Overview of the Subject
- Relevance - 13-14 Questions in Prelims & 2-4 questions in mains
- Sources- 9th & 10th NCERT, The Hindu, Indian Express, Monthly Magazine, Youtube channels, www.Indiascience.in, Prasarbharti
- Topics to be covered in the class:
- 1. Space technology
- 2. Nuclear Technology
- 3. ICT and Robotics
- 4. IPR
- 5. Defence technology
- 6. Contribution of Indian scientists
Space Technology
- Newton's three laws of motion
- Vector & scalar
- Kepler's laws of planetary motion
- Centripetal force
- Topics to be covered under space-
- Types of orbits
- Types of satellites
- Types of rockets of ISRO
- Past missions of ISRO
- Future missions of ISRO
- Space debris
Kepler's law of Planetary motion
- Every planet revolves around the sun in an elliptical orbit with the sun being at one of the foci of the ellipse.
- Planets sweep the equal area in equal time.
- The square of the time period of revolution of a planet is proportional to the cube of the semi-major axis of the ellipse.
Types of Orbits -
- Satellites can orbit around the earth because the earth provides the necessary centripetal force for a stable orbit.
- This centripetal force is because of gravitational attraction between the earth and the satellite.
- We can categorize orbits based on many parameters:
- 1. Based on height-
- -Low earth orbit (LEO)- 180-2000 Km
- -Medium earth orbit (MEO)- 2000-35785 Km
- -Geosynchronous and high earth orbit (>35785 Km)
- LEO is easier to achieve and useful for earth observation.
- However, they can only monitor a small part of the earth.
- Higher orbits are more difficult to achieve, they can monitor a large part of the earth simultaneously.
- However, resolution suffers hence, higher orbits are generally used for communication satellites.
- 2. Based on inclination-
- -Equatorial orbits (zero degrees)
- -Polar orbit (90 degrees)
- -Inclined orbit (rest)
- Polar launches are more difficult because they do not get any assistance from earth rotation.
- However polar orbits are more useful for earth observation because the earth is rotating below it and the satellite revolves around the earth hence it can monitor all points of the earth by being in a polar orbit.
- Because of the curvature of the earth polar orbits are very useful to monitor poles.
- 3. Based on earth's motion -
- -Rotation on its axis (Geosynchronous) -Satellites in such orbit, orbit around in a way that their orbital motion is synchronized with the earth's rotation on its axis i.e satellite will complete one revolution in one side real day which is 23 hours, 53 min, 4 sec.
- A special case of Geosynchronous is geostationary.
- Satellites in geostationary orbit above the equator will seem to be fixed above a point on the equator.
- These orbits are very useful for communication satellites as we can maintain communication channels without worrying about loss of line of sight due to the earth's rotation and satellite's revolution.
- The altitude is 35,786 Km.
- Launching into these orbits is regulated by the International Telecommunication Union an agency of the UN.
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