- ISRO was founded on August 15, 1969; its founding vision came from Vikram Sarabhai. India's first rocket was launched from Thumba (Kerala) on November 21, 1963.
- India's first satellite, Aryabhata, was launched on April 19, 1975 on a Soviet rocket. Most launches now take place from the Satish Dhawan Space Centre, Sriharikota.
- This page covers the lasting concepts and milestones; for the latest updates see the current affairs notes.
ISRO's Launch Vehicles
| Vehicle | Best known for |
|---|---|
| SLV-3 | India's first launch vehicle; placed Rohini in orbit in 1980 (project led by A.P.J. Abdul Kalam) |
| PSLV | ISRO's "workhorse" for polar and sun-synchronous orbits; launched Chandrayaan-1 (2008) and Mangalyaan (2013); put a record 104 satellites into orbit in one launch on February 15, 2017 |
| GSLV | Uses an indigenous cryogenic upper stage (liquid hydrogen and liquid oxygen) for heavier satellites and higher orbits; launched NISAR in 2025 |
| LVM3 (formerly GSLV Mk III) | India's heaviest rocket; launched Chandrayaan-2, Chandrayaan-3 and OneWeb satellites, and is the vehicle for Gaganyaan |
| SSLV | Small Satellite Launch Vehicle for low-cost, quick launches of small satellites |
Types of Orbits
| Orbit | Height | Used for |
|---|---|---|
| Low Earth Orbit (LEO) | About 160–2,000 km | Earth observation, space stations (the ISS) |
| Sun-synchronous (SSO) | A polar LEO, roughly 600–800 km | Remote sensing — passes over a place at the same local time each day |
| Medium Earth Orbit (MEO) | 2,000–35,786 km | Navigation constellations such as GPS |
| Geostationary (GEO) | 35,786 km above the equator | Communication and weather satellites (GSAT, INSAT) — period of 24 hours, so it seems fixed over one spot |
NavIC (formerly IRNSS) is India's regional navigation system, using satellites in geostationary and inclined geosynchronous orbits.
ISRO foundedAug 15, 1969
First satelliteAryabhata, 1975
GEO height35,786 km
Chandrayaan-3 landingAug 23, 2023
Mars orbitSept 24, 2014
SpaDeX dockingJan 16, 2025
Landmark Indian Space Missions
| Mission | Date | Why it matters |
|---|---|---|
| Chandrayaan-1 | Launched October 22, 2008 | India's first Moon mission; helped confirm water molecules on the lunar surface |
| Mangalyaan (Mars Orbiter Mission) | Launched November 5, 2013; reached Mars orbit September 24, 2014 | India became the first Asian country to reach Mars orbit, and the first nation to do so on its first attempt |
| Chandrayaan-2 | Launched July 22, 2019 | Orbiter still working; the Vikram lander crashed during descent |
| Chandrayaan-3 | Launched July 14, 2023; landed August 23, 2023 | First landing near the lunar south pole; India the fourth country to soft-land on the Moon. August 23 is now National Space Day and the landing site is named Shiv Shakti point |
| Aditya-L1 | Launched September 2, 2023; entered a halo orbit on January 6, 2024 | India's first solar observatory, at the Sun–Earth Lagrange point L1, about 1.5 million km away |
| XPoSat | Launched January 1, 2024 | India's first X-ray polarimetry satellite for studying black holes and neutron stars |
| SpaDeX | Docking achieved January 16, 2025 | India became the fourth country (after the USA, Russia and China) to dock two spacecraft in orbit — a key step for a space station |
| NISAR | Launched July 30, 2025 on GSLV-F16 | A joint NASA–ISRO radar satellite for mapping Earth's land and ice surfaces |
India plans its own space station, the Bharatiya Antariksh Station, with the first module targeted for 2028. The Gaganyaan human spaceflight programme is covered in our Gaganyaan and Chandrayaan-4 notes.
India's Missile Programme
The Integrated Guided Missile Development Programme (IGMDP) began in 1983 under A.P.J. Abdul Kalam at DRDO (founded 1958). It produced five missiles:
| Missile | Type |
|---|---|
| Prithvi | Short-range surface-to-surface ballistic missile |
| Agni | Ballistic missile family — Agni-V has a range of over 5,000 km; its first flight with MIRV technology (several warheads, each with its own target) was Mission Divyastra on March 11, 2024 |
| Akash | Medium-range surface-to-air missile |
| Nag | Third-generation "fire and forget" anti-tank guided missile |
| Trishul | Short-range surface-to-air missile (programme closed) |
BrahMos, a supersonic cruise missile, is a joint venture of India and Russia; its name combines the Brahmaputra and Moskva rivers.
Navy and the Nuclear Triad
- INS Vikrant, India's first indigenously built aircraft carrier, was commissioned on September 2, 2022.
- INS Arihant, the first indigenous nuclear-powered ballistic missile submarine, completed its first deterrence patrol in 2018, completing India's nuclear triad — the ability to launch nuclear weapons from land, air and sea.
- Tejas is India's indigenous light combat aircraft, built by HAL.
- Vehicle ↔ mission: PSLV → Chandrayaan-1 and Mangalyaan; LVM3 → Chandrayaan-3; GSLV → NISAR.
- "First" questions: first Asian country at Mars, first near the lunar south pole, fourth country to dock in space.
- Missile ↔ type: Akash (surface-to-air), Nag (anti-tank), Prithvi/Agni (ballistic), BrahMos (cruise).
Q1. Chandrayaan-3 landed near the Moon's south pole on:
✅ Answer: (b) August 23, 2023
💡 Explanation: The Vikram lander touched down on August 23, 2023, now National Space Day.
Q2. A geostationary satellite orbits at a height of about:
✅ Answer: (a) 35,786 km
💡 Explanation: At 35,786 km above the equator, the orbital period matches Earth's rotation (24 hours).
Q3. Which Indian launch vehicle placed a record 104 satellites in orbit in 2017?
✅ Answer: (d) PSLV
💡 Explanation: PSLV-C37 launched 104 satellites on February 15, 2017.
Q4. Akash is a:
✅ Answer: (a) Surface-to-air missile
💡 Explanation: Akash is a medium-range surface-to-air missile developed under the IGMDP.
Q5. With SpaDeX in January 2025, India became the ___ country to dock two spacecraft in orbit.
✅ Answer: (c) Fourth
💡 Explanation: India followed the USA, Russia and China.
🔁 Revise in 60 Seconds
- ISRO 1969 (Sarabhai); Thumba 1963; Aryabhata 1975; SLV-3 1980.
- PSLV workhorse (104 satellites, 2017); GSLV cryogenic; LVM3 heaviest.
- Mangalyaan Mars orbit 2014; Chandrayaan-3 landing Aug 23, 2023; Aditya-L1 at L1 (Jan 2024); SpaDeX docking Jan 2025; NISAR July 2025.
- IGMDP 1983: Prithvi, Agni, Akash, Nag, Trishul; BrahMos India–Russia.
📌 Prelims Traps to Avoid
- ✘ Aryabhata was launched on a Soviet rocket, not an Indian one.
- ✘ Chandrayaan-3 made India the fourth country to soft-land on the Moon but the first near the south pole.
- ✘ BrahMos is a cruise missile, not a ballistic missile.
What is the difference between PSLV and GSLV?
PSLV is mainly used to place satellites in polar and sun-synchronous low Earth orbits. GSLV uses a cryogenic upper stage to carry heavier satellites to geosynchronous transfer orbit. LVM3 is the heaviest variant.
When did Chandrayaan-3 land on the Moon?
On August 23, 2023, near the lunar south pole. India was the first country to land in that region, and August 23 is now celebrated as National Space Day.