On 23 August 2023, India achieved a space exploration milestone when ISRO’s Chandrayaan-3 mission successfully executed a precision soft landing on the lunar terrain, making India the fourth nation globally to land on the Moon and the first to touch down near the lunar South Pole.

Main Task of Chandrayaan-3 Unachieved in Chandrayaan-2

• Demonstration of a Safe and Soft Landing: The primary objective was demonstrating the technological capability to execute a controlled, autonomous soft landing on the Moon’s surface.
• Why Earlier Mission Failed: In September 2019, the Chandrayaan-2 lander (Vikram) experienced terminal velocity braking software deviations during the fine-braking phase, leading to a hard crash onto the lunar surface and preventing deployment of the Pragyan rover.
• Surface Rover Mobility & In-Situ Science: Successfully deploying a six-wheeled robotic rover to conduct in-situ chemical, mineralogical, and seismic experiments on the lunar regolith.

Countries That Have Achieved a Lunar Soft Landing

• The United States (Apollo and Surveyor programs).
• The Soviet Union / Russia (Luna program).
• China (Chang’e missions).
• India (Chandrayaan-3).

Subsystems and Payloads in the Spacecraft

Chandrayaan-3 comprised a Propulsion Module (PM) and a Lander Module (Vikram) housing the Rover (Pragyan):

• Lander Payloads (Vikram):
  • ChaSTE (Chandra’s Surface Thermophysical Experiment): Measured vertical thermal conductivity and temperature gradients of lunar topsoil.
  • ILSA (Instrument for Lunar Seismic Activity): Recorded lunar seismic ground vibrations to study crust-mantle boundaries.
  • RAMBHA-LP (Langmuir Probe): Measured near-surface plasma density variations.
  • LRA (Laser Retroreflector Array): Passive NASA retroreflector for precision laser lunar ranging.
• Rover Payloads (Pragyan):
  • APXS (Alpha Particle X-ray Spectrometer): Determined elemental composition (aluminum, silica, magnesium, iron) of lunar rocks and soil.
  • LIBS (Laser-Induced Breakdown Spectroscope): Used high-energy laser pulses to confirm the presence of sulfur, aluminum, calcium, and iron on the lunar surface.
• Propulsion Module Payload:
  • SHAPE (Spectro-polarimetry of Habitable Planet Earth): Studied Earth’s reflected spectral signatures to identify biomarkers for exoplanet research.

Role of the Virtual Launch Control Centre (VLCC) at VSSC

• Remote Pre-Launch Checkouts: Located at the Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram, the VLCC served as a networked telemetry facility that conducted digital checkouts on the LVM3 launch vehicle at Sriharikota.
• Simulation of Critical Actuators and Electronics: Monitored rocket avionics, guidance commands, stage separations, and propulsive valves in real time before formal launch countdowns.
• Multi-Centre Scientific Collaboration: Enabled real-time coordination between launch engineers at Sriharikota and core launch-vehicle design teams at VSSC, ensuring system readiness for flight.

The success of Chandrayaan-3 validates indigenous engineering design and establishes capabilities for future interplanetary missions, including Gaganyaan and Mangalyaan-2.