Lander and Rover Payloads

The Lander is equipped with various scientific instruments, including:

• Chandra's Surface Thermophysical Experiment (ChaSTE): This will measure the thermal conductivity and temperature of the lunar surface.
• Instrument for Lunar Seismic Activity (ILSA): This device will monitor seismic activity near the landing site.
• Langmuir Probe (LP): It will assess plasma density and its fluctuations.

Additionally, a passive Laser Retroreflector Array from NASA will be included for lunar laser ranging studies.

The Rover carries:

• Alpha Particle X-ray Spectrometer (APXS) and Laser Induced Breakdown Spectroscope (LIBS): These tools will analyze the elemental composition of the landing area.

Chandrayaan-3 integrates an indigenous Lander module (LM), a Propulsion module (PM), and a Rover, aiming to develop and demonstrate new technologies essential for interplanetary missions. The Lander is designed for a soft landing at a predetermined lunar site, subsequently deploying the Rover to conduct in-situ chemical analyses as it travels across the lunar terrain.

The PM’s primary role is to carry the LM from launch vehicle injection to a final circular polar orbit around the moon, as well as separate the LM from the PM. Besides this function, the Propulsion Module also carries a scientific payload that will be activated after the Lander separates. The GSLV-Mk3 has been selected for launching Chandrayaan-3, which will place the combined module into an elliptical parking orbit approximately 170 x 36,500 km in size.

Mission Goals and Advanced Technologies

The objectives of Chandrayaan-3 include:

1. To demonstrate a safe and soft landing on the lunar surface.
2. To showcase the Rover's ability to navigate on the moon.
3. To perform scientific experiments on-site.

To fulfill these mission goals, the Lander is equipped with several advanced technologies, including:

• Altimeters: Utilizing both Laser and RF-based systems.
• Velocimeters: Incorporating Laser Doppler Velocimeters and a Lander Horizontal Velocity Camera.
• Inertial Measurement: Featuring a Laser Gyro-based system for inertial referencing along with an accelerometer package.
• Propulsion System: Comprising 800N throttleable liquid engines and 58N attitude thrusters, alongside throttleable engine control electronics.
• Navigation, Guidance & Control (NGC): Involving powered descent trajectory design and associated software.
• Hazard Detection and Avoidance: Using a dedicated camera and processing algorithm for detecting landing hazards.
• Landing Leg Mechanism: Ensuring a safe touchdown.

To validate these advanced technologies under Earth conditions, a series of specialized tests for the Lander have been successfully conducted, including:

• Integrated Cold Test: Demonstrating the performance of integrated sensors and navigation using a helicopter as a test platform.
• Integrated Hot Test: Showcasing closed-loop performance with sensors, actuators, and NGC using a tower crane.
• Lander Leg Mechanism Performance Test: Conducted on a lunar simulant test bed to replicate various touchdown conditions.

Anticipation for Chandrayaan-3 is palpable. The first Chandrayaan mission achieved great success, while the second faced challenges. Now, all hopes are pinned on this third endeavor.