10th Class Science Earth and Universe NCERT Summary - Space Exploration

Space Exploration

SPACE SCIENCE IN WORLD

• The term "outer space" or "space" now usually refers to the vast limitless expanse that exists beyond the Earth's atmosphere.
• Space contains all the stars, planets, gases and dust particles, meteorites, comets, asteroids and radiations.
• The first step into space was taken on 4 October 1957 by the erstwhile Soviet Union (USSR), which successfully launched the first satellite named "Sputnik I" into space.
• Satellite, in general, refers to celestial body that revolves around a planet. The moon, for example, is a natural satellite of the planet Earth. These days, however, the term satellite is used for man made satellites which revolve around the Earth.
• The closed path of a satellite around the Earth is called its orbit. It may be circular or elliptical in shape.
• The characteristics define an orbit are apogee, perigee and inclination. Apogee is the farthest and perigee is the nearest point on the orbit of a satellite from the Earth. The inclination of an orbit is determined by the angle it makes with the equator.
• The USA followed the erstwhile Soviet Union and launched their first spacecraft a few months later. It was named "Explorer". Since then, space technology has made rapid progress. Not only have the satellites or other space probes called "payloads" grown many times in size and weight but their functions also have become more and more complex and demanding.
• Within a few weeks of launching Sputnik I, the erstwhile USSR launched Sputnik II, which had the distinction of carrying a dog, named Laika, for the first time into space. The weight of the satellite was 500 kg. The blood pressure, temperature and heartbeat of Laika were monitored from the Earth for eight days, after which she was allowed to die peacefully as there was no possibility of bringing her back.
• Sputnik II was successful in sending important data, which provided vital information and paved the way for sending the first human into outer space.
• The erstwhile Soviet Union sent the first human into space. Yuri Gagarin completed a single orbit around the Earth on 12 April 1961. The USA followed the event on 5 May 1961, when Alan Shepard became the first American to go into space.
• The main purpose of developing space technology included communication, resource, survey, meteorological studies, scientific experiments and most importantly, collecting information for military purposes, that is, for spying.
• The significant development in space science during the eighties was the establishment of permanent space stations and the development of space shuttles (used to carry astronauts into space), establishing a permanent observatory in space and the maiden flight of Voyager II, which passed very close to all planets of the solar system and sent their pictures to the earth.
• In Nineties (April 1992), another remarkable achievement was to carry out repair of a satellite in space by a team of American astronauts. Later, the repaired satellite was placed back in its original orbit.

Space Science in India

• The foundation of space research in India was laid in 1961. During that period, the task of developing a programme on space research was entrusted by the Government of India to its Department of Atomic Energy. A national committee set up by the Department of Atomic Energy identified two major objectives for the space research programme. These objectives were:

(i) Rapid development of mass communication and education, especially in widely dispersed rural communities

(ii) Timely survey and management of the country's natural resources

• In 1972, a space commission was set up to boost the technological efforts. A separate Department of Space was established.
• The Department of Space executes its space activities through the Indian Space Research Organisation (ISRO).
• The task assigned to ISRO involved development of the know- how to fabricate the rocket, its propellants, its control and guidance systems, and to design and fabricate satellites.
• In India, a beginning in exploration of outer space was made even before the Department of Space came into existence. The first Indian rocket RH-75 was launched in 1967 from Thumba Equatorial Rocket Launching Station (TERLS) near Thiruvananthapuram.
• The historic event of launching of an Indian satellite on an Indian launch vehicle took place on 10 July 1992. The launch vehicle was a 23-metre tall, a five-stage, solid-fuel rocket ASLV-D3, a modified version of ASLV.
• India entered the Space Age on 19 April 1975, when the first satellite was designed and fabricated in India and launched from the erstwhile Soviet Union. The satellite was named "Aryabhata" after the famous Indian mathematician. It was purely experimental in nature. The satellite enabled Indian scientists to develop the skills and facilities for fabricating satellites and monitoring their performance in orbit.
• Aryabhata also provided an opportunity to conduct some experiments in the field of X-ray astronomy, solar physics and meteorology.
• Bhaskara-I was the second Indian satellite that was launched on 7 June 1979 from the erstwhile Soviet Union. It was essentially intended to develop expertise in collecting data on natural resources through remote sensing techniques. Ground water surveys, forestry and geological surveys were conducted through this satellite by collecting valuable data until March 1981.
• Bhaskara-II, launched from the erstwhile Soviet Union on 20 November 1981 functioned successfully for over two years.
• The success of the Bhaskara series of satellites provided our scientists the necessary competence and confidence to design and fabricate the first fully operational remote sensing satellite. The first Indian Remote Sensing satellite, IRS-1A was launched on 17 March 1988, while IRS-IB was successfully put into orbit on 29 August 1991. Both these satellites were launched from the erstwhile USSR.
• To gain experience in using the satellites for communication, a third type of experimental satellite was fabricated by Indian scientists. This was named "APPLE" satellite. APPLE is abbreviation for Ariane Passenger Pay Load Experiment. The satellite was launched on 19 June 1981 with the help of the European Space Agency from the Kourou launching facility in French Guyana (South America). This was the first Indian satellite put up in a geostationary orbit.
• The first operational satellite intended to be used on a commercial basis was conceived in 1977. This programme was named Indian National Satellite System (INSAT). The satellite was expected to carry out three independent tasks, namely (i) communication (ii) television and radio broadcasting (iii) meteorological observation. The construction, testing and launching of the satellite was entrusted to the Ford Aerospace Corporation of the USA.