8.11 Satellites
Page 346-351
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