Space means outer space or the region beyond earth. It is that portion of the universe which is beyond the immediate influence of earth. The study of region beyond earth and the objects present in it is called space science.
Space science is used for continuous weather monitoring and weather forecasting on the earth. This is done by using weather satellites stationed in outer space.
Space science is used for making long distance communications, like long distance telephone calls, television broadcasts and radio broadcasts. This is done by means of communication satellite stationed in outer space and is known as satellite communications.
Space science is also used for the collection of information about other planets and outer space. This is done by sending the space probes.
A communications satellite is a spacecraft circling high above the earth which can receive radio-telephone, radio and T.V. signals from a particular earth station, amplify these communication signals and then retransmit these amplified signals to various other earth stations around the world. Communication satellites are being used increasingly to handle long distance telephone, television and other transmissions around the world. Our country has developed its own communication satellite INSAT series which have brought television service even to remote, inaccessible villages of our country.
Satellite Communication
Satellite communication is an important application of space science. ‘Satellite communication’ means ‘communication through the use of satellites.’
In satellite communications, the artificial earth satellites positioned in space above the earth are used as relay stations for amplifying and transmitting the signals of radio telephones, radio and television broadcasts from one part of the earth to other parts.
In fact, earth satellites provide radio and television services to much of the world. Communication satellites have also been used to relay educational and health information to isolated villages directly through satellite television.
An important advantage is that communication satellites can be used when other forms of communications are either impossible or too expensive. Another advantage of satellite communicaton is that the hour-to-hour changes in the atmosphere have no adverse effect on the quality of programmes broadcast via satellite. The signals received back from the satellite are absolutely free from any distortion.
A communication satellite is a spacecraft circling high above the earth. A communication satellite has an amplifier and a transmitter which work with solar energy. A network of transmitting and receiving ground-stations is set up throughout the country or throughout the world. The extremely short wavelength. T.V. waves, radio waves and radio-telephones waves carrying the message are beamed up to the satellite from one of the ground stations. The satellite amplifies these electromagnetic communication signals and then transmits the amplified signals to all far ground stations. These ground stations have receivers which re-convert the signals obtained from satellites into radio programmes, telephone conversation or T.V. programmes. Hence a communication satellite in the sky acts as a relay station, amplifying and re-transmitting radio. T.V. and radio-telephones signals.
Moon is the natural satellite of the earth but it cannot be used for communication purposes due to the distance between earth and moon is very large.
The time of rotation of moon on its axis is not 24 hours like that of earth.
Moon is not rotating in the equatorial plane of the earth.
Weather Monitoring
These days weather monitoring and forecasting is being done with the help of those artificial satellites called weather satellites stationed in outer space. The weather satellites contain a wide variety of scientific instruments to monitor the climatic factors like air pressure, humidity, air temperature, and other changes taking place in the upper layer atmosphere of earth. Weather satellites are fitted with powerful television cameras to take the pictures of cloud formations in the atmosphere over large areas of the earth’s surface.
Weather satellites also carry a large variety of scientific instruments of sense the weather conditions prevailing in the atmosphere. The photographs taken by satellite cameras provide large scale matter and weather photographs of the different parts of earth. From these satellite photographs and other related data relayed by weather satellite, it is possible to know in advance whether a particular area is going to have rainfall, snowfall or even a cyclone can be forecasted.
India has so far launched three artificial satellites which work both as communication satellites as well as weather satellites.
These are INSAT-1A, INSAT-1B and INSAT-1C. (INSAT stands for Indian National Satellite)
Out of these three artificial satellites INSAT-1A got damaged completely during the launch process whereas the power system of INSAT-1C got damaged partially. But INSAT-1B is in perfectly working order since October 1983 when it was launched. Even INSAT-1C is working but at a reduced capacity.
At present in our country, artificial satellite INSAT-1B is being used for weather forecasting, especially rainfall, snowfall and cyclone forecasting since 1983.
INSAT-1B is sending weather photographs showing the cloud formations over large areas of our country every half-hourly. These satellite photographs are studied by the experts of Meteorological department and then weather forecasting is done on the basis of these atmospheric pictures and other related data.
INSAT is being used for direct broadcasting of television programmes to the remote areas of our country and is being used for long-distance telephone calls like overseas communications.
INSAT is being used for continuous weather monitoring and weather forecasting by making meteorological observations in the sky and sending atmospheric pictures to the earth and is being used for connecting all the radio stations and television stations of the country to a National Hook-Up. The National-Network. T.V. programmes, Radio programmes and weather forecasting in India is being made possible by INSAT-1B.
Information from other planets
The collection of information about other planets and outer space is done by sending specially designed space vehicles called space probes. The space probes contain a wide variety of scientific instruments and television cameras, etc., to collect and transmit data and pictures of other planets and outer space. These space probes have provided us close-up pictures and other data about planets and other objects in the other space, and have vastly increased our knowledge about space and the objects in it. Sometimes manned space vehicles are also sent into outer space to collect data and make other studies. America and Soviet Union are now working towards establishing permanently manned space stations in outer space to collect information about other planets and outer space. Russians launched their space-station programme in 1971 with the Salyut series of space-station. Equipped for earth, solar and astronomical observations and material processing experiments, they are visited regularly by crews flown up in Soyuz space-craft. Some crew members have stayed on Salyut space-station for over 6 months at a time.
The exploration of outer space began with the successful launching of the Russian artificial satellite called Sputnik-1 in the year 1957, and accelerated by Yuri Gagarin’s first manned flight in space aboard a space-craft called Vostok-1 in the year 1961. In the same year, Alan Shepard piloted the first American manned spacecraft and President John Kennedy of America set the goal of landing a man on the moon and returning him safely within the same decade. The first spacewalk was undertaken by Alexei Leonove is October 1964.
The most exciting space programme involving the moon has been the Apollo project of America which ultimately landed man on the moon. It was the Apollo-11 space-craft of America which took man to the moon. The two astronauts who landed on the moon on July 20, 1969 were Neil Armstrong and Edvin Aldrin. They brought back samples of moon soil and rocks for analysis and examination. In 1973, Russia sent an unmanned wheeled vehicle Lunakhod aboard Luna space-craft to moon which also brought back samples of moon-soil to the earth for testing. Lunakhod was driven by remote control from the earth.
The moon has been explored by a variety of moon probes called ‘Luna’ series begun by Russia in the year 1959. Some space crafts crashed into the moon’s surface and others flew past the moon or went into moon’s orbit. Luna-3 was the first space-craft to go completely round the moon. In the year 1960, Luna-3 photographed that side of the moon which is not visible from the earth and transmitted the first photographs of this area. These photographs show the presence of craters, dark plane and mountains on the other side of the moon, just like those present on its visible side and observed through telescopes.
Exploration of the planets has been carried out by unmanned probes. Though the planets are millions of kilometres away, but space probes have already reached some of the planets and are approaching other planet. The American Mariner space programme has studied three planets: Mercury, Venus and Mars through space probes.
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