Orbit Simulator
Launch a satellite into orbit, tweak values below and experiment!
This interactive orbit simulator lets you pick a planet, place a satellite at a chosen altitude above its surface, and give it an initial radial (toward/away from the planet) and tangential (around the planet) velocity. A dashed line previews the resulting orbit before you even launch. Below the controls:
- Planet – Choose which body to orbit, from Mercury to Neptune. Each planet's mass and radius change the gravity, orbital speeds, and visual scale of the simulation.
- Altitude (km) – The satellite's starting height above the planet's surface. Enter a value between 1,000 km and 50,000 km, or use the slider. The circular and escape velocities shown underneath are reference speeds for that altitude.
- Radial V (m/s) – The initial speed along the radial direction (outward from or inward toward the planet's center). Positive pushes away; negative pulls inward.
- Tangential V (m/s) – The initial speed along the orbital path, perpendicular to radial. A positive value sends the satellite prograde (counterclockwise around the planet).
- Sim Speed – How many simulated seconds pass per real second, from 200x to 10,000x. Lower it to watch a single pass closely, or raise it to fast-forward through a full orbit.
The panel above the controls shows the orbit's eccentricity, semi-major axis, and periapsis/apoapsis altitude, plus its orbital period (or "Never returns" for an open, hyperbolic trajectory). These update live as you adjust the sliders, then lock to the launch values once the satellite is flying.
The dashed line is the predicted orbital path, with cyan and red dots marking its periapsis (closest approach) and apoapsis (farthest point) — apoapsis only appears for closed orbits. Click Launch to start the simulation: the satellite appears as a small glowing dot following that path, while the overlay tracks mission time, altitude, and radial/tangential/ground speed. Pause/Resume freezes the simulation in place. If the satellite dips below the planet's surface, you'll see "Satellite Crashed!"; if it climbs beyond 25 times the planet's radius, you'll see "Satellite Escaped!". Reset returns everything to the starting state.