India’s Successful Chandrayaan-3: Triumphantly Lands on Moon’s South Pole!
India has once again made history in the realm of space exploration. The Indian Space Research Organisation’s (ISRO) Chandrayaan-3 lunar exploration mission successfully landed its Vikram lander and deployed the Pragyan rover on the Moon’s south polar region on August 23, 2023, achieving a historic first landing on the unexplored lunar south pole.
This article provides an in-depth overview of ISRO’s monumental Chandrayaan-3 moon mission.
A game-changing moment emerged in 2008 when India’s Chandrayaan-1 mission unveiled an astonishing find: water on the moon’s surface.
This groundbreaking revelation reignited the world’s fascination with lunar exploration, triggering an international craze that saw major players like China, the United States, and Israel join the pursuit.
Fast forward to today, and India takes center stage once more with Chandrayaan 3, its third lunar mission.
This determined effort follows a setback experienced during the Chandrayaan 2 mission in 2019, showcasing India’s unwavering commitment to unraveling the moon’s mysteries.
Wondering about the past, present, and future of lunar exploration?
Chandrayaan-3 mission aims to touchdown on the Moon’s largely unexplored South Pole
Hello, friends! On 22 October 2008, the Chandrayaan-1 mission was launched by India.
This spacecraft reached the Moon and found something that was a headline all over the world.
Water on the Moon. For the first time, Chandrayaan-1 brought strong evidence that there is water on the Moon. Specifically speaking, it is present in the South Pole area of the Moon.
After this news, in countries all over the world, the craze to explore the Moon renewed. Missions are sent regularly by the USA and China to the Moon.
Israel tried to do a soft landing on the Moon. Besides this, many lunar missions were planned by Japan, Europe, and Russia. But today, the world is watching India’s Chandrayaan-3 mission.
Which new discovery will be made by Chandrayaan-3? And why did the Chandrayaan-2 mission fail? Let’s find out in this article.
“India is on its way back to the Moon”
“The historic mission to the moon and the launch of India’s Chandrayaan-3 spacecraft”
“India is already shooting for the Moon”
Chandrayaan-3 Mission Overview
The Chandrayaan-3 lunar probe represents India’s third moon mission after Chandrayaan-1 in 2008 and Chandrayaan-2 in 2019. Chandrayaan-3 was launched on July 14, 2023, and involved a series of complex orbital maneuvers around the Earth and Moon to prepare for landing.
The primary objectives of Chandrayaan-3 include:
- Demonstrating soft landing and rover operations on the lunar surface
- Conducting in-situ scientific experiments using the Pragyan rover
- Exploring the south polar region, which may contain water ice and other resources
The spacecraft consists of three modules — the Orbiter, Lander (Vikram), and Rover (Pragyan). The Orbiter provides navigation support and transmits data to Earth. The Lander carries the Rover and scientific instruments for analyzing the lunar surface.
Milestones Leading to Chandrayaan-3
India’s journey towards landing on the Moon has spanned multiple decades marked by key milestones:
- Chandrayaan-1 (2008): India’s first lunar probe conducted a detailed chemical and mineralogical mapping of the lunar surface. A notable discovery was the presence of water molecules on the Moon’s surface.
- Mars Orbiter Mission (2013): ISRO successfully placed a spacecraft in Martian orbit on its first attempt, demonstrating interplanetary exploration capabilities.
- Chandrayaan-2 (2019): India’s second lunar mission involved an orbiter, lander (Vikram), and rover (Pragyan). While the orbiter functioned normally, the lander crashed during the descent to the Moon’s south pole.
- Chandrayaan-3 (2023): Learning from Chandrayaan-2, ISRO redesigned the lander and succeeded in soft-landing on the lunar south pole.
Detailed Mission Profile and Key Events
Launch
Chandrayaan-3 lifted off at 02:43 UTC on July 14, 2023, onboard India’s most powerful launch vehicle, the GSLV MkIII, from the Satish Dhawan Space Centre (SDSC) in Sriharikota. The GSLV MkIII, also called LVM3, is a three-stage heavy lift rocket capable of launching a 4-ton class spacecraft into Geosynchronous Transfer Orbit (GTO).
The spacecraft was placed into a highly elliptical initial Earth parking orbit by the cryogenic upper stage of the rocket around 16.5 minutes after liftoff. ISRO confirmed the spacecraft’s health was normal.
Earth-Bound Orbit Raising Maneuvers
Over the next 11 days, five precise orbit-raising maneuvers were carried out using the spacecraft’s onboard propulsion system which consists of two clusters of Liquid Apogee Motors (LAM). These LAMs use indigenous mono methyl hydrazine and mixed oxides of nitrogen propellant combination.
The orbit-raising maneuvers progressively increased the apogee (farthest point) of the orbit and were essential to prepare the spacecraft for trans-lunar injection. Here are some key details:
First Orbit Raise
- Conducted on July 15, 2023
- Increased perigee from 168 km to 4,413 km
Second Orbit Raise
- Conducted on July 16, 2023
- Apogee raised to 71,162 km
Third Orbit Raise
- Conducted on July 19, 2023
- Apogee increased to 89,472 km
Fourth Orbit Raise
- Conducted on July 21, 2023
- Apogee raised to 1,71,717 km
Fifth Orbit Raise
- Conducted on July 25, 2023
- Increased apogee to 1,27,000 km
After the fifth orbit raise, the spacecraft was in a highly elliptical orbit where it coasted for the next five days. This orbit was optimal for setting up the trans-lunar injection (TLI) burn to send the spacecraft on a lunar intercept trajectory.
Trans-Lunar Injection and Lunar Journey
The TLI maneuver was executed on August 1, 2023, at 02:11 UTC, which enabled the spacecraft to escape Earth’s gravity and begin its journey toward the Moon.
This maneuver changed the spacecraft’s velocity by 1,350 m/s. TLI marked a major milestone as Chandrayaan-3 broke free of Earth’s orbit and entered a Lunar Transfer Trajectory.
Over the next 18 days after TLI, the composite Chandrayaan-3 spacecraft cruised on its lunar voyage covering a distance of approximately 3,84,000 km.
ISRO regularly tracked the spacecraft using antennas of its Deep Space Network located in Byalalu near Bangalore.
Additional tracking support was provided by ground stations in Australia, Russia, and the United States.
During the long coasting phase, ISRO tested and monitored all the onboard systems and scientific payloads. The parameters were found to be normal, boosting confidence ahead of the lunar operations.
By August 17, Chandrayaan-3 came under the influence of lunar gravity. Two days later, it entered into a Lunar Orbit of 114 km x 18036 km.
A series of four orbit-lowering maneuvers further reduced the orbit to reach a 100 km circular lunar orbit as intended on August 23.
Powered Descent — Landing Day Events
August 23 was the most important day that would determine the fate of Chandrayaan-3’s mission. Here is a detailed rundown of the major events that took place over the landing day:
Orbiter-Lander Separation
At 1:38 pm IST on August 23, the lander named Vikram separated from the orbiter. Vikram along with the Pragyan rover were packed inside the lander. The lander then performed a deboost burn using its 800N liquid main engines to lower its orbit in preparation for powered descent initiation.
Rough Braking Phase
The rover separated from the orbiter at 2:10 pm IST and was at an altitude of 30 km above the lunar surface with a high velocity of 1.68 km/sec.
Powered descent commenced with the firing of Vikram’s main engines and eight 100N throttleable liquid thrusters. This began the rough braking phase which lasted around 690 seconds.
During the initial 15 minutes, the high braking thrust decelerated the lander and reduced its velocity to 358 m/sec. The altitude at the end of this phase was lowered to 7.4 km.
Attitude Hold & Fine Braking Phase
Following the rough braking phase, the lander reoriented itself and nulled its horizontal velocity components to be aligned precisely vertically. This attitude-hold phase took around 10 seconds.
The next three minutes constituted the fine-braking phase. Vikram’s four 100N throttleable engines continued firing to further shed velocity to near-zero in preparation for the vertical descent. By the end of fine braking at approx 2:40 pm IST, the lander was positioned at an altitude of 750 meters above ground with near-zero velocity.
Vertical Descent Phase
Vikram began its near-vertical descent towards the lunar surface while taking camera images and using its sensors to detect any hazards on the surface. The firing of the lateral thrusters kept the lander aligned along its descent trajectory while avoiding obstacles.
The onboard computer autonomously guided Vikram towards a safe landing site free of craters and boulders. During the final moments, four engines were shut down and the lander made a controlled descent under the thrust of a single central engine.
Touchdown
At 2:52 pm IST, Vikram touched down safely on the hitherto unexplored lunar south pole in the Manzinus C crater region. The four legs of the lander absorbed the impact of landing while keeping it upright. This marked the historic culmination of Chandrayaan-3’s lunar landing attempt.
Minutes after landing, the ramps were deployed and the Pragyan rover rolled out onto the lunar surface. Soon, ISRO established radio contact with both Vikram and Pragyan — confirmation that India had successfully landed on the Moon’s south pole!
Landing Site Selection
The lunar south pole was chosen as Chandrayaan-3’s landing site given its scientific importance and unexplored nature. This region has unique lighting conditions where some areas like craters remain permanently shaded from sunlight. Scientists believe these permanently shadowed regions could harbor deposits of water ice — a vital resource for sustaining human presence on the Moon.
The South Pole also offers advantages like more moderate temperatures and higher surface area in contact with the perpetually dark interiors of craters. This increases the prospect of the presence of volatile substances like water ice.
Based on data from Chandrayaan-2’s orbiter and NASA’s Lunar Reconnaissance Orbiter (LRO), ISRO identified two prospective landing sites near craters Manzinus C and Simpelius N. Both sites are located within the larger Shackleton crater region at approximately 70° south latitude. The 4 km x 2.5 km landing ellipse covers rugged terrain with several small craters.
Ultimately, the Manzinus C site was chosen for Chandrayaan-3’s descent and landing attempt.
Powered Descent — Overcoming Key Challenges
The lunar landing on August 23 was among the most complex and challenging phases of the Chandrayaan-3 mission. The lander had to autonomously reduce its velocity from 1.68 km/sec to almost zero for a safe vertical touchdown.
Here are some of the key complexities involved:
No Atmospheric Drag
The Moon has an extremely thin atmosphere or exosphere with negligible drag that could slow the lander’s descent. unlike Earth where a dense atmosphere allows aerobraking.
Lunar Dust
Fine, jagged lunar dust particles kicked up by the lander’s thrusters could damage exposed optics and mechanisms. Dust mitigation was essential.
Hazard Avoidance
The South Pole’s rugged, cratered terrain posed risks like boulders, slopes, and depressions. The lander had to identify and avoid them.
Precision Landing
Nailing the precise touchdown spot required accurately controlling the lander’s descent rate, orientation, horizontal velocity, etc.
Autonomous Operations
The entire descent had to be controlled autonomously via pre-loaded software with no real-time commands from the ground.
To overcome these challenges, ISRO engineers made several key enhancements to Chandrayaan-3 compared to Chandrayaan-2:
- Terrain Mapping Algorithms — Computer vision algorithms were added to scan surface imagery and create 3D maps identifying safe, hazard-free areas.
- Higher Descent Rate Control — New sensors and algorithms increased the controllability of the vertical descent rate.
- Expanded Landing Ellipse — The landing site region is enlarged to 4km x 2.5km for more landing spot flexibility.
- Enhanced Navigation Sensors — Additional LiDAR and camera sensors improved hazard detection and navigation capability.
- Leg Shocks Absorbers — Energy-absorbing systems lessened impact at leg touchdown.
- Software Optimizations — Extensive simulations refined the autonomous landing programs and decision logic.
- Thrust Profile Management — Optimized engine thrust profiles and attitudes reduced propellant consumption.
Thanks to these improvements, Chandrayaan-3’s redesigned lander system effectively overcame past challenges and succeeded in the historic lunar soft landing at the south pole.
