Space and Defence Technology

Core concepts

ISRO and launch vehicles

• The Indian Space Research Organisation (ISRO) was founded in 1969; its first satellite was Aryabhata (1975), launched with Soviet help.
• Vikram Sarabhai is the father of the Indian space programme; the headquarters is in Bengaluru and the main launch site is the Satish Dhawan Space Centre, Sriharikota (Andhra Pradesh). A second launch site at Kulasekarapattinam (Tamil Nadu) is being developed for small launch vehicles.
• SLV and ASLV were the early experimental vehicles. A. P. J. Abdul Kalam led the SLV-3 that put Rohini into orbit in 1980.
• PSLV (Polar Satellite Launch Vehicle): the reliable workhorse for Earth-observation and many small satellites; it launched Chandrayaan-1 and Mangalyaan. A single PSLV mission placed 104 satellites in orbit in 2017, a record at the time.
• GSLV (Geosynchronous Satellite Launch Vehicle): for heavier communication satellites; it uses an indigenous cryogenic upper stage.
• LVM3 (GSLV Mk III): the heavy-lift vehicle that launched Chandrayaan-2 and Chandrayaan-3 and is the launcher planned for the Gaganyaan human-spaceflight mission. It has also flown commercial OneWeb satellites.

Headline missions (verify the latest status)

• Chandrayaan-1 (2008): India's first Moon mission; found evidence of water on the Moon.
• Mangalyaan / Mars Orbiter Mission (2013 to 2014): India's first Mars mission, making India the first nation to reach Mars orbit on its first attempt and at low cost.
• Chandrayaan-2 (2019): orbiter succeeded; the lander (Vikram) did not soft-land.
• Chandrayaan-3 (2023): soft-landed near the Moon's south pole, making India the fourth country to soft-land on the Moon and the first near the south pole; the landing site was named Shiv Shakti Point.
• Aditya-L1 (2023 to 2024): India's first solar observation mission, stationed at the Sun-Earth Lagrange point L1.
• Gaganyaan: India's planned crewed orbital mission (verify the latest schedule).

Satellite families

• INSAT and GSAT: communication, broadcasting, telemedicine and meteorology.
• IRS (Indian Remote Sensing): Earth observation, agriculture, water, forestry and disaster mapping.
• NavIC (IRNSS): India's own regional satellite navigation system, the Indian counterpart to the American GPS, the Russian GLONASS, the European Galileo and the Chinese BeiDou.
• Cartosat, RISAT and Oceansat: mapping, radar-imaging and ocean-observation satellites with civil and security uses.

DRDO and major missiles

• The Defence Research and Development Organisation (DRDO), founded 1958, develops India's defence systems. Its Integrated Guided Missile Development Programme (IGMDP), led by Dr A. P. J. Abdul Kalam (the Missile Man of India), produced several missile families.

• BrahMos is named after the Brahmaputra and the Moskva rivers; it can be launched from land, sea and air.
• India demonstrated an anti-satellite (ASAT) capability under Mission Shakti (2019), joining the United States, Russia and China.

Orbits and space terminology

• A satellite is any object that orbits a larger one; artificial satellites are launched for communication, observation, navigation and weather.
• A geostationary (geosynchronous) orbit is about 36,000 km above the equator; a satellite there appears fixed over one point and is ideal for communication and broadcasting (INSAT, GSAT).
• A polar (sun-synchronous) orbit is a low orbit passing near the poles, used for Earth observation and remote sensing (IRS, Cartosat).
• Escape velocity is the minimum speed needed to leave the Earth's gravity, about 11.2 km/s.
• A cryogenic engine burns liquid hydrogen with liquid oxygen at very low temperatures and gives high thrust for heavy launches; India mastered indigenous cryogenic technology for the GSLV.
• A multistage rocket drops empty stages to shed weight, applying Newton's third law (see physics everyday).

Nuclear technology basics

• Nuclear fission splits a heavy nucleus (uranium-235 or plutonium-239) and releases energy; it powers nuclear reactors and fission bombs. A chain reaction is controlled in a reactor (by control rods that absorb neutrons and a moderator such as heavy water that slows them) and uncontrolled in a bomb.
• Nuclear fusion joins light nuclei (hydrogen isotopes deuterium and tritium) and releases far more energy; it powers the Sun and the hydrogen bomb, but controlled fusion for power is still experimental.
• Homi J. Bhabha is the father of the Indian nuclear programme. India's first nuclear test was Pokhran-I (Smiling Buddha, 1974); the second series was Pokhran-II (1998), after which India declared itself a nuclear-weapon state.
• India follows a no first use nuclear doctrine and a credible minimum deterrent based on the nuclear triad, the ability to deliver nuclear weapons from land (Agni missiles), air (fighter aircraft) and sea (the Arihant-class submarines).
• The Department of Atomic Energy and the Atomic Energy Commission govern the programme. India is not a party to the Nuclear Non-Proliferation Treaty (NPT) but signed the India-US civil nuclear deal and is in the Missile Technology Control Regime.