Readouts Kepler's laws2nd law: equal areas3rd law: T² against a³
Settings
Changes apply immediately.
Satellite
kg
Website
Website preferences are remembered on this browser and shared with
the other simulations.
Presets
Ready-made launches. Loading one removes the satellites in flight, sets
the launch values and a suitable time warp, and waits: press Run when
you are ready. Each says what to check in the readouts.
Keyboard & mouse
Drag the arrow
Sets the launch speed and direction. Hold Shift to keep the direction
and change only the speed.
Drag the launch point
Moves it up or down, changing the launch altitude.
Click a satellite
Selects it for the readouts and graphs.
Drag · scroll
Pan and zoom the view. Either turns off “keep in view”.
L
Launch a satellite
Space · .
Run or pause · advance one frame while paused
[ · ]
Slower · faster time warp
R · C
Reset (remove every satellite) · clear trails
Arrow keys
Up and down change the launch speed by 1% of the circular speed; left
and right turn the launch direction by 1°.
V · G · P · T · K
Toggle velocity · gravitational force · predicted orbit · trails ·
equal areas
A · + · −
Keep the whole orbit in view · zoom in · zoom out
Escape
Closes any open panel
Gravity is Newton's law, F = GMm/r², with G = 6.674 × 10⁻¹¹ N·m²/kg².
The central body is held fixed, which is accurate while the satellite's
mass is negligible beside it. There is no atmosphere, the body does not
spin, and nothing else pulls on the satellite.