On 23 August 2023, ISRO's Chandrayaan-3 lander Vikram touched down near the Moon's south polar region, making India the first country to land there and only the fourth to achieve a soft landing on the Moon. Chandrayaan-3 was among India's most searched topics that year. Behind those final tense minutes was years of engineering, much of it learned from the Chandrayaan-2 lander's crash in 2019.
Why landing on the Moon is so hard
The Moon has no air, so parachutes are useless. The only way to slow down is with rocket engines, firing precisely to cancel the spacecraft's speed of well over a kilometre per second. And because radio signals take over a second each way, the lander must make all final decisions by itself, using its own sensors and software.
What ISRO changed after Chandrayaan-2
- A bigger landing zone: the target area was enlarged so the lander could choose a safe spot instead of aiming for a tiny patch.
- Stronger legs to tolerate a harder touchdown.
- More fuel so it could hover and reroute if needed.
- More sensors, including a laser Doppler velocimeter to measure speed accurately, plus better hazard-detection cameras.
- More tolerant software designed to handle sensor or engine failures and still land.
The final descent
- Rough braking: engines fire to slow the lander from orbital speed while it is still high above the surface.
- Attitude hold: the lander turns upright and checks its position against stored maps.
- Fine braking: speed and height reduce steadily.
- Hovering and hazard check: cameras scan for boulders and slopes and pick a safe spot.
- Terminal descent: a slow, vertical touchdown.
What Pragyan did
After landing, the Pragyan rover rolled down a ramp and explored the surface for about a lunar day, roughly 14 Earth days, powered by solar panels. Its instruments analysed the surface composition, and ISRO reported detecting sulphur and other elements. The lander's instruments measured temperature changes in the lunar soil and recorded vibrations.
Why the south pole matters
Some craters near the lunar poles stay permanently in shadow and are thought to hold water ice. Water could one day provide drinking water, oxygen and rocket fuel for future explorers, which is why many countries are now targeting this region.
Frequently asked questions
Why did the rover stop after two weeks?
The lunar night lasts about two weeks and is extremely cold. The lander and rover were designed for one lunar day and were put to sleep before nightfall.
What rocket launched Chandrayaan-3?
ISRO's LVM3, its heaviest launch vehicle, launched it from Sriharikota on 14 July 2023.