Chapter 10: Space Missions

Space Science | Satellite Technology | ISRO Achievements | Complete guide to space exploration and technology

1 Introduction

A space mission is a scientific journey undertaken to explore outer space using artificial satellites, space probes, rockets, and space stations.

Space missions help us understand the Earth, Moon, Sun, planets, stars, and the universe. India has made remarkable progress in space technology through ISRO (Indian Space Research Organisation).

2 Artificial Satellites

2.1 What is a Satellite?

A satellite is an object that revolves around a planet. Artificial satellites are man‑made objects launched into space to orbit the Earth or other celestial bodies.

2.2 Types of Artificial Satellites

Communication Satellites

Used for TV broadcasting, radio, internet, and mobile communication across the globe.

Examples: INSAT, GSAT series

Weather Satellites

Used for weather forecasting, cyclone tracking, and climate monitoring.

Examples: Kalpana, INSAT-3D

Remote Sensing Satellites

Used for resource mapping, agriculture monitoring, and disaster management.

Examples: IRS series, Cartosat

Navigation Satellites

Used in GPS, location services, and navigation systems.

Examples: IRNSS (NavIC), GPS satellites

3 Rockets and Launch Vehicles

A rocket is a vehicle used to launch satellites and spacecraft into space.

3.1 Principle of Rocket

Rockets work on Newton's Third Law of Motion: "For every action, there is an equal and opposite reaction." The expulsion of exhaust gases backward propels the rocket forward.

3.2 Types of Launch Vehicles (India)

PSLV

Polar Satellite Launch Vehicle

  • Used for launching satellites into polar orbits
  • Known as ISRO's reliable workhorse
  • Has launched Chandrayaan-1 and Mars Orbiter Mission
  • Can carry payloads up to 1,750 kg to Sun-synchronous orbit

GSLV

Geosynchronous Satellite Launch Vehicle

  • Used for heavier satellites and geostationary orbits
  • Features indigenous cryogenic engine
  • Can carry payloads up to 2,500 kg to GTO
  • Used for communication satellite launches

4 Orbits of Satellites

Polar Orbit

  • Satellite passes over Earth's poles
  • Altitude: 500-800 km
  • Orbital period: ~90 minutes
  • Covers entire Earth in a few days
  • Uses: Earth observation, remote sensing, weather monitoring

Geostationary Orbit

  • Satellite appears stationary relative to Earth
  • Altitude: ~36,000 km
  • Orbital period: 24 hours (matches Earth's rotation)
  • Positioned above equator
  • Uses: Communication, TV broadcasting, weather monitoring

5 Space Probes

Space probes are unmanned spacecraft sent to explore celestial bodies like the Moon, Mars, and other planets.

Chandrayaan‑1

Launch Date: October 2008

Mission: India's first lunar probe

Achievements:

  • Discovered water molecules on the Moon
  • Mapped lunar surface minerals
  • Confirmed magma ocean hypothesis
  • Operated for 312 days (planned 2 years)

Mangalyaan (MOM)

Launch Date: November 2013

Mission: Mars Orbiter Mission

Achievements:

  • India's first interplanetary mission
  • Studied Mars atmosphere and surface
  • Successfully entered Mars orbit in first attempt
  • One of the most cost-effective Mars missions
  • Operated for 7+ years (planned 6 months)

6 Space Stations

A space station is a large spacecraft that remains in orbit for long periods and allows astronauts to live and conduct experiments in microgravity.

Uses of Space Stations:

  • Scientific experiments in microgravity conditions
  • Study of human survival in space for long durations
  • Earth and space observation from unique vantage point
  • Testing new technologies for future space missions
  • International cooperation in space exploration

Examples: International Space Station (ISS), Tiangong (China), Mir (Russia, retired)

7 Indian Space Programme

7.1 ISRO (Indian Space Research Organisation)

ISRO is India's national space agency, founded in 1969 with headquarters in Bengaluru.

Achievements of ISRO:

  • Successful satellite launches with high reliability
  • Cost‑effective space missions (Mars mission at $74 million)
  • Development of indigenous launch vehicles (PSLV, GSLV)
  • Establishment of Indian Regional Navigation Satellite System (IRNSS/NavIC)
  • Recognition as a leading space agency globally

Major Indian Space Missions

Aryabhata (1975)

India's first satellite, named after the ancient Indian mathematician. Launched by Soviet Union.

Chandrayaan-1 (2008)

First Indian lunar probe that discovered water molecules on Moon's surface.

Mangalyaan (2013)

Mars Orbiter Mission, made India first Asian nation to reach Mars orbit.

Chandrayaan-2 (2019)

Second lunar exploration mission with orbiter, lander, and rover.

Aditya-L1 (2023)

India's first solar mission to study the Sun's corona and solar winds.

8 Applications of Space Technology

Communication
TV, radio, internet, mobile networks

Weather Forecasting
Cyclone tracking, climate monitoring

Navigation
GPS, location services, mapping

Disaster Management
Flood monitoring, earthquake assessment

Agriculture
Crop monitoring, soil assessment

National Security
Surveillance, border monitoring

9 Importance of Space Missions

  • Expands scientific knowledge about universe, planets, and space phenomena
  • Drives technological development with spin-off technologies
  • Improves daily life through satellite-based services
  • Enhances national prestige and international standing
  • Promotes international cooperation in peaceful space exploration
  • Inspires future generations to pursue STEM careers

Important Points for Examination

  • Know types of satellites and their specific uses
  • Understand rocket principle (Newton's Third Law)
  • Learn about Indian space missions and ISRO's role
  • Differentiate between polar and geostationary orbits
  • Identify achievements of Chandrayaan and Mangalyaan
  • Know about PSLV and GSLV launch vehicles
  • Understand applications of space technology in daily life
  • Remember timeline of major Indian space missions