Chandrayaan-3:
Following the lessons learned from Chandrayaan-2, the Indian Space Research Organisation (ISRO) meticulously designed Chandrayaan-3 to achieve the ultimate goal: a safe and soft landing on the Moon. Launched on July 14, 2023, using the LVM3-M4 launch vehicle, this mission successfully made India the fourth country to land on the Moon and the first country in the world to land a spacecraft near the challenging lunar South Pole.
Learning from the Past: A "Failure-Based" Design
Chandrayaan-3 was built using a unique “failure-based design” approach. Instead of only planning for success, ISRO scientists analyzed everything that could possibly go wrong based on the Chandrayaan-2 experience. They reinforced the new lander by strengthening its landing legs, increasing its fuel capacity, upgrading its navigation software, and adding solar panels on multiple sides to ensure it could generate power regardless of how it landed.
Mission Modules and Objectives
Unlike Chandrayaan-2, this mission did not carry a dedicated Orbiter, as the Chandrayaan-2 Orbiter was already functioning well in space. Instead, the Chandrayaan-3 spacecraft consisted of three main components:
- Propulsion Module: Its primary job was to carry the Lander and Rover from the Earth’s orbit to a 100 km circular orbit around the Moon.
- Vikram Lander: Designed to autonomously execute the complex soft-landing sequence.
- Pragyan Rover: A 6-wheeled robotic vehicle housed inside the lander, designed to roll out and explore the lunar soil.
The primary objectives of the mission were clear and focused:
- To demonstrate a safe and soft landing on the lunar surface.
- To demonstrate the Rover moving continuously on the Moon.
- To conduct on-site (in-situ) scientific experiments.
The Historic Touchdown
After a 40-day journey through space, the Vikram lander successfully touched down on the Moon’s surface on August 23, 2023. This historic landing spot was officially named “Shiv Shakti Point.” To honor this monumental achievement in science and technology, the Government of India declared August 23 as National Space Day.
Scientific Payloads on Chandrayaan-3
Once safely on the surface, the Lander and Rover activated their instruments to study the lunar environment. The table below outlines the scientific payloads carried by the different modules.
Module | Name of the Scientific Payload | Abbreviation | Primary Function |
Propulsion Module | Spectro-polarimetry of HAbitable Planet Earth | SHAPE | To study Earth’s atmosphere from lunar orbit to help identify habitable planets outside our solar system. |
Vikram (Lander) | Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere | RAMBHA-LP | To measure the density of plasma (ions and electrons) near the lunar surface and how it changes over time. |
Chandra’s Surface Thermo-physical Experiment | ChaSTE | To measure the temperature and thermal properties of the lunar topsoil. | |
Instrument for Lunar Seismic Activity | ILSA | To detect moonquakes and study the structure of the Moon’s crust and mantle. | |
Laser Retroreflector Array (NASA Contribution) | LRA | A passive mirror system used to measure the exact distance between the Earth and the Moon. | |
Pragyan (Rover) | Alpha Particle X-ray Spectrometer | APXS | To determine the mineral composition of the lunar rocks and soil. |
Laser Induced Breakdown Spectroscope | LIBS | To detect the exact chemical elements present in the lunar soil using powerful laser pulses. |
Major Scientific Discoveries
The Pragyan rover successfully rolled down its ramp and traveled over 100 meters on the lunar surface. During its operational life of one lunar day (equivalent to 14 Earth days), the mission yielded remarkable discoveries:
- Confirmation of Sulfur: The LIBS instrument provided the first-ever clear, on-site confirmation of the presence of Sulfur (S) on the lunar surface. It also detected other crucial elements like Aluminum, Calcium, Iron, Silicon, and Oxygen.
- Extreme Temperature Variations: The ChaSTE payload inserted a probe into the lunar soil and revealed a surprising temperature profile. While the surface temperature was around 50°C, just 8 centimeters below the surface, the temperature dropped sharply to -10°C. This proved that lunar topsoil is an excellent thermal insulator.
- Recording Moonquakes: The ILSA payload successfully recorded vibrations from the Rover’s movements and also captured a distinct natural seismic event (a moonquake), providing valuable data about the Moon’s internal structure.
