8.11 Satellites

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Natural Satellite

• The Moon

Artificial Satellites

• Help forecast weather• Monitor agriculture• Telecommunication• Navigation• Military Activities• Explore the Universe

International Space Station

Orbits at an altitude of 350 km above the Earth.

Continuous Earth Orbit

• A satellite travels at sufficient velocity so that when Earth’s gravity pulls it down, it continuously falls around Earth’s curvature.

Types of Orbits

• Low Earth Orbit Satellites (up to 2000 km)

Polar Orbit

• Required to see every part of the planet.• Altitude 200-900 km• Example: RADARSTAT for natural and human-

made events

Medium Earth Orbit Satellites

• Altitudes up to 35000 km• 12 make up the GPS • 3 satellites must be visible at any one time

from any point on the ground

Geostationary Orbit Satellites

• Altitude of 35790 km• One orbital period equals one rotation of

Earth.• Appear motionless in the sky• Examples: communication and weather

satellites

Geostationary Satellites

1/10 the way to the moon

Comparing Satellites

Orbital PeriodAltitudeRadius of OrbitOrbital Speed