Earth’s Moon is the only place beyond Earth where humans have landed. The Moon is a dusty ball of rock, measuring 3476km in diameter which is roughly a quarter of the size of the earth and a 5th largest natural satellite in our solar system. The brightest and largest object in our night sky helps us to have a stable climate on earth and it also causes tides. The moon was formed about 4.5 billion years ago, The most widely accepted explanation is that the moon formed from the debris left over when earth slammed into another early planet named Theia. The moon is rich in Helium-3, which is reported to be present on the lunar surface can be a solution to the energy crisis on earth.
Inching towards the edge of discovery, Chandrayaan 2 is an Indian lunar mission which will go where no country has ever gone before – The moon’s South Polar Region.
This is India’s second voyage to the moon and for the first time, ISRO will attempt to perform a soft landing on the moon and will become the 4th country to do so. Chandrayaan 2 will not only perform the soft landing but it also has a rover which will move on the surface of the moon and will capture pictures of the moon’s surface and will send data on the earth.
Indian entry on the moon was effective as it reached to the moon in its first attempt. In the year 2008 ISRO launched Chandrayaan 1 and became the 4th country on the planet to reach on the moon. Chandrayaan 1 carried an impactor which impacted on the moon and an orbiter which revolved around the moon for almost a year.
The aim of the mission is to improve our understanding of the moon that will benefit India and humanity as a whole. These insights and experiences aimed at a paradigm shift in how lunar expeditions are approached for years to come.
A NEW AGE
The moon is the closest cosmic body from the earth at which space discovery can be attempted. Moon has remained the area of research from several centuries for astrophysicists. After the successful journey of Chandrayaan 1 in 2008, Chandrayaan 2 attempts to foster a new age of discovery, increase our understanding of space, stimulate the advancement of technology, promote global alliances and inspire a future generation of explorers and scientists.
HUNT FOR EVIDENCE
Ever wondered the origin of the earth and our solar system? Moon provides the best linkage to earth’s early history. Like the moon’s atmosphere and the surface took undisturbed, it provides an accurate historical record of the solar system environment. Evidence for water molecules discovered by Chandrayaan-1 requires further studies on the extent of water molecule distribution on the surface, below the surface and lunar exosphere to address the origin of water on the moon.
DIMENSIONS OF CHANDRAYAAN-2
- 1st space mission to land on the South Pole region of the moon.
- 1st Indian expedition to attempt a soft landing on the lunar surface with homegrown technology.
- 1st Indian mission to explore the lunar terrain with home-grown technology.
THE SOUTH POLE OF THE MOON
The lunar South Pole is especially interesting because of the lunar surface area here thatremains in shadow are much larger than that at the North Pole. There is a possibility of the presence of water in permanently shadowed areas around it. In addition, the South Pole region has craters that are cold traps and contain a fossil record of the early Solar System. Accordingly, Chandrayaan-2 will attempt to soft land the Lander -Vikram and rover- Pragyan in a high plain between two craters, Manzinus C and Simpelius N.
LAUNCH OF CHANDRAYAAN-2
It will be injected into an earth parking 170 x40400 km orbit.
A series of maneuvers will be carried out to raise its orbit and put Chandrayaan-2 on Lunar Transfer Trajectory.
On entering Moon's sphere of influence, on-board thrusters will slow down the spacecraft for Lunar Capture. On the day of landing, the lander will separate from the Orbiter and then perform a series of complex maneuvers comprising of rough braking and fine braking.
Imaging of the landing site region prior to landing will be done for finding safe and hazard-free zones.
The lander-Vikram will finally land near the South Pole of the moon on 6th September 2019.
Subsequently, Rover will roll out and carry out experiments on lunar surface for a period of 1 lunar day which is equal to 14 Earth days.
The orbiter will continue its mission for duration of one year.
EXPERIMENTS AND PAYLOADS
Chandrayaan-2 will carry more than 10 instruments and will focus on the study of topography, seismography, mineral identification and distribution, surface chemical composition, thermo-physical characteristics of topsoil and composition of the lunar atmosphere, leading to a new understanding of the origin and evolution of the Moon.
Terrain Mapping Camera 2(TMC 2): Prepares detailed 3-D map.
Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS): Maps abundance of major rock-forming elements
Solar X-ray Monitor (XSM): Observes X-rays emitted from the sun and supports CLASS.
Orbiter High Resolution Camera (OHRC): Provide a high resolution image of the landing site.
Imaging IR Spectrometer (IIRS): Identifies minerals and signatures of hydroxyl and water molecules.
Dual Frequency Synthetic Aperture Radar (SAR): Maps lunar craters and other features especially in Polar Regions.
Chandrayaan-2 Atmospheric Compositional Explorer 2(CHACE 2): Will carry out a detailed study of lunar exosphere.
Dual Frequency Radio Science (DFRS): To study the temporal evolution of electron density in the lunar ionosphere.
LANDER – VIKRAM
Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA): Measures total electron content.
Chandra’s Surface Thermo-physical Experiment (ChaSTE): Measures thermal properties of regolith and the polar region.
An instrument for Lunar Seismic Activity (ILSA): To detect minute ground displacement, Velocity or acceleration caused by lunar quakes.
ROVER - PRAGYAN
Alpha Particle X-ray Spectrometer (APXS): Determines elemental composition of rock and soil
Laser-Induced Breakdown Spectroscopy (LIBS): To identify and determine the abundance of elements near the landing site.
Laser Retroreflector Array (LRA): To understand the dynamics of Earth’s Moon system and also derive clues on the Lunar interior.
India’s most powerful launch vehicle GSLV Mark III will carry Chandrayaan 2 to its destined orbit. Chandrayaan 2 will consist of Orbiter, Lander – Vikram and Rover – Pragyan.
At the time of launch, the chandrayaan 2 orbiters will be capable of communicating with Indian Deep Space Network (IDSN) at Bangalore as well as the Vikram Lander. The mission life of the orbiter is one year, and it will be placed in a 100x100 km lunar polar orbit.
Lander - Vikram:
The Lander of Chandrayaan 2 is named Vikram after Dr Vikram A Sarabhai, the Father of the Indian Space Programme. It is designed to function for one lunar day, which is equivalent to about 14 Earth days. Vikram has the capability to communicate with IDSN at Byalalu near Bangalore, as well as with the Orbiter and Rover. The Lander is designed to execute a soft landing on the lunar surface.
Rover - Pragyan:
Chandrayaan 2's Rover is a 6-wheeled robotic vehicle named Pragyan, which translates to 'wisdom' in Sanskrit. It can travel up to 500 m (½-a-km) and leverages solar energy for its functioning. It can only communicate with the Lander.
1. CHALLENGES FOR THE LUNAR MISSION:
A. Trajectory Accuracy: Distance to the moon is 3844 lakh km. Ensuring trajectory accuracy is important and it is influenced by the moon’s gravity which is different at different places, due to uneven surface. Other astronomical bodies and solar radiation pressure also influence the trajectory.
B. Space communications: Owing to distance and limited onboard power, there’ll be a communication delay. There will be a delay of a few minutes in every message sent.
C. Translunar injection & lunar capture: The mission will have a series of engine burns to get close to the moon whose location changes continuously. The intersection of spacecraft & moon’s path must be predicted in advance with accuracy.
D. Orbiting around the moon: Lunar gravity is ‘lumpy’ due to uneven mass distribution. Precise knowledge of temperatures 100km away from the moon is the key.
E. Soft Landing on the moon: Variation in local gravity must be factored into lunar descent trajectory. All systems have to work in unison & landing site landscape features shouldn’t result in a communication shadow area.
F. Lunar Dust: Firing on-board engines close to surface results in a backward flow of hot gases & dust. Lunar dust is hard and its negative charge makes it stick to surfaces and can cause a disruption in deployment mechanisms, solar panel performance and so on.
G. Extreme Temperatures and Vacuum: A lunar day or night lasts 14 earth days. This results in extreme surface temperature variations. Ambient pressure of surface is a hard vacuum which makes it a hostile environment for lander and rover.
1. ISRO Chandrayaan-2 website page
2. ISRO Chandrayaan-1 website page
3. TOI “Chandrayaan-2 nearly ready for July Launch” 10th June article.
Harsh Kumar Khatwani