Chandrayaan-3: India's Ongoing Lunar Exploration Mission

India's Chandrayaan-3 mission is part of the country's ambitious lunar exploration program conducted by the Indian Space Research Organisation (ISRO). Chandrayaan-3 is the third mission in this program and aims to build on the achievements and lessons learned from its predecessor, Chandrayaan-2. This article provides an in-depth overview of the ongoing Chandrayaan-3 mission, including its objectives, spacecraft design, payloads, mission profile, and team involved.

Background

The Chandrayaan-3 mission follows the launch of Chandrayaan-2 in July 2019. Chandrayaan-2 consisted of an orbiter, a lander, and a rover, with the objective of landing on the lunar surface near the south pole. Unfortunately, the lander lost contact with Earth and deviated from its intended trajectory, leading to a crash landing. Despite this setback, the mission provided valuable insights into the challenges of landing near the lunar south pole, an area of great scientific interest due to the presence of ice. Chandrayaan-3 aims to capitalize on these learnings and successfully achieve a soft landing on the Moon.

Objectives

The primary objectives of the Chandrayaan-3 mission are as follows:

1. Safe Lunar Landing: The mission aims to successfully land a lander on the lunar surface, demonstrating the capability of achieving a soft landing.

2. Rover Exploration: An integral part of the mission is the deployment and operation of a rover on the lunar surface. The rover, named Pragyan, will showcase its driving capabilities and conduct experiments to better understand the composition of the Moon.

3. Scientific Experiments: Chandrayaan-3 will carry out various experiments to study the materials available on the lunar surface. These experiments will provide valuable insights into the composition of the Moon and its geological history.

Spacecraft Design

Chandrayaan-3 consists of three main components: the propulsion module, the lander (Vikram), and the rover (Pragyan).

Propulsion Module

The propulsion module plays a crucial role in carrying the lander and rover configuration to a lunar orbit of about 100 kilometers. It features a box-like structure with a large solar panel mounted on one side and a cylindrical mounting structure, known as the Intermodular Adapter Cone, on top.

Lander (Vikram)

The Vikram lander is responsible for the soft landing on the Moon's surface. It is box-shaped, equipped with four landing legs and four landing thrusters capable of producing 800 newtons of thrust each. The lander carries the rover and various scientific instruments for on-site analysis. Notably, the Chandrayaan-3 lander has four variable-thrust engines with enhanced attitude control capabilities compared to its predecessor, Chandrayaan-2. The lander's impact legs have also been strengthened, and instrumentation redundancy has been improved to enhance survivability during descent and landing.

Rover (Pragyan)

The Pragyan rover is a six-wheeled vehicle with a mass of 26 kilograms. It measures approximately 917 millimeters x 750 millimeters x 397 millimeters in size. The rover will conduct multiple measurements to support research on the lunar surface's composition, the presence of water ice in the lunar soil, the history of lunar impacts, and the evolution of the Moon's atmosphere.

Payloads

The payloads carried by the lander and rover on the Chandrayaan-3 mission are designed to gather crucial scientific data about the Moon.

Lander Payloads

The lander carries the following payloads:

1. Chandra's Surface Thermophysical Experiment (ChaSTE): This experiment aims to measure the thermal conductivity and temperature of the lunar surface, providing valuable insights into its heat transfer properties.

2. Instrument for Lunar Seismic Activity (ILSA): ILSA is designed to measure the seismic activity around the landing site, contributing to our understanding of the Moon's interior and geology.

3. Langmuir Probe (LP): LP will estimate the near-surface plasma density over time, helping scientists study the Moon's plasma environment.

Rover Payloads

The rover is equipped with the following payloads:

1. Alpha Particle X-Ray Spectrometer (APXS): APXS will analyze the chemical composition of the lunar surface and infer its mineralogical composition, providing essential data for understanding the Moon's geology.

2. Laser-Induced Breakdown Spectroscope (LIBS): LIBS will determine the elemental composition of lunar soil and rocks, specifically measuring the presence of magnesium, aluminum, silicon, potassium, calcium, titanium, and iron.

Propulsion Module Payload

The propulsion module carries the Spectro-polarimetry of Habitable Planet Earth (SHAPE) payload, which will study spectral and polarimetric measurements of Earth from the lunar orbit in the near-infrared wavelength range.

Mission Profile

The Chandrayaan-3 mission involves several phases, including launch, orbit insertion, descent, and rover deployment.

Launch

Chandrayaan-3 was launched on 14 July 2023, aboard an LVM3-M4 rocket from the Satish Dhawan Space Centre in Sriharikota, India. The launch vehicle lifted off from the Second Launch Pad, entering an Earth parking orbit with a perigee of 170 kilometers and an apogee of 36,500 kilometers.

Orbit

After a series of maneuvers, Chandrayaan-3 was placed in a trans-lunar injection orbit. On 5 August 2023, the spacecraft successfully entered a lunar orbit, thanks to a lunar-orbit insertion (LOI) operation carried out from the ISRO Telemetry, Tracking, and Command Network in Bengaluru.

Descent and Landing

On 23 August 2023, as the lander approached the low point of its orbit, it initiated a braking maneuver using its four engines. This maneuver slowed the lander's descent, and it stabilized itself using eight smaller thrusters, transitioning from a horizontal to a vertical position. The lander then used two of its four engines to further slow its descent to approximately 150 meters above the lunar surface. After hovering for about 30 seconds to locate the optimal landing spot, the lander touched down at 12:32 UTC.

Rover Deployment

Following the successful landing, the rover, Pragyan, was deployed onto the lunar surface on 23 August 2023. It will commence its exploration and scientific experiments, providing valuable data for further analysis.

Mission Life

The expected mission life for each component of Chandrayaan-3 is as follows:

• Propulsion module: Operational for up to six months in a 100-by-100-kilometer lunar orbit, primarily for experimental payload operations.

• Lander module: Expected to operate for one lunar daylight period, equivalent to approximately 14 Earth days.

• Rover module: Designed to function for one lunar daylight period, matching the duration of the lander's operational life.

Funding and Domestic Response

ISRO requested an initial funding of ₹75 crore (approximately US$9.4 million) for the Chandrayaan-3 project. This funding was allocated for machinery, equipment, capital expenditure, and operational expenses. The estimated cost of the mission was around ₹615 crore (equivalent to ₹721 crore or US$90 million in 2023).

The successful Chandrayaan-3 mission received accolades from India's Prime Minister, Narendra Modi. He congratulated the ISRO team and declared the touchdown point of the Vikram lander as 'Shivshakti Point.' Additionally, he proclaimed August 23, the day of the Vikram lander's landing, as 'National Space Day.'

Conclusion

Chandrayaan-3 represents India's ongoing commitment to lunar exploration and scientific research. With its mission objectives of achieving a soft landing, rover exploration, and conducting scientific experiments, Chandrayaan-3 aims to contribute valuable data to our understanding of the Moon's composition, geology, and plasma environment. The mission's success not only demonstrates India's technological prowess but also serves as an inspiration for future space exploration endeavors.