SatellitesSatellites

Satellites OverviewSatellites Overview

History History Launching of SatellitesLaunching of Satellites How Satellites WorkHow Satellites Work Orbit DistanceOrbit Distance Types: Types: Low-Earth-Orbit (LEOs)Low-Earth-Orbit (LEOs)

Medium-Earth-Orbit (MEOs)Medium-Earth-Orbit (MEOs)Global Positioning System (GPS)Global Positioning System (GPS)Geostationary (GEOs)Geostationary (GEOs)

ApplicationsApplications

History of SatellitesHistory of Satellites The First Satellites

The theory of satellites was simple enough - shoot something out into space at the right speed and on the correct trajectory and it will stay up there, orbiting Earth, for years - if not forever.

If the orbit is the right distance in space the satellite will keep pace with the rotation of the Earth.

Early in October 1957 communications stations started picking up a regular beeping noise coming from space.

The signals were coming from Russia's Sputnik 1, the world's first man-made satellite.

It was January 1958, before a Jupiter rocket successfully launched Explorer 1, the first American satellite.

History of SatellitesHistory of Satellites On October 4, n October 4, 19571957, the Soviet Union successfully launched , the Soviet Union successfully launched Sputnik ISputnik I. .

The world's first artificial satellite was about the size of a basketball, The world's first artificial satellite was about the size of a basketball, weighed only 183 weighed only 183 poundspounds, and took about 98 minutes to orbit the , and took about 98 minutes to orbit the Earth on its elliptical pathEarth on its elliptical path

on November 3, Sputnik II was launchedon November 3, Sputnik II was launchedOn January 31, 1958, the United States successfully launched Explorer IOn January 31, 1958, the United States successfully launched Explorer I

The first satellite that was used for communication purpose in INDIA was The first satellite that was used for communication purpose in INDIA was ARYABHATTA and it was launched in 19ARYABHATTA and it was launched in 19thth April.1975. APPLE was April.1975. APPLE was launched in space which was the first Indian Experimental launched in space which was the first Indian Experimental communication satellite communication satellite

INSAT (Indian National Satellite System) is a series of multipurpose INSAT (Indian National Satellite System) is a series of multipurpose geostationary satellites launched by ISRO to satisfy the geostationary satellites launched by ISRO to satisfy the telecommunications, broadcasting, and search-and-rescue needs of telecommunications, broadcasting, and search-and-rescue needs of India. Commissioned in 1983, INSAT is the largest domestic India. Commissioned in 1983, INSAT is the largest domestic communication system in the Asia-Pacific Regioncommunication system in the Asia-Pacific Region

Chandrayaan-1Chandrayaan-1)). It was launched by the Indian Space Research )). It was launched by the Indian Space Research Organisation in October 2008, and operated until August 2009. Organisation in October 2008, and operated until August 2009.

19571957First Artificial Satellite First Artificial Satellite

(Sputnik)(Sputnik)

The first artificial satellite was The first artificial satellite was Sputnik 1, launched by the Sputnik 1, launched by the Soviet Union on October 4, Soviet Union on October 4, 1957. At about the size of a 1957. At about the size of a basketball, Sputnik 1 was basketball, Sputnik 1 was

equipped with a radio equipped with a radio transmitter that gave off a transmitter that gave off a

beeping signal—helping the beeping signal—helping the Soviets to track it on its 98-Soviets to track it on its 98-minute orbit and to signal to minute orbit and to signal to the world that the U.S.S.R. the world that the U.S.S.R.

was the leader in spacewas the leader in space

Photograph courtesy Photograph courtesy NOAA/NESDIS HeadquartersNOAA/NESDIS Headquarters

19601960First Orbiting Observations First Orbiting Observations (TIROS-1 Weather Satellite)(TIROS-1 Weather Satellite)

The first aerial images of the The first aerial images of the Earth from space were taken by Earth from space were taken by

TIROS 1 (Television InfraRed TIROS 1 (Television InfraRed Observation Satellite). TIROS 1 Observation Satellite). TIROS 1

was launched in 1960 to find out if was launched in 1960 to find out if it was possible to watch cloud it was possible to watch cloud

cover and weather patterns from cover and weather patterns from space. Although it was an space. Although it was an

experimental satellite, TIROS experimental satellite, TIROS images were immediately put to images were immediately put to

use by meteorologistsuse by meteorologists

19721972

First Surveying Satellite (Landsat)First Surveying Satellite (Landsat)

The first Landsat satellite was called The first Landsat satellite was called the Earth Resources Technology the Earth Resources Technology

Satellite, or ERTS. Since its launch on Satellite, or ERTS. Since its launch on July 23, 1972, six Landsats have July 23, 1972, six Landsats have

followed, with the latest, Landsat 7, followed, with the latest, Landsat 7, lifting off on April 15, 1999. Over the lifting off on April 15, 1999. Over the years successive Landsats have not years successive Landsats have not

only carried better land-viewing only carried better land-viewing sensors, but they have created a sensors, but they have created a

valuable archive of images that are valuable archive of images that are being used to see how the land is being used to see how the land is

changing over the years. Landsat 7 changing over the years. Landsat 7 carries the Enhanced Thematic carries the Enhanced Thematic

Mapper Plus, which scans the Earth in Mapper Plus, which scans the Earth in eight bands of visible and invisible lighteight bands of visible and invisible light

19741974First Geostationary Satellite First Geostationary Satellite

(GOES)(GOES)

Best known as weather satellites, Best known as weather satellites, the first GOES (Geostationary the first GOES (Geostationary

Operational Environmental Satellite) Operational Environmental Satellite) was launched on October 16, 1975. was launched on October 16, 1975. Their high orbits and visible-light and Their high orbits and visible-light and infrared sensors allow for constant infrared sensors allow for constant

surveillance of weather patterns surveillance of weather patterns over the entire planet and have over the entire planet and have

enabled GOES to revolutionize the enabled GOES to revolutionize the science of weather prediction. science of weather prediction.

GOES-10, launched in 1998, images GOES-10, launched in 1998, images the 48 contiguous U.S. states every the 48 contiguous U.S. states every

five minutes.five minutes.

Launching of Artificial SatelliteLaunching of Artificial Satellite

To enable a satellite to orbit around any planet, we have To enable a satellite to orbit around any planet, we have to consider height from which the satellite must be to consider height from which the satellite must be

thrown. thrown. Consider yourself, if you throw a stone, it comes to earth Consider yourself, if you throw a stone, it comes to earth after some time, why? It is because of the gravitational after some time, why? It is because of the gravitational

attraction of earth and the stone. By the Newton 's law of attraction of earth and the stone. By the Newton 's law of gravitation, stone and earth would be attracted towards gravitation, stone and earth would be attracted towards

each other by force each other by force F = GMm / RF = GMm / R22

Where M is mass of earth Where M is mass of earth m is mass of stone m is mass of stone

R is distance between centre of earth and stone R is distance between centre of earth and stone

Since, throwing the satellite from Since, throwing the satellite from earth's surface will make the satellite earth's surface will make the satellite to come down to earth's surface due to gravitational pullto come down to earth's surface due to gravitational pullF F 1/ R 1/ R22 i.e. greater is the distance, lesser the force of attraction. As we have seen i.e. greater is the distance, lesser the force of attraction. As we have seen earlier that value of g decreases with increase in height and expression is earlier that value of g decreases with increase in height and expression is given by given by gghh / g = g ( 1 - 2h / R ) / g = g ( 1 - 2h / R )

We can say that to put on object into earth's orbit. We can say that to put on object into earth's orbit. •  Move the object to suitable height. •  Move the object to suitable height. •  Then, project it with high velocity. •  Then, project it with high velocity. Remember, less the height to which object is moved, greater the velocity Remember, less the height to which object is moved, greater the velocity needed for projecting. needed for projecting. I would like to state that the velocity that I was talking about is called as ‘ I would like to state that the velocity that I was talking about is called as ‘ ORBITAL VELOCITYORBITAL VELOCITY

SatelliteSatellite

  A Satellite is a solid object which revolves around some heavenly A Satellite is a solid object which revolves around some heavenly body due to the effect of gravitational forces which are mutual in body due to the effect of gravitational forces which are mutual in nature. We can categorize satellites in two types, namely Passive nature. We can categorize satellites in two types, namely Passive Satellites and Active satellites. A passive satellite can be further Satellites and Active satellites. A passive satellite can be further subdivided into two types, namely Natural satellites and artificial subdivided into two types, namely Natural satellites and artificial satellites. A moon is a natural satellite of earth. But spherical balloon satellites. A moon is a natural satellite of earth. But spherical balloon with metal coated plastic serve as artificial satellites.with metal coated plastic serve as artificial satellites.

  Active satellites are complicated structures having a processing Active satellites are complicated structures having a processing equipment called Transponder which is very vital for functioning of equipment called Transponder which is very vital for functioning of the satellite. These transponders serve dual purpose i.e. provides the satellite. These transponders serve dual purpose i.e. provides amplification of the incoming signal and performs the frequency amplification of the incoming signal and performs the frequency translation of the incoming signal to avoid interference between the translation of the incoming signal to avoid interference between the two signals.   two signals.   

How Satellites WorkHow Satellites Work

1.1. A Earth Station sends A Earth Station sends message in GHz range. message in GHz range. (Uplink) (Uplink)

2.2. Satellite Receive and Satellite Receive and retransmit signals back. retransmit signals back. (Downlink)(Downlink)

3.3. Other Earth Stations Other Earth Stations receive message in receive message in useful strength area. useful strength area. (Footprint)(Footprint)

Microwaves are electromagnetic waves with frequency from Microwaves are electromagnetic waves with frequency from 30MHz to 1 GHz. The ionosphere cannot reflect microwaves back 30MHz to 1 GHz. The ionosphere cannot reflect microwaves back to the earth. They pass through the to the earth. They pass through the iionosphereonosphere A satellite used to A satellite used to

receive microwaves and then transmit them back to the earth.receive microwaves and then transmit them back to the earth.

Satellites provide links in two ways. Firstly a satellite provide point Satellites provide links in two ways. Firstly a satellite provide point to point communication link between one ground station and the to point communication link between one ground station and the

other. One ground station transmit signal to the other satellite and other. One ground station transmit signal to the other satellite and next ground station receives them from the satellite. Secondly, next ground station receives them from the satellite. Secondly,

satellite receives signals from one ground station and transmits to satellite receives signals from one ground station and transmits to them to the number of ground receivers.them to the number of ground receivers.

Most satellite use frequency bandwidth through from 5.92 to Most satellite use frequency bandwidth through from 5.92 to 6.4GHz from transmission of data from earth to the satellite and a 6.4GHz from transmission of data from earth to the satellite and a

frequency bandwidth from 3.7 to 4.1GHz for transmission from frequency bandwidth from 3.7 to 4.1GHz for transmission from satellite to the earth.satellite to the earth.

Water discovered on moon

Low-Earth-Orbit (LEO)Low-Earth-Orbit (LEO)

Altitude (375-1000 miles)Altitude (375-1000 miles) Revolution time: 90 min - 3 hours.Revolution time: 90 min - 3 hours. Advantages:Advantages:

Reduces transmission delay Reduces transmission delay Eliminates need for bulky Eliminates need for bulky

receiving equipment.receiving equipment. Disadvantages:Disadvantages:

Smaller coverage area.Smaller coverage area. Shorter life span (5-8 yrs.) Shorter life span (5-8 yrs.)

than GEOs (10 yrs).than GEOs (10 yrs).

Middle-Earth-Orbiting (MEO)Middle-Earth-Orbiting (MEO)

MEOs orbits between the altitudes of 5,600 and 9,500 miles.

These orbits are primarily reserved for communications satellites that cover the North and South Pole.

Unlike the circular orbit of the geostationary satellites, MEOs are placed in an elliptical (oval-shaped) orbit.

GPS: What is it ?GPS: What is it ?A constellation of 24 satellites

The Global Positioning System (GPS) is a space-based global navigation satellite system (GNSS) that provides reliable location and time information in all weather and at all times and anywhere on or near the Earth

The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations.

They are constantly moving, making two complete orbits in less than 24 hours.

These satellites are traveling at speeds of roughly 7,000 miles an hour.

GPS Satellites

Name: NAVSTAR Manufacturer: Rockwell International Altitude: 10,900 nautical miles Weight: 1900 lbs (in orbit)Size: 17 ft with solar panels

extended Orbital Period: 12 hours Orbital Plane: 55 degrees to

equatorial plane Planned Lifespan: 7.5 years Current constellation: 24 Block II production

satellites

The spacing of the satellites are arranged so that a minimum of five satellites are in view from every point on the globe.

Geosynchronous-Earth-Orbit (GEO)Geosynchronous-Earth-Orbit (GEO) Orbit is sychroneous Orbit is sychroneous

with the earths with the earths rotation.rotation.

From the ground the From the ground the satellite appears satellite appears fixed.fixed.

Altitude is about Altitude is about 23,000 miles.23,000 miles.

Coverage to 40% of Coverage to 40% of planet per satellite.planet per satellite.

Basics of GEOsBasics of GEOs

Geostationary satellites are commonly used for communications and Geostationary satellites are commonly used for communications and weather-observation.The typical service life expectancy of a geostationary weather-observation.The typical service life expectancy of a geostationary satellite is 10-15 years. Because geostationary satellites circle the earth at satellite is 10-15 years. Because geostationary satellites circle the earth at the equator, they are not able to provide coverage at the Northernmost and the equator, they are not able to provide coverage at the Northernmost and

Southernmost latitudesSouthernmost latitudes.. Advantages:Advantages:

Weather images can be displayed.Weather images can be displayed.

Television broadcasts are uninterrupted.Television broadcasts are uninterrupted.

Used to track major developments such as hurricanes 24 hours a day.Used to track major developments such as hurricanes 24 hours a day.

Disadvantages:Disadvantages:

It takes longer for the signal to get to earth and back to satellite.It takes longer for the signal to get to earth and back to satellite.

Increased difficulty of telephone conversations.Increased difficulty of telephone conversations.

GEOs are not positioned in the farthest northern and southern orbits.GEOs are not positioned in the farthest northern and southern orbits.

ApplicationsApplicationsIndia uses its satellites communication network – one of the largest in the world – India uses its satellites communication network – one of the largest in the world – for applications such as land management, water resources management, natural for applications such as land management, water resources management, natural disaster forecasting, radio networking, weather forecasting, meteorological imaging disaster forecasting, radio networking, weather forecasting, meteorological imaging

and computer communicationand computer communication

The INSAT-2 satellites also provide telephone links to remote areas; data The INSAT-2 satellites also provide telephone links to remote areas; data transmission for organizations such as the mobile satellite service communications transmission for organizations such as the mobile satellite service communications for private operators, railways and road transport; and broadcast satellite services, for private operators, railways and road transport; and broadcast satellite services,

used by India’s state-owned television agency as well as commercial television used by India’s state-owned television agency as well as commercial television channelschannels

ISRO has applied its technology to "telemedicine", directly connecting patients in ISRO has applied its technology to "telemedicine", directly connecting patients in rural areas to medical professionals in urban locations via satellites Since high-rural areas to medical professionals in urban locations via satellites Since high-

quality healthcare is not universally available in some of the remote areas of India, quality healthcare is not universally available in some of the remote areas of India, the patients in remote areas are diagnosed and analyzed by doctors in urban the patients in remote areas are diagnosed and analyzed by doctors in urban

centres in real time via video conferencingcentres in real time via video conferencing

INSAT-4CR was launched on 2 September 2007 by GSLV-F04.INSAT-4CR was launched on 2 September 2007 by GSLV-F04. It is a replacement It is a replacement satellite of INSAT-4C which was lost when GSLV-F02 failed and had to be destroyed satellite of INSAT-4C which was lost when GSLV-F02 failed and had to be destroyed

on its courseon its course

This satellite is used by Airtel Digital TV and Sun Direct DTH to broadcast their DTH This satellite is used by Airtel Digital TV and Sun Direct DTH to broadcast their DTH services.services.

India to Launch 3D Weather Forecasting Satellite in 2011India to Launch 3D Weather Forecasting Satellite in 2011

  

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