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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.
Vikram Lander - Key Characteristics
Vikram is a fully autonomous lander designed and developed in India by ISRO. It carries the Pragyan rover inside it during the powered descent and landing phases.
Here are some of its key characteristics and capabilities:
- Mass - Approx 1,471 kg including 138 kg Pragyan rover
- Propulsion - One 800N main pulsing engine, eight 100N throttleable engines, and sixteen 50N attitude control thrusters. Burns monomethylhydrazine (MMH) and nitrogen tetroxide (NTO) propellants.
- Power - Two solar panels totaling 650W capacity, 36AH lithium-ion battery
- Navigation - LiDAR, four camera sensors, altitude sensors, accelerometer, gyroscopes
- Hazard Avoidance - 3D vision algorithms, terrain relative navigation techniques
- Flight Control - Fully autonomous landing using onboard Guidance, Navigation & Control (GNC) software and landing sequencer. No real-time ground commands.
- Structure - Four landing legs with electromechanical shock absorbers. Descent ramps for rover egress post-landing.
- Communication - S-band system with two dish antennas for communicating with orbiter and ground stations. UHF system for rover communications.
Vikram builds on ISRO's learning from the Chandrayaan-2 mission, incorporating major subsystem improvements and enhanced reliability based on detailed failure analysis. Its successful lunar landing paves the way for more complex lander and rover missions to the Moon, Mars, and other celestial bodies.
Pragyan Rover - Key Features and Capabilities
The Pragyan (wisdom in Sanskrit) rover housed inside Vikram played a key role post-landing by conducting detailed in-situ surface experiments.
Some salient features include:
- Mass - 27 kg
- Mobility - 6 wheels, each driven independently with a max speed of 1 cm/second. Can climb slopes up to 20°. Travel range up to 500 meters.
- Power - 50W capacity solar panel, lithium-ion batteries
- Navigation cameras - Stereo camera pair helps autonomously navigate around hazards
- Manipulator arm - 2 joint robotic arm extends to pick up samples for on-board analysis
- Communications - UHF radio system relays data to the orbiter via lander
- Mission life - Designed to operate for 1 lunar daytime (14 Earth days)
Science payload
- LIBS - Laser-induced breakdown spectroscopy to detect surface elemental composition
- APXS - Alpha particle X-ray spectrometer to analyze the elemental composition of lunar rocks and soil
Pragyan's successful deployment and operations demonstrate India's proficiency in lunar rover development. It expands ISRO's experience beyond fixed landers to mobile surface exploration. Lessons from Pragyan will inform future lunar and Martian rover design.
Detailed Overview of Payload Instruments
Chandrayaan-3 carries a complement of sophisticated science payloads to study the lunar soil, subsurface features, ionosphere, and more.
Lander Payloads:
- RAMBHA - Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere aims to assess the Moon's incredibly thin atmosphere and ionosphere. It consists of a set of RF and IR sensors.
- Chaste - Chandra's Surface Thermo-physical Experiment deploys a thermal probe into the lunar regolith to measure thermal conductivity and temperature gradient down to a depth of 10 cm. Provides insights on the moon's subsurface thermal properties.
- ILSAA - Instrument for Lunar Seismic Activity is a seismometer to study seismic waves from moonquakes caused by tremors arising due to tidal forces or meteorite impacts. Will provide a detailed understanding of the lunar interior.
- LRA - Laser Retroreflector Array is used as a target for laser ranging measurements. LRO and other space-based laser altimeters can precisely determine Chandrayaan-3's landing site coordinates by measuring LRA reflectance. Also enables computing lunar orbit perturbations.
Rover Payloads
- LIBS - Laser-Induced Breakdown Spectroscope focuses a pulsed laser on the lunar surface, vaporizing soil and rocks to excite atomic emissions unique to each element present. This helps quantify lunar surface chemistry.
- APXS - Alpha Particle X-ray Spectrometer uses alpha particle sources to irradiate rock and soil samples, detecting the characteristic X-ray photons emitted. It determines elemental composition up to a depth of a few mm. Provides ground truthing of remote sensing data.
In addition, the orbiter carries eight scientific instruments to map lunar morphology, mineralogy, elemental abundances, and more. The payload suite will provide unprecedented insights into lunar origin and evolution.
Mission Operations - Supporting Spacecraft Tracking & Communication
Mission operations play a critical role in executing and monitoring all spacecraft activities, tracking its trajectory, receiving health data, transmitting commands, and acquiring scientific data.
For Chandrayaan-3, ISRO's mission control center was located at its Telemetry, Tracking, and Command Network (ISTRAC) in Bengaluru. The spacecraft was visible to ISTRAC antennas for around 7-8 hours every day when it came in their visibility range.
To supplement ISTRAC's network, ISRO also utilized ground station support worldwide under international collaboration agreements:
- NASA Deep Space Network - Provided additional tracking from antennas in Spain, Australia, and the United States.
- ESA's ESTRACK Network - Expanded coverage via antennas in Argentina and Australia.
- Roscosmos Ground Stations - Augmented visibility and data receipt from stations across Russia.
The globally distributed antennas facilitated continuous monitoring and communication with Chandrayaan-3 during critical phases like the trans-lunar coasting and lunar descent when the spacecraft was not visible to Indian stations.
During spacecraft passes, the ground stations acquired telemetry data on its health, status, and payload.
Lunar Surface Operations
With the successful landing of Vikram and deployment of Pragyan, Chandrayaan-3 entered the surface operations phase.
Vikram Lander
The lander is designed to operate on the lunar surface for one lunar day, which equals 14 Earth days. Vikram carries a suite of scientific instruments to study the lunar soil, plasma, seismic activity, and more. The lander is powered by 650W capacity solar panels and a 36AH lithium-ion battery to survive the two-week-long lunar day.
Vikram will continue operating until the extremely cold lunar night sets in when surface temperatures dip below -200°C. The lunar dawn at the south pole is unique with peaks of eternal light and permanent shadows. Vikram is not designed to withstand the low temperatures and darkness of lunar night.
Pragyan Rover
Minutes after landing, the ramps of Vikram were deployed and Pragyan rolled onto the lunar soil, its wheels dispersing the surface and imprinting ISRO and Indian symbols.
During its 1 lunar day lifetime, Pragyan will carry out detailed on-site investigations around the landing site using its Alpha Particle X-ray Spectrometer and Laser-Induced Breakdown Spectroscope. These experiments will provide ground-truth validation of Chandrayaan-3 orbiter data.
Pragyan is also not designed to survive lunar night conditions. Before sunset, the rover will return close to Vikram. The lander will reposition itself such that its payloads are thermally shielded during the lunar night with hopes of extending the mission lifetime.
Communications
Throughout the surface operations phase, the orbiter will continue orbiting around the Moon for around one year. It serves as an essential communications relay hub between the lander rover and Earth.
The orbiter captures Vikram's low-power UHF signals and retransmits them to ISTRAC antennas on S-band frequencies. The orbiter also relays surface images, instrument data, and housekeeping telemetry acquired from the lander and rover.
Legacy of Chandrayaan-3
Chandrayaan-3's monumental success provides a major boost to India's space program.
Key outcomes include:
- Joins an exclusive club of nations with lunar landing capability
- Provides technical validation for future interplanetary missions
- This opens up the possibility of leveraging lunar resources like water ice
- Offers ground validation of orbiter data and new lunar surface insights
- Catalyzes the Indian private space industry and startups
- Inspires the next generation towards STEM careers
- Showcases indigenous launch vehicles, spacecraft, and operations capabilities
The mission showcases the extraordinary creativity, perseverance, and problem-solving skills of ISRO scientists. It highlights India's space capabilities and the success of its innovative, low-cost model of frugal engineering.
Chandrayaan-3 added over a decade's worth of updates to lunar topological and mineralogical maps. It revealed new findings on lunar geology, seismicity, and the rarefied lunar exosphere.
The mission added rich scientific and engineering knowledge to India's legacy of lunar exploration inaugurated by Chandrayaan-1 and continued by Chandrayaan-2.
Future Space Plans
Emboldened by Chandrayaan-3's accomplishments, ISRO is progressing on several upcoming projects:
- Gaganyaan - India's first manned orbital spaceflight slated for 2024. It will carry 3 astronauts in a low Earth orbit for 5-7 days. Extensive technology developments are underway including human-rated launch vehicles, crew escape systems, environmental control systems, spacesuits, and more.
- Chandrayaan-4 - A follow-on lunar landing mission currently under formulation. Planned for 2028-2029 timeframe.
- Mangalyaan-2 - Second Mars orbiter planned for 2024 launch, building on the success of the first Mars mission.
- Aditya L-1 - Mission to study the Sun's corona planned for 2024-25. Will be inserted in a halo orbit around the Sun-Earth L1 point and carry a coronagraph for solar observations.
- Space station - India plans to establish its own small space station in the next decade. It will enable microgravity experiments and serve as a platform for deep space exploration.
- Reusable launch vehicle development - Engineers are working on technology demonstrators for reusable rocket systems to reduce launch costs.
- Human spaceflight center - ISRO is establishing a new facility to support its future human spaceflight missions like Gaganyaan.
- Private sector participation - ISRO is proactively promoting industry participation in end-to-end space activities including satellite fabrication, launch services, and ground segment operation.
India's space odyssey continues its rapid upward trajectory thanks to the contributions of ISRO, industry partners, academia, and research institutions. Chandrayaan-3 marks another signature accomplishment that will inspire even more ambitious interplanetary exploration.
Frequently Asked Questions: Chandrayaan-3
What was the total cost of the Chandrayaan-3 mission?
Chandrayaan-3 had a total budget of approximately ₹250 crores or $35 million. This highlights ISRO's frugal engineering approach that delivered a world-class lunar mission at a relatively low cost.
How long will the Pragyan rover operate on the lunar surface?
The Pragyan rover is designed for a lifetime of 1 lunar day, which equates to 14 Earth days. It aims to complete all science experiments within this duration before lunar night sets in.
What are some key instruments on the Chandrayaan-3 lander and rover?
Key instruments include spectrometers (to study mineralogy), seismometers (to study moonquakes), thermal probes (to measure heat flow), and retroreflectors (for precise distance measurement). The rover also carries an Alpha Particle X-ray Spectrometer and Laser-Induced Breakdown Spectroscope.
Does Chandrayaan-3 prove the presence of water on the Moon?
While detection of water ice at the south pole is a key objective, the results from Chandrayaan-3's science experiments are still awaited. However, previous missions like Chandrayaan-1 found evidence of lunar hydration.
What technological improvements were incorporated after Chandrayaan-2?
Key improvements include upgraded navigation sensors, software enhancements, reinforced landing legs, additional propellant, expanded landing ellipse, improved hazard avoidance capabilities, and more robust rover design.
What are the future plans for India's space program after Chandrayaan-3?
Upcoming milestones include the Gaganyaan manned spaceflight, Chandrayaan-4 lunar mission, Mangalyaan-2 Mars orbiter, space station, and development of reusable launch vehicles.
How did Chandrayaan-3 overcome the challenges faced during the Chandrayaan-2 landing?
By enhancing navigation and hazard avoidance systems, optimizing descent algorithms, expanding target landing zone, adding landing leg shock absorbers, and performing extensive ground simulations to validate all scenarios.
Conclusion: Chandrayaan-3 Mission Soft Landing
India has cemented its position among the world's foremost spacefaring nations through the remarkable success of Chandrayaan-3 and its landmark lunar landing. This mission will inspire generations and spur more ambitious interplanetary exploration by India in the years ahead.
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