Chandrayaan-3 is the third and most recent Indian Moon Exploration programme conducted by The ISRO. The Chandrayaan-3 is similar to the Chandrayaan-2 consisting of lander named Vikram and rover named Pragyan. The propulsion module acted like an orbiter, which carried the lander and rover configuration until the spacecraft was in a 100-kilometer (62 mi) lunar orbit.
Rover Pragyan
A memorable day for India
The Chandrayaan-3 was launched on 14 July 2023, at 2:35 pm IST. The lander and rover landed near the lunar south pole region on 23 August 2023. The powered descent commenced on August 23, 2023, around 1745 Hrs(05:45 pm) IST and successful touchdown executed on the same day around 06:05 pm IST. India is now the fourth country to successfully to land on the moon and the first one to land on the lunar south pole.
Significance of The Lunar South Pole
The area around the lunar South Pole has captured the attention of scientific explorers because it harbors substantial quantities of ice. This ice is of particular significance due to its potential to reveal unique solid-state compounds that would typically liquefy under the warmer conditions found in other lunar regions. However, landing scientific probes in this area is exceptionally challenging, primarily because of the rugged terrain and the unpredictable lighting conditions. These factors not only safeguard the ice from melting but also pose significant obstacles for successful landings.
Lunar South Pole
The ice hidden in this region holds the promise of unraveling the history of the Moon, Earth, and the broader Solar System. Furthermore, it serves as a valuable resource, offering the potential for extracting drinking water, hydrogen for fuel, and oxygen for sustaining future manned missions and establishing lunar outposts. This makes the lunar South Pole a pivotal destination for scientific exploration and future human endeavors in space.
Spacecraft design
Chandrayaan-3 is composed of three principal components:
Propulsion module
The propulsion module transports the lander and rover configuration to a lunar orbit located 100 kilometers (62 miles) away. This module takes the form of a rectangular structure featuring a sizable solar panel affixed to one side and a cylindrical mounting structure, known as the Inter-modular Adapter Cone, positioned on top to secure the lander.
Lander
The Vikram lander plays a pivotal role in executing a gentle lunar touchdown. This box-shaped lander is equipped with four landing legs and four landing thrusters, each capable of generating 800 newtons of thrust. It serves as the carrier for the rover and a diverse array of scientific instruments, enabling on-site analyses and investigations.
The Chandrayaan-3 lander distinguishes itself from its predecessor, Chandrayaan-2, in several key ways. Notably, Chandrayaan-3 employs four variable-thrust engines with the capacity for changing slew rates. This contrasts with Chandrayaan-2’s lander, which featured five engines, with the fifth one centrally positioned and only capable of fixed thrust.
Chandrayaan Propulsion System with Vikram Lander with Pragyan rover inside the Lander
One of the primary factors contributing to Chandrayaan-2’s landing setback was an unwanted increase in attitude during the camera coasting phase. This issue has been addressed in Chandrayaan-3 by enabling the lander to manage both attitude and thrust throughout all descent phases. Furthermore, the attitude correction rate has been significantly enhanced, surging from Chandrayaan-2’s 10 degrees per second to a more robust 25 degrees per second with Chandrayaan-3.
In an additional upgrade, the Chandrayaan-3 lander is equipped with a Laser Doppler Velocimeter(LDV), which allows for the measurement of attitude in three directions. These advancements collectively enhance the lander’s capabilities and increase the likelihood of a successful lunar landing.
Compared to Chandrayaan-2, Chandrayaan-3 has fortified its impact legs for increased strength and bolstered instrumentation redundancy. The landing target zone has been refined to a more precise 4 km by 4 km area, using images previously captured by the Orbiter High-Resolution Camera (OHRC) aboard Chandrayaan-2’s orbiter as reference.
ISRO has undertaken several enhancements to ensure the lander’s robustness. This includes reinforcing the structural integrity, elevating instrument polling frequency, enhancing data transmission rates, and incorporating supplementary contingency systems. These improvements collectively bolster the lander’s ability to withstand potential challenges during the descent and landing phases, enhancing its survivability in adverse scenarios.
Rover
The Pragyan rover is a six-wheeled vehicle weighing 26 kilograms (57 pounds). It measures 917 millimeters (3.009 feet) in length, 750 millimeters (2.46 feet) in width, and 397 millimeters (1.302 feet) in height.
The rover is anticipated to conduct numerous measurements aimed at advancing research on several fronts, including lunar surface composition, the potential existence of water ice within lunar soil, the lunar impact history, and the evolutionary changes in the Moon’s atmosphere.
Payloads
Lander
The Vikram Lander will house three distinct payloads which will perform different tasks assigned to them.
Chandra’s Surface Thermophysical Experiment (ChaSTE) is designed to assess the thermal conductivity and temperature of the lunar surface.
The Instrument for Lunar Seismic Activity (ILSA) is tasked with gauging seismic activity in the vicinity of the landing site.
The Langmuir Probe (LP) is intended to calculate the evolving plasma density near the lunar surface.
Rover
The Pragyan Rover will carry two scientific instruments which will carry out its assigned tasks.
The Alpha Particle X-Ray Spectrometer (APXS) will determine the chemical composition and deduce the mineralogical makeup of the lunar surface.
The Laser-Induced Breakdown Spectroscope (LIBS) will ascertain the elemental composition (including Mg, Al, Si, K, Ca, Ti, and Fe) of lunar soil and rocks in the vicinity of the lunar landing site.
Propulsion module
The Spectro-polarimetry of Habitable Planet Earth (SHAPE) mission will investigate Earth’s spectral and polarimetric characteristics from the lunar orbit, focusing on the near-infrared (NIR) wavelength range spanning from 1 to 1.7 micrometers (3.9×10-5 to 6.7×10-5 inches).
Mission plan
Launch
On July 14, 2023, at 09:05 UTC, Chandrayaan-3 embarked on its journey, taking flight atop an LVM3-M4 rocket. The launch occurred at the Second Launch Pad of the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh, India. Following liftoff, the spacecraft entered an Earth parking orbit characterized by a perigee of 170 kilometers (106 miles) and an apogee of 36,500 kilometers (22,680 miles).
Chandrayaan orbiting around the Earth
Orbit
Following a sequence of maneuvers that positioned Chandrayaan-3 in a trans-lunar injection orbit, ISRO executed a lunar-orbit insertion (LOI) on August 5th, effectively establishing the Chandrayaan-3 spacecraft in lunar orbit. This precise operation took place at the ISRO Telemetry, Tracking, and Command Network (ISTRAC), situated in Bengaluru.
On August 17th, the Vikram lander disengaged from the propulsion module, commencing the final phase of the mission.
Chandrayaan exiting Earth’s gravity and entering Moon’s gravity
Descent
On August 23, 2023, as the lander neared the lowest point of its orbit, its four engines engaged in a braking maneuver approximately 30 kilometers (19 miles) above the Moon’s surface. After 11.5 minutes, the lander’s altitude reduced to 7.2 kilometers (4.5 miles) above the surface. It held this altitude for approximately 10 seconds before employing eight smaller thrusters to stabilize itself. During this stabilization process, the lander transitioned from a horizontal to a vertical orientation, all the while continuing its descent.
Following this, the lander deployed two of its four engines to decelerate, bringing its descent to an altitude of approximately 150 meters (490 feet). It hovered at this altitude for approximately 30 seconds, during which it identified an ideal landing site. Subsequently, it resumed its descent and successfully made contact with the lunar surface at 06:02 pm IST (Indian Standard Time).
Chandrayaan after entering Moon’s gravity
Mission Life
Propulsion module
The propulsion module’s primary function is to transport the lander and rover to a 100-by-100-kilometer (62 mi × 62 mi) lunar orbit, facilitating the operation of experimental payloads for a duration of up to six months.
Lander Module
The lander module is designed to function effectively during one lunar daylight period, which lasts approximately 14 Earth days.
Rover Module
The rover module is designed to function effectively during one lunar daylight period, which lasts approximately 14 Earth days.
Team
- ISRO Chairperson: S. Somanath
- Mission Director: S. Mohanakumar
- Associate Mission Director: G. Narayanan
- Project Director: P. Veeramuthuvel
- Deputy Project Director: Kalpana Kalahasti
- Vehicle Director: Biju C. Thomas
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