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April 12, 2026
The International Space Station (ISS) orbits Earth at an altitude of approximately 400 kilometers (250 miles). It travels at a staggering speed of about 28,000 kilometers per hour (17,500 miles per hour). This speed is necessary to maintain its orbit.
Staying in orbit is essentially a delicate balance between gravity and the station's forward momentum. The ISS is constantly falling toward Earth due to gravity, but it is moving so fast sideways that it follows the curvature of the Earth, staying in a continuous state of freefall. Periodic "reboosts" are necessary because the thin atmosphere at that altitude causes drag, which slowly slows the station down.
How the ISS Stays in Orbit
Staying in orbit is essentially a delicate balance between gravity and the station's forward momentum. The ISS is constantly falling toward Earth due to gravity, but it is moving so fast sideways that it follows the curvature of the Earth, staying in a continuous state of freefall. Periodic "reboosts" are necessary because the thin atmosphere at that altitude causes drag, which slowly slows the station down.
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