Strategic significance of RISAT-1 launch

The flawless launch of  India’s first fully home-grown, all weather  radar imaging satellite RISAT-1 by means of an uprated XL version of the four stage space workhorse,  Polar Satellite Launch Vehicle(PSLV), on 26 April 2012,  marks a major breakthrough for the Indian space programme and also a leap forward for Indian security capabilities. In around nineteen minutes of its smooth take off, the PSLV-XL, driven by alternate liquid and solid fuel driven stages, deployed the satellite into a polar/circular orbit. Earlier, the PSLV-XL weighing 321 tons, had been pressed into service for launching India’s maiden lunar probe Chandrayaan-1 in 2008 and GSAT-12 communications spacecraft in 2011. With a lift off weight 1858 kg, RISAT-1 happens to be the heaviest satellite to be hurled into space from Satish Dhawan Space Centre (SDSC), the Indian space port at Sriharikota Island on India’s eastern coast. Moments after this “text book” perfect launch, an elated ISRO (Indian Space Research Organisation) Chairman K.Radhakrishnan said, “The PSLV mission is a grand success. This is the twentieth consecutive successful flight of PSLV. India’s first radar imaging satellite was injected precisely into orbit.”  By all means, RISAT-1 represents a quantum jump for the Indian space agency in terms of mastering the technology of building an advanced radar imaging satellite with day and night observation capability.  The significance of RISAT-1 lies in the fact only a few countries in the world have mastered the radar imaging technology.

As things stand now, RISAT-1 will help India minimise its dependence on the data from the Canadian Radarsat-II satellite. In particular, RISAT data will have applications in areas such as soil moisture estimation, crop growth monitoring, food grains yield forecast as well as mapping and management of natural disasters. Further, RISAT-1 data can also be used for glacier studies, estimation of snow melting in summer, terrain mapping and forestry studies. On the defence front, it can help keep an eye on the country’s borders for various defence applications. Radar imaging satellites are powerful tools of surveillance and as pointed out by Prof Bhupendra Jasani of the Department of War Studies at King’s College in London, can even be used for detecting naval movements. Currently, research efforts are on to develop powerful space based radar instrumentation system capable of penetrating the dense thermal layers of the oceanic surface to detect the movement of submarines.

The Indian Remote Sensing Satellite (IRS) system being operated by ISRO with as many as eleven operational satellites happens to be one of the largest constellations of earth observation platforms, providing imageries in a variety of spatial resolutions, spectral bands and swaths. The data from IRS series of satellites are used for several applications covering agriculture, mineral prospecting, environment, forestry, drought and flood forecasting, ocean resources prospecting and disaster management. On another front, India has also succeeded in marketing the IRS data to customers from across the world.  However, excepting for RISAT-1 and  RISAT-II radar imaging satellite that ISRO had realised in association  with Israel Aerospace Industries(IAI), all other satellites in IRS constellation are passive systems based on optical imaging that make use of the solar radiance.

Clearly and apparently, Indian defence forces can look forward to fall back on “smart eye in the sky” in form of RISAT-1 to enhance their situational awareness and surveillance capability along India’s international borders. The Indian Army has been vigorously seeking uninterrupted access to a range of high resolution earth imaging space platforms to obviate a repeat of future Kargil’s from occurring and RISAT 1 can give that capability. Its high performance Synthetic Aperture Radar (SAR) payload is capable of functioning even under conditions of cloud, dust and haze. As of now, Indian defence forces have limited access to the IRS constellation of earth observation spacecraft. The Cartosat series of satellites being operated by ISRO are particularly relevant to Indian defence forces for terrain modelling and understanding the landscape features in great depth.

Significantly, the C-band SAR payload of RISAT-1 operating in a multi polarisation and multi resolution mode, is designed to provide images with coarse, fine and high spatial resolutions. The active phased array technology of the SAR payload  uses TR (transmit and receive) modules  to  provide necessary electronic agility for achieving the multi -mode capability to provide spatial resolutions of 1m to 50m and a swath of  10-240 km, catering to a wide ranging of applications. Being an active radar sensor operating in the microwave region of electromagnetic spectrum, SAR provides target parameters such as dielectric constant and surface roughness.

In April 2009, ISRO had launched 300 kg RISAT-II microwave imaging spacecraft featuring an X-band SAR payload by means of PSLV. The RISAT-II mission realised on a fast track mode was widely perceived as a response to the insecurity complex generated by the 26/11 Mumbai terror attack. Though ISRO describes the satellite as a civilian space system meant to enhance India’s earth observation capability with special reference to floods, landslides, cyclones and disaster management, strategic analysts view it as a high tech space platform which has multiple defence applications including keeping a tab on terrorist movement along India’s international borders. Earth observation and surveillance are two faces of the same coin and RISAT-II’s revisit capability of four to five days is considered an advantageous factor in the dynamic monitoring of developments of strategic importance. Added to that, the highly agile RISAT-II can be manoeuvred to change its viewing angle as per the requirements of the users.