Chandrayaan-2: India’s Orbiter-Lander-Rover Mission
Chandrayaan-2 mission was a significant technological leap compared to the previous missions of ISRO, which brought together an Orbiter, Lander and Rover with the goal of exploring South Pole of the Moon. This was a unique mission aimed at studying not just one area of the Moon but all the areas combining the exosphere, the surface as well as the sub-surface of the moon in a single mission. Though the mission failed to place the lander on lunar surface, ISRO achieved scientific knowledge.
- Moon provides the best linkage to Earth’s early history. It offers an undisturbed historical record of the inner Solar system environment. Extensive mapping of lunar surface to study variations in lunar surface were essential to trace back the origin and evolution of the Moon. Evidence for water molecules discovered by Chandrayaan-1, required further studies on the extent of water molecule distribution on the surface, below the surface and in the lunar exosphere to address the origin of water on Moon.
- The Lunar South Pole is especially interesting because of the lunar surface area that remains in shadow is much larger than that at the North Pole. There could be a possibility of presence of water in permanently shadowed areas around it. In addition, South Pole region has craters that are cold traps and contain a fossil record of the early Solar System.
About Orbiter, Lander and Rover of Chandrayaan-2
Orbiter
It weighs 2,397 Kg and is capable of communicating with Indian Deep Space Network (IDSN) at Byalalu as well as the Vikram Lander.
| Orbiter Payloads | |
| Terrain Mapping Camera 2 (TMC 2) | Its primary objective is mapping the lunar surface in the panchromatic spectral band (0.5-0.8 microns) with a high spatial resolution of 5 m and a swath of 20 km from 100 km lunar polar orbit. The data collected by TMC 2 will give us clues about the Moon’s evolution and help us prepare 3D maps of the lunar surface. |
| Chandrayaan 2 Large Area Soft X-ray Spectrometer (CLASS) | CLASS measures the Moon’s X-ray Fluorescence (XRF) spectra to examine the presence of major elements such as Magnesium, Aluminium, Silicon, Calcium, Titanium, Iron, and Sodium |
| Solar X-ray Monitor (XSM) | XSM observes the X-rays emitted by the Sun and its corona, measures the intensity of solar radiation in these rays, and supports CLASS. |
| Orbiter High Resolution Camera (OHRC) | OHRC provides high-resolution images of the landing site — ensuring the Lander’s safe touchdown by detecting any craters or boulders prior to separation |
| Imaging IR Spectrometer (IIRS) | It is used for Global mineralogical and volatile mapping of the Moon and Complete characterization of water/hydroxyl feature. |
| Dual Frequency Synthetic Aperture Radar (DFSAR) | The main scientific objectives of this payload are High-resolution lunar mapping in the polar regions and Quantitative estimation of water-ice in the polar regions |
| Chandrayaan 2 Atmospheric Compositional Explorer 2 (CHACE 2) | CHACE 2’s primary objective is to carry out an in-situ study of the composition and distribution of the lunar neutral exosphere and its variability. |
| Dual Frequency Radio Science (DFRS) Experiment | It is used to study the temporal evolution of electron density in the lunar ionosphere |
Lander
It is christened as Vikram after Dr Vikram A Sarabhai, the Father of the Indian Space Programme and weighs 1,471 Kg.
Vikram Payloads
| Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA) | Its objective is to measure ambient electron density/temperature near the lunar surface and temporal evolution of lunar plasma density near the surface. |
| Chandra’s Surface Thermo-physical Experiment (ChaSTE) | ChaSTE measures the vertical temperature gradient and thermal conductivity of the lunar surface. |
| Instrument for Lunar Seismic Activity (ILSA) | Its primary objective is to characterize the seismicity around the landing site. |
Rover
It is named Pragyan which weighs 27 Kg and is a 6-wheeled robotic vehicle.
| Pragyan Payloads | |
| Alpha Particle X-ray Spectrometer (APXS) | APXS’ primary objective is to determine the elemental composition of the Moon’s surface near the landing site. |
| Laser Induced Breakdown Spectroscope (LIBS) | LIBS’ prime objective is to identify and determine the abundance of elements near the landing site. |
Passive Experiment
Laser Retroreflector Array (LRA): To understand the dynamics of Earth’s Moon system and also derive clues on the Lunar interior.
Launch Vehicle: Geosynchronous Satellite Launch Vehicle Mark-III (GSLV Mk-III)
- The GSLV Mk-III carried Chandrayaan 2 to its designated orbit. This three-stage vehicle is India’s most powerful launcher to date, and is capable of launching 4-ton class of satellites to the Geosynchronous Transfer Orbit (GTO). Its components are: S200 solid rocket boosters (solid strap-on motors), L110 liquid stage and a C25 upper stage (cryogenic upper stage).
Challenging Aspects of Chandrayaan-2
Some of the technological challenges of this mission were:
- Soft Landing: The propulsion system consisting of throttleable engines to ensure landing at low touchdown velocity for soft landing.
- Mission Management: Propellant management at various stages, engine burns, orbit and trajectory design
- Lander Development:Navigation, guidance and control, sensors for navigation and hazard avoidance, communication systems and lander leg mechanism for soft landing
- Rover Development:Roll down (from the lander) mechanism, roving mechanism (on the lunar surface), development and testing of power systems, thermal systems, communication and mobility systems.
Significance of Chandrayaan-2 Mission
- To develop and demonstrate the key technologies for end-to-end lunar mission capability, including soft-landing and roving on the lunar surface.
- This mission was to further expand our knowledge about the Moon through a detailed study of its topography, mineralogy, surface chemical composition, thermo-physical characteristics and atmosphere leading to a better understanding of the origin and evolution of the Moon.
