In under fifty years India went from a 360 kg satellite launched on a Soviet rocket in 1975 to landing Chandrayaan-3 near the Moon's south pole in 2023.
India's first satellite, Aryabhata, was designed and built in India but rode a Soviet Kosmos-3M rocket from Kapustin Yar on 19 April 1975. It weighed 360 kg and carried experiments in X-ray astronomy, aeronomy and solar physics.
It circled Earth in a 563 × 619 km orbit. Its planned mission was six months, but it stayed in orbit for nearly seventeen years and re-entered on 10 February 1992.
India's first satellite launch on its own rocket came five years later. On 18 July 1980 the SLV-3 lifted off from Sriharikota and put the Rohini satellite RS-1 into orbit. SLV-3 was a 22 m, four-stage rocket that burned only solid fuel, weighed 17 tonnes and could carry about 40 kg to low Earth orbit.
Working satellites followed: INSAT-1B for communication and weather in 1983, and IRS-1A for Earth observation in 1988. The GSLV flew for the first time on 18 April 2001, carrying GSAT-1.
Chandrayaan-1 left for the Moon on PSLV-C11 on 22 October 2008. The Mars Orbiter Mission followed on PSLV-C25 on 5 November 2013.
Chandrayaan-2 launched on 22 July 2019. Its orbiter reached the Moon, and all eight of its instruments worked. The Vikram lander did not. During the powered descent on 7 September 2019 it lost speed faster than designed in the second phase. It hard-landed within 500 m of its target site.
Chandrayaan-3 was built as a follow-on to show safe landing and roving. It launched on LVM3 M4 on 14 July 2023 with a lander, a rover inside it and a propulsion module. The Vikram lander touched down near the south pole and released the Pragyan rover. That made India the fourth country to land on the Moon and the first to land near its south pole. 23 August, the landing day, is now India's National Space Day.
Worked example: SLV-3 could lift about 40 kg to low orbit. Today PSLV, GSLV and LVM3 can launch up to 10 tonnes to low Earth orbit. That is 10,000 ÷ 40 = 250 times more, in about four decades.
Scroll from 1975 to 2023 and watch the rocket names change from SLV-3 to PSLV, GSLV and LVM3 as the payloads grow. Open the ISRO missions timeline
Orbit of Aryabhata. Its orbit was 563 × 619 km. The semi-major axis is a = 6,378 + (563 + 619)/2 = 6,969 km. Kepler's third law gives the period T = 2π √(a³/GM), with GM = 398,600 km³/s². So a³ = 3.385 × 10¹¹ km³, a³/GM = 8.49 × 10⁵ s², √ = 921 s, and T = 2π × 921 ≈ 5,790 s ≈ 96.5 minutes.
Mass growth. Aryabhata weighed 360 kg. Chandrayaan-3 weighed 3,900 kg at launch: a 2,148 kg propulsion module and a 1,752 kg lander that carried a 26 kg rover. That is about 10.8 times heavier, and it went to the Moon rather than low orbit.
Why landing is hard. In Chandrayaan-2's first braking phase, from 30 km down to 7.4 km, the lander's speed fell from 1,683 m/s to 146 m/s. Kinetic energy per kilogram is ½v². At 1,683 m/s that is ½ × 1,683² ≈ 1.42 MJ/kg; at 146 m/s it is about 10.7 kJ/kg. So the engines had already removed over 99% of the energy, yet the last few kilometres decided the mission.
Chandrayaan-3's lander was designed to touch down at no more than 2 m/s vertically and 0.5 m/s sideways, on a slope of 12° or less. Going from 1,683 m/s to 2 m/s is a speed cut of more than 800 times, done by engines alone because the Moon has no air for parachutes.
Landing site. The prime site was planned at 69.37° S, 32.35° E, inside a 4 km × 2.4 km zone.
Aryabhata, built in India and launched by a Soviet Kosmos-3M rocket from Kapustin Yar on 19 April 1975.
On 18 July 1980, when SLV-3 placed Rohini RS-1 in orbit from Sriharikota.
During powered descent on 7 September 2019 its speed fell faster than designed in the second phase. The lander started fine braking outside its design limits and hard-landed within 500 m of the target.
It made India the fourth country to land on the Moon and the first to land near the lunar south pole.