Orbit Sandbox

Throw a satellite around a planet. Circular, elliptical or escape.

0/3challenges

mission time 0.0 min

Near-circular orbit.

Launch altitudekm

Launch speedkm/s

Flight path angle°

Time warpx

At 408 km, circular speed is 7.67 km/s and escape speed is 10.84 km/s.

Periapsis altitude: 380km
Apoapsis altitude: 408km
Eccentricity: 0.002
Period: 1.54 h
Altitude now: 408km
Speed now: 7.66km/s
Specific energy: -29.46MJ/kg
Energy drift: 0.0e+0%

The model

Two bodies, one of them fixed: the satellite feels a = -μ r / |r|³ with μ = GM = 3.986 × 10¹⁴ m³/s² for an Earth-like planet. It is integrated with velocity Verlet, which conserves energy well over many orbits.

Circular speed is √(μ/r); escape speed is √2 times that. Orbit shape follows from specific energy ε = v²/2 - μ/r and angular momentum.

Try this

Start at the ISS preset and add 0.5 km/s. The far side of the orbit rises thousands of kilometres while the launch point stays put. Every burn moves the other side of the orbit.

Assumes a spherical planet with no atmosphere, no rotation and no other bodies. Educational model, not an engineering design or validation tool.

Achievements0/3

Circularise +40Make an orbit with eccentricity under 0.01 above 1,000 km, by hand.
Escape velocity +20Launch onto an escape trajectory.
High apogee +30Reach an apoapsis above 30,000 km without hitting the planet.

Astronomy and space
Gravity Sandbox
Throw planets around a star. Binary stars, the figure eight, collisions.
Mechanics
Projectile Motion
Launch angle, speed, gravity and air drag, with the trajectory traced live.
Energy systems
Gridfall
Run a national grid with real DC power flow. A coach shows you how.
Biology
Flocking
Boids: three local rules, and a murmuration emerges. Chase it with a hawk.

Try next

Gravity Sandbox

Projectile Motion

Gridfall

Flocking