How Does the ISS Stay Up Without Constantly Falling?
Trick question: it IS constantly falling. It just keeps missing the ground.
By Cosmic Discovery Hub Editorial · Published 2026-09-05 · Updated 2026-09-05
Falling, forever
The International Space Station orbits about 400 km above Earth at roughly 7.66 km/s. Gravity up there is still about 90% as strong as at the surface. The station is not beyond gravity — it is in continuous free-fall.
Missing the Earth
Newton imagined a cannon on a mountain firing faster and faster until the cannonball's falling curve matched Earth's curve. At orbital velocity, that is exactly what happens.
Compute the speed for any orbit with the Orbital Velocity Calculator, then watch the station's real position on the Live Space page.
Why it slowly sinks anyway
At 400 km there is still a whisper of atmosphere. Drag bleeds energy, so the ISS needs periodic re-boosts from visiting spacecraft to stay aloft.