Space Missions Science Notes
- The visible portion of the atmosphere and outer space seen by simple eyes, without any equipment from the earth, is known as the sky.
- The infinite three-dimensional expanse in which the Solar system, stars, celestial bodies, galaxies and the endless Universe exist is known as space.
- Both sky and space lack a definite boundary However, the sky is a very tiny part of space.
- Our Solar system is a very tiny part of a huge Galaxy-Milky Way.
- The Sun is at the centre of the Solar system. Sun is a star.
- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune are planets in our Solar system.
- These planets revolve around the Sun. Some of these planets have their own natural satellites.
- Besides, there are asteroids, meteoroids, comets and meteors in the Solar system.
- An astronomical object orbiting any planet of our Solar system is called a satellite.
- Mercury and Venus have no satellites.
- Some planets have more than one satellite. E.g. Jupiter has 69 satellites.
- The earth has one natural satellite called the moon.
→ The following three types telescopes are orbiting around the earth :
- Optical Refracting Telescope.
- Optical Reflecting Telescope.
- Radio Telescope.
→ 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.
→ The first person to go into space in a spacecraft was Yuri Gagarin of the then USSR. He orbited the earth in 1961. The first person to step on the Moon (1969) was Neil Armstrong of USA. Rakesh Sharma of India orbited the earth in 1984 in a Russian spacecraft.
→ Kalpana Chawla and Sunita Williams of Indian origin also participated in space explorations through missions organized by NASA (National Aeronautics and Space Administration) of USA.
→ In nearby area of our residence, many mobile towers are installed at various places. Cellphones receive signals from one of these mobile towers.
→ All mobile towers are connected to satellites. Cellphone signal reaching the nearest mobile tower in our vicinity is first transmitted to the satellite. The satellite transmits the signal to the mobile tower near the destination.
→ Television Centre or Studio transmits the TV programme which first reaches the satellite. The dish antenna of the cable operator in our area receives these signals. The TV programmes reach our TV set through a cable connected between the cable operator’s receiving station and our TV set.
→ Alternatively, a small portable dish antenna fixed on the rooftop is also used to receive the TV signals directly from the satellites. Finally, a cable connected to the dish antenna and TV set brings the programme to our TV set.
→ Weather satellites take photographs of the sky above the earth’s surface at regular intervals. Some satellites, capable of receiving radio signals, also collect the information of weather conditions and finally images of the sky are built with computers. Territorial boundaries of the states and the country are drawn later on these images. Such satellite images with imposed boundaries are printed in media or shown on the television.
→ Students can prepare this presentation on the basis of the following outline:
- Formation and objectives of ISRO
- Indian space scientists
- Space missions of India
- Current functional satellites of India
- Research and other centres of ISRO in India
- India’s moon mission and mars mission
- Information regarding the launching of satellites of other countries by India.
- Indian astronauts and astronauts of Indian origin
- Future plans of India’s space mission.
→ Keep it in mind/Do Remember :
- INSAT : Indian National Satellite
- GSAT : Geosynchronous Satellite
- IRNSS : Indian Regional Navigation Satellite
- System IRS : Indian Remote Sensing Satellite
- GSLV : Geosynchronous Satellite Launch
- Vehicle PSLV : Polar Satellite Launch Vehicle