From Chris Hadfield's MasterClass

Rockets: Fuels and Propulsion

Chris explains the pros and cons of different types of rocket fuels including liquid fuel, solid fuel, and ionized gas.

Topics include: "Getting a Shirt to Mars • Stored Energy, Fuel, and an Oxidizer • Solids vs. Liquids • Ion Rockets • The Rocket Equation • Additional Fuel Variables"


Chris explains the pros and cons of different types of rocket fuels including liquid fuel, solid fuel, and ionized gas.

Topics include: "Getting a Shirt to Mars • Stored Energy, Fuel, and an Oxidizer • Solids vs. Liquids • Ion Rockets • The Rocket Equation • Additional Fuel Variables"

Chris Hadfield

Teaches Space Exploration

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Like all spaceships, rockets are a compromise design. You're trying to take something to space, and you have a finite amount of fuel inside your fuel tanks, you only have so much ability to steer through the atmosphere, and so you really want this thing we're taking up to be as light and as small as possible, because then you don't need so much fuel. The problem gets harder and harder if you're going somewhere, if, say, you're going all the way to Mars, because when you get to Mars, somehow you have to be able to slow down and land. So you're not just bringing the stuff that you need, but you have to bring another rocket ship up here in the end that will be able to take you down to land on the surface of Mars. And you need fuel for that rocket. And every ounce that is carried on the top is going to take pounds and pounds of fuel to get it away from the world and to slow down when you get to Mars. And it gets even worse, because you got to come back from Mars probably. And where does that fuel come from? Unless you can manufacture fuel on the surface of Mars using the raw materials that are there, that means not only are you bringing enough fuel to leave Earth, but you're bringing enough fuel to leave Earth and slow down and stop at Mars, land on Mars, blast off of Mars, accelerate, come all the way back to Earth again, and then land back on Earth. And it just magnifies on the amount of fuel that you need. So what does it really take, say, to put one thing on the surface of Mars? For every pound that we put on the surface of Mars, it takes about 200 pounds of rocket here on the surface of the world. Most of that is fuel. But for every pound that gets to the surface of Mars, it took 200 pounds to get it off the surface of the world, accelerate it out to the speed, and safely there. So every little fraction of a pound, every ounce that you can save on what it is you're putting on Mars will decrease the size of the rocket that you need to leave the Earth. So let's think. I want my T-shirt to be on Mars. Your T-shirt weighs some fraction of a pound. If your T-shirt weighs, I don't know, a third of a pound, then you need a third of 200. You're going to need, like, 70 pounds of rocket just to get your T-shirt onto Mars. So you really want to be efficient in packing, and thinking about what's the minimum amount of stuff that we can bring to Mars so that we can keep the size and the scale and the complexity and, therefore, the cost of the rocket to be as small as possible. What type of fuel do rockets use? It's varied over time. But essentially, it's fairly similar. We have some sort of fuel in a tank or a solid fuel inside a rocket like this, and then we have the oxidizer or oxygen that's stored in a separate tank. On the Saturn V, the rocket that took us to the moon, these first stages couldn't have been simpler. It was just kerosene. That was the fuel. Kerosene and oxygen. It was a pretty good first fuel, just using kerosene, oxygen....

Explore the unknown

Impossible things happen. At age nine, Chris Hadfield knew he wanted to go to space. He eventually went there three times, becoming a commander of the International Space Station. In his MasterClass, Chris teaches you what it takes to explore space and what the future holds for humans in the final frontier. Learn about the science of space travel, life as an astronaut, and how flying in space will forever change the way you think about living on Earth.


Students give MasterClass an average rating of 4.7 out of 5 stars.

So easy to listen to the stories and wonderfully accessible explanations of some fairly complex ideas. Enjoyed every bit of this class!

These lessons provide inspiration. It usually comes in small ways, a phrase or key moment when the teacher is talking. They are starting points for my own imagination.

Find multiple layer of satisfaction as you move toward your goals. We have become who we are through all the small accomplishments along the way. Chris, you are a hero to me! Loved your book, and love listening and learning from you. You have shifted me over slightly again to my dreams.

Space travel is more complex than I realized.


Ugo A. D.

Good break down of propulsion systems for rockets. I appreciate the chemical engineering required to find a fuel source to provide thrust for these rockets to get their destination and back.

Sergio N A.

Excellent. It revives what I learned from my lessons with the ISA League of New Worlds way back in the 90's. Going to Mars needs a mixture of rocket propulsion systems and ionic propulsion aystem. From Earth to an orbital height, we can use liquid fueled rockets and shot to escape velocity towards Mars where we can use ionic propulsion rocket. Towards Mars we can have another slingshot from Venus to speed up travel time and conserve more fuel and eneegy going to Mars. The spacecraft for Mars should be a little more complicated to maintain an Earth like gravity to prevent health hazards of prolonged exposure to microgravity otherwise we will have crippled or dying astronauts arriving in Mars. The vehicle in question shall be rotating to maintain an earth-like gravity to maintain good health among all of the astronauts. FROM Sergio N.Andres Jr.

A fellow student

very interresting just saw a lecture on youtube about a antimatter engine, is this a serious possible engine? or just a guy looking for funding? Regards

A fellow student

I've heard about solar propulsion engine. When you heat your gas/fuel by concentrated solar light. The final impulse you have is about 9km/s which is twice or even 2.5 times more efficient then the most efficient chemical rocket engine. You don't have problem with radiation shield as you have for nuclear power engine, you have pretty much same impulse and you can increase your "rocket ratio" when it will be about 60% or even 50%, may be

Phillip K.

Can gas particles for an ion engine propulsion be collected while traveling through space? It isn't a complete void right. In some science fiction I hear about collectors on space ships. Then someone mentioned solar sails and sling shotting.

Larry R.

This is as close as I've had someone come to making math (especially this level of math) fun for me. Thank you!

Bill M.

The math is so far over my head, but still fascinating. Still, I wish there were more videos and graphics explaining the lessons.

Jim S.

Nice summary of this topic. The fuel is really the limiting factor in many ways. I wonder if astronauts pack lightly in their earthly trips?

A fellow student

First, use a white board with black marker for seeing clarity on a home PC. Second, use graphics with real numbers for clarity of explanation of equations. Third, stop drawing on notebook for explanation use graphics. Fourth, use archive footage to illustrate points during lecture. Being an astronaut does not make you a good teacher to non astronauts.

Jerry R.

Since we have unmanned traffic to Mars, the question is not getting there but how do to carry more and greater weight of stuff there. Maybe we could make a giant slingshot and slingshot it all there?? Have to have something I suppose to magnetically attract it to the right spot or a good slingshot thrower.