From lunar voyage to Mars Mission and now, 104 satellites in one go, remote sensing and geographical information system (GIS) have played a pivotal role in spatial context in the incredible journey.
In a single payload or say mission, the launch of PSlV-C-37, including the Cartosat-2 series indigenously built for earth observation satellite, followed by two other satellites of ISRO INS-1A , INS-1B, and 101 foreign nano co-passengers sun synchronous satellites set the remarkable feet in space by the ISRO after it put one by one satellite into the orbit.
The show of injecting these satellites in the video released by the ISRO is a rip-roaring success. In case of sun synchronous orbit, the satellite’s orientation is fixed relative to the sun throughout the year which is useful for very accurate weather forecasting, apart from imaging and spying. Earlier the Cartosat-2series spatial resolution was less than 1m which is far less than 2.5m compared to Cartosan-1series. The Cartosan-2C having spatial resolution of 25cm lunched by the Polar Satellite launching Vehicle (PSlV) and Cartosan-2D is identical one to 2C satellite carrying the same instrument and operating from similar orbit.
In the previous years, the Cartosat mission used a sun synchronous orbit 640 km in altitude while in recent case from PSlV-C-37, satellites fly about 520 km in order to increase the resolution of the state of art technology panchromatic and multispectral cameras aboard these satellites. As the images having higher spatial resolution are composed with a higher number of pixels than those of lower spatial resolution, the greater number of pixels is used in sensors of satellites. It is important to distinguish between pixel size and spatial resolution-they are interchangeable.
If a sensor has a spatial resolution of 10 meters and the image from that sensor is displayed at full resolution, each pixel represents an area of 10mx10m on the ground. But it is possible to display an image with a pixel size different than the resolution. After all, the ISRO has left no stone unturned to see the distinguished image. Even the smallest possible feature that can be detected after it processed digitally. There are two spectral resolution, such as temporal and radiometric for obtaining colour image, movie with high speed cameras and typical of computer image file with subtle difference of intensity or reflectivity respectively.
During the early eighties the Skylab satellite generated fears of falling among people in the whole world. Things have quite changed now. However, with advancement of technology at its cutting edge, Director of Vikram Sarabhai Space Centre K Sivan asserted and ensured they (satellites) don’t collide. Images from these remote sensing satellites will be used for cartographic application, urban and rural application, coastal land use and regulation, utility management like road network, water distribution, and geographical information system (GIS) applications etc.
litigation over land ownership and its associated conflicts is witnessed with increasing population and consequent competition for lands in India. Keeping in view of this, the Government of India is mulling as part of digital India, a cadastral mapping to be carried out with air borne satellites using remote sensing and GIS in order to develop digital cadastral information system which has the ability to integrate the map and record of rights (ROR) and use. It will be seen in near future the unmanned aircrafts fitted with satellites hovering over land in low altitude for cadastral layout which later is to be scanned and geo-referenced in Arc GIS software and other relating software. Thereafter, properties will be digitally distinguished and given unique identification numbers to land owners i.e. a cadastral map to contain systematically arranged information all properties within a given village or district.
Both the map and registers may be stored in computers. In this process the problems like forgeries of land documents, multiple allocation of properties and overlapping allocations, inefficient system of revenue generation (property tax etc.) can be mitigated. Airborne liDAR (airborne laser scanning) is when a laser scanner while attached to a plane during flight create a 3D point cloud model of the landscape which is currently the most accurate method of creating digital elevation models (DEMs). Eventually, high resolution imagery from multi-temporal satellite imagery will create DEMs to support the production of ortho images which will be an effective tool in determining the land right as local people can read image plotted on paper and recognise the boundaries of their plot.
Several States like Andhra Pradesh, Uttarakhand, Haryana and Karnatak etc are in a way ahead of application of remote sensing using high spatial resolution and GIS in seeking of better planning of agriculture extension, irrigation, effective water management and disaster management etc. The GIS based maps are being developed by APSRSC for twelve major projects and involves GIS mapping of canal networks. The GIS layers proposed include area localised under each project area irrigated under each source, seasoned area, cropped wise productions and productivity maps, disaster mapping ground water levels and quality. At a time when it is very cumbersome procedure to ascertain the area of vegetation, town expansion, conversion of lands etc by attempt through conventional mapping, the temporal satellite imagery plays a significant role in quantifying spatial and temporal phenomena.
The watershed mission in Kundeimal of Bolangir and Narsinghpur of Korkonda of Malkangiri district are developed to greater extent through remote sensing by satellite image of WORlDVIEW-II for sustainable land use and water conservation. In order to fortify the food security and allied disciplines in India, crop monitoring, forecasting and estimation on vegetation indices is being carried out using remote sensing around the year. By using satellite images, various plant diseases and pests in agricultural crops can be observed where hyper spectral imagery from Hyperion satellites can be used to detect orange rust diseases in sugarcane. Satellite images are particularly very useful to estimate vegetation water content over vast agricultural area, total evaporative water demand for crops, recognition of weeds too and can support effective water management.
Be it Phailin in 2014, Hudhud in 2015 and Kant in 2016, we all have witnessed the tidbit information such as the turnaround time from a disaster occurrence , its movement from time to time , damage assessment report and mitigation agencies etc through remote sensing satellites imagery. Understanding the propagation of waves is very crucial when tsunami occurs, the model of Earth Topography-2 minute (ETOPO2) and near bathymetry data from national hydrographical chart. The model shows the arrival time and expected run up at various points in Indian coast. Further heavy snowfalls in Kashmir valley in February and March lead to a threat of floods. The snow accumulation and depletion patterns from satellite data, discharge data snowfall and temperature were analysed and the study revealed that major threat of floods from snowfall in the valley are not envisaged. For continuous monitoring of atmospheric as well as surface parameter in case of droughts and floods, earth observation satellites including both geostationary and polar orbiting satellites provide comprehensive synoptic and multi temporal coverage of large areas in real time and at frequent intervals of time. Advancement in the remote sensing technology and GIS helps in monitoring in real time, quick damage assessment and early warning of both drought and flood disasters. Design of water supply schemes in both the sector of RWSS and PHED can be analysed using GIS and remote sensing.
Currently, operational communication satellites are INSAT-3A,INSAT-3C,INSAT-3E,INSAT-4A,INSAT-4B,INSAT-4CR,GSAT-8,GSAT-10 &GSAT-12 which provides service to telecommunications, television broadcasting, satellite news gathering, societal applications, disaster warning, weather forecasting, search and rescue operations.