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How does a plasma thruster work? · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Daniel, have you guys made any progress on the
• 0:11
  Speaker 1: new spaceship engine that can cross the vast distances between stars?
• 0:15
  Speaker 1: Nothing to report yet? Sorry? Oh man, I feel kind
• 0:19
  Speaker 1: of cheated that I made that a rush order. Well,
• 0:21
  Speaker 1: no problem. You know, once we finished building it, delivery
• 0:24
  Speaker 1: is going to be a snap. Yeah. Are you going
• 0:26
  Speaker 1: to deliver my spaceship on a spaceship now? It's sort
• 0:30
  Speaker 1: of like when you buy a new car, it comes
• 0:31
  Speaker 1: on a huge truck. Oh nice, So I can expect
• 0:35
  Speaker 1: a huge giant space truck pulling up next to my
• 0:38
  Speaker 1: house soon. Absolutely. The kids are gonna love it. It's
• 0:41
  Speaker 1: gonna come with a nice big bowl tied around it.
• 0:43
  Speaker 1: For an extra twenty million dollars, I'll put a bowl
• 0:45
  Speaker 1: on it. Hi am more handmade cartoonists and the creator
• 1:02
  Speaker 1: of PhD comics. Hi. I'm Daniel. I'm a particle physicist,
• 1:06
  Speaker 1: and I've never actually bought a new car. You've never
• 1:09
  Speaker 1: bought a new car, Never bought a new car, always
• 1:11
  Speaker 1: a used car. Wow. I guess they are cheaper, right,
• 1:14
  Speaker 1: because as soon as you buy a car and they
• 1:15
  Speaker 1: start depreciating. That's right. But I've never had that amazing
• 1:18
  Speaker 1: experience of seeing your brand new, shiny zero miles car,
• 1:22
  Speaker 1: pull up on the fancy truck. What's new to you?
• 1:25
  Speaker 1: So it is technically a new car, that's right. And
• 1:28
  Speaker 1: we like to drive our cards into the ground until
• 1:30
  Speaker 1: they're falling apart around us, like the podcast is that
• 1:33
  Speaker 1: what we're doing here now? Is this a used podcast? Technically?
• 1:36
  Speaker 1: It is right because we record this a few weeks
• 1:39
  Speaker 1: in the van, so by the time people listen to it,
• 1:41
  Speaker 1: it's got some mileach on it, but it's new to them.
• 1:43
  Speaker 1: That's right. Let's maybe spray some of that new car
• 1:46
  Speaker 1: smell around. That's right, new podcast smell yeah. Whip an
• 1:50
  Speaker 1: end people, But anyways, welcome to our podcast. Daniel and
• 1:53
  Speaker 1: Jorge explain the university production of I Heart Radio, in
• 1:56
  Speaker 1: which we take you around this very very old universe
• 1:59
  Speaker 1: that been around longer than we have and trying to
• 2:02
  Speaker 1: answer some questions about it and what questions do we ask?
• 2:05
  Speaker 1: We ask all the questions we asked, the biggest questions,
• 2:08
  Speaker 1: the hardest questions, the silliest questions, and the deepest questions,
• 2:12
  Speaker 1: and we try to find answers, and when we don't
• 2:14
  Speaker 1: find them, we are happy to admit what science doesn't know.
• 2:17
  Speaker 1: We take all that, we mix it around, we throw
• 2:19
  Speaker 1: in some bananas, and we serve it to you as
• 2:21
  Speaker 1: a podcast smoothie. That's right, because the universe might be
• 2:24
  Speaker 1: old and it might be used. In fact, it's actually
• 2:27
  Speaker 1: a several billions of years old, but it's still full
• 2:30
  Speaker 1: of amazing and new things to discover for us puny humans.
• 2:33
  Speaker 1: That's right. Do you think we have to pay full
• 2:35
  Speaker 1: price for this universe? I mean it's like really pretty
• 2:37
  Speaker 1: old by time we got it, we should have gotten
• 2:39
  Speaker 1: some kind of discount. Really, did you think we have
• 2:41
  Speaker 1: an option? Do we have like other newer universe we
• 2:44
  Speaker 1: could have bought. I guess you've got to have another
• 2:46
  Speaker 1: option if your negotiation is gonna be credible, Right, you're
• 2:48
  Speaker 1: gonna be able to walk out of the universe dealership
• 2:50
  Speaker 1: and say, I'm just gonna go down the street and
• 2:52
  Speaker 1: get a universe somewhere else. We have no leverage. We
• 2:56
  Speaker 1: have no leverage. We're stuck with this universe, and we
• 3:00
  Speaker 1: love it. It's the only car and a lot, that's right,
• 3:03
  Speaker 1: And let's not protect we don't love it. It's a wonderful, amazing,
• 3:06
  Speaker 1: crazy place filled with all sorts of mysteries. I just
• 3:09
  Speaker 1: sometimes wish we could see more of it. Well, we
• 3:11
  Speaker 1: can see a lot of it, right, We can see
• 3:13
  Speaker 1: up to billions and billions and billions of light years away.
• 3:16
  Speaker 1: But the hard part is getting to those places and
• 3:19
  Speaker 1: seeing them up close. Yes, exactly. That's why I mean
• 3:21
  Speaker 1: that we could visit more than that, we could go there,
• 3:23
  Speaker 1: that we could walk on the surface of Pluto, or
• 3:26
  Speaker 1: we could see what the atmosphere of Venus is like.
• 3:28
  Speaker 1: It feels like there are so many amazing mysteries of
• 3:30
  Speaker 1: science and physics that are right in our neighborhood, and
• 3:33
  Speaker 1: yet it's still so strangely hard to get there. Yeah,
• 3:36
  Speaker 1: or not just even our Solar system. It'd be cool
• 3:39
  Speaker 1: to travel to other galaxies and see if things are
• 3:41
  Speaker 1: quite the same as they are here in the Milky Way.
• 3:43
  Speaker 1: That's right. I'd like to be home before dinner, though,
• 3:45
  Speaker 1: so I'm not sure I'm gonna join you on that
• 3:46
  Speaker 1: intergalactic voyage. But somebody should go, and somebody should report back.
• 3:51
  Speaker 1: What if you make the spaceship your home, Daniel, and
• 3:52
  Speaker 1: then you'll always be home like a space RV. That
• 3:55
  Speaker 1: sounds great. It's just a couch and a rocket and
• 3:58
  Speaker 1: rocket field. That's all. Well, if my family is going along,
• 4:02
  Speaker 1: then my kids definitely need their own rooms, because there's
• 4:04
  Speaker 1: no way they're getting along if they're sharing a room
• 4:06
  Speaker 1: in the space RV. Al right, we can at an addition,
• 4:11
  Speaker 1: but yeah, getting around space is difficult because space is
• 4:14
  Speaker 1: so big. It's gigantic, it's ginormous, it's a pretty spacious.
• 4:18
  Speaker 1: It's hard to really wrap your mind around how big
• 4:21
  Speaker 1: space is. We have this image of the Solar System
• 4:23
  Speaker 1: is sort of this cozy place where all the planets
• 4:25
  Speaker 1: are zooming around the Sun and kind of near each other,
• 4:28
  Speaker 1: but there are vast distances. You know, even just from
• 4:30
  Speaker 1: the Earth to the Moon is a much bigger distance
• 4:33
  Speaker 1: than most people imagine. Did you know that if you
• 4:35
  Speaker 1: took all the planets in the Solar System you could
• 4:38
  Speaker 1: fit them in the distance between the Earth and the Moon. Wow?
• 4:41
  Speaker 1: I take it that's a bad idea that you're not
• 4:43
  Speaker 1: actually planning on doing that. You know what, I'd love
• 4:45
  Speaker 1: to see it. So if you have somehow the power
• 4:46
  Speaker 1: to do that, go ahead from your underground layer. Well,
• 4:49
  Speaker 1: if you just want to see it, then you know,
• 4:51
  Speaker 1: I can do that in photoshop easily. But the idea
• 4:54
  Speaker 1: I think is that space is big right, like between
• 4:56
  Speaker 1: here and the Moon, it's several hundred thousand miles even
• 4:59
  Speaker 1: right absolute, it's really really far. And you know, the
• 5:01
  Speaker 1: outer planets are really really far away, Like we are
• 5:05
  Speaker 1: much much closer to the Sun than we are to Jupiter,
• 5:08
  Speaker 1: for example. Yeah, I think we're used to maybe thinking
• 5:10
  Speaker 1: of our Solar System is this cozy, little like collection
• 5:13
  Speaker 1: of planets, but really it's quite sparse. It's quite empty,
• 5:16
  Speaker 1: like if you took a picture of it, you would
• 5:17
  Speaker 1: always see little tiny thoughts as the planets. Yeah, that's
• 5:20
  Speaker 1: why Jupiter seems like almost a star because it's so big,
• 5:23
  Speaker 1: but it's so so far away, and so the Solar
• 5:26
  Speaker 1: System is hard to get around because everything is so
• 5:29
  Speaker 1: far away. And when we launch even robotic probes to
• 5:32
  Speaker 1: the outer Solar System, it can take ten, fifteen, twenty
• 5:35
  Speaker 1: years to reach those places. Yeah. I think the trip
• 5:38
  Speaker 1: to Mars, just to Mars, it takes several months, right, Yeah,
• 5:40
  Speaker 1: and that's if you're lucky, right Earth end Mars are
• 5:43
  Speaker 1: near each other sometimes and far apart other times, and
• 5:46
  Speaker 1: so the shortest trip to Mars is like more than
• 5:49
  Speaker 1: half a year, and so it'd be awesome to be
• 5:52
  Speaker 1: able to get to Mars much faster and make it
• 5:54
  Speaker 1: easier to explore the Solar System, to send people there
• 5:56
  Speaker 1: if they didn't have to spend like seven months in
• 5:59
  Speaker 1: a tin can together. Yeah, I think the big question
• 6:02
  Speaker 1: is like, how can we get to these planets faster?
• 6:04
  Speaker 1: Like how can we you know, make a new kind
• 6:06
  Speaker 1: of spaceship or a new kind of propulsion technology to
• 6:09
  Speaker 1: basically pushes there faster, because traveling through space is really hard.
• 6:14
  Speaker 1: It's all about the speed. You know. A hundred years ago,
• 6:16
  Speaker 1: the Earth seemed much bigger because it was a bigger
• 6:19
  Speaker 1: deal to get to the other side of it. To
• 6:21
  Speaker 1: go to China two or three hundred years ago was
• 6:23
  Speaker 1: a days, weeks, months long endeavor. Now you can do
• 6:26
  Speaker 1: it in just you know, eighteen hours or so on
• 6:28
  Speaker 1: an airplane. It's not that big a deal. And that
• 6:30
  Speaker 1: transformation came because we had new technology, new engines that
• 6:34
  Speaker 1: could take us there faster. And so we hope we
• 6:36
  Speaker 1: fantasize about the technology that could take us around the
• 6:39
  Speaker 1: Solar system faster, that could effectively compress the Solar system
• 6:42
  Speaker 1: so it doesn't seem so big to shrink the Solar system.
• 6:46
  Speaker 1: In a sort of metaphorical way of speaking, right, maybe
• 6:49
  Speaker 1: when day you could buy a ticket to Jupiter and
• 6:51
  Speaker 1: all you have to worry about is like, how many
• 6:52
  Speaker 1: movies am I going to watch? Have they made enough
• 6:55
  Speaker 1: Avengers movies so I could just watch them all between
• 6:57
  Speaker 1: here and Jupiter. Well, by then they will make five
• 7:01
  Speaker 1: months worth of Avenger movies. Yeah, and maybe by then
• 7:04
  Speaker 1: the Avengers movies will each be forty hours long. So right, yeah,
• 7:07
  Speaker 1: they seem to be getting longer and longer. That's right.
• 7:10
  Speaker 1: It's the opposite of time dilation. It's movie dilation, which
• 7:12
  Speaker 1: works in the opposite direction. It's marvel dilation. Marvel, it's
• 7:16
  Speaker 1: like the quantum realm. Yeah, well, what if I watched
• 7:19
  Speaker 1: the Avengers movies while moving at high speed? Maybe they'll
• 7:22
  Speaker 1: shrink it back down to two hours long. Maybe you
• 7:25
  Speaker 1: actually like them? I like those movies. Come on. But anyways,
• 7:30
  Speaker 1: there are people out there working on new technologies that
• 7:33
  Speaker 1: might get us to other planets and other stars faster
• 7:35
  Speaker 1: and faster. And in particular, there's kind of a new
• 7:38
  Speaker 1: exciting technology with a pretty cool name. That's right. People
• 7:41
  Speaker 1: are working on this, People trying to develop ideas. People
• 7:43
  Speaker 1: have all sorts of different plans for how to develop
• 7:46
  Speaker 1: new engines for spaceships. So today on the program, we'll
• 7:49
  Speaker 1: be asking the question how do plasma thrusters work? Now, Daniel,
• 7:59
  Speaker 1: I'd just like to say the word plasma thrusters. I
• 8:01
  Speaker 1: feel like that's so you know, science fiction. I feel like,
• 8:05
  Speaker 1: you know, some some something out of a movie. I know,
• 8:07
  Speaker 1: it sounds a lot like plasma blaster, right, it sounds
• 8:10
  Speaker 1: like a weapon you could use against something with like
• 8:13
  Speaker 1: lots of limbs and gooey insides. Yeah, some sort of
• 8:16
  Speaker 1: glowing technology that you know, kind of like what you
• 8:19
  Speaker 1: see behind the starship Enterprise. Yes, but that's the exciting
• 8:22
  Speaker 1: thing about science fiction is that it gives people ideas
• 8:25
  Speaker 1: and then we try to make it real. Scientists watch
• 8:28
  Speaker 1: science fiction and go, man, why can't we actually do that.
• 8:31
  Speaker 1: We've got an idea, maybe we could actually do that,
• 8:34
  Speaker 1: And then they go off into their laboratories and they
• 8:36
  Speaker 1: tinker until boom, it's a reality. And the funny thing
• 8:39
  Speaker 1: is that those science fiction writers probably got these names
• 8:41
  Speaker 1: and these ideas from science itself, like plasma is a
• 8:45
  Speaker 1: real thing and thrusters are a real thing. They just
• 8:47
  Speaker 1: but hey, why don't we put the two together and
• 8:49
  Speaker 1: sell more books? Is that the process of science fiction.
• 8:52
  Speaker 1: You're like, take two things sticking together. Can we get
• 8:54
  Speaker 1: a banana thruster or a plasma banana? Yeah, it's like
• 8:58
  Speaker 1: taking two words like science and fiction and then sticking
• 9:01
  Speaker 1: them together and see what happens. Boom, new genre invented. Yeah,
• 9:06
  Speaker 1: I think that's the whole process. So plasma thrusters sounds cool,
• 9:10
  Speaker 1: but what is it? So we were wondering what people
• 9:13
  Speaker 1: out there knew about these two words stuck together and
• 9:15
  Speaker 1: whether or not they can actually be real. As usual,
• 9:18
  Speaker 1: Daniel went out there into the internet to ask people
• 9:21
  Speaker 1: if they knew how a plasma thruster works. And so
• 9:24
  Speaker 1: my eternal gratitude to those of you who volunteered to
• 9:27
  Speaker 1: answer random physics questions for the podcast and enjoy hearing
• 9:30
  Speaker 1: your voice speculating on the podcast. If you'd like to
• 9:33
  Speaker 1: contribute your voice as well, please write to me two
• 9:36
  Speaker 1: questions at Daniel and Jorge dot com. So think about
• 9:39
  Speaker 1: it for a second. Do you know how a plasma
• 9:42
  Speaker 1: thruster works? Here's what people had to say. I have
• 9:45
  Speaker 1: absolutely no idea what a plasma thruster is or how
• 9:49
  Speaker 1: it works, but it sounds pretty naughty. Well, I don't
• 9:54
  Speaker 1: know exactly, but it's way better than a chemical like
• 9:59
  Speaker 1: we have now would luck to us. I'm guessing the
• 10:02
  Speaker 1: plasma thrusters would work by igniting this ionized gas in
• 10:08
  Speaker 1: one direction that causes a force that pushes whatever rocket
• 10:13
  Speaker 1: or object it's in in the other direction. I'm a
• 10:16
  Speaker 1: hundred cent sure that the plasma thrust is a dance
• 10:22
  Speaker 1: move that particle physicists do at parties. Well, this is
• 10:27
  Speaker 1: a guess on my part based on the words, but
• 10:31
  Speaker 1: I assume that it excites an atom to the point
• 10:35
  Speaker 1: where the electron is stripped off, and it throws the
• 10:39
  Speaker 1: nucleus through some sort of magnetic or field at rather
• 10:47
  Speaker 1: high velocity out the back, which gives you thrust the
• 10:50
  Speaker 1: same way any normal rocket motor would work, except instead
• 10:53
  Speaker 1: of using chemical energy, you're using magnetic or electric energy
• 10:58
  Speaker 1: to throw out plasma. Uh nuclear, All right, pretty cool answers.
• 11:05
  Speaker 1: I like the one that says it's a dance move
• 11:07
  Speaker 1: that particle physicists do at parties. You like that? Do
• 11:10
  Speaker 1: you really want to imagine a bunch of particle physicists dancing?
• 11:13
  Speaker 1: I mean, does that a mental image you want in
• 11:14
  Speaker 1: your mind? I've seen it, and trust me, you don't
• 11:17
  Speaker 1: the particle physicists have party coal parties. There are particularly
• 11:21
  Speaker 1: good parties, yes, particularly awkward, as I think, when we
• 11:25
  Speaker 1: discover a nice particle, then yes, we have a party.
• 11:28
  Speaker 1: We celebrate, we drink champagne, we shake our booties just
• 11:30
  Speaker 1: like everybody else. Wow. Sounds exciting, all right, And so
• 11:34
  Speaker 1: a lot of people don't seem to have a pretty
• 11:36
  Speaker 1: good idea, although they definitely you know, I have some
• 11:39
  Speaker 1: ideas of what plasma is, but maybe not what a
• 11:41
  Speaker 1: plasma thruster is. Yeah, but they're excited about it. They
• 11:45
  Speaker 1: want this thing to be a reality. That sounds like
• 11:47
  Speaker 1: a promising step in the direction of getting us around
• 11:50
  Speaker 1: the Solar System. And so I think everybody is in favor.
• 11:52
  Speaker 1: All right, Well, Daniel, let's talk about first why we
• 11:55
  Speaker 1: might need a plasma thruster. You know why this idea
• 11:59
  Speaker 1: of creating something that can push you in the vacuum space,
• 12:02
  Speaker 1: why is that so hard? Right? So, one of the
• 12:04
  Speaker 1: reasons that this is a hard problem is that when
• 12:08
  Speaker 1: you are in space, you need to push against something. Right,
• 12:11
  Speaker 1: If you're in space and you want to get speed,
• 12:13
  Speaker 1: what you have to do is throw something out the
• 12:16
  Speaker 1: back of your rocket ship. Because of conservation momentum. If
• 12:19
  Speaker 1: you're going to go in one direction, something else has
• 12:22
  Speaker 1: to go in the other direction. So this is like
• 12:25
  Speaker 1: the reaction. You know, you could like fire a bullet,
• 12:28
  Speaker 1: for example, out the back of your spaceship and the
• 12:31
  Speaker 1: gun will push you in one direction and the bullet
• 12:34
  Speaker 1: in the other direction. So the basic elements you need
• 12:36
  Speaker 1: of any thruster are some energy and then something to
• 12:40
  Speaker 1: throw out the back, some reaction mass to push the
• 12:43
  Speaker 1: other direction, right, Because I guess when you're in space,
• 12:45
  Speaker 1: you're if you're out there floating, it's not like you
• 12:47
  Speaker 1: can swim your way to Mars or to the moon.
• 12:51
  Speaker 1: You can't just there's something to like push against, right,
• 12:53
  Speaker 1: So you need to throw something out the back, and
• 12:56
  Speaker 1: for that you need energy. So that's what you're saying.
• 12:58
  Speaker 1: You need energy and then something to throw out the bag.
• 13:00
  Speaker 1: Using that energy exactly, you have to carry with you
• 13:03
  Speaker 1: stuff that you can throw away so that you can
• 13:06
  Speaker 1: move along. As you say, you can't like grab space
• 13:08
  Speaker 1: and swim through space itself, right, it's not like air
• 13:12
  Speaker 1: or water that you can pull against, right. You can't
• 13:14
  Speaker 1: just like blow out the back like or maybe you
• 13:17
  Speaker 1: can can you Yeah, actually that would work. I mean,
• 13:19
  Speaker 1: that is a form of a rocket engine, right, you
• 13:22
  Speaker 1: blow air out the back, and you can even use
• 13:24
  Speaker 1: a flashlight. Right, if you turn on a flashlight on
• 13:26
  Speaker 1: a spaceship out the back of your spaceship, then that's
• 13:29
  Speaker 1: a form of a thruster because you're shooting energy in
• 13:32
  Speaker 1: one direction and so the spaceship will go the other direction. Right,
• 13:36
  Speaker 1: that would be a photon thruster. That's a different episode.
• 13:38
  Speaker 1: That's a different episode. Yeah, exactly. But you know, it
• 13:41
  Speaker 1: reminds me some listener rode in and asked about their headlights.
• 13:44
  Speaker 1: Every time you turn on headlights in your car, are
• 13:46
  Speaker 1: those effectively like photon brakes? And they kind of are,
• 13:50
  Speaker 1: because you're like throwing energy forwards, sort of like having
• 13:53
  Speaker 1: tiny little thrusters pointing forward. So every time you turn
• 13:57
  Speaker 1: on your headlights, your car slowed down the tiny a
• 14:00
  Speaker 1: little bit. And it just made me think when you
• 14:02
  Speaker 1: hit the brakes and you turn on the brake lights
• 14:04
  Speaker 1: in the back, and you're also sort of working against
• 14:07
  Speaker 1: yourself there because you're breaking, but you're also kind of
• 14:10
  Speaker 1: propelling yourself using photons. Yeah, brake lights should be in
• 14:12
  Speaker 1: the front. Oh my god, it's so much better. I
• 14:15
  Speaker 1: think that would defeat the purpose of brake lights. So
• 14:18
  Speaker 1: one of the problems with using a rocket is that
• 14:21
  Speaker 1: you've got to have all this stuff on board. You're
• 14:23
  Speaker 1: gotta have the fuel, you've got to have the stuff
• 14:25
  Speaker 1: to throw out the back, and then the further you
• 14:27
  Speaker 1: want to go, the more fuel you need, and the
• 14:29
  Speaker 1: more fuel you need, the more fuel you need to
• 14:32
  Speaker 1: push that fuel, and so pretty quickly this is sort
• 14:34
  Speaker 1: of like a runaway mass problem. You need to have
• 14:37
  Speaker 1: a really really big ship to get anywhere at all
• 14:40
  Speaker 1: because you need fuel to push all the fuel that
• 14:43
  Speaker 1: you're pushing with all the fuel, right, And that's kind
• 14:45
  Speaker 1: of how rockets work right now, right like the ones
• 14:48
  Speaker 1: on current spaceships and spacecraft and rockets, that's how they work.
• 14:51
  Speaker 1: They use a chemical reaction to explode something and then
• 14:55
  Speaker 1: that explosion pushes the stuff out the back. That's right.
• 14:57
  Speaker 1: The fuel itself is the propellant and the source of energy,
• 15:01
  Speaker 1: right Like, you have something along like diesel fuel or
• 15:05
  Speaker 1: liquid oxygen or something that has energy stored inside of it,
• 15:08
  Speaker 1: and then you release that energy and at the same
• 15:11
  Speaker 1: time creates something at high velocity which can get thrown
• 15:14
  Speaker 1: out the back. So most chemical rockets work in that way.
• 15:17
  Speaker 1: They're both the propellant and the source of energy. And
• 15:20
  Speaker 1: that's how, for example, rockets lift off the Earth, and
• 15:23
  Speaker 1: that's how the Space Shuttle maneuvers in space. All these
• 15:26
  Speaker 1: are chemical rockets, right, And what makes it work, I
• 15:29
  Speaker 1: think is the idea is this kind of this difference
• 15:31
  Speaker 1: or this ratio between the energy and the mass of
• 15:34
  Speaker 1: what you're throwing behind you. If your planets to like
• 15:37
  Speaker 1: throw out you know, your trash or throughout your couch
• 15:40
  Speaker 1: to propel yourself in space, that wouldn't last very long, right,
• 15:42
  Speaker 1: because you would run out of couches. Yeah, and you
• 15:48
  Speaker 1: know maybe r vs and children you want to get
• 15:50
  Speaker 1: very far. But the idea with the chemical fuel is
• 15:53
  Speaker 1: that it has a lot of energy stored in it, right,
• 15:55
  Speaker 1: So like it you release that energy, it throws a
• 15:57
  Speaker 1: little bit of mass out there back, but with so
• 15:59
  Speaker 1: much energy it actually pushes you forward, that's right. The
• 16:02
  Speaker 1: key thing is having high exhaust velocity, so that those
• 16:05
  Speaker 1: particles you're throwing out, whatever they are, particles of couch
• 16:08
  Speaker 1: or particles of smoke, or particles of burnt rocket fuel, whatever,
• 16:12
  Speaker 1: are carrying a lot of momentum. Because any momentum that's
• 16:15
  Speaker 1: going at the back is equivalent to the momentum gained
• 16:18
  Speaker 1: by your rocket ship. Right, This is all about conservation
• 16:21
  Speaker 1: of momentum. And so the higher speed, the higher exhaust
• 16:23
  Speaker 1: velocity that goes out the back, the more momentum you're
• 16:26
  Speaker 1: throwing away in your exhaust, and so the more momentum
• 16:29
  Speaker 1: your rocket ship is going to get. Right, because momentum
• 16:31
  Speaker 1: is like mass times velocity. So if you want to
• 16:34
  Speaker 1: conserve on how much stuff you throw out the back
• 16:36
  Speaker 1: the mass, then you just need a lot of velocity. Yeah, exactly,
• 16:40
  Speaker 1: that's the way to do it. So those are chemical
• 16:42
  Speaker 1: kind of rockets, and that's what we used to get
• 16:44
  Speaker 1: off the Earth, but those are kind of tough for
• 16:46
  Speaker 1: going across to other planets or stars. Right. Yeah, if
• 16:50
  Speaker 1: you wanted to travel, for example, to the nearest star
• 16:53
  Speaker 1: system like Alpha Centauri, and get up to a reasonable speed,
• 16:57
  Speaker 1: like you know, a few percent of the speed of light,
• 16:59
  Speaker 1: so that a trip which is just a few light
• 17:01
  Speaker 1: years would only take you know, fifty or a hundred years,
• 17:04
  Speaker 1: you would need an enormous amount of chemical fuel to
• 17:07
  Speaker 1: accelerate you up to that speed. And because you need
• 17:10
  Speaker 1: so much fuel, you need a lot more fuel to
• 17:12
  Speaker 1: push that fuel, and so you'd end up with like
• 17:14
  Speaker 1: a toothpick sized chip pushing a Jupiter sized gas tank.
• 17:19
  Speaker 1: That sounds crazy. I think A good analogy I think
• 17:22
  Speaker 1: we've read once was that it's sort of like if
• 17:24
  Speaker 1: you're trying to drive a truck across the country without
• 17:29
  Speaker 1: stopping for fuel, you sort of need to bring all
• 17:31
  Speaker 1: your fuel with you. But then the more fuel you bring,
• 17:35
  Speaker 1: the more fuel you have to use because you're heavier, exactly.
• 17:38
  Speaker 1: And then pretty quickly you're driving basically like a stadium
• 17:42
  Speaker 1: size gas tank behind you, and that's pretty inefficient and
• 17:45
  Speaker 1: takes a lot of fuel, so it really limits how
• 17:48
  Speaker 1: far you can go, right, And that's kind of why
• 17:50
  Speaker 1: rockets are so big. Like if you look at a
• 17:52
  Speaker 1: rocket that goes to space, most of it is just
• 17:54
  Speaker 1: a giant fuel tank. Right. Yeah, I'm not sure people
• 17:56
  Speaker 1: really understand how massive these things are. Like the Earned
• 18:00
  Speaker 1: five rockets, one of the workhorses of the American space program,
• 18:03
  Speaker 1: is taller than the Statue of Liberty. Like, this thing
• 18:06
  Speaker 1: is enormous, but most of the actual active part of
• 18:09
  Speaker 1: it is this tiny little nose cone on the very top. Basically,
• 18:13
  Speaker 1: it's a huge gas tank with a tiny little cab
• 18:16
  Speaker 1: on top, because you need to bring a lot of
• 18:18
  Speaker 1: that fuel with you. And so that's really the hard
• 18:21
  Speaker 1: part about space travel, is like bring all the fuel
• 18:23
  Speaker 1: that you will need later because there are no gas
• 18:25
  Speaker 1: stations in other planets. Right, there are no gas stations
• 18:29
  Speaker 1: out there in space. It sounds like you're identifying a
• 18:31
  Speaker 1: business opportunity here, you know, rocket fuel for sale on
• 18:34
  Speaker 1: Pluto or halfway between here and Alpha Centauri. You could
• 18:37
  Speaker 1: sell a lot of slim gyms also, you know, yeah,
• 18:40
  Speaker 1: there you go and and turkey turkey. But then what
• 18:43
  Speaker 1: do you do with the restroom waste? That's the hard part.
• 18:46
  Speaker 1: That's just more rocket fuel. Man, you can just mix
• 18:48
  Speaker 1: it all in there you go, biomass, biomass fuel, biofuels
• 18:53
  Speaker 1: and solutions solved all at once. All right, Well, so
• 18:56
  Speaker 1: that's the main problem with thrusters and getting around the
• 19:00
  Speaker 1: Solar system in space. And so there's this new idea
• 19:02
  Speaker 1: of using plasma based thrusters. So let's get into that
• 19:06
  Speaker 1: and whether or not they're real and where they they
• 19:08
  Speaker 1: can work. But first let's take a quick break. Alright,
• 19:24
  Speaker 1: we're talking about plasma based thrusters. Now, this sounds really
• 19:28
  Speaker 1: sci Fi Daniel, Plasma. Anything I think with the word
• 19:31
  Speaker 1: plasma sounds cool, but it's the opposite. It's not cool, No,
• 19:35
  Speaker 1: it's not cool. It's very very hot, and it's actually
• 19:38
  Speaker 1: one of the most common forms of matter in the universe. Right.
• 19:41
  Speaker 1: People think of plasma is weird and rare and unusual,
• 19:43
  Speaker 1: but it's really just weird and rare and unusual here
• 19:46
  Speaker 1: on Earth, where it's sort of weirdly cold, Like the
• 19:49
  Speaker 1: Sun is basically a huge ball of plasma. And since
• 19:52
  Speaker 1: the Sun is most of the stuff in the Solar System,
• 19:54
  Speaker 1: the Solar system is basically all plasma with a few
• 19:57
  Speaker 1: crumbs like us, we should just call the Sun the
• 20:00
  Speaker 1: plasma ball, the giant plasma ball in the sky. It
• 20:03
  Speaker 1: basically is, it's such a big, hot plasma that we
• 20:06
  Speaker 1: can feel it even ninety three million miles away, and
• 20:08
  Speaker 1: thank goodness. But maybe step us through what is exactly
• 20:11
  Speaker 1: a plasma? You said, it's a state of matter. Yeah,
• 20:14
  Speaker 1: you're familiar with several states of matter right there. Solids
• 20:17
  Speaker 1: when the atoms are cool and sort of locking into
• 20:20
  Speaker 1: a crystal structure, so they become solid and then liquid.
• 20:23
  Speaker 1: If you heat it up, then those atoms get liberated.
• 20:25
  Speaker 1: From those bonds and squish around. Keep heating something and
• 20:28
  Speaker 1: it becomes a gas. As those atoms like to whizz
• 20:31
  Speaker 1: around and aren't even connected to each other. If you
• 20:34
  Speaker 1: keep heating it, then what happens is that the electrons
• 20:37
  Speaker 1: that are whizzing around those atoms get so much energy
• 20:40
  Speaker 1: that they're no longer held on by the nucleus. So
• 20:44
  Speaker 1: you have a positive nucleus and a negative electron, and
• 20:47
  Speaker 1: usually the strength of that electromagnetic bond is enough to
• 20:50
  Speaker 1: keep the electrons bound to the nucleus of the atom.
• 20:53
  Speaker 1: But if you get them hot enough, then they escape,
• 20:55
  Speaker 1: and then you have something which has nuclei and electrons
• 20:59
  Speaker 1: floating around, whizzing around. You have charged particles. So a
• 21:03
  Speaker 1: plasma is like a gas that's been heated up so
• 21:05
  Speaker 1: much that it becomes ionized that the electrons are now free. Right,
• 21:09
  Speaker 1: it's basically like just regular matter, right, that's heated up
• 21:13
  Speaker 1: so much that it breaks the atoms, like the items
• 21:15
  Speaker 1: kind of break apart. Yeah, they're broken apart, and it's
• 21:18
  Speaker 1: sort of like the original state, you know, before things
• 21:21
  Speaker 1: cooled down the electrons got captured by the nuclei, they
• 21:24
  Speaker 1: were free. Electrons were born free. They were captured, and
• 21:27
  Speaker 1: some of them have been in this state for billions
• 21:29
  Speaker 1: of years, and now if you heat something up, you're
• 21:32
  Speaker 1: returning them back to their original state of freedom. Oh man,
• 21:35
  Speaker 1: Now you make me sad for the atoms in my
• 21:37
  Speaker 1: body and the electrons in my body. You make it
• 21:39
  Speaker 1: sound like I'm trapping them and I'm keeping them from
• 21:42
  Speaker 1: being free. No, some atoms very happy to be married forever,
• 21:44
  Speaker 1: you know, but other ones want to be single, and
• 21:46
  Speaker 1: so you know, there's good sides of both to each
• 21:49
  Speaker 1: their own. But a plasma is basically like a singles
• 21:53
  Speaker 1: bar right now. It can anything be a plasma? Like
• 21:55
  Speaker 1: can any kind of matter be a plasma if I
• 21:58
  Speaker 1: heated up enough, Yeah, anything can be a plasma. As
• 22:00
  Speaker 1: long as you heat it up enough that it starts
• 22:02
  Speaker 1: to lose its electrons and it is made out of
• 22:04
  Speaker 1: ions and its components are now charged instead of neutral,
• 22:07
  Speaker 1: then that's a plasma. So yeah, you can have a
• 22:08
  Speaker 1: plasma out of hydrogen. That's what most of the universe is.
• 22:11
  Speaker 1: You can also have a plasma out of like iron.
• 22:13
  Speaker 1: You eat, have iron enough, you get an iron plasma.
• 22:16
  Speaker 1: And you know you said it happens in the sun
• 22:18
  Speaker 1: and it happens when you heat things up a love.
• 22:19
  Speaker 1: But there are other ways that you can make plasma
• 22:21
  Speaker 1: that doesn't heat them up that much, right, Like there's
• 22:24
  Speaker 1: I think you can use radio waves or some sort
• 22:26
  Speaker 1: of radiation to create a plasma, like in your desktop. Yeah,
• 22:29
  Speaker 1: we have plasma all around us. Like fluorescent lights have
• 22:32
  Speaker 1: a plasma in them, right, that's why they glow. You know,
• 22:35
  Speaker 1: you can talk about the definition of temperature. I found
• 22:38
  Speaker 1: it's a little fuzzy. You are making those particles move
• 22:41
  Speaker 1: fast enough. You're giving them enough energy to be released
• 22:43
  Speaker 1: from their atoms, so they have that high velocity even
• 22:46
  Speaker 1: if there's not that much actual heat. Right. A plasma
• 22:49
  Speaker 1: doesn't have to be very very hot, even if it's
• 22:51
  Speaker 1: high temperature because it doesn't store a lot of heat
• 22:54
  Speaker 1: because the gas is very diffuse and dilute. Then you
• 22:56
  Speaker 1: might not like burn yourself from touching a container that
• 22:59
  Speaker 1: has plasma in it, but it's still would be officially
• 23:02
  Speaker 1: high temperature because the particles are moving fast. So fluorescent lights,
• 23:07
  Speaker 1: like the lights we all have in our offices and
• 23:09
  Speaker 1: in stores and stuff, that's plasma. That's like a canister
• 23:12
  Speaker 1: of plasma, right, that's a canister of plasma and neon.
• 23:15
  Speaker 1: For example, neon lights those have plasma inside them. So
• 23:18
  Speaker 1: those are atoms that are whizzing around. They have so
• 23:20
  Speaker 1: much energy that they glow and they give off photons
• 23:23
  Speaker 1: right there, just like shedding energy constantly. I wonder if
• 23:26
  Speaker 1: they had named those plasma lights, if we would feel
• 23:30
  Speaker 1: the same way we feel about fluorescence lights right now,
• 23:34
  Speaker 1: like they would be this name that's associated with something
• 23:37
  Speaker 1: like unpleasant, boring, an unpleasant Yeah, yeah, a fluorescent blaster.
• 23:43
  Speaker 1: I'm gonna shoot fluorescent light at you and give you
• 23:46
  Speaker 1: a headache. There you go. That will make for a
• 23:49
  Speaker 1: Nokward science fiction marble, the headache gun. All right. So
• 23:53
  Speaker 1: that's plasma. So how does the plasma thruster work? Like,
• 23:56
  Speaker 1: how would you use something like fluorescent light to push
• 23:58
  Speaker 1: yourself through space? A plasma is glowing, it's giving off energy,
• 24:03
  Speaker 1: it's stuff moving around fast. The problem with the plasma
• 24:06
  Speaker 1: is that generally glows in every direction, and so it's
• 24:08
  Speaker 1: sort of throwing momentum off in every direction. Like the
• 24:11
  Speaker 1: sun isn't an engine, it's not flying in one direction
• 24:14
  Speaker 1: because it's giving off energy in every direction. So if
• 24:16
  Speaker 1: you want to take a plasma and turn it into
• 24:19
  Speaker 1: a thruster or what you need to do is make
• 24:21
  Speaker 1: it only point it's glow only shoot particles out, only
• 24:25
  Speaker 1: send momentum away in one direction. And the way you
• 24:28
  Speaker 1: do that is you just take a plasma and you
• 24:30
  Speaker 1: put it in basically a magnetic bottle. I mean, the
• 24:32
  Speaker 1: plasmas are charged particles, and charge particles bend in magnetic fields,
• 24:37
  Speaker 1: and so it's hard to contain a plasma because has
• 24:40
  Speaker 1: so much energy. You'll basically eat through anything. It's sort
• 24:43
  Speaker 1: of like acid. But if you could build a bottle
• 24:45
  Speaker 1: around it that bends the particles back into the plasma,
• 24:48
  Speaker 1: but leave a hole in one side, then particles will
• 24:51
  Speaker 1: shoot out through that hole and effectively push the whole
• 24:53
  Speaker 1: plasma the other direction. I see. It's like you're heating
• 24:56
  Speaker 1: a water, kind of like you're making a water a gun,
• 25:01
  Speaker 1: kind of like you heat up the water, it steams up,
• 25:04
  Speaker 1: becomes a high pressure gas, and then you shoot it
• 25:06
  Speaker 1: on on one side, and that's kind of what would
• 25:08
  Speaker 1: push you in space, but you're doing it with a
• 25:10
  Speaker 1: plasma material. You take a water balloon, for example, if
• 25:14
  Speaker 1: you poke a water balloon on one side, then water
• 25:16
  Speaker 1: is going to squirt out through the hole that you made,
• 25:18
  Speaker 1: and the rest of the balloon is going to go
• 25:20
  Speaker 1: the other direction. And so that's basically what a plasma is.
• 25:23
  Speaker 1: It's hot and high speed, and so it's always shooting
• 25:25
  Speaker 1: particles off. It's basically trying to expand. But if you
• 25:29
  Speaker 1: contain it in every direction but one, but only where
• 25:32
  Speaker 1: the hole is, can particles leave and they will carry momentum.
• 25:34
  Speaker 1: And that's basically an engine. And so that's kind of
• 25:36
  Speaker 1: the basic mechanism of a plasma thruster. It's like you're
• 25:39
  Speaker 1: heating something up and then you're letting it escape out
• 25:42
  Speaker 1: one end of your space. That's the basic mechanism. And
• 25:44
  Speaker 1: you remember once we talked on the podcast about using
• 25:47
  Speaker 1: the Sun as an engine, or building an engine that
• 25:49
  Speaker 1: could move the whole Sun. It was the same basic idea.
• 25:52
  Speaker 1: It's to build something around the Sun that reflects its
• 25:55
  Speaker 1: energy back into the Sun, except in one direction. And
• 25:58
  Speaker 1: so you can use this idea to move the whole Sun,
• 26:01
  Speaker 1: or you can build your own little mini plasma, your
• 26:03
  Speaker 1: mini sun, and reflect most of its energy back into itself,
• 26:07
  Speaker 1: except in one direction. So that's the basic premise, right.
• 26:10
  Speaker 1: It's kind of like a flashlight or even your headlights, right,
• 26:13
  Speaker 1: Like you're heating up an element, it's creating photons, but
• 26:15
  Speaker 1: then you're focusing those photons to one side. Yeah, because
• 26:18
  Speaker 1: flashlights usually have like a mirror on one side, so
• 26:21
  Speaker 1: the photons that are generated that come back towards the
• 26:24
  Speaker 1: handle get reflected to go the other direction, so it
• 26:26
  Speaker 1: produces a more calmnated beam. So that's the basic principle.
• 26:29
  Speaker 1: If you can shoot off momentum in one direction, then
• 26:32
  Speaker 1: the rest of the engine goes the other way. And
• 26:35
  Speaker 1: so what you need to do is get some cold stuff,
• 26:37
  Speaker 1: really almost anything, and heat it up until it becomes
• 26:40
  Speaker 1: a plasma and confine it in all but one direction.
• 26:44
  Speaker 1: I guess the tricky thing here that I'm not seeing
• 26:46
  Speaker 1: is how is this better than a chemical reaction because
• 26:49
  Speaker 1: it seems like you're just you have to spend a
• 26:51
  Speaker 1: lot of energy to heat up this plasma as opposed
• 26:53
  Speaker 1: to like rocket fuel, which explodes because it has that
• 26:57
  Speaker 1: energy stored inside of it. Yeah, that's true. It's sometimes
• 27:00
  Speaker 1: times can be an advantage to decouple those things. Like here,
• 27:03
  Speaker 1: you're right that the source of energy is something else,
• 27:05
  Speaker 1: and that means that you're sort of free to get
• 27:07
  Speaker 1: that energy from another source. Like solar power. If you
• 27:10
  Speaker 1: have huge solar cells, you can collect that energy, turn
• 27:13
  Speaker 1: it into electricity, and then hook it up to a
• 27:15
  Speaker 1: plasma rocket and use it for propulsion. So that's one advantage,
• 27:18
  Speaker 1: sort of like the way you have an electric car.
• 27:20
  Speaker 1: It's nice that you have an electric car because it
• 27:22
  Speaker 1: means that you can accept energy from lots of different
• 27:24
  Speaker 1: kind of sources, not just dirty coal burning power plants,
• 27:27
  Speaker 1: but also clean solar panels. For example. Oh, I see,
• 27:31
  Speaker 1: they said, do you want to somehow collect solar energy
• 27:34
  Speaker 1: while you're out there in space and somehow convert that
• 27:37
  Speaker 1: to thrust and instead of brain to fuel with you. Yeah,
• 27:41
  Speaker 1: because it's lower mass, right, So if you can gather
• 27:44
  Speaker 1: the energy along the way, then you can have this
• 27:46
  Speaker 1: plasma thruster and you don't need to bring all that
• 27:48
  Speaker 1: fuel with you. But it can also be a disadvantage, right,
• 27:50
  Speaker 1: because you need to gather that solar energy and that's complicated,
• 27:54
  Speaker 1: or you need to have some other source of electricity.
• 27:56
  Speaker 1: The nice thing about rocket fuels that it's sort of
• 27:58
  Speaker 1: like all in one, as you say, So there are
• 28:00
  Speaker 1: pros and cons there. What are some of the other cons. Well,
• 28:04
  Speaker 1: one of the cons is that plasma is really really
• 28:06
  Speaker 1: hard to contain. You know, like you have a plasma,
• 28:09
  Speaker 1: it's going to be eating away at the walls that
• 28:11
  Speaker 1: you're trying to use to contain it all the time.
• 28:14
  Speaker 1: One of the big challenges we have with fusion research
• 28:16
  Speaker 1: here on Earth is that we're trying to make a
• 28:18
  Speaker 1: plasma and contain it. We can't just like have our
• 28:21
  Speaker 1: own little sun a little destroy the Earth. So we
• 28:23
  Speaker 1: need to build these magnetic bottles. But they are hard.
• 28:25
  Speaker 1: Plasmas are always trying to escape and keeping them stable
• 28:29
  Speaker 1: and keeping them contained is really tricky. And you don't
• 28:32
  Speaker 1: want your spaceship engine breaking down or the plasma leak
• 28:35
  Speaker 1: out and basically destroy your ship. So it's got to
• 28:38
  Speaker 1: be really really robust, especially if you're talking about like
• 28:40
  Speaker 1: a year's or decades long journey and there are no
• 28:43
  Speaker 1: repair stations along the way, right. Yeah, you need like
• 28:46
  Speaker 1: a cool container to keep that plasma in check. Yeah,
• 28:50
  Speaker 1: And the plasma gets hot and it generates a lot
• 28:53
  Speaker 1: of waste heat, and so you need some like large
• 28:56
  Speaker 1: way to radiate off all of that heat from the
• 28:58
  Speaker 1: plasma that you're not using, and so that's a huge
• 29:01
  Speaker 1: waste of energy. It's inefficient and sometimes it requires like
• 29:04
  Speaker 1: large fins just to cool this thing, which means more mass,
• 29:08
  Speaker 1: which means that you're not going to be moving as quickly.
• 29:10
  Speaker 1: So there really are some disadvantages there. I think the
• 29:13
  Speaker 1: main disadvantage though, is that plasmas don't get particles up
• 29:16
  Speaker 1: to very very high speeds like a rocket engine or
• 29:20
  Speaker 1: ion thrusters or other things that have like active acceleration
• 29:24
  Speaker 1: of these ions can get much higher exhaust velocities. A
• 29:27
  Speaker 1: plasma is basically just saying, hey, you've got something that's
• 29:29
  Speaker 1: kind of already hot, The particles are already kind of
• 29:32
  Speaker 1: moving around, so why don't you just use that. You're
• 29:35
  Speaker 1: not really getting very high exhaust velocity. Yeah, it doesn't
• 29:37
  Speaker 1: seem that efficient because you're you're basically just throwing stuff
• 29:41
  Speaker 1: out the back, right, You're not sort of like releasing
• 29:44
  Speaker 1: any sort of inherent energy on it. You're literally like
• 29:47
  Speaker 1: just pushing stuff out the back, like you're throwing your
• 29:49
  Speaker 1: couches out the back of Yeah. Well, there is some
• 29:52
  Speaker 1: extra flexibility there, for example, because you can almost use anything,
• 29:55
  Speaker 1: Like you said, you can turn anything into a plasma,
• 29:58
  Speaker 1: and so you can use like astro not urine or
• 30:00
  Speaker 1: astronaut waste and throw it in the engine and it
• 30:03
  Speaker 1: will turn into fuel. Yes, you really can, or your
• 30:06
  Speaker 1: couch if you want to take more cleanly. You know,
• 30:09
  Speaker 1: other things sometimes require very special chemicals, like you got
• 30:12
  Speaker 1: to use rocket fuel in a chemical engine, or if
• 30:14
  Speaker 1: you have an ion thruster for example, and needs some
• 30:17
  Speaker 1: very sort of like inert gas like zenon. You know,
• 30:20
  Speaker 1: things that like those Starlink satellites have. These are little
• 30:23
  Speaker 1: ion engines that create a little plasma, but they have
• 30:26
  Speaker 1: to start from zenon. But if you have a real
• 30:29
  Speaker 1: plasma engine on your spaceship, you can basically toss anything
• 30:32
  Speaker 1: in their banana peels, coffee grounds, astronaut urine, whatever. Right,
• 30:36
  Speaker 1: you can have a poop plasma. That's a crappy idea,
• 30:40
  Speaker 1: I know, let's flush that down the toilet. All right.
• 30:43
  Speaker 1: Well then, so what are some of the pros of
• 30:46
  Speaker 1: using a plasma thruster? Like why convinced me that it's
• 30:49
  Speaker 1: a good thing? Well, I'm not sure I can give
• 30:51
  Speaker 1: in too is a great thing. This is sort of
• 30:52
  Speaker 1: the basic design for a plasma thruster. There are improvements
• 30:56
  Speaker 1: will talk about in a minute that make it more appealing,
• 30:58
  Speaker 1: but they do have some advantages over other approaches, like,
• 31:01
  Speaker 1: for example, the exhaust is naturally uncharged, doesn't have electric
• 31:06
  Speaker 1: charge because what you have are both positive and negative
• 31:10
  Speaker 1: particles shooting out the back, and so as they come
• 31:12
  Speaker 1: out the back, they naturally sort of recombine into neutral particles.
• 31:16
  Speaker 1: You don't need to do something extra to make sure
• 31:18
  Speaker 1: their neutral. Like for ion thrusters, you're only shooting positively
• 31:21
  Speaker 1: charged particles out the back, and you need to add
• 31:24
  Speaker 1: electrons to them as they come out the back to
• 31:26
  Speaker 1: recombine them so they don't get like sucked back into
• 31:28
  Speaker 1: your ship. So there's one positive. Another positive is that
• 31:32
  Speaker 1: they're sort of simple. You know, they're basically just magnetic
• 31:34
  Speaker 1: bottles that you're heating up using some sort of electrical energy,
• 31:38
  Speaker 1: So there's not a whole lot of stuff to break,
• 31:40
  Speaker 1: except of course, for the plasma eating the bottle. All right, Well,
• 31:43
  Speaker 1: it sounds like simplicity and flexibility in the kind of
• 31:47
  Speaker 1: fuel is a good thing. So let's get into how
• 31:51
  Speaker 1: it to actually make one of these and whether or
• 31:54
  Speaker 1: not it would be practical to do. First, let's take
• 31:57
  Speaker 1: another quick break. Or we're talking about plasma thrusters that
• 32:12
  Speaker 1: may or may not be made out of p and
• 32:14
  Speaker 1: poop in space. Definitely on the mayn or hopefully not.
• 32:19
  Speaker 1: You don't want to be like the car behind that
• 32:22
  Speaker 1: spaceship that's getting all that you know, high energy waste. Yeah,
• 32:27
  Speaker 1: then again, do you really want to carry all that
• 32:29
  Speaker 1: waste with you to Alpha Centauri so that when you
• 32:31
  Speaker 1: show up and you meet the aliens, the first thing
• 32:33
  Speaker 1: you ask him is like, Hey, do you have a
• 32:34
  Speaker 1: place I could put all this stuff? Because I have
• 32:36
  Speaker 1: a huge storage tank filled with it? Right, do you
• 32:40
  Speaker 1: want to recycle it? All? Right, we'll talk to us
• 32:44
  Speaker 1: about whether or not people are actually making this and
• 32:47
  Speaker 1: maybe what kind of specific technology people are focusing on.
• 32:50
  Speaker 1: So people are definitely working on this. They are developing
• 32:53
  Speaker 1: these things in the laboratory, and the one that we
• 32:55
  Speaker 1: just talked about, the most basic sort of plasma thruster.
• 32:58
  Speaker 1: There's a version of a called Vasa mirror v A
• 33:01
  Speaker 1: s I m ARE that people are working on, and
• 33:04
  Speaker 1: it has like a magnetic nozzle at the end of it,
• 33:07
  Speaker 1: so you can sort of tune how much of the
• 33:09
  Speaker 1: plasma comes out and at what velocity. That's cool because
• 33:12
  Speaker 1: it lets you adjust this exhaust velocity and so you
• 33:15
  Speaker 1: can like ramp it up when you get into outer
• 33:16
  Speaker 1: space and get more thrust. So that's pretty cool. People
• 33:19
  Speaker 1: are working on that. But then there are some other
• 33:21
  Speaker 1: exciting ideas that's sort of more cutting edge that people
• 33:24
  Speaker 1: are working on to improve plasma thrusters and sort of
• 33:27
  Speaker 1: next generation devices. Yeah, and these involve another pretty cool
• 33:30
  Speaker 1: science fiction work, which is fusion. Are we actually considering
• 33:34
  Speaker 1: like making fusion plossible for space travel, Yeah, we are,
• 33:37
  Speaker 1: because what we talked about so far is just plasma
• 33:40
  Speaker 1: right now. Plasma is an important component of fusion in
• 33:42
  Speaker 1: the sun, but you can have plasma without fusion or
• 33:45
  Speaker 1: plasma and your fluorescent light is not doing nuclear fusion.
• 33:48
  Speaker 1: It's not like a bomb. But the way that we
• 33:50
  Speaker 1: do fusion is through a plasma. You gotta get a gas,
• 33:54
  Speaker 1: you've gotta heat it up, then you've gotta squeeze it
• 33:56
  Speaker 1: down so that those very high energy particles smash into
• 33:59
  Speaker 1: each other and make heavier elements. And so people are
• 34:02
  Speaker 1: working on taking plasma thrusters to the place where they
• 34:05
  Speaker 1: actually can fuse some fuel to release additional energy as
• 34:09
  Speaker 1: a way to avoid having a pump in external energy
• 34:12
  Speaker 1: like from solar panels or from some sort of electrical source.
• 34:15
  Speaker 1: So now we're talking about making fusion in space. Fusion
• 34:19
  Speaker 1: in space like a fusion engine that you put on
• 34:21
  Speaker 1: a spaceship. Yeah, and it's called a direct fusion drive.
• 34:24
  Speaker 1: And you might be wondering why you would want to
• 34:26
  Speaker 1: do that, because the whole idea of a plasma thruster
• 34:29
  Speaker 1: was that you could take energy from all sorts of
• 34:31
  Speaker 1: different directions. What the idea here is that, again, like
• 34:34
  Speaker 1: a chemical rocket, you're now bringing the fuel that has
• 34:38
  Speaker 1: the energy inside it. Right, it's more like a chemical rocket,
• 34:41
  Speaker 1: but this fuel is very, very dense. You know, fusion
• 34:44
  Speaker 1: is much more efficient than chemical burning because you're turning
• 34:48
  Speaker 1: mass into energy much more effectively. That's why I like,
• 34:51
  Speaker 1: for example, hydrogen bombs are much more powerful than T
• 34:55
  Speaker 1: and T because fusion is much more powerful than just
• 34:58
  Speaker 1: chemical burning, and so you have a much denser source
• 35:01
  Speaker 1: of fuel, and so it's more efficient transformation of that
• 35:03
  Speaker 1: fuel into energy. So you just don't have to bring
• 35:06
  Speaker 1: nearly as much fuel if you can use fusion as
• 35:09
  Speaker 1: the source of energy. Right, it's like you're bringing all
• 35:11
  Speaker 1: the energy that's trapped inside of the bonds or that's
• 35:15
  Speaker 1: trapped in the potential bonds of the fuel that you're
• 35:17
  Speaker 1: bringing so it's almost like you're being extra clever about it. Yeah,
• 35:20
  Speaker 1: it's all about getting as much energy as possible out
• 35:22
  Speaker 1: of the same mass of fuel, because then you need
• 35:25
  Speaker 1: less fuel mass for that energy. You know, the best
• 35:28
  Speaker 1: case scenarios to bring like antimatter fuel and to smash
• 35:31
  Speaker 1: matter and antimatter together because it's total annihilation of mass
• 35:35
  Speaker 1: into energy. But you know, antimatter is basically impossible to
• 35:38
  Speaker 1: fabricate in large quantities and very difficult to transport. Fusion
• 35:42
  Speaker 1: is sort of like at the edge of plausibility, like
• 35:45
  Speaker 1: it might be possible to build a fusion reactor in
• 35:48
  Speaker 1: space that transforms the energy stored in the nucleus into
• 35:52
  Speaker 1: energy you can throw at the back of your rocket. Yeah,
• 35:54
  Speaker 1: that's the thing, because I feel like, you know, we've
• 35:57
  Speaker 1: been working on trying to get fusion working here on
• 35:59
  Speaker 1: Earth for like fifty years, and we still don't have
• 36:03
  Speaker 1: a pretty good or a working or an efficient fusion generator.
• 36:07
  Speaker 1: What makes this thing that we can suddenly do it
• 36:08
  Speaker 1: in space? Well, I talked to some plasma physicists and
• 36:12
  Speaker 1: they don't They don't think this is possible. They're like, no,
• 36:16
  Speaker 1: I don't think so. I mean, some people make the
• 36:18
  Speaker 1: argument that it's simpler. They think it doesn't have to
• 36:21
  Speaker 1: be such a huge, massive thing, like you could build
• 36:23
  Speaker 1: basically a minivan sized fusion container rather than like the
• 36:27
  Speaker 1: fusion reactors were building here on Earth, like either this
• 36:30
  Speaker 1: new reactor they're building in France is like sixty meters high,
• 36:34
  Speaker 1: and so they think it could be simpler. It can
• 36:36
  Speaker 1: be smaller. But frankly, there's a lot of skepticism in
• 36:39
  Speaker 1: the plasma physics community about whether this is plausible at all.
• 36:42
  Speaker 1: It's basically relying on an uninvented technology, small scale fusion
• 36:48
  Speaker 1: that would have to work and be reliable for years.
• 36:51
  Speaker 1: And so what's the basic idea that we somehow trapped
• 36:53
  Speaker 1: plasma and then somehow ignited so that it fuses together
• 36:57
  Speaker 1: and then that energy goes out the back. That's the
• 37:00
  Speaker 1: basic idea. You start the plasma with some other external
• 37:03
  Speaker 1: heat source, maybe r F energy or whatever you've captured
• 37:06
  Speaker 1: from before, and then once you've got it hot, you
• 37:08
  Speaker 1: put in your fuel and then that fuel releases more
• 37:11
  Speaker 1: energy and sort of then it's sort of like a
• 37:13
  Speaker 1: fire because it releases the energy needed to ignite the
• 37:17
  Speaker 1: next piece of fuel, and so it's self sustaining, So
• 37:19
  Speaker 1: you're putting in energy, but only in terms of this
• 37:21
  Speaker 1: like very very dense fuel that releases a huge amount
• 37:25
  Speaker 1: of energy. So then the particles are now very high
• 37:28
  Speaker 1: speed and they flow around the field lines of your
• 37:31
  Speaker 1: magnetic bottle and they shoot out the back. And so
• 37:33
  Speaker 1: that's pretty cool. It generates very high speed particles, which
• 37:37
  Speaker 1: are very good for a rocket engine, and at the
• 37:39
  Speaker 1: same time you can capture some of that energy and
• 37:41
  Speaker 1: turn it into energy for your spaceship. Right, you also
• 37:44
  Speaker 1: want to like heat coffee and power your life support systems. Well,
• 37:48
  Speaker 1: you have a fusion reactor on board now that not
• 37:50
  Speaker 1: just is generating thrust, but also can generate direct electricity.
• 37:54
  Speaker 1: I guess when maybe one advantage to is that, unlike
• 37:56
  Speaker 1: a future generator here on Earth, you're not trying to
• 37:58
  Speaker 1: like power a whole city, right, Like it doesn't have
• 38:01
  Speaker 1: to me maybe energy positive for a space engine, like
• 38:05
  Speaker 1: you actually want to spend some energy to push yourself,
• 38:08
  Speaker 1: so it doesn't maybe have the same requirements as a
• 38:11
  Speaker 1: fusion generator here on Earth. Yeah, that's true. Some of
• 38:14
  Speaker 1: these designs that are even more complicated than the ones
• 38:17
  Speaker 1: that are working on here on Earth, Like here on Earth,
• 38:19
  Speaker 1: we try to use simpler fuels like deuterium and tritium.
• 38:22
  Speaker 1: These are isotopes of hydrogen with extra neutrons on them.
• 38:26
  Speaker 1: But the ones that people are talking about for space
• 38:28
  Speaker 1: travel use like advanced fuels like helium three. And these
• 38:32
  Speaker 1: are cool because you can find like deposits of it
• 38:34
  Speaker 1: on the Moon. But nobody has made fusion for helium
• 38:37
  Speaker 1: three work. It's even much more complicated than the kind
• 38:39
  Speaker 1: of fusion we're talking about on Earth that we also
• 38:42
  Speaker 1: haven't made work. And so this is definitely in the
• 38:45
  Speaker 1: category of like the could work, would be awesome, might
• 38:48
  Speaker 1: never work. It's currently at the science fiction novel stage. Yeah,
• 38:52
  Speaker 1: it's currently at the Marvel movie name drop stage. No,
• 38:55
  Speaker 1: they're like, there are prototypes. They are working on it
• 38:57
  Speaker 1: at Princeton. Princeton has an incredible plasma physics obratory. They're
• 39:00
  Speaker 1: grade at fusion, and so there are people working on it,
• 39:03
  Speaker 1: but you know, it's far away from being a proven technology. Well,
• 39:06
  Speaker 1: there are some pretty new and interesting ideas. I think
• 39:09
  Speaker 1: you spoke to some of the scientists there at the
• 39:11
  Speaker 1: Princeton Lab and they have some new concepts for making
• 39:14
  Speaker 1: this happen. Yeah, there was a new idea just this
• 39:17
  Speaker 1: year from an Iranian scientist at plasma, Dr Fatima Abrahimi,
• 39:22
  Speaker 1: And she was actually thinking about the way the Sun
• 39:24
  Speaker 1: works because the Sun is a huge ball of plasma
• 39:27
  Speaker 1: and the Sun has these crazy releases of energy, right,
• 39:30
  Speaker 1: like these huge coronal mass ejections, and these happened when
• 39:34
  Speaker 1: the magnetic fields on the Sun like reconfigure themselves and
• 39:37
  Speaker 1: snap into a new direction in which you get are
• 39:40
  Speaker 1: these like bubbles of plasma that are trapped in these
• 39:42
  Speaker 1: little magnetic field ripples and they move really really fast
• 39:46
  Speaker 1: through the plasma. So she thought, well, I wonder if
• 39:48
  Speaker 1: you could use that to build an engine, Like what
• 39:50
  Speaker 1: if you could have a plasma to generate these little
• 39:54
  Speaker 1: magnetic bubbles and then shot them out the back. That
• 39:57
  Speaker 1: would be an effective way to take your plasma. You
• 40:00
  Speaker 1: wouldn't necessarily need it to be fusing and to shoot
• 40:03
  Speaker 1: really high energy plasmoids out the back. So that's what
• 40:06
  Speaker 1: these little magnetic bubbles are called plasmoids. This is just
• 40:10
  Speaker 1: some like phenomenon that happens with all plasmas. And she's saying,
• 40:14
  Speaker 1: let's capture those bubbles and use them. Yeah, let's capture
• 40:17
  Speaker 1: those bubbles and direct them and if we can make
• 40:19
  Speaker 1: our magnetic fields in such a way that they always
• 40:21
  Speaker 1: shoot in one direction, then we can basically shoot these
• 40:24
  Speaker 1: magnetic bubbles out the back. And because they move at
• 40:27
  Speaker 1: very high speeds, like twenty kilometers per second, then you
• 40:30
  Speaker 1: can get a very high exhaust velocity from your plasma,
• 40:33
  Speaker 1: much higher than the generic plasma thruster we were talking
• 40:36
  Speaker 1: about before, which is just like a hot gas with
• 40:38
  Speaker 1: stuff leaking out. This is like magnetically directed and accelerated
• 40:41
  Speaker 1: inside the plasma. Yeah, the generic version is always you know,
• 40:45
  Speaker 1: a little suspect cheaper, but yeah, cheaper, Yeah, but you
• 40:48
  Speaker 1: never know, right, So this is sort of like using
• 40:52
  Speaker 1: plasma burbs, right, Like this could be called the plasma
• 40:54
  Speaker 1: burp engine. Yeah, the plasma burp engine. I'm sure she'd
• 40:57
  Speaker 1: love to have it called that, better than the other
• 41:00
  Speaker 1: name you could give it for, you know, shooting gas. Yeah, well,
• 41:03
  Speaker 1: these are high velocity burps. Right. This is like ten
• 41:06
  Speaker 1: times faster exhaust speed than a generic plasma engine. And
• 41:10
  Speaker 1: that's exciting because the exhaust speed is key, right, That's
• 41:13
  Speaker 1: the thing that gives you that push of momentum. That's
• 41:15
  Speaker 1: what lets you really get your spaceship going up to
• 41:18
  Speaker 1: high speeds very quickly. Yeah, these are name brand burps,
• 41:21
  Speaker 1: not the generic kind. All right, Well, let's be hopeful,
• 41:25
  Speaker 1: and so let's say they make this work and we
• 41:26
  Speaker 1: have this exciting technology. Can it takes us around the
• 41:29
  Speaker 1: source system faster? Like could we get to Mars in
• 41:32
  Speaker 1: less than a month? Yeah? If you had this kind
• 41:34
  Speaker 1: of technology and it was reliable and you trusted it,
• 41:37
  Speaker 1: then you could get to Mars in like thirty nine days.
• 41:40
  Speaker 1: They've done these calculations and this kind of engine again,
• 41:43
  Speaker 1: if it works can get you to Mars in a
• 41:46
  Speaker 1: pretty short amount of time. That's great because it means
• 41:48
  Speaker 1: you could also get to like Saturn in just a
• 41:50
  Speaker 1: couple of years. You can get to Pluto in like
• 41:53
  Speaker 1: less than five years where its currently it takes more
• 41:56
  Speaker 1: than a decade to get out to those outer parts
• 41:58
  Speaker 1: of the Solar system Mars and already nine days that
• 42:00
  Speaker 1: is like a Marvel movie a day. So your dream
• 42:05
  Speaker 1: might come true. Yeah, and they keep making them so
• 42:08
  Speaker 1: they can just beam them to you. You You can download them.
• 42:10
  Speaker 1: There you go. I hope they have free WiFi. You
• 42:13
  Speaker 1: can you can burp your way through the Marble catalog.
• 42:17
  Speaker 1: What if you shoot avengers movies out the back of
• 42:19
  Speaker 1: your ship. That's the potential engine right there. They're pretty massive. Yeah,
• 42:23
  Speaker 1: definitely takes them. All the money that marble and is
• 42:25
  Speaker 1: made to make these engines work. So and it's not
• 42:28
  Speaker 1: just humans that need to get around the Solar System.
• 42:30
  Speaker 1: They're very real reasons why we want faster ways to
• 42:33
  Speaker 1: move around the Solar System, and one is to intercept asteroids.
• 42:37
  Speaker 1: You know that we're always on the lookout for objects
• 42:39
  Speaker 1: that might hit the Earth, that might come and impact
• 42:42
  Speaker 1: the Earth and cause an extinction event, and we're pretty
• 42:45
  Speaker 1: good at watching these things, but sometimes they appear with
• 42:47
  Speaker 1: very little warning. And the critical thing when you're trying
• 42:50
  Speaker 1: to avoid getting hit by a rock is just spotted
• 42:53
  Speaker 1: as early as possible, because that's when you can give it,
• 42:55
  Speaker 1: like just a little bit of a nudge and push
• 42:57
  Speaker 1: it off course to spare the Earth. But if you
• 43:00
  Speaker 1: see this rock, you gotta get to it. You gotta
• 43:02
  Speaker 1: get out there to give it a nudge. And so
• 43:04
  Speaker 1: a faster rocket like a plasma based interceptor might literally
• 43:08
  Speaker 1: save the Earth someday if it means that we can
• 43:11
  Speaker 1: get it out there and give that asteroid a nudge
• 43:13
  Speaker 1: before it comes and hits the Earth. Interesting, just gives
• 43:17
  Speaker 1: you faster first responders in case of an emergency. Yeah,
• 43:20
  Speaker 1: so you can get to it sooner, which means you
• 43:22
  Speaker 1: need a smaller push, which means there are a lot
• 43:24
  Speaker 1: more asteroids that you could deflect. Right, A really really
• 43:27
  Speaker 1: tiny push two years in advance is the equivalent of
• 43:30
  Speaker 1: like a massive nuclear thrust five minutes before it hits
• 43:34
  Speaker 1: the Earth. It's much easier to deflect these things if
• 43:36
  Speaker 1: you catch them early. All right, Well, then maybe you
• 43:38
  Speaker 1: should stop watching so many Marvel movies and get to
• 43:40
  Speaker 1: work on this, Daniel. Come on, would you never know
• 43:44
  Speaker 1: when that asteroid might come? I would happily do it
• 43:46
  Speaker 1: if anything I did ever had any practical benefits. But
• 43:49
  Speaker 1: you know that's not true. Yeah, maybe you're not the
• 43:53
  Speaker 1: person to put on this project. All right, Well, last question, Daniel.
• 43:57
  Speaker 1: If somebody did make a spaceship but it is powered
• 44:00
  Speaker 1: by direct fusion and plasma plasma thruster, would you buy
• 44:04
  Speaker 1: it if it was used? Well, I guess it depends
• 44:08
  Speaker 1: on what happened the last people who used it, Right,
• 44:11
  Speaker 1: if they're still around and they had a good trip,
• 44:13
  Speaker 1: then yeah, I would trust it better than spending all
• 44:16
  Speaker 1: that money on a new fusion drive. Geez who space?
• 44:21
  Speaker 1: All right, Well, I think that answer is the question
• 44:23
  Speaker 1: what is a plasma thruster and how that might work
• 44:26
  Speaker 1: and how it could work in the future. And again,
• 44:29
  Speaker 1: scientists are hard at work trying to get us out
• 44:31
  Speaker 1: there into space so that we can explore more and
• 44:33
  Speaker 1: see things up close and learn more about the universe.
• 44:36
  Speaker 1: That's right. Some of these things are real and working
• 44:39
  Speaker 1: in the laboratory, and some of these things are still
• 44:41
  Speaker 1: pipe dreams that scientists are working on. And there's lots
• 44:43
  Speaker 1: of room for new ideas. So if you have an
• 44:45
  Speaker 1: awesome idea for a new spaceship engine that let's just
• 44:48
  Speaker 1: get around the Solar system. Hey, get to work, that's right,
• 44:51
  Speaker 1: and you could create the next name brand spaceship. All right,
• 44:54
  Speaker 1: thanks for joining us, see you next time. Thanks for listening,
• 45:05
  Speaker 1: and remember that Daniel and Jorge explained. The Universe is
• 45:08
  Speaker 1: a production of I Heart Radio or more podcast from
• 45:11
  Speaker 1: my Heart Radio. Visit the I Heart Radio app, Apple Podcasts,
• 45:15
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