A higher orbit doesn't mean a faster satellite — it means a slower one. Gravity weakens with distance, and a weaker pull needs less orbital speed to balance it.
Orbital mechanics describes how satellites and spacecraft move under gravity. A stable circular orbit requires a specific balance: the object's speed must be exactly right for the outward tendency of its motion to match the inward pull of gravity at that altitude. Because gravitational pull weakens with distance, that balance point requires progressively less orbital speed at higher altitudes — the opposite of many people's first intuition.
Gravitational acceleration falls off with the square of distance from Earth's center, so a satellite farther out experiences weaker gravitational pull. A stable circular orbit requires just enough speed for centripetal acceleration to match that gravitational pull — since gravity is weaker at higher altitude, less orbital speed is needed to maintain that balance, which is exactly why orbital speed decreases as altitude increases.
Orbital period depends on both the orbital speed (which decreases with altitude) and the orbital circumference (which increases with altitude) — both effects push period in the same direction, causing period to increase with altitude even more dramatically than the speed decrease alone would suggest. This is why a low Earth orbit satellite can circle the planet in about 90 minutes, while a geostationary satellite at much higher altitude takes a full 24 hours.
Geostationary orbit exists at the one specific altitude (roughly 35,786 km) where orbital period exactly matches Earth's 24-hour rotation period — a satellite there appears to hang motionless over a fixed point on Earth's equator, which is exactly why it's the standard choice for many communications and weather satellites that need to stay pointed at the same ground location continuously.
Because gravity itself is weaker at higher altitude — a stable orbit balances centripetal requirement against actual gravitational pull, and since that pull is weaker farther out, less speed is needed to achieve the balance. The intuition that 'higher needs more speed' doesn't hold because it ignores that gravity's strength itself is changing with altitude.
The ISS orbits at a relatively low altitude (roughly 400 km), where Earth's gravitational pull is still quite strong, requiring a high orbital speed (about 7.7 km/s) to maintain its orbit — completing a full orbit in about 90 minutes. A geostationary satellite, at roughly 35,786 km altitude, experiences much weaker gravity and needs far less orbital speed (about 3.1 km/s), taking a full 24 hours to complete one orbit.
It's the unique altitude where the orbital period, governed by orbital mechanics (Kepler's third law), exactly equals 24 hours — Earth's rotational period. This isn't an arbitrary design choice; it's a direct mathematical consequence of the gravity-speed-period relationship at that specific distance from Earth's center.
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