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Chapter 1: What inspired humanity to explore space travel?
Taking flight. It's the stuff dreams are made of. And it says something about us as a species that we once looked at the birds soaring in the sky and said, bet we could do that. But in spite of our lack of wings and feathers, we did. And we didn't stop there. Once in the sky, we found a new limitation above us. Space. A place where all the air ran out.
And in spite of our very real need to breathe, we thought, bet we could go there. And we did. Sitting on top of controlled explosions that we named rockets all the way to the moon. Humans, apparently, don't like being told we have limits. But soon, the age of combustion rockets will be over too.
They burn up their fuel too quickly, and using them for travel to the places we're thinking of going, like Mars, or even other stars, will simply take too long. And so, new technologies are needed. But what will get us there this time? For journeys that could take months or even generations to complete, what solutions could help us bridge such gaps?
The exciting part is, the answers are in development. And it turns out, these new ideas are even crazier than rockets. I'm Alex McColgan, and you're watching Astrum. Join me in this video as we explore the future of space travel, from the next generation solutions that are just around the corner, to the proposals that feel science fiction, but could one day become science reality.
It's only in the last 100 years that humanity has truly begun to venture into space. On the 16th of March 1926, Robert Goddard, the father of American rocketry, launched the world's first liquid-fueled rocket on a farm in Auburn, Massachusetts.
It may have only reached about 12.5 meters and was done to little fanfare, but this moment was the beginning of 100 years of chemical-powered rocketry that ultimately let man walk on the moon. Understanding where we came from is important in understanding where we're going. So, let's take a closer look at chemical rockets.
Here, thrust is generated by mixing some kind of fuel source, often RP-1 kerosene, or other variations refined from crude oil with some kind of oxygen source, for instance pure oxygen in liquid form, in a combustion chamber and then igniting them. Hot things expand, and in such an explosion as this, they expand a lot. A chemical rocket points that explosion downwards.
Then, thanks to Newton's third law, where every action has an equal and opposite reaction, the rocket as a whole goes up. Chemical rockets have been the key driving factor in more than 7,000 launches globally since the dawn of the space race in 1957.
And even in space itself, chemical propulsion methods, whether burning fuel in thrusters or just spraying compressed coal gas out of a nozzle to get a little extra oomph at the right moment, are the primary way that probes and spacecraft have explored the various planets, moons and asteroids that make up our solar system. But chemical propulsion has a big problem.
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Chapter 2: What limitations do chemical rockets face for long-distance travel?
Hall effect thruster or the gridded ion thruster work by creating electric or magnetic fields. Particles of noble gases like xenon or krypton are accelerated in these fields up to speeds of 140 thousand kilometres an hour in ion thrusters and are sent flying off into space. When the particles accelerate one way, the spacecraft is pushed the other way.
This is the advantage of electric thrusters in general. If you're accelerating your fuel up to 140 thousand kilometers per hour, you're getting some really good mileage for each atom accelerated. When it comes to most thrusters, a key principle towards understanding them is momentum. And the thing with momentum is, if you don't know where to start with it, it can be hard to get the ball rolling.
When I was studying at uni and was finding myself as stuck as an object at rest, I sometimes needed a helping hand to become an object in motion. For me, that didn't come from reading textbooks. It came from practice, testing my understanding with questions that forced me to engage my brain, which is why I really like Brilliant, today's sponsor.
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See if it gives you a little momentum too. Now, back to the pros and cons of electric thrusters. With all that acceleration, surely electric thrusters are just better then? Well, actually no. There is a downside, a significant one. You see, electric thrusters actually have terrible thrust. Think of it like putting your thumb over the nozzle of a hose.
By limiting the hole the water is coming through, the stream of water coming out of the hose turns into a powerful jet. But removing your thumb to create a bigger hole does not mean you get an even bigger jet. you only have so much water to work with. For electric thrusters, the problem is similar, except instead of water, it's electricity.
Electric thrusters connected to a solar panel can get plenty of energy if you leave them to run for long enough in sufficient sunlight But you don't get that energy all at once. You have a limit on how much fuel can be accelerated based on the electricity you get in a given moment. So, how little thrust are we talking about here? How much can electric thrusters generate?
It turns out about the same amount of force as you'd feel from the gravity of a piece of paper lying flat on your hand. It can take days for an electric thruster to accelerate a spacecraft to just 90 kilometers per hour. And while it can get up to 320,000 kilometers per hour eventually,
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