1.
Navigation/Location:
Navigation satellites allow the operators of land vehicles, ships,
and aircraft to determine their
locations within 100 feet any where on earth.
These vehicles have on board a computerized receiver which can pick up radio
signals from satellites miles in space.
The signal receiver can be used in cars, cellphones, and other
devices. Navigation satellite can indicate the nearest restaurants, business
centers, railway stations, airports, etc. Also, one may be in a position to locate roads with traffic jams, the nearest
free parking space, and SO On.
To pinpoint your location accurately, your receiver needs to
receive signals from at least two navigational satellites. The receiver
determines your distance from each of the satellites. This is possible by measuring the time taken by the signal to
travel from the satellite to your receiver antenna. Three to four satellites
are the minimum needed to determine positions on the surface of the Earth and
above it. In general, the more satellites used, the greater the positioning
accuracy. Many receivers have channels for receiving signals from up to 15
satellites.
GPS: The United
States Global Positioning System (GPS) consists of up to 32 medium Earth orbit
satellites in six different orbital planes, with the exact number of satellites
varying as older satellites are retired and replaced. Operational since 1978
and globally available since 1994, GPS is currently the world's most utilized
satellite navigation system.
GAGAN: The GPS
Aided Geo-Augmented Navigation (GAGAN) is a planned implementation of a
regional satellite based augmentation system (SBAS) by the Indian Govt. It is a
System to improve the accuracy of Global Navigation Satellite System (GNSS)
receiver by providing reference signals. The Airports Authority of India (AAI)
efforts towards implementation of operational SBAS is viewed as the first step
towards introduction of modern communication, navigation, surveillance/Air
Traffic Management system over Indian airspace. GAGAN is planned to get into
operation by the year 2014. It will be able to help pilots to navigate in the
Indian airspace by an accuracy of 3 meters. This will be helpful for landing
aircraft in tough weather and terrain like Mangalore airport and Leh airport.
2. Prediction of Weather:
Weather satellites are one of the most important instrumentation used to predict the weather. Weather satellites
photograph the earth regularly in visible and infrared light, and they provide
data to weather stations on earth, thus enabling the forecasting of weather
conditions around the world.
Using environmental satellites to observe the Earth from space is
one of the key tools in forecasting weather, analyzing climate, and monitoring
hazards worldwide. This 24-hour global coverage provides us with a never-ending
stream of information critical for making decisions affecting everything from
what you are going to wear today to governments making decisions about how to
deal with climate change. The National Oceanic and Atmospheric Administration
(NOAA) in collaboration with the National Aeronautics and Space Administration
(NASA) and the U.S. Air Force, manages and operates fleets of weather and
environmental monitoring satellites. There are two main types of environmental
satellites geostationary and polar-orbiting.
Meteorologists (meteorologist is a specialist who studies
processes in the earth's atmosphere that cause weather conditions) generally
use two types of satellites:
Geostationary Operational Environmental Satellites (Goo - GOES
orbit 35,800 km (22,300 miles) above the Earth's equator at speeds equal to
Earth's rotation, which maintain those positions relative to Earth.
The GOES provide constant monitoring of various areas of the
planet. To fully cover Alaska, Hawaii, the entire continental United States,
and the Pacific and Atlantic Ocean (for tropical storms), NOAA operates two
GOES satellites simultaneously GOES-East and GOES-West.
The satellites provide constant coverage of the western hemisphere
by taking photographic images every 15 minutes. These are critical for
identifying severe weather, snow storms, tropical storms and hurricanes. GOES
protect our lives and property every day – constantly watching for new storms
and severe weather. NOAA GOES are also used in identifying when satellite
emergency locator beacons have been activated to help with Search and Rescue
activities.
• Polar Operational Environmental Satellites (POES) – help to
predict weather conditions. POES Satellites orbit longitudinally from pole to
pole. They have a sun-synchronous orbit, which allows them to scan the entire
earth's surface in 14 orbits over a day's time
(24 hours).
By having imagery of the whole globe, meteorologists are able to
develop models to predict the weather out to five to ten days. When
polar-orbiting satellites fly over severe weather, they can also give us very
detailed pictures of the storms given how much closer they are to storms than
GOES.
In addition to weather analysis and forecasting, data from the
POES series support a broad range of environmental monitoring applications
including climate research and prediction, global sea surface temperature
measurements, measurements of temperature and humidity of the atmosphere, ocean
dynamics research, volcanic eruption monitoring, forest fire detection, and
global vegetation analysis. Instruments on POES are critical for providing
long-term, sustained observations used for determining the long term changes in
climate conditions around the world. Finally, POES assist in search and rescue
by locating people,
planes and ships, who have activated emergency locator beacon.
Other Satellites of NOAA: (National Oceanic and Atmospheric Administration)
(a) Defense Meteorological Satellite Program: Since the mid1960's,
when the Department of Defense (DOD) initiated the Defense Meteorological
Satellite Program (DMSP), low, earth orbiting satellites have provided the
military with important environmental information. NOAA operates these
satellites on behalf of the U.S. Air Force. DMSP satellites "see"
such environmental features as clouds, bodies of water, snow, fire, and
pollution and record information, which can help determine cloud type and
height, land and surface water temperatures, water currents, ocean surface features,
ice, and snow. DMSP is ultimately
used in planning and conducting U.S. military operations worldwide.
(b) Ocean Surface Topography Mission (OSTM)/JASON-2. One aspect of
climate change is sea level rise, which affects much of the world's population
that live in coastal areas. OSTM is a joint effort by the four organizations to
measure sea surface height by using a radar altimeter mounted on a low-earth
orbiting satellite called Jason-2. Satellite altimetry data provides sea
surface heights for determining ocean circulation, climate change and sea-level
rise. These sea surface height measurements are necessary for ocean modeling,
forecasting El Niño/La Niña events, and hurricane intensity Prediction.
Under the OSTM program, NOAA provides day-to-day operation of the
Jason-2 satellite distributing data to users around the world.
3.
Communications:
The satellites are also used for the purpose of communications in
respect of television, phones (cellular as well as others), the Internet,
beepers, etc. Communications Satellites have been around since 122°. One of the
best known uses of communications satellites is for the radio/television
transmission.
Satellites facilitate high bandwidth, which in turn allow easy
sending of television broadcasts. In addition, developments in broadcast
technology allow different types of transmissions to be sent, taking advantage of sharing the same satellite signal.
Communications satellites not only help out a person in distress
but also allow a person walking on the street in Mumbai to use the cellular
phone to speak with someone in Mexico or some other place. More and more
satellites are being launched each year to support new and growing uses for
business, military and communication needs.
Satellite can be used for transmitting news through various media.
Press Trust of India is the only news agency in South Asia which
operates its own communication satellite, an INSAT, to broadcast news and information.
4. Scientific Research:
Certain satellites are important for scientific research. These
satellites gather data for scientific analysis. This includes observations of
the atmosphere of our planet, the stars, the sun and other parts of space.
The earth orbiting satellites can observe celestial objects
without the interference from the Earth's atmosphere. These satellites are able to record data without the interference of
gases, lights, and magnetic fields produced on earth. Scientific satellites are
not restricted to earth orbits; they
also orbit the sun, moon, and other planets.
5. Observation of earth’s surface:
Observation satellites help to observe many features of the
earth's surface. Scientists use earth observation satellites to locate mineral
deposits, to determine the location and size of freshwater supplies and to
detect the spread of disease in crops and forests. Satellites are also used in
the field of surveillance.
For instance, The U.S. satellites of the LANDSAT and SEASAT series
find such data. The LANDSAT satellites have been used "for making
estimates of global wheat production, for forest and range land inventories,
for mineral and oil exploration and geological mapping, and for environmental
monitoring and impact assessments.
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