Reimagining Lunar Landings: Chandrayaan-3’s Quest for Success. Satish Dhawan Space Center

The Chandrayaan-3 is a mission to exhibit the comprehensive ability of the lander and rover for safe landing and roving on the surface. It will be launched from the Launch Vehicle Mark 3(LMV-3) from Satish Dhawan Space Center(SDSC), Sriharikota. It is a follow-up mission of Chandrayaan-2. 

Objectives of Chandrayaan-3

The mission objectives of Chandrayaan-3 are:

  1. To demonstrate a Safe and Soft Landing on Lunar Surface 

    Achieving a safe and soft landing on the lunar surface involves demonstrating a controlled descent and touchdown that ensures the spacecraft lands without damaging or disturbing its surroundings.
  2. To demonstrate Rover roving on the moon

    A robotic vehicle would be deployed to traverse the lunar surface, collecting data and conducting experiments while navigating the challenging terrain of the lunar landscape.
  3. To conduct in-situ scientific experiments.

    Will be performing research or analysis directly at the location of interest, gathering data and observations firsthand without the need for sample collection or remote sensing techniques.

Structure of Chandrayaan-3

Chandrayaan-3 is a mission that aims to develop and demonstrate new technologies for interplanetary missions. It consists of three main components: the Lander module, the Propulsion module, and the Rover.

Source: image showing the Lander Module, Rover, and Propulsion module of Chandrayaan-3.
An image showing the Lander Module, Rover, and Propulsion module of Chandrayaan-3.

The Lander Module(LM):

The lander module is the main structure that will touch down and land on the moon’s surface. It includes various subsystems such as communication equipment, power supply, and other scientific instruments. Chandrayaan-3 has the following lander payloads:

  • Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere (RAMBHA)
  • Chandra’s Surface Thermophysical Experiment (ChaSTE)
  • Instrument for Lunar Seismic Activity (ILSA)
  • LASER Retroreflector Array (LRA)
    Source: image showing the Lander Module of Chandrayaan-3.
    An image showing the Lander Module of Chandrayaan-3.

    To achieve the mission objectives, several advanced technologies are present in Lander such as,

    1. Altimeters: Laser & RF based Altimeters
    2. Velocimeters: Laser Doppler Velocimeter & Lander Horizontal Velocity Camera
    3. Inertial Measurement: Laser Gyro based Inertial referencing and Accelerometer package
    4. Propulsion System: 800N Throttleable Liquid Engines, 58N attitude thrusters & Throttleable Engine Control Electronics
    5. Navigation, Guidance & Control (NGC): Powered Descent Trajectory design and associate software elements
    6. Hazard Detection and Avoidance: Lander Hazard Detection & Avoidance Camera and Processing Algorithm
    7. Landing Leg Mechanism

The Propulsion Module(PM):

The propulsion module is a component that is responsible for providing the necessary thrust and control during the landing phase. It consists of engines, propellant tanks, and guidance systems that will control the touchdown on the surface of the moon. Chandrayaan-3 has the following Propulsion Module Payload:

  • Spectro-polarimetry of HAbitable Planet Earth (SHAPE)
Source: image showing the Propulsion module of Chandrayaan-3
An image showing the Propulsion module of Chandrayaan-3

The Rover :

The rover is a vehicle designed to operate on the surface of the moon and carry out different experiments which typically don’t involve remote sensing but rather conducting on-site experiments and a close observation of the surface of the moon. The rover consists of various instruments, sensors, and cameras to gather information on the surface of the moon.

Chandrayaan-3 consists of the following Rover payloads:

  • LASER Induced Breakdown Spectroscope (LIBS)
  • Alpha Particle X-ray Spectrometer (APXS)
Source: image showing The Rover of Chandrayaan-3.
An image showing The Rover of Chandrayaan-3.

The Lander will softly land on the Moon and deploy the Rover to analyze the lunar surface. Both the Lander and Rover carry scientific instruments for experiments. The Propulsion module will carry the Lander to the Moon’s orbit and separate from it. It also has a scientific payload of its own. The GSLV-Mk3 launcher will place the entire mission in an elliptical orbit around Earth before heading to the Moon.

Exploring The Earth along with the moon

With the help of Remote Sensing, it is going to gather information about the Earth’s surface and atmosphere. This would be done by two techniques: Spectral and Polarimetric techniques.

Spectral Measurements:

This technique involves the interaction of electromagnetic radiation with various materials of the Earth. Different materials have the ability to either absorb, reflect or transmit electromagnetic radiation at different degrees and different wavelengths. The sensors on Chandrayaan-3 would collect data across various segments of the electromagnetic spectrum, encompassing the visible, near-infrared, shortwave infrared, thermal infrared, and microwave domains. By analyzing the data, Scientists can make inferences about vegetation health, land cover types, atmospheric conditions, and more.

Polarimetric Measurements:

Polarimetry involves the measurement and analysis of the polarization characteristics of electromagnetic waves that are reflected or emitted from the Earth’s surface. Polarization refers to the alignment of the electric field vector of an electromagnetic wave, indicating the orientation of its electric field component. By evaluating the polarization state of the reflected or emitted radiation, scientists can acquire supplementary information regarding surface properties, such as surface roughness, composition, and structural attributes.

Through polarimetric measurements, valuable insights can be gained into diverse phenomena, including land cover classification, forest structure, soil moisture content, ice properties, and atmospheric conditions.

Special Features

Chandrayaan-3 is a follow-on mission of Chandrayaan-2 and thus along with various improved features. It consists of 3 Telemetry, Tracking, and Command(TTC) antennas: top, front, and back which increases data rate and redundancy. The Chandrayaan-3 has added a Laser Doppler velocimeter which Chandrayaan-2 didn’t have. The Rover and Lander life which was 5 ampere hours in Chandrayaan-2 has been increased to 10 ampere hours in Chandrayaan-3.