Lesson 1 of 7 | Science & Technology / Space, Biotechnology and Emerging Technologies
India's Space Programme: ISRO, Launch Vehicles and Orbits
1 practice test
Institutions
- INCOSPAR was set up in 1962 under Dr Vikram Sarabhai; it became ISRO in 1969.
- Department of Space and the Space Commission were created in 1972. ISRO headquarters: Bengaluru.
- IN-SPACe (2020) authorises private space activity; NSIL is ISRO's commercial arm.
Launch vehicles
- PSLV: workhorse for Sun-Synchronous / polar orbits; launched Chandrayaan-1 (2008) and Mangalyaan (2013).
- GSLV (Mk II): uses an indigenous cryogenic upper stage; places satellites in GTO.
- LVM3 (GSLV Mk III): heavy-lift; launched Chandrayaan-2 (2019) and Chandrayaan-3 (2023).
- SSLV: small satellite launch vehicle for quick, low-cost launches.
Types of orbits
| Orbit | Altitude | Use |
|---|---|---|
| Low Earth Orbit (LEO) | ~160–2,000 km | Earth observation, ISS |
| Sun-Synchronous (SSO) | ~600–800 km, polar | Remote sensing (same local time over a place) |
| Geostationary (GEO) | ~35,786 km above equator | Communication, weather (INSAT/GSAT) |
Landmark missions
- Aryabhata (1975): India's first satellite (launched by the USSR).
- Mangalyaan / Mars Orbiter Mission (2013): India reached Mars orbit in its first attempt (2014).
- Chandrayaan-3 (2023): first soft landing near the Moon's south polar region; landing point named Shiv Shakti.
- Aditya-L1 (2023): solar observatory at the Sun–Earth Lagrange point L1, about 1.5 million km from Earth.
- NavIC: India's regional navigation satellite system.
- Gaganyaan: human spaceflight programme.
Prelims tips
- Geostationary satellites have a 24-hour period and appear fixed over the equator.
- Cryogenic engines use liquid hydrogen and liquid oxygen.
Analogy
Orbits are like lanes on a circular running track. Inner lanes (LEO) are short, so runners (satellites) finish a lap in about 90 minutes and see different parts of the field each time. The far outer lane (GEO) is so long that a runner takes exactly 24 hours — the same time the field itself rotates — so, to a spectator on the ground, that runner seems to stand still.