Dearborn Public Schools



TYPES OF SATELLITESSatellites are usually classified according to the type of orbit they are in. There are four types of orbit associated with satellites, and the type of orbit dictates?a satellite's use.Low Earth OrbitsSatellites in low Earth orbits are normally military reconnaissance satellites that can pick out tanks from 160 km above the Earth. They orbit the earth very quickly, one complete orbit normally taking 90 minutes. However, these orbits have very short lifetimes in the order of weeks compared with decades for geostationary satellites. Simple launch vehicles can be used to place these satellites of large masses into orbit.Sun-Synchronous orbitsMeteorological satellites are often placed in a sun-synchronous or heliosynchronous orbit. These satellites are in polar orbits. The orbits are designed so that the satellite's orientation is fixed relative to the Sun throughout the year, allowing very accurate weather predictions to be made. Most meteorological satellites orbit the Earth 15 to 16 times per day.Geosynchronous satellitesEarth-synchronous or geosynchronous satellites are placed into orbit so that their?period?of rotation exactly matches the Earth's rotation. They take 24 hours to make one rotation. However, the plane of orbit for these satellites is generally not the equatorial plane. Apart from geostationary satellites (see below), the satellites are used for communications at high latitudes, particularly in Russia and Canada. The orbits are called Molniya orbits. The satellites are placed in highly elliptical orbits which enable them to appear to hover above one point on the Earth for most of the day. In twenty four hours they move over the Earth in a figure of eight pattern centered on a fixed longitude, moving slowly where they can be useful and quickly where they are of little use.Geostationary satellitesThe majority of communications satellites are in fact geostationary satellites. Geostationary satellites like geosynchronous satellites take 24 hours to complete a rotation. However, geostationary satellites are positioned directly over the equator and their path follows the equatorial plane of the Earth. As a result geostationary satellites don't move North or South during the day and are permanently fixed above one point on the equator of the Earth.Most video or T.V. communications systems use geostationary satellites. Geosynchronous and geostationary satellites are typically orbiting at 35,788 km (22,238 miles) above the surface of the planet (42,000 km from its center).Modern satellites have a mass of several thousand kilograms, compared with just 180 kilograms for Sputnik. Modern satellites are placed in space using launch vehicles like the Arianne Rocket or the Space Shuttle. Once in space, most satellites obtain their power from the Sun using solar panels. Satellites travelling deep into space often carry additional nuclear power supplies.Name _________________________________________ # _______ Date _________________ Hour______Hours 5/6 Types of Satellites Partner Poster Activity(50 point Formative Assessment)Part I Directions: Read the article "Types of Satellites” and answer the following questions._____ 1. Identify the object that is NOT a natural satellite: a. the Earth’s moonc. the Moons of Jupiterb. The International Space Stationd. asteroid debris_____ 2. How are satellites classified?a. type of orbitc. compositionb. sized. distance from Earth3. Most TV or communications systems use ______________________ ___________________________.4. If a satellite orbits the Earth 15 times a day; how long does it take to make one orbit? __________________________________________________________________________________________________________5. Describe satellites in low earth orbits: ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________6. If a satellite is in a sun-synchronous orbit, what does that mean? __________________________________________________________________________________________________________________________________________________________________________________________________________________7. If a satellite is in a geosynchronous orbit, what does that mean? ___________________________________________________________________________________________________________________________________________________________________________________________________________________8. How high is a geostationary satellite above the center of the Earth?________________________________________________________________________________________________________________________9. What are geosynchronous satellites used for? ________________________________________________________________________________________________________________________________________10. What is the primary difference between a geostationary and a geosynchronous satellite? _____________________________________________________________________________________________________________________________________________________________________________________________Teacher check-in __________________Part II Directions: Get a computer and follow the steps listed below:1. Decide which type of satellite interests you the most and circle it:weathercommunicationbroadcastscientificnavigationalearth observationrescuemilitary2. Use the Internet to find a specific example of the type you circled and write it here: ___________________3. Circle the type of orbit your satellite has (might be a combination of two)Natural GeosynchronousGeostationarySunsynchronousTeacher check-in __________________Part III Directions: You and your partner will create a poster that includes all of the questions asked and the objectives listed in the rubric below.Objective orQuestionPoints PossibleStudent ChecklistPoints EarnedYour names, numbers, the date and the hour are on the front of the poster2Your title is what you wrote in question #2 above3The type of orbit is identified (question #3)5How did this satellite get placed into orbit?5Why does this satellite stay in Earth’s orbit?5What keeps this satellite from flying into space or crashing into Earth?5If this satellite appears stationary, why?5What is the revolution period/ orbiting time of this satellite?5The poster is illustrated, neat, and colorful5There are no spelling or grammar errors5Part I of this activity is complete and correct5Points Earned: _________50 ................
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