Stella Lab
A desktop physics and maths workbench: edit the equations behind each space mission, plot telemetry curves live, export SVG graphs for reports or slides, and share your setup with a link.
Widescreen Mission Control Workbench · Visual Sliders + Live Equations
Orbital Speed & Escape Velocity
Higher orbits are slower because Earth’s gravity weakens with distance. Drag the altitude and satellite mass sliders to see how altitude changes orbital speed, while satellite mass changes gravitational pull (F = GMm/r²) without changing orbital speed at all.
Drag a slider to experiment
Moving a slider updates the script, the spacecraft diagram and the telemetry graph together.
400 km = Space Station · 20,200 km = GPS · 35,800 km = Geostationary TV satellites
Changes gravity force F (in N) and kinetic energy, while orbital speed v stays the same!
- r = R_earth + h_orbit
Distance from Earth’s centre is Earth’s radius (6,370 km) plus height above the ground.
- v_orbit = sqrt(GM / r)
Orbital speed depends on height r, not on the satellite’s mass m_sat.
- F_gravity_N = (GM * 1e9 * m_sat) / (r * 1000)^2
Gravitational pull in newtons (N) is proportional to satellite mass m_sat and 1/r².
What happens in space
Free to use, not free to run
Stella Lab runs in your browser and lets you share custom physics scripts by URL without an account. If it helps your sixth-form project, EPQ or classroom, please chip in on Ko-fi or suggest a new lab preset.