pushing 2 pieces of paper, now it can push 3 pieces of paper or what? Cause these things suck, really suck at pushing anything.

  12. I am glad that we are talking about a real thrust system. The EM drive was a hyped farce. With with more therminal loss than anything and thrust so low that is was nearly all measurement error or a result of heat radiation.

  13. The obvious solution seems to be using chemical rockets to get up to a certain speed then switch to the electric propulsion.

  14. 0:25 no, chemical rockets are not the only way to move us thru space, they are the only way to get into orbit, into space. Even the hall thruster equipped upper stage will get into orbit by being carried on chemical rockets. Those two have different specializations, one does not make the other obsolete.

  15. There's already nuclear thermal propulsion. Which is more than enough to send manned missions to any of the planets in the Solar System.

  16. Why not just send a thruster up to start acellerating and then attach a spacecraft to it once it’s going fast enough?

  17. So until we develop a engine that will accomplish the things we want as far as moving people around the solar system it seems like we could develop a system that would get it self into low Earth orbit. Possibly in 2 or 3 sections, then couple together. Then fuel could be shuttled, to it, also fuel could be made at the destination or using unmanned ships could be sent well before the people leave using slower propulsion methods. It's arrival would be confirmed prior to the point of no return for the ship with the people on it. Once they arrive a lander takes them down and back up and they return in the return ship, or a refuled transport vehicle. This ship never touching down until it gets replaced. By doing some manner of this heavier loads could be taken and everything left behind will be added to construction of a long term space station or surface base or both. Allowing shorter travel for the humans. The long trips will be done by robotics. A multinational space organization would be needed to cover the cost, but in the end to get to other planets and beyond that will be needed anyway.

  18. i want to know how possible and helpful it would be to drill a hole in the moon and ships out of it by rail gun that would provide a reasonable starter speed for your spacecraft and if you kept it in line with the orbital plane of most objects in the solar system, it would only take a bit of post launch course correction to get your ship to any stellar body

  19. Why not have a small amount of chemical propulsion to get the vehicle up to speed and then flip on the ion thrusters hypothetically it could work if your main goal is just to get to Mars

  20. That's cute, but nuclear propulsion is far better. once we have the infrastructure on the moon built we could even make Orion drives. Think spacecraft with 250k people on board, with walls so thick we don't need to worry about radiation in space at all. Using antimatter eventually we could hit 10-20% the speed of light, and have enough energy at the other end to slow down. A Hall thruster might work in deep space probes, but people want to get there in the shortest amount of time. Hall thrusters are not going to provide that.

    Ten there was NERVA. Not something you would want to launch from Earth (unless you're Russian) but vastly better than chemical rockets and already tested. Build these types of drives on the moon and you circumvent the "launching nuclear materials" NIMBY issue.

    https://en.wikipedia.org/wiki/NERVA

  21. Thanks for sharing. However, it would be more useful with information on energy density and the mass of the technology vs. chemical propellant technology.

  22. I had an idea while watching this: chemical rockets are too fuel inefficient, electric propulsion is too slow to accelerate, but has anyone ever thought of combining the two? So, you use a burst from chemical rockets to get you started (possibly in a removable stage), then speed up your journey by coasting along with electric propulsion. I realise it's adding weight and complexity, but I'd be curious to see someone try the maths. Anyone know if this has been considered before?

  23. Fun fact: studied independently in US and Soviet Union. First developed into an efficient propulsion system in Soviet Union. USA built their version of the thruster after 1992 after visiting Russian laboratories.

  24. It takes so long to get up to speed because of the difference in spacecraft propulsion speed for different propulsion systems. Suppose though that various spacecraft with different propulsion systems were only used to temporarily accelerate pods on their way between planets, and then reused for the next, that way the transmission of materials could happen in stages at waypoints between Earth and Mars? That's how the first space pioneers will have to think.

  25. if there is no atmosphere to push off from, then how do you suppose the thrusters have any effect in a near perfect vacuum? the answer is they don't. it's impossible .

  26. I was gonna say. Wtf are you talking about? What about solar sails or ion engines? But you're talking about modified ion engines

  27. True the ion drive is the future of space flight but we can't leave it up to NASA if they keep going about it the same way We all know NASA and there mk3 which was a big waste of time and money because by the p/w ratio it's 500lbs has a thrust of 278 millinewtons and the original ion drive they made was around 10lbs with a thrust of 92millinewtons so the mk3 has 3x more thrust because they made it have 3ion rings cuz it looks cool but they didn't focus on ion speed improvement no they made it 17x less efficient 3x more thrust and 50x heavier ,spent probably millions and years making it when they could've just used 3 mk1's to get the same thrust.a and used that money and time to improve the mk1 with a ion coil rail drive. God damn it some give me a job! rant over

  28. Obviously we will never inhabit the Solar System with anything less than electromagnet propulsion, that pulls it self around without throwing something out the back. If you believe this violates the laws of physics then be content to stay on cradle Earth.

  29. Getting to and from Mars without refueling is the problem. Once you get into the vacuum of space you just let your momentum carry you forward and spend little to no fuel for travel. the problem would be carrying enough fuel to get off of earth and then the Martian surface once you’re ready to leave. It takes around 7 months to get to mars at the closest orbits with our current tech, it took curiosity 253 days. Sounds like a cool way to travel through space, but it won’t be used to get to mars.

  30. The maker of this video must do some research on Escape velocity of Earth. Must know how much velocity is required to escape from earth's gravitational pull if you want to go to space. The way you describe..they seem to be suitable for moving in space…but I doubt if it can achieve enough velocity to escape earth's gravity.

  31. 0:28 Let's try that again. Nuclear thermal rockets are currently the only engines that can get us to Mars at a reasonable speed.

  32. Where are Master Therion, Muscle Hank, Hustle Hank, Dank Hank, and all the other regulars? Everybody done got up and left. Also, main benefit of ion thruster isn't firing for long time, it's efficiency. Thrust, integrated over time, and divided by the mass of the fuel is maximized, thus highest efficiency.

  33. How about we use traditional chemical thrusters to escape earth's gravity and in zero g, fire up the Hall Thrusters to get reliable and efficient acceleration on our way to Mars?

  34. We should put all our efforts into cleaning up this beautiful planet we abuse ,we won't find better or even close and we should start looking after all life on earth rather than looking elsewhere for it. We'll only enslave it,kill it or have an almighty war with it because we are not fit for purpose.

  35. They should make a modular Hall Thrust engine and launch it into orbit to gain speed for some years. Then launch the transportation module with chemical thrust, catch up with the engine and go to Mars (or Titan, etc). In there, detach the transportation module for landing (the Hall Thrust remains in orbit) and do the same thing again to come back.

  36. Launch a large rocket with hull thrusters, let it loop around the solar system for 50 years, lasso it, aim for deep space. Problem solved.

  37. I INVENTED SELF POWERED MAGNETIC MOTOR/GENERATORS, AND PROPULSION BY COUNTER-ROTATING AND OSCILLATING WEIGHTS (USING CENTRIFUGAL FORCE)!
    NO FUEL NEEDED AT ALL!
    And I did build the 2 magnet test device AND IT WORKED! Then when I started putting the first magnet on a rotor with 9 stationary stator magnets, I lost everything to petty and unconstitutional 'colorable laws', so after 9 YEARS studying Human laws, now I've got 6+ harmless civil and criminal 'offenses' dismissed, around 12 officers to stop trying to enforce what they pulled me over for AND THANK ME, for proving, like 2 COPS have said, 'that's over 90% of what we do!
    AND I figured out how weights oscillating back and forth while spinning (2, in opposite directions), can move in the same direction ('down') every time it oscillates back and forth, through a central rotor, every half rotation… And with 2 rotating in opposite directions, all forces cancel out except a net propulsion in one direction!
    And Electromagnetic shock absorbers will recycle otherwise wasted mechanical energy!
    The magnetic motor powers itself by converting a repulsive force between like magnetic poles into an attractive force using soft iron on the front side of the stator magnets, which should wrap around the edge of the magnet so they don't attract at strong when aligned edge to edge, but still pass that point on momentum, then are finally repelled away when they aren't aligned!
    I built that and it DID WORK!
    NOW, I'm taking paralegal clients on Facebook to start making a good living again, and seeking people from all 50 States to join a 'class action suit' to force all US and State govts to stop ALL these 'deprivation of rights under color of law'!
    I'm giving those away on www.GovernPublicServants.com btw, free!
    Anyone wanna invest and help me RE-Build the self propelled motor?!?
    Then we can make the propulsion device, and spacecraft which don't need fuel at all! (Should still probably have Solar panels and a way to remagnetize worn out magnets using a strong electric pulse, stored in batteries though).
    Who's with me?

  38. There's nothing stopping you running a bunch of these in parallel. The real problem is the tens of mega Watts you need to power them on any realistic flight. Solar arrays give you issues to do with mass, robustness and decreasing power the further away from the Sun you get. Nuclear (electrical) is inherently heavy (shielding) – plus the mass of the thermal radiator. So the thrusters is not really the critical problem. Its actually the electrical power source.

  39. Never be good enough for getting into orbit – only fit for use when in space. So why start off talking about lift off? Very misleading.

  40. For deep-space missions, would it be a crazy idea to quickly accelerate a craft up to a reasonably quick speed using a chemical booster then switch over to to a Hall Engine to further build on the velocity?

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