Satellites
A satellite is a celestial or man-made object that revolves around a planet.
Satellites are classified as:
- Natural Satellites β like Earthβs Moon
- Artificial Satellites β human-made devices launched into orbit
In Bihar, satellites play a vital role in disaster warning, flood mapping, crop monitoring, and e-learning via EDUSAT.
Natural Satellites
- Earth has one natural satellite: the Moon
- Other planets also have moons (e.g. Jupiter: 92+, Saturn: 146+)
- Functions:
- Cause tides and eclipses
- Stabilize planetary motion
- Aid in biological rhythms
π PYQ (BPSC 66th): Distance of Moon from Earth? β 3.84 lakh km
Artificial Satellites
Man-made satellites launched by rockets for specific purposes.
Orbits:
-
Geostationary Orbit (GEO):
- 36,000 km altitude
- Stays fixed above one point on Earth
- Used for: TV, telecom, weather
-
Polar Orbit/LEO:
- 500β2,000 km altitude
- Covers full Earth in strips
- Used for: remote sensing, spy satellites, earth observation
π Expected MCQ: Geostationary satellites are used for? β Telecommunication
Key Types of Artificial Satellites
1. Communication Satellites
- Transmit signals for TV, phone, internet
- Example: INSAT series
- Bihar uses them for e-learning, telemedicine
2. Remote Sensing Satellites
- Collect images/data for land, water, crops
- Example: IRS series, CartoSat
- Bihar uses them for flood mapping, crop monitoring
π PYQ: What is CartoSat used for? β Earth imaging
3. Weather Satellites
- Monitor clouds, cyclones, rainfall
- Example: INSAT-3D, Kalpana-1
- Used by IMD Patna for forecasts
4. Navigation Satellites
- Provide GPS-like services
- Example: NavIC (India's own GPS system)
π Expected MCQ: What is the name of India's GPS system? β NavIC
5. Scientific Satellites
- Study space, radiation, atmosphere
- Example: ASTROSAT, Chandrayaan-1, Aditya-L1 (Sun mission)
6. Defense & Spy Satellites
- Used for surveillance, border security
- Example: RISAT series, GSAT-7
7. Student/Education Satellites
- Built by students, used in academics
- Example: ANUSAT, EDUSAT
- Bihar has used EDUSAT for virtual classrooms
India's Major Satellite Achievements
- Aryabhata (1975): First Indian satellite
- INSAT series: Communication & weather
- IRS series: Remote sensing
- Chandrayaan-1 & 2: Moon missions
- Mangalyaan (2013): Mars Orbiter Mission
- Aditya-L1: First Indian solar observatory in space
- ISRO launches via PSLV and GSLV rockets
π PYQ (BPSC Teacher): First Indian satellite? β Aryabhata
π Expected MCQ: Which satellite was India's first interplanetary mission? β Mangalyaan
Satellite Applications in Bihar
- Flood Monitoring: Ganga-Kosi plains via CartoSat
- Crop Condition Analysis: Satellite NDVI mapping
- e-Shiksha & EDUSAT: Used in remote schools
- Disaster Early Warning: Monsoon + cyclone data via INSAT
- Solar Energy Planning: Rooftop mapping via ISRO + BREDA
- Land Use Surveys: Irrigation and soil usage pattern
PYQs + Expected MCQs
π PYQ (BPSC 66th): Distance of Moon from Earth? β 3.84 lakh km
π PYQ: CartoSat is used for? β Earth imaging
π PYQ: First Indian satellite? β Aryabhata
π Expected MCQ: NavIC is? β Indiaβs GPS system
π Expected MCQ: Satellite used for flood monitoring? β IRS/CartoSat
π Expected MCQ: Orbit where weather satellites are placed? β Geostationary Orbit
π Expected MCQ: Satellite for Sun studies? β Aditya-L1
Quick Revision Points
- Satellite = Object revolving around a planet
- Moon: Earth's natural satellite
- Orbits: GEO (fixed), LEO (pole-to-pole)
- First Indian satellite: Aryabhata (1975)
- ISRO: Launches via PSLV, GSLV
- INSAT: Telecom & weather
- IRS, CartoSat: Earth observation
- EDUSAT: Education in Bihar
- NavIC: Indian navigation
- Aditya-L1: Studies the Sun
- Bihar: Uses satellites for flood mapping, agri-planning, remote schooling
Sources Used
- NCERT Class 6β10 Science (Space Tech sections)
- Lucent GK β Astronomy & ISRO updates
- Drishti Science Quick Book
- ISRO official website (isro.gov.in)
- Ghatna Chakra + EduTeria BPSC PYQs
- Bihar Disaster Management Portal
- BREDA β Solar Mapping Documents