Course
How orbits work
Work out why going to space is easy, staying there is hard, and coming back is the dangerous part.
The shape of it
7 lessons
About 23 minutes in total. Your progress is kept on this device — no account, nothing sent anywhere.
Course complete
Put your name on it and print it, or save it as a PDF. Nothing is sent anywhere.
The lessons
Falling, and missing
Explain why something in orbit is not beyond gravity.
6 steps · about 3 min
Sideways is the whole problem
Tell apart the energy needed to go up and the energy needed to stay up.
6 steps · about 3 min
To catch up, slow down
Predict what happens to an orbit when you push in a given direction.
7 steps · about 4 min
The tyranny of the fuel
Explain why rockets are almost entirely propellant.
6 steps · about 3 min
Why everyone wants the same orbits
Match an orbit to the job it is uniquely good at.
7 steps · about 4 min
What goes up mostly stays
Predict how long debris lasts at different altitudes.
7 steps · about 4 min
Coming back is the hard part
Explain re-entry as an energy problem rather than a heat problem.
7 steps · about 4 min