Physics- Satellites

A document of the different types of satellites

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  • Created on: 28-04-10 09:03
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Physics ­ Satellites
Geostationary Orbit
Geostationary Orbit is one in which the satellite is always in the same position with
respect to the rotating Earth. The satellite orbits at an elevation of approximately
35,790 km because that produces an orbital period (time for one orbit) equal to the
period of rotation of the Earth (23 hrs, 56 mins, 4.09 secs). By orbiting at the same
rate, in the same direction as Earth, the satellite appears stationary (synchronous
with respect to the rotation of the Earth).
Geostationary satellites provide a "big picture" view, enabling coverage of weather
events. This is especially useful for monitoring severe local storms and tropical
cyclones. Because a geostationary orbit must be in the same plane as the Earth's
rotation, that is the equatorial plane, it provides distorted images of the polar
regions with poor spatial resolution.
Geostationary satellites are used for weather forecasting, satellite TV, satellite radio
and most other types of global communications.
Polar Orbit
Polar-orbiting satellites provide a more global view of Earth, circling at near-polar
inclination (the angle between the equatorial plane and the satellite orbital plane -- a
true polar orbit has an inclination of 90 degrees). Orbiting at an altitude of 700 to 800
km, these satellites cover best the parts of the world most difficult to cover in situ
(on site). For example, McMurdo, Antartica, can be seen on 11-12 of the 14 daily
NOAA polar-orbiter passes.
These satellites operate in a sun-synchronous orbit. The satellite passes the equator
and each latitude at the same local solar time each day, meaning the satellite passes
overhead at essentially the same solar time throughout all seasons of the year. This
feature enables regular data collection at consistent times as well as long-term

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The orbital plane of a sun-synchronous orbit must also rotate
approximately one degree per day to keep pace with the Earth's surface. Polar orbits
are often used for earth-mapping, earth observation, and reconnaissance satellites,
as well as for some weather satellites. The disadvantage to this orbit is that no one
spot on the Earth's surface can be
sensed continuously from a satellite in
a polar orbit.…read more

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Telescope style Ritchey-Chretien reflector
Wavelength Optical, ultraviolet, near-infrared
Diameter 2.4 m (7 ft 10 in)
Collecting area 4.5 m2 (48 sq ft)[3]
Focal length 57.6 m (189 ft)
Hubble Space Telescope had an initial price
tag was $1.5 billion (US dollars).
Moreover, the cost did not stop
there, but continued to balloon
throughout the next several years. By 1992 costs had increased to $2.5 billion (6). By
1999, approximately $3.8 billion had been invested (7).…read more


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