The Moon is tidally locked with the Earth. The Moon is in stable configuration with the Earth. The Moon has the same hours of rotation as the Earth.
There are many theories as to how the Earth-Moon pair was formed. The Moon and the Earth are said to have formed together – Accretion Theory. A massive objected divides as the bigger part became the Earth, while the smaller part became the Moon – Fission Theory. A big object collided with the Earth – Collision Theory. Giant Impact Theory. A conclusion could be drawn only when the Rover Pragyan collected rocks from the Fossil Region of the dark side of the Moon – insitu analysis.
Fun Fact: 1 Rotation of the Moon = 1 Revolution of the Moon = 28 days. Therefore one side of the Moon always remains in the shadow region.
ISRO through the years has launched many satellites – Communication Satellites for our mobile phones, Earth Observation Satellites for the floods’ detection, Scientific Spacecraft for a better atmosphere and astronomy, Navigation Satellites for your Google Maps, Experimental Satellite for space recovery vehicles and other small satellites like StudSat Satellites, which are student made.
Now, let’s talk about the Moon Impact Mission, GSAT - Chandrayaan 2. It all started when water was detected, apparently in solid form. More than 95% indigenous, Chandrayaan 2 has the following components:
1. The Orbiter which requires about 650 to 1kW of power to capture high resolution photographs, while it’s orbiting around the moon. The efficiency of the solar panels on the Orbiter, is about 40 to 45% in space, whereas on Earth the efficiency is much less than 35%. The Orbiter orbits initially in the Lower Earth Orbit, then slowly increases the trajectory for the Higher Earth Orbit. From the Higher Earth Orbit, it further moves to the polar orbit.
The Orbiter contains a ReSAT radar to communicate with humanity on earth. It acts a bridge between ISRO and the Rover Pragyan.
2. The Lander Vikram which expels out the Rover from the Orbiter, by soft landing a parachute. Soft landing! That’s A Breakthrough Made In India. Named after Dr. Vikram A Sarabhai, the Father of the Indian Space Programme, the Lander takes about a lunar day to be dropped off the Orbiter, depending on the nature of rotation and revolution of the earth.
3. The Rover Pragyan, the smallest component, generates about a 50W power to function effectively at a speed 0.5km/hr on the lunar terrain (the speed is slow in order for it to perform scientific experiments). The Rover is a gold plated robot, with 6 wheels (for navigation stability and precise rotation), which effectively navigates lunar terrain. Why Gold? Gold acts a shield for radiation insulation, as it manages the temperature perfectly well.
One cannot communicate directly with the Rover due to a small battery life and less powerful signal. The Rover communicates with the Orbiter, and the ISRO communicates with the Orbiter.
The Chandrayaan 2 was launched from the Shriharikota into Deep Space. The GSAT (Geosynchronous Satellite Launch Vehicle Mark III), which weighs 3 tones, follows the protocol written by telemetry in Hassan, developed by ISRO. This interplanetary mission is universally accepted as an exemplary achievement by the IDSCN – Indian Deep Space Communication Network.
Why Geosynchronous Satellite Launch Vehicle Mark III, you may ask. GSAT was used because it is the most effective heavy mass, up to 4 tones, lifting rocket. Whereas Mangalyaan was a PSLV as the number of payloads to be carried were much less. The GSAT, a development of cryogenic technology, is fueled by liquid Nitrogen and liquid Oxygen in super cold temperatures.
As the temperature is low, density of fuel is more due to which ignition efficiency of Vikas engine becomes highly increased.
The point on the Moon that interests us the most is the South Pole (70°S 30°E). Why? Well, for the following reasons:
a. The South Pole is a permanent shadow region, a poorly lit area, sunlight almost never reaches here. The probability of finding frozen water is maximum.
b. Known as the Fossil Region, unaffected by the heat of the sun, may contain the origins of the solar system as it is unadulterated. The region may contain unevolved, unweathered rocks due to lack of access to sunlight.
c. The region has never been explored before because of poor visibility.
d. The most favorable reason being, it is a highland between two craters which makes it easier for soft landing.
Key Payloads On The Chandrayaan 2 GSLV MkIII:
1. Chandrayaan 2 Large Area Soft X-ray Spectrometer - Elemental composition of the Moon
2. Imaging IR Spectrometer - Mineralogy mapping and water-ice confirmation
3. Synthetic Aperture Radar L & S Band - Polar-region mapping and sub-surface water-ice confirmation
4. Orbiter High Resolution Camera - High-resolution topography mapping
5. Chandra's Surface Thermo-physical Experiment - Thermal conductivity and temperature gradient
6. Alpha Particle X-ray Spectrometer and Laser Induced Breakdown Spectroscope - In-situ elemental analysis and abundance in the vicinity of landing site
Chandrayaan-2 mission was thus a highly complex mission, which represents 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.
Sources:
Information - The Nehru Planetarium, Bangalore
Images - Chandrayaan2 Gallery - ISRO
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