The launch of two remote-sensing satellites today is part of ISRO’s plans for expanding its constellation of earth-observing satellites.
Twenty years ago, the Indian Space Research Organisation (ISRO) launched the country’s first operational earth-observation satellite, the IRS-1A. In the years since then, ISRO has sent up 10 more remote-sensing satellites. (Six of these satellites are currently operational, including the ageing IRS-1D, which was launched more than 10 years ago with a design life of three years and is reportedly used sparingly these days.)
“Today, India is one of the major providers of earth observation data in the world in a variety of spatial, spectral and temporal resolutions, meeting the needs of many applications of relevance to national development,” point out Ranganath R. Navalgund, director of ISRO’s Space Applications Centre at Ahmedabad, V. Jayaraman, director of Earth Observations System at ISRO Headquarters in Bangalore, and P.S. Roy of the National Remote Sensing Agency in Hyderabad in a journal paper published last December.
In the early days, well before its own satellites were launched, ISRO used data from foreign satellites, such as the American Landsat and French SPOT satellites, to demonstrate the practical benefits that could be got from remote sensing, says S. Chandrasekhar, who was earlier at ISRO headquarters and is currently on the faculty of IIM, Bangalore. ISRO also worked closely with government departments and other user agencies to understand their needs as well as to make their staff familiar with the technology. As a result, when the IRS satellites became available there was already a user community within the country that wanted the data.
The images from IRS satellites’ watchful eyes are put to use in many ways. They are used to make more accurate crop acreage and production estimates; for drought and flood damage assessment; environmental monitoring, including of forest cover, and to assess biodiversity; for better water resource management; to map minerals and other resources; for snow and glacier studies; urban planning; watershed monitoring and management; and for coastal and ocean studies.
The constellation of Indian remote-sensing satellites is set to grow further. ISRO plans to carry out over 30 remote sensing satellite missions by 2025, Dr. Jayaraman told The Hindu.
On Monday (April 28), two such satellites are to travel into space aboard the Polar Satellite Launch Vehicle (PSLV). The Cartosat-2A is similar to the Cartosat-2 that was launched in January 2007. The panchromatic camera on these satellites offer a resolution of better than one metre, the best so far of any operational Indian satellite. Such resolution makes it possible to discriminate even small features on the ground, distinguish characteristics of buildings and see individual vehicles.
An ISRO press release last year pointed out that such high-resolution images would be invaluable for the planning, monitoring and implementation of urban infrastructure and transportation systems; the mapping of individual settlements, roads, urban complexes and urban utilities; and for planning rural roads and infrastructure that required detailed terrain evaluation. It could also be used for delineation and characterisation of micro watersheds and monitoring of coastal land use.
But the cameras on the Cartosat-2 and 2A take images that cover the ground in strips just 10 km wide. Having two such satellites in the orbit at the same time would therefore allow large areas to be imaged more quickly and to revisit certain areas with less delay. The latest annual report of the Department of Space indicates that the Cartosat-2B could also be launched during the current financial year.
The Indian Mini Satellite-1 (IMS-1), which was earlier called the Third World Satellite (TWSAT), will be a co-passenger with the Cartosat-2A on the PSLV. While the latter weighs 690 kg, the IMS-1, a small satellite, weighs slightly over 80 kg at lift-off.
“The IMS-1 should be seen as a technology demonstrator for miniaturising both space and ground segments,” said Dr. Jayaraman. “The low-cost user terminal has been designed as an integrated one that can receive data directly from the satellite and process that data. With such terminals, developing countries that do not currently use remote-sensing can learn to receive and use imageries from the satellite’s multi-spectral camera. The idea is to aid capacity building in such countries.”
Hyperspectral camera
The IMS-1 will also carry the country’s first hyperspectral camera. Remote-sensing cameras that take images in different colours typically do so in just a few bands. The IMS-1’s multi-spectral camera, for instance, captures images in four colour bands. The satellite’s hyperspectral camera, on the other hand, distinguishes 64 colour bands. (This hyperspectral camera is said to be a slightly modified version of the instrument that will fly on Chandrayaan-1, India’s first lunar mission.)
Hyperspectral imaging has been extensively used for mineral exploration in Australia, according to George Joseph, who played a key role in developing optical cameras for the IRS satellites and retired as director of the Space Applications Centre in Ahmedabad. It could reveal many fine details about vegetation, such as morphological differences, biochemical changes occurring in the leaf and water and nutrient stress, which do not show up when observations are made in broad spectral bands. Hyperspectral imaging could be useful for a variety of ocean studies too, Dr. Joseph told The Hindu. He currently heads the Centre for Space Science and Technology Education in Asia and the Pacific, a United Nations-affiliated body based in Dehra Dun.
The Oceansat-2 satellite, which too may be launched this year, is intended to replace the Oceansat-1 satellite that was launched in 1999. Apart from an ocean colour monitor, Oceansat-2 will be equipped with an instrument that uses a narrow radar beam to ascertain wind direction and velocity. The satellite will also carry an Italian instrument to use signals from GPS satellites for deriving temperature and humidity profiles of the atmosphere.
Over the next four to five years, ISRO could launch a dozen or so earth-observation satellites, going by the mission profile given in the Department of Space’s annual report for 2007-2008.
Next year could see the launch of the country’s first active radar satellite, the Radar Imaging Satellite-1 (RISAT-1). Optical cameras on the IRS satellites rely on picking up sunlight reflected from the earth’s surface. So they cannot work at night or when clouds block their view of the ground below. A radar satellite, on the other hand, can take images by night as well as by day and can see through clouds, fog and haze. The radar images from the satellite could also provide information on soil moisture.
Megha-Tropiques, a joint Indo-French effort at building a satellite dedicated to atmospheric and climate research in the tropics, could be ready by the end of 2009. A Statement of Intent to build such a satellite was signed by the space agencies of the two countries nine years ago. The instruments on the satellite are intended to help scientists understand better the water cycle in the tropics as well as how rain-bearing cloud systems (including cyclones) form and evolve. Another advanced meteorological satellite, the Insat-3D, could also fly during the 2009-2010 financial year.
Remote-sensing satellites usually circle the Earth at a height of a few hundred kilometres. ISRO plans to put a Cartosat-type camera on a satellite that will be placed in geostationary orbit at a distance of about 36,000 km. In this orbit, the satellite matches the Earth’s rotation and therefore appears stationary from the ground. Stationed over India, the ‘Geo-HR Imager’ (as the satellite has been named) would be able to take images of the country and neighbouring regions whenever needed. By contrast, an orbiting satellite would be able to image the ground only when it flies overhead, which could be after a few days or even weeks depending on its orbit. Geo-HR Imager could therefore significantly aid disaster management efforts. Its imagery would also provide inputs for natural resources management. ISRO has currently scheduled the satellite for launch during 2010-2011.
In 2011-12, Cartosat-3 could go into the orbit. The panchromatic camera on this satellite is expected to provide images with a resolution of 30 cm. Currently, the American WorldView-1 satellite launched in September last year offers the highest resolution imageries that are commercially available and the resolution of those images is 50 cm. WorldView-2, which will be launched next year, will provide images with a resolution of 46 cm.
Apart from meeting Indian application and user demands, ISRO’s earth observation programme would also complement global efforts to use satellites for monitoring and studying the planet, said Dr. Jayaraman. There is considerable international interest in including several Indian missions as part of the planned global constellation of earth observation satellites, he added.
Twenty years ago, the Indian Space Research Organisation (ISRO) launched the country’s first operational earth-observation satellite, the IRS-1A. In the years since then, ISRO has sent up 10 more remote-sensing satellites. (Six of these satellites are currently operational, including the ageing IRS-1D, which was launched more than 10 years ago with a design life of three years and is reportedly used sparingly these days.)
“Today, India is one of the major providers of earth observation data in the world in a variety of spatial, spectral and temporal resolutions, meeting the needs of many applications of relevance to national development,” point out Ranganath R. Navalgund, director of ISRO’s Space Applications Centre at Ahmedabad, V. Jayaraman, director of Earth Observations System at ISRO Headquarters in Bangalore, and P.S. Roy of the National Remote Sensing Agency in Hyderabad in a journal paper published last December.
In the early days, well before its own satellites were launched, ISRO used data from foreign satellites, such as the American Landsat and French SPOT satellites, to demonstrate the practical benefits that could be got from remote sensing, says S. Chandrasekhar, who was earlier at ISRO headquarters and is currently on the faculty of IIM, Bangalore. ISRO also worked closely with government departments and other user agencies to understand their needs as well as to make their staff familiar with the technology. As a result, when the IRS satellites became available there was already a user community within the country that wanted the data.
The images from IRS satellites’ watchful eyes are put to use in many ways. They are used to make more accurate crop acreage and production estimates; for drought and flood damage assessment; environmental monitoring, including of forest cover, and to assess biodiversity; for better water resource management; to map minerals and other resources; for snow and glacier studies; urban planning; watershed monitoring and management; and for coastal and ocean studies.
The constellation of Indian remote-sensing satellites is set to grow further. ISRO plans to carry out over 30 remote sensing satellite missions by 2025, Dr. Jayaraman told The Hindu.
On Monday (April 28), two such satellites are to travel into space aboard the Polar Satellite Launch Vehicle (PSLV). The Cartosat-2A is similar to the Cartosat-2 that was launched in January 2007. The panchromatic camera on these satellites offer a resolution of better than one metre, the best so far of any operational Indian satellite. Such resolution makes it possible to discriminate even small features on the ground, distinguish characteristics of buildings and see individual vehicles.
An ISRO press release last year pointed out that such high-resolution images would be invaluable for the planning, monitoring and implementation of urban infrastructure and transportation systems; the mapping of individual settlements, roads, urban complexes and urban utilities; and for planning rural roads and infrastructure that required detailed terrain evaluation. It could also be used for delineation and characterisation of micro watersheds and monitoring of coastal land use.
But the cameras on the Cartosat-2 and 2A take images that cover the ground in strips just 10 km wide. Having two such satellites in the orbit at the same time would therefore allow large areas to be imaged more quickly and to revisit certain areas with less delay. The latest annual report of the Department of Space indicates that the Cartosat-2B could also be launched during the current financial year.
The Indian Mini Satellite-1 (IMS-1), which was earlier called the Third World Satellite (TWSAT), will be a co-passenger with the Cartosat-2A on the PSLV. While the latter weighs 690 kg, the IMS-1, a small satellite, weighs slightly over 80 kg at lift-off.
“The IMS-1 should be seen as a technology demonstrator for miniaturising both space and ground segments,” said Dr. Jayaraman. “The low-cost user terminal has been designed as an integrated one that can receive data directly from the satellite and process that data. With such terminals, developing countries that do not currently use remote-sensing can learn to receive and use imageries from the satellite’s multi-spectral camera. The idea is to aid capacity building in such countries.”
Hyperspectral camera
The IMS-1 will also carry the country’s first hyperspectral camera. Remote-sensing cameras that take images in different colours typically do so in just a few bands. The IMS-1’s multi-spectral camera, for instance, captures images in four colour bands. The satellite’s hyperspectral camera, on the other hand, distinguishes 64 colour bands. (This hyperspectral camera is said to be a slightly modified version of the instrument that will fly on Chandrayaan-1, India’s first lunar mission.)
Hyperspectral imaging has been extensively used for mineral exploration in Australia, according to George Joseph, who played a key role in developing optical cameras for the IRS satellites and retired as director of the Space Applications Centre in Ahmedabad. It could reveal many fine details about vegetation, such as morphological differences, biochemical changes occurring in the leaf and water and nutrient stress, which do not show up when observations are made in broad spectral bands. Hyperspectral imaging could be useful for a variety of ocean studies too, Dr. Joseph told The Hindu. He currently heads the Centre for Space Science and Technology Education in Asia and the Pacific, a United Nations-affiliated body based in Dehra Dun.
The Oceansat-2 satellite, which too may be launched this year, is intended to replace the Oceansat-1 satellite that was launched in 1999. Apart from an ocean colour monitor, Oceansat-2 will be equipped with an instrument that uses a narrow radar beam to ascertain wind direction and velocity. The satellite will also carry an Italian instrument to use signals from GPS satellites for deriving temperature and humidity profiles of the atmosphere.
Over the next four to five years, ISRO could launch a dozen or so earth-observation satellites, going by the mission profile given in the Department of Space’s annual report for 2007-2008.
Next year could see the launch of the country’s first active radar satellite, the Radar Imaging Satellite-1 (RISAT-1). Optical cameras on the IRS satellites rely on picking up sunlight reflected from the earth’s surface. So they cannot work at night or when clouds block their view of the ground below. A radar satellite, on the other hand, can take images by night as well as by day and can see through clouds, fog and haze. The radar images from the satellite could also provide information on soil moisture.
Megha-Tropiques, a joint Indo-French effort at building a satellite dedicated to atmospheric and climate research in the tropics, could be ready by the end of 2009. A Statement of Intent to build such a satellite was signed by the space agencies of the two countries nine years ago. The instruments on the satellite are intended to help scientists understand better the water cycle in the tropics as well as how rain-bearing cloud systems (including cyclones) form and evolve. Another advanced meteorological satellite, the Insat-3D, could also fly during the 2009-2010 financial year.
Remote-sensing satellites usually circle the Earth at a height of a few hundred kilometres. ISRO plans to put a Cartosat-type camera on a satellite that will be placed in geostationary orbit at a distance of about 36,000 km. In this orbit, the satellite matches the Earth’s rotation and therefore appears stationary from the ground. Stationed over India, the ‘Geo-HR Imager’ (as the satellite has been named) would be able to take images of the country and neighbouring regions whenever needed. By contrast, an orbiting satellite would be able to image the ground only when it flies overhead, which could be after a few days or even weeks depending on its orbit. Geo-HR Imager could therefore significantly aid disaster management efforts. Its imagery would also provide inputs for natural resources management. ISRO has currently scheduled the satellite for launch during 2010-2011.
In 2011-12, Cartosat-3 could go into the orbit. The panchromatic camera on this satellite is expected to provide images with a resolution of 30 cm. Currently, the American WorldView-1 satellite launched in September last year offers the highest resolution imageries that are commercially available and the resolution of those images is 50 cm. WorldView-2, which will be launched next year, will provide images with a resolution of 46 cm.
Apart from meeting Indian application and user demands, ISRO’s earth observation programme would also complement global efforts to use satellites for monitoring and studying the planet, said Dr. Jayaraman. There is considerable international interest in including several Indian missions as part of the planned global constellation of earth observation satellites, he added.
No comments:
Post a Comment