Chandrayaan 2 Is One Of The Vehicles For Indian Space Journey
Indian space program entered public consciousness with the launch of its satellite, Aryabhata in 1975. Its latest act is launch of a lunar exploration mission, Chandrayaan 2 (Vehicle to the Moon). The program follows 3 main tracks, i.e. manufacture of satellites, improvisation of launch vehicles and space missions.
Satellites
Remote sensing
After Aryabhata, India launched Bhaskara 1 and 2 as experimental remote sensing satellites. Rohini series of small satellites weighing less than 50 Kgs were also meant for experimental remote sensing. IRS (Indian Remote Sensing) satellites followed by Cartosat (Cartographic Satellites) started providing remote sensing data for commercial applications. They are placed in polar orbits and hence they circle the earth from North to South and not along the equator. Their orbits are also sun synchronous and hence they pass over any given point on Earth’s surface at the same local solar time. They are placed in low earth orbits of less than 1000 Km. The advanced Cartosat 2 series carry panchromatic camera which can take pictures in all wavelengths of visible spectrum making them ideal for remote sensing. Agriculture, water resources, forestry and ecology, infrastructure planning, urban planning, geology, water sheds, marine fisheries and coastal management etc benefit from remote sensing data.
Communication
For communication, satellites need to be placed in geo synchronous orbit which is approximately 36000 Km above the earth’s surface. These satellites rotate with the same frequency as the Earth and hence appear stationary and can reflect the electromagnetic signals. INSAT and GSAT are series of communication satellites. They use C, S, Ka, Ku bands (from 2.025 Ghz to 27 Ghz) of electromagnetic spectrum for communication and TV needs.
Other uses
Some of the INSAT and GSAT satellites also help in meteorology, search and rescue, hydrology and oceanography. They carry special instruments e.g. Very High Resolution Radiometer (VHRR), Data Relay Transponder (DRT), specialized cameras etc for these activities.
Indian Regional Navigation Satellite System (IRNSS) satellite series provide accurate position information service like GPS. It uses dual frequency (S and L bands) to improve accuracy using a spread of 1-4 GHz while GPS uses a spread of 1-2 GHz,
Oceansat series are remote sensing satellites that carry Ocean Colour Monitor (OCM) to study surface biology, atmospheric aerosols and particulate matter of the oceans and microwaves scanners to study physical surface characteristics. Similarly Resourcesat series are specialized in providing micro and macro level information about land and water bodies.
Planned launches
The satellite program has many planned launches e.g. that of Cartosat-3 that will improve resolution to 0.25 m from 1 m of Cartosat-2 series and will further help in weather mapping, cartography and strategic applications. The planned launch of GSAT-20 will fulfill data needs for various smart cities
Launch Vehicles
India's performance in Launch Vehicle technology was comparatively slower and it banked upon other countries for the initial satellite launches.
PSLVs
However it tasted success with PSLV (Polar Solar Launch Vehicle) technology. PSLVs put satellites in polar orbits They can also put relatively lighter satellites weighing about 1200 Kg in geo synchronous orbits. PSLVs are also capable of launching multiple satellites and PSLV C37 launched 103 nano satellites and 1 main satellite in a single launch. They have 4 stage propulsion system using solid and liquid systems alternatively. India has commercialized the use of PSLV and more than 200 foreign satellites have been launched by it.
GSLVs
India has GSLVs for launching satellites in geo synchronous orbits. GSLV use 3 stage propulsion systems. While the first two stages are similar to that of PSLVs but the third stage uses cryogenic engines which use mixture of liquid Oxygen and liquid Hydrogen for greater thrust. The latest version GSLV MK III can carry payload of about 4000 Kg. However GSAT-11 had a weight of about 6000 Kg, hence GSLVs need to improvise further to increase their payloads. Use of Kerolox which is a mixture of Oxygen and Kerosene in the second stage of the propulsion will be experimented for achieving this
Strategic
India also wants to use space program to showcase its technological prowess and gain strategic importance.
Military
India has been developing satellites for military use e.g. GSAT-7 for navy to monitor Indian ocean and provide real-time input capabilities to Indian warships, submarines and maritime aircraft, GSAT-7A for communication by Air Force, CARTOSAT-2A for dedicated military use and RISAT (Radar Imaging Satellite ) 2B to monitor India’s borders and general surveillance. This year India also demonstrated that it can destroy satellites in space by striking down its own satellite at an altitude of 300 Km.
Space missions
India has been launching probes to other celestial bodies e.g. Chandrayaan I and II for the Moon. Mangalyaan for Mars etc. Chandrayaan I orbited the Moon and also touched it in a control manner. It was launched by a PSLV rocket and carried mapping of Moon’s surface and searched for presence of minerals. Besides a terrain mapping camera, it carried Laser Ranging Instrument for determining height of the surface, High Energy gamma x ray spectrometer for detecting radioactivity, a spectrometer for determining the constituents of the Moon’s atmosphere etc
This was followed by Mangalyaan or Mars Orbiter Mission which also used PSLV for lift and objective was to study Mar’s surface and atmosphere. It carried a photometer to study Deuterium and Tritium on Mar’s atmosphere by monitoring the Lyman-Alpha spectrum, sensor to measure Methane, a spectrometer to study its surface by observing Infrared spectrum etc It continues to orbit Mars. India has also launched space telescope, Astrosat which has instruments to study Ultra Violet rays and soft and hard X rays from celestial objects.
Chandrayaan II also had a land rover for moving on Moon's surface and one of the aim is to check for water ice besides mapping lunar surface. It will land at the uncharted South pole of the Moon. Its Stereoscopic camera will provide a 3D view of the Moon’s surface. It used GSLV MK III for the lift.
These missions are for research and for paving way for future missions e.g. Venus orbiter, a manned space station, Solar probe, a land rover for Mars etc
Future
In future, India will continue to use its space program for social and economic benefits as well as for testing and demonstrating new technologies.
