Notes-Class 10-Science & Technology-1-Chapter-10-Space Mission-Maharashtra Board - (2023)

Necessary of Telescopes to put in the space: Visible light and radio waves emitted by celestial bodies in space pass through the atmosphere before reaching the earth’s surface.

• During this journey, some light is absorbed by the atmosphere. Hence, the intensity of the light reaching the earth’s surface decreases.
• Besides, temperature and air pressure cause the atmospheric turbulence. Hence, light rays change their path, resulting in a change in the position of the image of a celestial body.
• City lights during night, and bright sunlight during day also put limitations on usage of optical telescopes on the earth.
• To minimize these problems, optical telescopes are situated on mountain top, away from inhabited places. However, limitations caused by the atmosphere still persist.

To get rid of these problems scientists have successfully launched telescopes in space. Images obtained by these telescopes are brighter and clearer than those obtained by the telescopes located on the earth’s surface.

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Importance of space mission :

Space missions are now essential to understand the origin and evolution of our solar system as well as to study the Universe beyond the Solar system. Space missions have given us many benefits and made our life simpler.

It is because of space missions that we are getting,

• Real-time information, communication across the globe.
• Entertainment and receiving the abundant information from the desk at any place.
• Access to huge information available on the internet.
• Management of natural resources.
• Advanced alerts and Management of some natural calamities and Polution.
• Satellite surveillance for defence purpose.
• Access to various activities like trade, tourism and navigation.

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Classification of artificial satellites -

(1) Weather satellite : To study and predict the weather conditions.

• It records temperature, air pressure, wind direction, humidity, cloud cover, etc. this information is sent to the space research station on the earth, and then with this information weather forecast is made.

The names of Indian satellite: INSAT and GSAT. Launcher: GSLV.

(2) Communication satellite : To communicate between different locations in the world.

• Many artificial satellites placed at various locations in the earth’s orbit are well interconnected and help us to have communication with any place, from anywhere, at any time and in any form including voicemail, email, photographs, audio mail, etc.
• In order to establish communication between different places on the earth through mobile phones or computer assisted internet, communication satellites are used.

The names of Indian satellite: INSAT and GSAT. Launcher: GSLV.

(3) Broadcasting satellite : To telecast television and radio programmes.

• Due to this satellite we can have access to information about current incidents, events, programmes, sports and other events right from drawing room.

The names of Indian satellite: INSAT and GSAT. Launcher: GSLV.

(4) Navigational satellite: To locate the place precisely in terms of its latitude and longitude and assist the surface, water and air transportation.

• These satellites also assist the user with current live maps as well as real time traffic conditions.

The names of Indian satellite: IRNSS. Launcher : PSLV.

(5) Military satellite: Collecting information regarding security aspects including international borders.

• Satellites help to monitor all movements of neighbouring countries or enemy countries.
• Military satellites also help to guide the missiles effectively.

(6) Earth observation satellite : To study various aspects of the earth’s surface including forests, oceans, polar regions and collect information about natural calamities.

• These satellites also help us to collect the information about the resources, their management, continuous observation about a natural phenomenon and the changes within it.

The names of Indian satellite: IRS. Launcher : PSLV.

(7) Other satellites : Apart from these various satellites, certain satellites for specific works or purposes are also sent in the space.

Examples:

• India has sent EDUSAT for educational purpose.
• CARTOSAT for surveys and map making.
• Satellites with telescopes, like Hubble telescope or a satellite like International Space Station help to explore the universe.
• ISS (International Space Station) provides a temporary residence where astronauts can stay for a certain short or long period and can undertake the research and study space activities

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Based on the height of the satellite from the earth’s surface, satellites are classified as follows :

• High Earth Orbit Satellites
• Medium Earth Orbit Satellites
• Low Earth Orbit Satellites

High Earth Orbit Satellite (HEO) : A satellite orbiting at a height equal to or greater than 35780 km above the earth’s surface is called High Earth Orbit satellite.

• If such a satellite revolves in the equatorial plane of the earth, in the same sense as the earth’s rotation and has period equal to that of the earth’s rotation, it will appear stationary with respect to a place on the earth. This satellite is, therefore, called geostationary or geosynchronous satellite.
• Such satellites are used for climatology, telecommunication, transmission of TV and radio programmes, etc.

Medium Earth Orbit Satellite (MEO): A satellite orbiting at a height between 2000 km and 35780 km above the earth’s surface is called a Medium Earth Orbit satellite.

• The orbital path of such a satellite is normally elliptical and passes through the North and the South polar regions. These satellites are useful for navigation.

Low Earth Orbit Satellite (LEO) : A satellite orbiting at a height between 180 km and 2000 km above the earth’s surface is called a Low Earth Orbit satellite.

• Weather satellites, and International Space Station are low Earth orbit satellites.

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Satellite Launch Vehicle :

• A Satellite Launch Vehicle carries an artificial satellite to a desirable height above the earth’s surface and places it in the desired orbit. It needs a specific velocity as well as a thrust to reach to the desired height.
• The velocity and thrust of a Satellite Launch Vehicle depend on the weight and orbital height of the satellite. Accordingly, the structure of the launch vehicle is decided and designed.
• The weight of the fuel also contributes a major portion in the total weight of the launch vehicle. This also influences the structure of the launch vehicle.
• In order to use the fuel optimally, multiple stage launch vehicles are now designed and used.
• As the journey of the launch vehicle progresses, the vehicle achieves a specific velocity and a certain height. The fuel in the first stage is exhausted and the empty fuel tank gets detached from the main body of the launch vehicle and falls back into a sea or on unpopulated land.
• As the fuel in the first stage is exhausted, the fuel in the second stage is ignited.
• However, the weight of the launch vehicle is now less than what it was earlier and hence it can move with higher velocity.
• Most of the launch vehicles are made up of two or more stages.
• Polar Satellite Launch Vehicle, that is, PSLV, developed by ISRO (Indian Space
• Research Organisation) has four stages.
• Launch vehicles are very costly as they can be used only once.
• To overcome this problem, USA has developed space shuttles which can be reused many times.
• Space shuttles can be used for both, (a) launching a satellite in space and (b) journey of astronauts.

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Moon mission :

(i) As of now, only Russia, USA, European Union, China, Japan and India have successfully undertaken moon missions.

(ii) Russia executed 15 moon missions between 1959 and 1976. Of these, last four missions brought the stone samples from the moon for study and analysis.

However all these missions were unmanned.

(iii) USA executed moon missions between 1962 and 1972. Some of these missions were unmanned. However, the historic moon mission took place on 20th July

1969, when American astronaut Neil Armstrong became the first human to step on the moon.

(iv) Indian Space Research Organisation (ISRO) successfully launched Chandrayaan-I and placed it in the orbit of the moon. It sent useful information to the earth for about a year. The most important discovery made during the mission was the presence of water on the moon’s surface. India was the first country to discover this.

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Mars mission :

(i) Many nations have sent space crafts towards Mars, but only few of these missions have been successful.

(ii) However, performance of Mangalyaan, the Indian spacecraft sent by ISRO towards Mars was remarkable. Mangalyaan was launched in November 2013 and was placed in the orbit of Mars successfully in September 2014. It has obtained useful information about the surface and atmosphere of Mars.

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Contribution of ISRO:

(1) India has indigenously built various launchers which can put the satellites having the mass up to 2500 kg in the orbit.

(2) Indian Space Research Organisation (ISRO) has designed and built two important launchers; Polar Satellite Launch Vehicle (PSLV) and Geo Satellite Launch Vehicle

(GSLV).

(3) Successful space missions as well as scientific and technological accomplishments by India in space technology have made a significant contribution in the national and social development of our country.

(4) Many satellites in INSAT and GSAT series are active in telecommunication, television broadcasting, meteorological services, disaster management and monitoring and management of natural resources.

(5) EDUSAT is used specifically for education while satellites in IRNSS series are used for navigation.

(6) Thumba, Sriharikota and Chandipur are Indian satellite launch centres.

(7) Vikram Sarabhai Space Centre at Thiruvananthapuram, Satish Dhawan Space

Research Centre at Sriharikota and Space Application Centre at Ahmadabad are space research organisations of India.

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Management of space debris :

Though very few countries in the world have the capability to launch satellites in orbit, the international cooperation and commercial prospects have led to many other countries having their own satellites in space.

• Due to failed launching, there are many satellites and parts of launchers, which are roaming freely in different orbits around the earth.
• In a way, they form space debris (fragments of satellites and launchers) orbiting in uncontrolled manner.
• By an estimate there are about two crore small and large pieces of satellites and launchers revolving around the earth.
• These debris certainly pose a threat to the current functional satellites, space shuttles and space stations.
• If this collection of fragments remains unchecked and uncontrolled, it is likely to be risky to all future launching of satellites and space shuttles and there is a growing possibility of space accidents.
• Research and dedicated efforts are on to find the means and ways of managing the space debris.

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