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- Physics
- Geosynchronous Orbits
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- Geosynchronous Orbits + Geostationary Orbits
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- Webster's dictionary defines a Geostationary orbit as of, relating to, or being a
- satellite that travels above Earth's equator from west to east at an altitude of
- approximately 35,900 kilometers (22,300 miles) and at a speed matching that of Earth's
- rotation, thus remaining stationary in relation to Earth. 2. Of, relating to, or being the
- orbit of such a satellite. In plain English, a satellite matches the earth's rotation making it
- seemingly hover over one spot of the globe enabling coverage of half the earth's surface.
- Three such satellites, appropriately spaced longitudinally, have worldwide coverage
- except for relatively small areas over the poles. Three main classes are typically placed
- into a GSO: Communications, missile early warning, and navigational satellites. The uses
- are unlimited ranging from commercial use to weather forecasts!
- The GSO originated in the mid-1970's. The U.S. Air Force designed a two-stage
- interim upper stage (later renamed inertial upper stage, or IUS) to carry satellites
- weighing as much as 5,000 pounds (2,300 kg) from the shuttle to Geostationary orbit,
- and a three-stage version for boosting NASA' s space probes from the shuttle into
- interplanetary trajectories. IUS development problems, however, prompted NASA in the
- early 1980' s to design a widebody version of the Centaur upper stage to replace
- the three-stage IUS.
- In its first use (1983) aboard the shuttle, the IUS's second-stage nozzle burned
- through and left the first Tracking and Data Relay Satellite (TDRS-1) in a useless orbit.
- Ground controllers were able to use the satellite's onboard thrusters to put it in the
- proper Geostationary orbit over a period of weeks, but the IUS was grounded until the
- nozzle problem was resolved.
- Because the IUS was too large and expensive for most satellites going
- to Geostationary orbit, McDonnell Douglas developed the payload assist module, a
- special cradle with a turntable to spin and then release satellites. A small rocket motor
- and the satellite's own rockets then boost it into Geostationary orbit.
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