by Gurbir Singh
RISAT-1
26 Apr
2012
A remote-sensing satellite designed for applications in agriculture and management of natural disasters, like flood and cyclone. The sub 1m imaging resolution supported strategic applications.
SARAL
25 Feb 2013
Satellite with ARgos and ALtiKa (SARAL) is a joint mission between the Indian and French space agencies to monitor sea surface elevation and sea circulation.
Table 12‑2 ISRO’s Earth Observation Satellites Operational in mid-2016
A slight tweak was required to the orbit to ensure Sun-synchronisation, and IRS-1A was declared operational three weeks after launch. It would cross the equator at 10:30 am local time during ascending node, which brought it to the same point on Earth every 22 days. It operated until July 1996. IRS-1A was entirely an Indian project except for a few components that had to be imported.[674]
The National Remote Sensing Agency (now known as the National Remote Sensing Centre) in Hyderabad was equipped with ground-receiving systems for payload data reception and storage and processing facilities to meet the needs of IRS-1A. IRS-1B was launched in 1991 and was identical to IRS-1A. It operated successfully until 20 December 2003. By mid-2016, ISRO was operating nine EO satellites in SSO (Resourcesat-2; Cartosat-1, 2, 2A and 2B; Risat-1 and 2; Oceansat 2 and SARAL), three EO satellites in GEO (INSAT-3D, Kalpana-1 and INSAT-3A) and one in equatorial orbit (Megha-Tropiques).
Remote Sensing Instrument
In the almost four decades since Bhaskara, not only has the number of satellites in orbit increased but also the complexity and sensitivity of the onboard instruments. These instruments are designed to detect and measure four physical attributes seen from space, spectral (variation in colour), spatial (degree of resolution), temporal (changes over time) and polarisation (a property of reflected light that carries information about the physical and chemical attributes of the reflecting source). Collectively, these instruments allow scientists to identify and quantify characteristics, such as the temperature of the air or sea surface, salinity, soil moisture, sea ice, the amount of water in the atmosphere, wind speed and direction. Remote-sensing technology can be passive or active.
The passive technology uses cameras or radio receivers to analyse the electromagnetic radiation reflected by the Earth. The active technology involves the satellite illuminating the Earth using an onboard radio or light source (Light Detection and Ranging (LIDAR) or Radio Detection and Ranging (RADAR) systems) and analysing the reflections. LIDAR and RADAR are conceptually identical; LIDAR operates in the visible range of the Electromagnetic Spectrum and RADAR in the radio (microwave) range. Instruments onboard ISRO's EO satellites include:
Passive instruments
SAMIR: Satellite Microwave Radiometer designed to measure liquid water content in the atmosphere, water vapour and ocean surface characteristics. It was first used in Bhaskara-1 in 1979.
MSMR: Multi-frequency Scanning Microwave Radiometer designed to measure wind speed and direction. It was used in Oceansat-1, also known as IRS-P4, in 1999.
MADRAS: Microwave Analysis and Detection of Rain and Atmospheric Structures designed to measure ice particles in cloud tops. It was used in Megha-Tropiques in 2011.
SAPHIR: Sondeur Atmosphérique du Profil d'Humidité Intertropicale par Radiométrie designed to determine humidity by measuring water vapour distribution associated with convection and vertically between cloud layers. A joint venture between ISRO and CNES, it was used in Megha-Tropiques in 2011.
OCM: Ocean Colour Monitor designed to look at the ocean using visible and near-infrared light in the range of 400–800 nm. Radiation from sea water in this range is characterised by a small-scale content of the reflecting source. This includes suspended particulates, minerals, chemical compounds and phytoplankton. It is used in Oceansat-2 launched in 2009.
Active instruments
SAR: Synthetic Aperture Radar designed to measure soil moisture using radar backscatter. With a resolution of up to 1 m, it could also measure Earth’s surface albedo (the measure of how well a surface reflects the light shining on it; for example, a snow-covered surface reflects most of the light so has a high albedo), sea ice sheet topography, land surface imagery, ocean-dynamic topography, sea ice cover, soil moisture at the surface and vegetation type. It was used in Risat-2 in 2009.
ALTIKA: Altimeter using Ka band transmission. It is used to measure humidity, wind speed, ocean surface wind speed, sea level and ocean wave height. Used in SARAL, the joint ISRO and CNES mission in 2013.
Scatterometer: A radar technique used to measure ocean surface wind speed and direction. It is used in Oceansat-2 launched in 2009.
Over the last three decades, key innovations in the development of both passive and active sensors have enhanced the number and range of attributes and the accuracy with which they can be measured. The spatial resolution three decades ago was much lower but sufficient to detect man-made structures, such as roads, railways, buildings and bridges. Modern technology offers higher resolution that can detect individuals, vehicles and group activities from space. It can provide images or real-time video.
Global coverage and the orbital configuration that brings the satellite over the same point repeatedly every few days or weeks have made remote-sensing data a unique resource for research and applications, such as cartography, agriculture, geology, urban planning, forestry and surveillance. A third of India’s population lives in about 8,000 towns and cities. Satellite information plays a key role in the urbanisation that is expected to double in the next 20 years. Data from satellite technology is a powerful resource that contributes to the economic growth of a nation. Since satellites cover all the globe and not just the countries that launch them, data collected can also be sold to countries that do not have satellites of their own.
Data from Earth Observation Satellites
The US recognised the commercial value of the data it had been capturing since the 1960s. The EO programme was pioneered by the US’s Landsat-1 in 1972. Presidential directive 54 in 1979 formally directed NASA to pass on the operational management of its three Landsat satellites to the private sector. In 1985, the Earth Observation Satellite Company (EOSAT) took on the responsibility for Landsat operations. It assumed responsibility to grow the Landsat constellation on a commercial basis. Eight Landsat satellites were launched between 1972 and 2013, of which one failed to reach orbit. In mid-2016, only Landsat-7 and Landsat-8 were operational. In October 1993, ISRO signed an agreement with EOSAT that gave the latter exclusive worldwide rights for a fee of Rs.1.8 crore ($0.6 million) for each ground station it built to receive IRS data.
Within India, the government established two organisations in parallel during the 1970s and 1980s to manage the EO data, the National Remote Sensing Centre (NRSC) and the National Natural Resources Management System (NNRMS). NRSC has gone through a number of reorganisations since being established, and today, it has a large campus in Hyderabad with an Earth station about 60 km away at Shadnagar. It is tasked with acquiring, processing and disseminating satellite data from Indian satellites, as well as foreign satellites with which India has agreements. It also provides 24 × 7 support for the disaster monitoring service. Its commercial function includes providing user-customised geospatial solutions and sale of low, medium and high-resolution images captured by the various instruments on Indian EO satellites.
NNRMS makes available EO satellite data of India’s natural resources to those government agencies and ministries that can make direct use of it. NNRMS was first proposed as a centre to manage this data in 1983 and operated under the auspices of the DOS. It is now an integrated national management system responsible for managing a central repository of EO data used to sustainably exploit India’s natural resources for national interest. Since its initial founding, NNRMS has expanded to support weather forecasting, disaster management, environmental monitoring, infrastructure development and urban planning. Over the years, NNRMS has de
veloped three specific resources from the data it has accumulated.
An inventory of mapping data for forests, wastelands, surface-water bodies, wetlands, coastal land use, groundwater targets and urban land use. Geographical Information Systems (GIS) incorporating satellite images for developing applications, such as crop-production estimation, land and water resources optimisation in watersheds, coastal zone regulation, environmental and landslides hazard impact analysis. Large GIS databases of state-specific software tools to support unique planning and governance needs in a consistent, effective and standard approach across India. Loss of lives on a large scale, whether through flood, earthquake, drought or famine, has been a regular feature of the Indian subcontinent throughout history.
The 2004 Indian Ocean and the 2011 Japanese tsunamis, captured in harrowing high-definition images, help illustrate the immense destructive power of nature. In part, this loss has vindicated the application-centric thinking of the founders of India's space programme. A wide variety of sensors on meteorological satellites, the advent of space-age technology for early warning systems and space-based search and rescue have for the first time enabled a mechanism to mitigate the consequence of natural disasters. During the Bhola Cyclone in November 1970, Bangladesh lost half a million people. In the1999 Odisha cyclone, the loss of life was reduced to around 10,000 because of improved space-based monitoring. With the incremental enhancement of the space infrastructure, only a relatively tiny number of fatalities were reported during cyclone Phailin in October 2013 because around 10 million people had been evacuated by the time it arrived.[675]
Benefits of India’s EO programme are substantial but intangible and often unquantifiable. For example, it is impossible to quantify the value of lives saved through the Indian Tsunami Early Warning System, preventing crop failure and famine through irrigation made possible by finding groundwater using space-based sensors, mitigating cyclone damage by timely forecasts modelled on years of EO data and the commercial potential of a new regional navigation system to the national economy. Some specific examples of where ISRO’s EO capability has or can mitigate the impact of natural disasters in India include:
Uttarakhand flash floods: The sudden deluge between 16 and 17 June 2013 and the resulting landslides swept away roads, houses and infrastructure. Following the inevitable death and destruction, space-based assets supported the relief activities, which included making available 12 satellite phones, five transportable satellite terminals to facilitate video conferences, and voice and data to facilitate recovery activities in the immediate aftermath. Subsequently, 2,400 landslides were mapped from space to aid long-term repair.[676]
Tropical Cyclone Phailin: A significant and severe weather event was forecasted several days in advance. Phailin was monitored by INSAT-3D as it approached the Bay of Bengal making a landfall on the coast of Odisha on 12 October 2013. The close monitoring and early warning prompted large-scale evacuation limiting the loss of lives to around 44. Fourteen years earlier, the casualties were around 15,000 with an estimated damage of $2 billion.[677] The huge reduction in the impact of Phailin was the result of space-based assets, associated ground elements, as well as the prompt action to engage relief services.
Groundwater: Most of India relies on groundwater, up to 90% for rural domestic use and 60% for irrigation. Locating groundwater can be costly and time-consuming. A nationwide map identifying groundwater has been produced using space-based remote sensing and hydro-geological and geophysical investigations on the ground. Over 300,000 bore holes were drilled across the country with 90-95% success in locating groundwater.[678]
Land reclamation: The Ministry of Rural Development initiated a project to detect and map wastelands, that is, land that could potentially be used for agricultural or other purposes but is currently unused. Using remote-sensing data, a wasteland map for the whole of the country was generated, which characterised 16% of India (46.72 mha in 2009) as wasteland.[679] Using this data, the Ministry of Rural Development is implementing wasteland development activities across the country. Forecasting natural disasters: ISRO scientists continue to develop models and establish early warning systems for parts of India with challenging geography. For example, alerts for heavy rainfall/cloudburst in western Himalayas, rainfall-triggered landslide alerts for the pilgrimage route in the Uttarakhand region, early warning for floods in critical locations in flood-prone regions of Assam and short-term models for snow-melt run-off into rivers, including Alaknanda, Bhagirathi, Yamuna, Sutlej, Beas and Chenab basins.[680]
As the more developed economies have demonstrated, space-based services enhance both the quality of life and the national economy. As ISRO's infrastructure and experience grow, so does the potential for introducing new imaginative space-based solutions. In 2015, ISRO actively considered 170 projects that could have a direct impact on improving the lives of ordinary Indians. Three of ISRO's recent projects include:
Heritage site conservation: Working with the Ministry of Culture, ISRO plans to document heritage sites and monuments of national importance by creating a database of heritage sites from data collected by Cartosat-1, Cartosat-2 and Resourcesat.
Mining Surveillance System: A space-based system to detect illegal mining. India has 3,843 mining leases of which 1,710 are working, and 2,133 are non-working mines. The software will automatically scan satellite images for around a 500-m range and trigger an alert on detecting unauthorised activity.[681]
Unmanned railway crossings: Enhance safety by equipping trains with GPS Aided GEO Augmented Navigation (GAGAN) receivers as used by aircraft. Barriers can be lowered as a train approaches and retracted once it has passed. This space-age technology would boost the safety of India’s 150-year-old railway network.[682]
EO has played a key role in helping India on its journey towards economic development. Industries, such as mining, oil, raw materials, farming, fishing and agriculture, have directly benefited. This technology is instrumental for India’s strategy of sustainable growth. For example, Potential Fishery Zone forecast is issued every three days. On cloudless days, it is issued daily and during the breeding and spawning periods of 45–60 days, advisories are not issued at all.[683] The impact of services, such as search and rescue, tsunami warning system, urban planning, groundwater detection and post-disaster crises management, are probably beyond quantitative measure, but all play a profound role in fulfilling ISRO’s stated goal to harness space technology for national development.
ISRO initially secured the key experience of building and operating satellites in LEO through Rohini, Aryabhata and Bhaskara series of satellites. It still had no experience of communication satellites that could provide communication services with an equal potential to transform society. The larger mass and more distant GEO (36,000 km) orbit was beyond ISRO’s reach until the PSLV was operationalised near the end of the 20th century. In 1975, ISRO leveraged another free offer, this time from the ESA, to launch a communication satellite to GEO.
Ariane Passenger Payload Experiment
In 1975, the ESA published an open offer to the international community for a free launch to GEO as part of the development programme for its new launcher, Ariane.[684] Coming a few months after the successful launch of Aryabhata, the timing was perfect for ISRO. Of all the types of satellites, communication satellites provide perhaps the most tangible of services, such as direct-to-home (DTH) TV and radio broadcast and international telephone coverage. A key requirement for a communication satellite is its orbit, GEO. ISRO's SLV-3 launcher was too small to deliver a satellite to GEO, and the launch sites of USSR that ISRO had used (Kapustin Yar at latitude 48.5°N and Baikonur at 45.6°N) were located too far north for efficient launch to GEO.[685] Although technically possible (and such launches do take place), launch sites in Russia are not best placed for launch to GEO. To efficiently reach GEO, launch sites on or near the equator are used.[686] ESA’s launch site located at the Guiana Space Centre 5°N of the equator is ideal for GEO.[687]
; A free launch offer from ESA was an invaluable opportunity for ISRO to experiment with a communication satellite. ESA's offer came with the understanding that it would not guarantee success and the supplier had to accept the loss if the launch failed and the spacecraft was destroyed. Insurance is seldom available for an experimental launcher. ESA had designated Ariane's first four flights as experimental. By 1976, ISRO and 72 other organisations from around the world had submitted proposals for ESA to launch their home-built communication satellites. ISRO’s was among those selected.[688] A formal agreement was signed between ESA and the Government of India in May 1977. On 19 June 1981, India’s first GEO satellite was placed in orbit by ESA’s launcher Ariane, and it operated successfully for over two years. This very first experimental communication satellite was called the Ariane Passenger Payload Experiment (APPLE), and it was used for television and radio broadcast.
The Soviet offer to launch Aryabhata had provided ISRO with a steep learning curve for building and operating remote-sensing satellites. APPLE would do something similar for the more complex technologies associated with communication satellites. ISRO signed an agreement with ESA on 24 October 1977 with a planned launch date about three years later. Delays at ESA increased this interval by about a year. This 4-year period became another intense learning cycle in which ISRO consolidated it’s operational, organisational and technical competences.
What
When
The initial offer from ESA for free launch in late 1975.
ISRO’s proposal is accepted by ESA and agreement signed on 24 October 1977