Orbit Keeper
Find the launch speed that keeps a satellite circling a planet instead of crashing or flying away. Six missions from the Space Station to Mars.
Space station
Launch sideways from 400 km up, the height of the real International Space Station. Find a speed that keeps you from falling back.
- Height now
- –
- Speed now
- –
- One lap takes
- –
- Tries
- 0
Speed for a round orbit: speed = √(GM ÷ distance from the centre). The picture is a time-lapse, so a lap that takes hours plays in seconds.
The science behind it
Read these after a few missions.
Why don't satellites fall down?
They do fall! They just keep missing the ground. See how sideways speed turns a fall into an orbit.
How fast is orbit speed?
Why high satellites go slower than low ones, what an oval orbit is, and how fast you need to go to leave Earth for good.
Orbits you can feel: string, ball and funnel
Three safe hands-on demos that pair with Orbit Keeper, with questions to ask along the way.
Using Orbit Keeper in class
Missions 1–4 find the round-orbit speed at different heights and worlds, so students see that higher means slower. Mission 5 introduces oval orbits and Mission 6 introduces escape speed. Free Play keeps the last four orbits on screen for “predict, then test” questions. See the hands-on demos.