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Science & Technology

Rockets: Orbital Mechanics

Chris Hadfield

Lesson time 23:51 min

Chris uses familiar situations—like driving a car and jumping off a diving board—to illustrate how the laws of orbital mechanics govern spaceflight and navigation

Chris Hadfield
Teaches Space Exploration
The former commander of the International Space Station teaches you the science of space exploration and what the future holds.
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The first human being to ever leave the earth was, of course, Yuri Gagarin. And then the next was Al Shepard, and then Gus Grissom, and onto eventually John Glenn orbiting the world as well. And they launched from two specific places. Yuri launched from Baikonur, Kazakhstan and the Americans launched from Florida from Cape Canaveral and what became the Kennedy Space Center. So why did they choose those places on board this globe? And it's actually sort of a question of physics. The world, of course, turns. It spins around on its axis once every 24 hours. And at the equator , the world, it's about 24,000 miles around or 25,000, and it goes around in 24 hours. So that's nice, easy math. If you're standing on the equator, you're 24,000 or 25,000 miles around, and you go around 24 hours. You're going about 1,000 miles an hour if you think about it. If you're standing on the equator, you are going 1,000 miles an hour to the east just by standing there. If you're on the North Pole, you're not going anywhere. You're just standing there, and the world sort of turns underneath you. So if you're a rocket designer, you want to get that 1,000 miles an hour for free if you can. So you want to launch as close to the equator as you possibly can. And that's why the Russians got as far south as they could down here into Baikonur right into Kazakhstan so that they could launch and take advantage of the rotation of the Earth. Politics didn't let them go any further south. The Americans did the same thing. They launched as far south down on the east coast as they could, because they're going east. And they launched down here on what became the Kennedy Space Center in Florida for the same reason. Since then, we've built launch sites closer-- even in Brazil has built one on the equator. And we actually have portable launch sites that sometimes get on a barge and get on a launch from the equator just to steal as much of that Earth's rotation as possible. Because every bit of spin you get from the Earth is one less kilogram of fuel that you need to put in your rocket. Sometimes, though, you want to launch into a different orbit for a scientific purpose. Let's say you want to map the whole world and have it turn underneath you. It would be kind of nice if your satellite was orbiting around the world from north pole to south pole, because then the whole world would turn underneath you. If you just launch east out of Florida, then you won't go any further north than Florida or no further south than that as you're orbiting around the equator of the world, and you'll never see the north or the south. And so sometimes, we launch rockets rather than taking advantage of the spin of the Earth, and we launch them straight south or straight north. And then they end up in an orbit. Even though it may not take advantage of the Earth's spin, it does put us in an orbit that serves the purposes of that rocket launch. I like holding a globe. It reminds me of act...

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.

I am preparing to go to Adult Space Camp in Huntsville and just hope that the world calms down by mid-June 2020. I'll be writing about this course in my publication: Great job Chris!

The class has made me think more critical and holistic about my experiences on Earth.

Amazing class! It's elevating and inspirational. From this class I learned things about which I had no idea. I have so much respect for people who does important and highly skilled things, of which most people don't even know. Although I'll not be an astronaut, I'll use knowledge I gained here in my life and for my art. Thank you!

Just kept getting better and better. Totally “alien” and yet totally relatable.


Bernardo F.

Great lesson, this remind me of lots of thins, like Verne's book "From the Earth to the Moon" were he states that the launch ocurred somewhere near the equator. And although I agree Newton was a smart guy and that his gravitational equation has been used, I'd liked Chris to say that Einstein actually did a small modification so it's coherent with the relativity theory, as otherwise ther would be a small error in calculations.

Alvaro M.

This lesson is mind blowing. The explanation of weightlesness is something that I've never imagined

A fellow student

Had to replay some of it to understand better but this lesson definitely made me aware of the intricacies and calculations etc involved

Mário Filipe P.

One thing that I loved about this lesson, is that even though we are just grasping the surface of some basic physics concepts, for people like me with reduced academic background on this subject, it allowed me to see and think about the world in a totally different way. I started having new ideas and thoughts of things that were completely unknown to me prior to this class. I feel almost like... it's slowly changing the way I look and think about the World and Universe, and that's empowering!


I love the way hw he explains it its like if your actually in space I love the part of *snap * your weightless I can feel it


I love the way he explains complicated calculus in really simple terms that even I can understand. I hate math OR maybe I had a bad teacher in school that did not know to explain it to make it interesting.

Xavier M.

French here. There is also the European spacial center at Kourou French Guiana. Closer to the equator than the Florida one. ;)

Frederick K.

Since traveling in orbit a ship is technically falling. If a ship escapes orbit how does that affect things inside a ship? Does it all suddenly become free of a gravitational pull until a ship gets closer to the moon or would it then switch to what the moons pull would be?

Patty R.

To go to Mars, is it necessary to stop on the Moon first and then use that orbit to keep jumping higher?

Patty R.

For Orbital Mechanics, let's say you moved away from Earth and are traveling slower as if in "deep space". If it were possible to to warp speed (like Star Trek), how would you travel past the orbital mechanics of other solar systems and planets?