ACKNOWLEDGEMENT
The cites of Google expressing its gratefulness towards the deep knowledge of satellite,
Origin of satellite. There are various types of satellite on the basis of various factors.
I also wish to thank Dr.Kailash Juglan, who gave me some comments and
Special thanks to Dr. Joginder Singh for his concern.
ABSTRACT OF WORK UNDERTAKEN
I avail this opportunity to convey the entire knowledge of Satellite through this paper.
This paper gives the information about the origin of satellite, type of satellite.
The main information of satellite is of ACTIVE & PASSIVE SATELLITE is conveyed by this paper.
INTRODUCTION TO THE PROBLEM
In communication system, there are various methods or techniques for propagation. We use all the methods for communication to one place to another place.
Satellite is one of the most popular technique for communicate the information from one place to another place.
CORE CHAPTER
HISTORY OF SATELLITE
In 1945 an RAF ELECTRONICS officer and member of the British Interplanetary society, Arthur C.Clarke, wrote a short article in wireless world that described the use of satellite in 24 hours orbits high above the world landmasses to distribute television programmer
By 1964, two TELESTARS, two RELAYS and two syncoms had operated successfully in space. This timing was in fortunate because the communications satellite corporation formed as a result of the communications satellite Act of 1962.
On April 6, 1965 COMSATs first satellite. EARLY BIRD, was launched from Cape Canaveral, Global satellite communication
DEFINITION OF SATELLITE
A satellite is basically any object that revolves around a planet in a circular or elliptical path. The moon is Earth's original, natural satellite, and there are many manmade (artificial) satellites, usually closer to Earth.
• The path a satellite follows is an orbit. In the orbit, the farthest point from Earth is the apogee, and the nearest point is the perigee.
• Artificial satellites generally are not mass-produced. Most satellites are custom built to perform their intended functions. Exceptions include the GPS satellites (with over 20 copies in orbit) and the Iridium satellites (with over 60 copies in orbit)
• Approximately 23,000 items of space junk -- objects large enough to track with radar that were inadvertently placed in orbit or have outlived their usefulness -- are floating above Earth
• IMAGE OF FIRST SATELLITE
SPUTNIK 1
Photo courtesy NASA
Sputnik 1, the first satellite, shown with four whip antennas
ACTIVE AND PASSIVE SATELLITES
Active communications satellites were not feasible in the 1940s because of the low power of early space rockets and the heavy weight of the necessary electronics; so early communications satellites were designed to operate in a passive mode. Instead of actively receiving, amplifying, and retransmitting radio signals, they merely reflected signals that were beamed up to them by transmitting stations on the ground. Signals were reflected in all directions, so any receiving station within sight of the satellite could pick them up.
Echo 1, launched by the U.S. in 1960, was an aluminized plastic balloon 30 m (100 ft) in diameter. Launched in 1964, Echo 2 was 41 m (135 ft) in diameter. The capacity of such systems was severely limited by the need for powerful transmitters and large ground antennas.
Active systems.
With advances in technology, satellite systems are now exclusively active systems, in which each satellite carries its own equipment for reception and transmission.
Score, launched by the U.S. in 1958, was the first active communications satellite. It was equipped with a tape recorder that stored messages received while passing over a transmitting ground station. These messages were retransmitted when the satellite passed over a receiving station; the utility of these systems was limited
Launched by American Telephone and Telegraph Co. on July 10, 1962, provided direct television transmission between the U.S., Europe, and Japan and could also relay several hundred voice channels. Launched into a 952–5632-km (590–3500-mi) elliptical orbit inclined 45° to the equatorial plane,
Telstar 1 could relay signals between two ground stations for only a short period during each orbit, when it was in view of both stations
To develop new technologies, the low-altitude Relay 1 and Relay 2 satellites followed in 1962 and 1964, however, plans to orbit dozens of such low-altitude satellites—each tracking in turn and then “handing off” the signal to the next satellite—were still impractical.
In the 1970s, with the development of more efficient and sensitive electronics and more powerful launch vehicles, transmission from higher orbits became possible, and the satellite communications industry expanded rapidly. Hundreds of active communications satellites are now in orbit. They receive signals from one ground station, amplify them, and then retransmit them at a different frequency to another station.
PASSIVE SATELLITE
A passive satellite relay could consist of an omni directional scattered such as a spherical body, like a balloon satellite, or a directive scattered such as a corner reflector. A corner reflector has the advantage that it tends to reflect radiation in the approximate direction from which the radiation came.
Passive satellite relays would require surface transmitters of much greater power than would active relays (unless the passive reflectors are extremely large); however, active satellite relays must carry aboard receiving and transmitting equipment and the necessary power sources, thus decreasing reliability and longevity.
One may provide all active satellite with omni directional transmitting antennas (radiating roughly equally in all directions) or directive antennas (radiating most of the energy toward the Earth). Directive antennas would require much less transmitted power, thus saving weight in that part of the payload devoted to transmission equipment and power supply, but would also require antenna stabilization so as to direct the radiated energy toward the Earth, thus increasing the payload weight devoted to attitude stabilization and its power supply.
BASICALLY SATELLITE
The term satellite refers essentially to one thing--a small body, natural or artificial, that revolves around a larger astronomical object. Data gathered from these satellites help promote an awareness of the environment, the world, and the universe. The new technologies developed from these satellites have additional applications that benefit on Earth. Life
APPLICATION OF SATELLITE
Satellites were used as spies during the Cold War to photograph the activities of the Soviet Union and China. These can be used to study desertification, urbanization, and other environmental changes. They can also help scientists spot many surface features from space.
Many once-super secrets Cold War spy satellite began to be released under an executive order by President Clinton. This is when more advanced systems took over.
The reconnaissance pictures, taken regularly to monitor arms developments and produce maps, will help establish a baseline in the 1960s for measuring changes, such as
Global warming,
Desertification, and
Forest shrinkage (Wolf 1).
First Early Communications Satellites
National Aeronautics and Space Administration (NASA) was created in October 1958 and took control of space activities. It is exploring ways to provide frequent flight opportunities for inexpensive space missions.
NASA hopes to continue learning about the balance of life on our planet. NASA, though, has confined itself to experiments with "mirror" or "passive" communications satellites, while the Department of Defense was responsible for "repeater" or "active" satellites, which amplify signals that they receive, at the satellite.
In 1960, American Telephone and Telegraph (AT&T) filed with the Federal Communications Commission (FCC) for permission to launch an experimental communications satellite. Communications Satellite Corporation (COMSAT) was formed in 1962 as a result of the Communications Satellite Act and was in the process of contracting to build a system of dozens of medium-orbit satellites. Other companies that provide service to the United States include GE American, Alas COM, GTE, and Hughes Communications (Whalen 1).
Satellites are put to a wide variety of uses. Applications range from scientific research to military reconnaissance.
The first satellites were used to study the Earth's upper atmosphere and inner space. Today, scientific satellites study a far greater range of objects. The major application of artificial satellites has been to provide long-distance communication links. Telephone companies, cable television stations, newspapers, and magazines use communications satellites to transmit data to various parts of the globe.
Meteorological satellites use highly sensitive instruments for modern weather forecasting.
Navigation satellites use laser-beam signals to determine the exact location of a ship on Earth.
The technique used by navigation satellites is also used to make accurate maps of remote areas of the Earth. Countries use military surveillance or spy satellites to monitor the activity of other nations
Important Satellites
Several well-known satellites were used to experiment the cutting-edge of satellite technologies.
In 1962, AT&T launched Telestar I. This satellite transmitted phone calls and photos between Europe and America. Telestar was the first satellite to transmit black-and-white color between two continents. It was capable of 600 telephone channels or one television channel.
In 1963, Telestar 2 was launched and established the first direct link between Japan and Europe.
NASA launched Echo, a silvery balloon that orbited Earth every 114 minutes, August 12, 1960. It was a passive satellite that reflected radio signals back to Earth. Echo 2 was launched January 1964.
NASA's first active experimental satellite and was launched December 13, 1962. It handled simultaneous two-way telephone conversations or one television channel. It provided the first satellite communication link between North and South America and Europe.
Relay 2, an improved version, was launched in January 1964 ("Early Communications Satellites" 1).
The Syncoms were three experimental active satellites.
Syncom I was launched February 14, 1963, but did not reach synchronous orbit and communications failed.
Syncom II was launched July 26, 1963. It was the first satellite placed in synchronous orbit.
Syncom III was launched August 19, 1964. It was the first stationary Earth satellite.
In orbit near the International Date Line, it was used to telecast the 1964 Olympic Games in Tokyo to the United States. It was the first television program to cross the Pacific.
A French satellite, SPOT, helped illustrate the damage caused by the explosion of the former Soviet Union's nuclear reaction in Chernobyl ("Satellites" 2).
Television Infrared Observation Satellite (TIROS) was the first series of meteorological satellites to carry television cameras to photograph the Earth's cloud cover and demonstrate the value of using spacecraft for meteorological forecasting. The first TIROS were launched in 1960. It returned data that showed a large degree of organization within the cloud cover over the Earth.
Nimbus 1, a meteorological satellite, had a one-month life span. It tracked the storm pattern of Hurricane Cleo and helped prevent severe damage. Nimbus 7 operated from 1978 to 1993. It played a major role in the study of the global ozone and the "ozone hole" over the Atlantic Ocean.
Present Satellites
Satellites today have improved tremendously since the first satellite and are continuing to rapidly progress into the future. Around the world, satellites put people and their computers on the information super highway. They are used in our everyday lives and will continue to improve life on Earth.
Defensive Systems Development
Active and passive satellite defenses will increase the survivability of a satellite system in 2025 (fig. 5-5). As more and more civilian satellites are launched, civilians will protect their investments by making their satellites more survivable in the natural space environment. The military will need to pursue defenses against man-made attacks.
Advances in Satellite Defensive Systems
Satellite-based rainfall estimation
Why estimating rainfall from space?
Precipitation is a crucial link in the hydrologic cycle, and its spatial and temporal variations are enormous. Knowledge of the amount of regional rainfall is essential to the welfare of society. Rainfall also drives the hydrological cycle, and to improve weather and climate predictions, an accurate global coverage of rainfall records is necessary. Rain gauge data are available on land only, mainly in densely populated areas.
Rainfall can be estimated remotely, either from ground-based weather radars or from satellite. Radars are active devices, emitting radiation at wavelengths ranging between 1 and 10 cm, and receiving the echo from targets such as raindrops. The maximum range of radars is only about 300 km, so offshore coverage is limited. Also, radars are prohibitively expensive in the Third World. Satellite-based measurements offer global coverage or a good part thereof.
At night no visible imagery is available. One can then use an empirical relationship between cloud-top temperature (deduced from the outgoing radiation in the 10.7-micron waveband), the simultaneous precipitation rate inferred from surface radar reflectivity, and the humidity profile (derived from radiosonde data). The rainfall rate (R mm/h) depends on the cloud-top temperature (T degrees Kelvin) thus (2):
R = 1.1183 x 1011 x exp ( - 3.6382 x 10-2 x T0.5)
Adjustments are then made according to the perceptible water and surface relative humidity. The rate of change of cloud-top temperature can be used as well. It indicates the speed of cloud growth, and hence the areas of heavy rainfall.
In practice, the procedure allows useful estimates over 6 hour’s periods. However, it overestimates rainfalls over 24-hours in the case of slowly moving thunderstorms with a broad anvil, by exaggerating the area of rainfall. On the other hand it underestimates rainfall from warm-top stratus, especially near coastlines and in mountainous terrain.
In short, quantitative precipitation estimates from geostationary satellites can yield cumulative rainfall and thus flood warnings, for instance, because of the continuous coverage, but large discrepancies with rain gauge data occur.
SOME MICROWAVE PASSIVE SENSORS
SSM/I
Since 1978 one or more passive microwave sensors have been available on polar orbiting satellites, such as the Special Sensor Microwave/Imager on the Defense Meteorological Satellite Program (DMSP).
In most areas, including the tropics, most rainfall results from cold clouds, i.e. clouds with ice aloft. So at least over the oceans cold clouds can be easily detected by the SSM/I.
TRMM
In November 1997 the (Tropical Rainfall Measuring Mission) satellite was launched (3). This satellite carries the entire above (passive microwave, infrared, and visible), plus active radar. This combination provides a far superior estimate of rainfall.
Except for TRMM, because low-level, topographically forced updrafts may trigger heavy rainfall. For instance, the annual rainfall on Mt Waialeale on the island of Kauai, Hawaii’s, is nearly 10 m
SOME INTERSTING PICTURES OF SATELLITE
Launch Date: 05/04/1976
Solid spherical passive satellite to provide a reference point for laser ranging experiments.
REFERENCES
.
www.hq.nasa.gov/pao/history/conghand/commsat.htm
www.tpub.com/neets/book/17/76.htm
www.wikepedia.org.com
Katiyar, S., satellite communication Ed.1st (2007), S.k.katiyar&sons, New Delhi
ACKNOWLEDGEMENT
The cites of Google expressing its gratefulness towards the deep knowledge of satellite,
Origin of satellite. There are various types of satellite on the basis of various factors.
I also wish to thank Dr.Kailash Juglan, who gave me some comments and
Special thanks to Dr. Joginder Singh for his concern.
ABSTRACT OF WORK UNDERTAKEN
I avail this opportunity to convey the entire knowledge of Satellite through this paper.
This paper gives the information about the origin of satellite, type of satellite.
The main information of satellite is of ACTIVE & PASSIVE SATELLITE is conveyed by this paper.
INTRODUCTION TO THE PROBLEM
In communication system, there are various methods or techniques for propagation. We use all the methods for communication to one place to another place.
Satellite is one of the most popular technique for communicate the information from one place to another place.
CORE CHAPTER
HISTORY OF SATELLITE
In 1945 an RAF ELECTRONICS officer and member of the British Interplanetary society, Arthur C.Clarke, wrote a short article in wireless world that described the use of satellite in 24 hours orbits high above the world landmasses to distribute television programmer
By 1964, two TELESTARS, two RELAYS and two syncoms had operated successfully in space. This timing was in fortunate because the communications satellite corporation formed as a result of the communications satellite Act of 1962.
On April 6, 1965 COMSATs first satellite. EARLY BIRD, was launched from Cape Canaveral, Global satellite communication
DEFINITION OF SATELLITE
A satellite is basically any object that revolves around a planet in a circular or elliptical path. The moon is Earth's original, natural satellite, and there are many manmade (artificial) satellites, usually closer to Earth.
• The path a satellite follows is an orbit. In the orbit, the farthest point from Earth is the apogee, and the nearest point is the perigee.
• Artificial satellites generally are not mass-produced. Most satellites are custom built to perform their intended functions. Exceptions include the GPS satellites (with over 20 copies in orbit) and the Iridium satellites (with over 60 copies in orbit)
• Approximately 23,000 items of space junk -- objects large enough to track with radar that were inadvertently placed in orbit or have outlived their usefulness -- are floating above Earth
• IMAGE OF FIRST SATELLITE
SPUTNIK 1
Photo courtesy NASA
Sputnik 1, the first satellite, shown with four whip antennas
ACTIVE AND PASSIVE SATELLITES
Active communications satellites were not feasible in the 1940s because of the low power of early space rockets and the heavy weight of the necessary electronics; so early communications satellites were designed to operate in a passive mode. Instead of actively receiving, amplifying, and retransmitting radio signals, they merely reflected signals that were beamed up to them by transmitting stations on the ground. Signals were reflected in all directions, so any receiving station within sight of the satellite could pick them up.
Echo 1, launched by the U.S. in 1960, was an aluminized plastic balloon 30 m (100 ft) in diameter. Launched in 1964, Echo 2 was 41 m (135 ft) in diameter. The capacity of such systems was severely limited by the need for powerful transmitters and large ground antennas.
Active systems.
With advances in technology, satellite systems are now exclusively active systems, in which each satellite carries its own equipment for reception and transmission.
Score, launched by the U.S. in 1958, was the first active communications satellite. It was equipped with a tape recorder that stored messages received while passing over a transmitting ground station. These messages were retransmitted when the satellite passed over a receiving station; the utility of these systems was limited
Launched by American Telephone and Telegraph Co. on July 10, 1962, provided direct television transmission between the U.S., Europe, and Japan and could also relay several hundred voice channels. Launched into a 952–5632-km (590–3500-mi) elliptical orbit inclined 45° to the equatorial plane,
Telstar 1 could relay signals between two ground stations for only a short period during each orbit, when it was in view of both stations
To develop new technologies, the low-altitude Relay 1 and Relay 2 satellites followed in 1962 and 1964, however, plans to orbit dozens of such low-altitude satellites—each tracking in turn and then “handing off” the signal to the next satellite—were still impractical.
In the 1970s, with the development of more efficient and sensitive electronics and more powerful launch vehicles, transmission from higher orbits became possible, and the satellite communications industry expanded rapidly. Hundreds of active communications satellites are now in orbit. They receive signals from one ground station, amplify them, and then retransmit them at a different frequency to another station.
PASSIVE SATELLITE
A passive satellite relay could consist of an omni directional scattered such as a spherical body, like a balloon satellite, or a directive scattered such as a corner reflector. A corner reflector has the advantage that it tends to reflect radiation in the approximate direction from which the radiation came.
Passive satellite relays would require surface transmitters of much greater power than would active relays (unless the passive reflectors are extremely large); however, active satellite relays must carry aboard receiving and transmitting equipment and the necessary power sources, thus decreasing reliability and longevity.
One may provide all active satellite with omni directional transmitting antennas (radiating roughly equally in all directions) or directive antennas (radiating most of the energy toward the Earth). Directive antennas would require much less transmitted power, thus saving weight in that part of the payload devoted to transmission equipment and power supply, but would also require antenna stabilization so as to direct the radiated energy toward the Earth, thus increasing the payload weight devoted to attitude stabilization and its power supply.
BASICALLY SATELLITE
The term satellite refers essentially to one thing--a small body, natural or artificial, that revolves around a larger astronomical object. Data gathered from these satellites help promote an awareness of the environment, the world, and the universe. The new technologies developed from these satellites have additional applications that benefit on Earth. Life
APPLICATION OF SATELLITE
Satellites were used as spies during the Cold War to photograph the activities of the Soviet Union and China. These can be used to study desertification, urbanization, and other environmental changes. They can also help scientists spot many surface features from space.
Many once-super secrets Cold War spy satellite began to be released under an executive order by President Clinton. This is when more advanced systems took over.
The reconnaissance pictures, taken regularly to monitor arms developments and produce maps, will help establish a baseline in the 1960s for measuring changes, such as
Global warming,
Desertification, and
Forest shrinkage (Wolf 1).
First Early Communications Satellites
National Aeronautics and Space Administration (NASA) was created in October 1958 and took control of space activities. It is exploring ways to provide frequent flight opportunities for inexpensive space missions.
NASA hopes to continue learning about the balance of life on our planet. NASA, though, has confined itself to experiments with "mirror" or "passive" communications satellites, while the Department of Defense was responsible for "repeater" or "active" satellites, which amplify signals that they receive, at the satellite.
In 1960, American Telephone and Telegraph (AT&T) filed with the Federal Communications Commission (FCC) for permission to launch an experimental communications satellite. Communications Satellite Corporation (COMSAT) was formed in 1962 as a result of the Communications Satellite Act and was in the process of contracting to build a system of dozens of medium-orbit satellites. Other companies that provide service to the United States include GE American, Alas COM, GTE, and Hughes Communications (Whalen 1).
Satellites are put to a wide variety of uses. Applications range from scientific research to military reconnaissance.
The first satellites were used to study the Earth's upper atmosphere and inner space. Today, scientific satellites study a far greater range of objects. The major application of artificial satellites has been to provide long-distance communication links. Telephone companies, cable television stations, newspapers, and magazines use communications satellites to transmit data to various parts of the globe.
Meteorological satellites use highly sensitive instruments for modern weather forecasting.
Navigation satellites use laser-beam signals to determine the exact location of a ship on Earth.
The technique used by navigation satellites is also used to make accurate maps of remote areas of the Earth. Countries use military surveillance or spy satellites to monitor the activity of other nations
Important Satellites
Several well-known satellites were used to experiment the cutting-edge of satellite technologies.
In 1962, AT&T launched Telestar I. This satellite transmitted phone calls and photos between Europe and America. Telestar was the first satellite to transmit black-and-white color between two continents. It was capable of 600 telephone channels or one television channel.
In 1963, Telestar 2 was launched and established the first direct link between Japan and Europe.
NASA launched Echo, a silvery balloon that orbited Earth every 114 minutes, August 12, 1960. It was a passive satellite that reflected radio signals back to Earth. Echo 2 was launched January 1964.
NASA's first active experimental satellite and was launched December 13, 1962. It handled simultaneous two-way telephone conversations or one television channel. It provided the first satellite communication link between North and South America and Europe.
Relay 2, an improved version, was launched in January 1964 ("Early Communications Satellites" 1).
The Syncoms were three experimental active satellites.
Syncom I was launched February 14, 1963, but did not reach synchronous orbit and communications failed.
Syncom II was launched July 26, 1963. It was the first satellite placed in synchronous orbit.
Syncom III was launched August 19, 1964. It was the first stationary Earth satellite.
In orbit near the International Date Line, it was used to telecast the 1964 Olympic Games in Tokyo to the United States. It was the first television program to cross the Pacific.
A French satellite, SPOT, helped illustrate the damage caused by the explosion of the former Soviet Union's nuclear reaction in Chernobyl ("Satellites" 2).
Television Infrared Observation Satellite (TIROS) was the first series of meteorological satellites to carry television cameras to photograph the Earth's cloud cover and demonstrate the value of using spacecraft for meteorological forecasting. The first TIROS were launched in 1960. It returned data that showed a large degree of organization within the cloud cover over the Earth.
Nimbus 1, a meteorological satellite, had a one-month life span. It tracked the storm pattern of Hurricane Cleo and helped prevent severe damage. Nimbus 7 operated from 1978 to 1993. It played a major role in the study of the global ozone and the "ozone hole" over the Atlantic Ocean.
Present Satellites
Satellites today have improved tremendously since the first satellite and are continuing to rapidly progress into the future. Around the world, satellites put people and their computers on the information super highway. They are used in our everyday lives and will continue to improve life on Earth.
Defensive Systems Development
Active and passive satellite defenses will increase the survivability of a satellite system in 2025 (fig. 5-5). As more and more civilian satellites are launched, civilians will protect their investments by making their satellites more survivable in the natural space environment. The military will need to pursue defenses against man-made attacks.
Advances in Satellite Defensive Systems
Satellite-based rainfall estimation
Why estimating rainfall from space?
Precipitation is a crucial link in the hydrologic cycle, and its spatial and temporal variations are enormous. Knowledge of the amount of regional rainfall is essential to the welfare of society. Rainfall also drives the hydrological cycle, and to improve weather and climate predictions, an accurate global coverage of rainfall records is necessary. Rain gauge data are available on land only, mainly in densely populated areas.
Rainfall can be estimated remotely, either from ground-based weather radars or from satellite. Radars are active devices, emitting radiation at wavelengths ranging between 1 and 10 cm, and receiving the echo from targets such as raindrops. The maximum range of radars is only about 300 km, so offshore coverage is limited. Also, radars are prohibitively expensive in the Third World. Satellite-based measurements offer global coverage or a good part thereof.
At night no visible imagery is available. One can then use an empirical relationship between cloud-top temperature (deduced from the outgoing radiation in the 10.7-micron waveband), the simultaneous precipitation rate inferred from surface radar reflectivity, and the humidity profile (derived from radiosonde data). The rainfall rate (R mm/h) depends on the cloud-top temperature (T degrees Kelvin) thus (2):
R = 1.1183 x 1011 x exp ( - 3.6382 x 10-2 x T0.5)
Adjustments are then made according to the perceptible water and surface relative humidity. The rate of change of cloud-top temperature can be used as well. It indicates the speed of cloud growth, and hence the areas of heavy rainfall.
In practice, the procedure allows useful estimates over 6 hour’s periods. However, it overestimates rainfalls over 24-hours in the case of slowly moving thunderstorms with a broad anvil, by exaggerating the area of rainfall. On the other hand it underestimates rainfall from warm-top stratus, especially near coastlines and in mountainous terrain.
In short, quantitative precipitation estimates from geostationary satellites can yield cumulative rainfall and thus flood warnings, for instance, because of the continuous coverage, but large discrepancies with rain gauge data occur.
SOME MICROWAVE PASSIVE SENSORS
SSM/I
Since 1978 one or more passive microwave sensors have been available on polar orbiting satellites, such as the Special Sensor Microwave/Imager on the Defense Meteorological Satellite Program (DMSP).
In most areas, including the tropics, most rainfall results from cold clouds, i.e. clouds with ice aloft. So at least over the oceans cold clouds can be easily detected by the SSM/I.
TRMM
In November 1997 the (Tropical Rainfall Measuring Mission) satellite was launched (3). This satellite carries the entire above (passive microwave, infrared, and visible), plus active radar. This combination provides a far superior estimate of rainfall.
Except for TRMM, because low-level, topographically forced updrafts may trigger heavy rainfall. For instance, the annual rainfall on Mt Waialeale on the island of Kauai, Hawaii’s, is nearly 10 m
SOME INTERSTING PICTURES OF SATELLITE
Launch Date: 05/04/1976
Solid spherical passive satellite to provide a reference point for laser ranging experiments.
REFERENCES
.
www.hq.nasa.gov/pao/history/conghand/commsat.htm
www.tpub.com/neets/book/17/76.htm
www.wikepedia.org.com
Katiyar, S., satellite communication Ed.1st (2007), S.k.katiyar&sons, New Delhi
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