marcos98
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TRISHUL: China Ups The Ante
While the October 1 parade for celebrating 60th anniversary of the People’s Republic of China (PRC) saw the People’s Liberation Army’s (PLA) 2nd Artillery Corps publicly showcasing for the first time its 2,500-km range DF-21C road-mobile ‘cannistered’ medium-range ballistic missile and the road-mobile ChangJiang-10Zai (Long Sword) 2,200km-range land-attack cruise missile (LACM), what was not revealed was how exactly would these missiles be guided to their intended targets. For strategic targetting of both land-based and sea-based targets, the 2nd Artillery Corps has been, since the late 1990s, deployed a mix of overhead recce satellites equipped with both optronic sensors as well as synthetic aperture radars (SAR). Belonging to the ‘Yaogan’ or ‘JianBing’ family, the constellation presently comprises the Yaogan-1 Yaogan-3 and Yaogan-5 satellites equipped with SAR antennae (supplied off-the-shelf by Russia’s NPO Mashinostroneyie), and the Yaogan-2, Yoagan-4 and Yaogan-6 satellites equipped with optronic sensors. All these satellites were designed by the China Aerospace Science and Technology Corp’s (CASC) No5 Research Institute and No8 Research Institute, with final fabrication and systems integration taking place at the CASC’s Shanghai Academy of Spaceflight Technology.
To date, the 2nd Artillery Corps has already implemented the launch-control protocols and ultra-secure SATCOMS-based communications networks required for employing both the land-launched and air-launched variants of the CJ-10A cruise missile against both land-based and seaborne targets. Development of the CJ-10A and its launch platforms (including the Hong 6K bomber) was led by the Hubei-based 9th Academy of the China Aerospace Science and Industry Corp (CASIC), which is also known as the Sanjiang Aerospace Group, or 066 Base. Series-production is now underway at the Beijing-based 3rd Academy, also belonging to CASIC. The navigational and fire-control components of the CJ-10 are produced at the Shanghai-based Xinxin Factory, which was set up in the late 1990s with the help of military-technical assistance from Ukraine and Kyrgyzstan. The CJ-10’s maiden test-flight took place on August 10, 2004. It is widely believed that the CJ-10 is an exact clone of the Korshun LACM (developed in Ukraine) and weighs 1,090kg, has a wingspan of 3.1 metres and diameter of 0.514 metres, and a length of 6.3 metres, 0.26 metres longer than the Kh-55. This slight difference in length comes from placing the Korshun’s R95-300 turbofan within the rear of the missile’s fuselage, with an air intake underneath. The Kh-55’s engine, in contrast, pops out of the rear section after launch, and hangs beneath the missile’s fuselage during cruise flight. By making the Korshun (and the CJ-10) more streamlined, like the Tomahawk cruise missile, Ukrainian designers succeeded in reducing the missile’s overall radar cross-section by eliminating the unwanted right angles of the exposed engine, which reflect telltale radar energy.
Another new-generation nuclear-armed missile deployed since 2007 by the 2nd Artillery Corps is the Dong Feng 21C (NATO reporting name: CSS-5 Mod-3) MBRM, which has a range of 1,700km when carrying a 2,000kg payload. The fully cannistered ballistic missile is carried on a 10 x 10 wheeled WS-2500 transporter-erector-launcher vehicle, which has a maximum load capacity of 28 tonnes. According to the US Defense Intelligence Agency (DIA), the DF-21C can be armed with fuel air explosive-based (FAE) and electromagnetic pulse-based (EMP) warheads, which could typically be employed against high-value strategic land-based targets, or against aircraft carrier-led battle groups. When used as part of a coordinated strike package, both the CJ-10 and DF-21C could significantly up the ante (as force multipliers with strategic reach) against any adversary, while keeping the threshold of hostilities limited to the conventional level. In India’s case, the widespread deployment of these two missile systems by the PLA in either the Tibet Autonomous Region or the Chengdu Military Region could in one stroke neutralise the operational advantages of offensive airpower projection now enjoyed by the Indian Air Force (IAF) in northeastern and northern India, unless India begins a large-scale deployment of theatre-based ballistic missile/cruise missile defence networks that are backed up by a robust constellation of overhead recce satellites for strategic reconnaissance-cum-targetting purposes.
To this end, India’s satellite-based overhead reconnaissance and related strategic targetting capabilities were significantly boosted when the state-owned Indian Space Research Organisation (ISRO) launched India’s second dedicated, military-specific, operational recce satellite—RISAT-2—on board the Polar Satellite Launch Vehicle (PSLV-C12) from the Sriharikota-based Satish Dhawan Space Centre on April 20 this year. The RISAT-2 was bought off-the-shelf from Israel Aerospace Industries (IAI) for India’s Dehra Dun-based National Technical Research Organisation (NTRO) as part of the fast-tracking of procurements of critical hardware required for strategic deterrence, along with related ground receiving stations and imagery interpretation systems. It is virtually identical to the 300kg TecSAR/Polaris synthetic aperture radar-equipped satellite that was launched by ISRO’s subsidiary Antrix Corp for Israel on board the PSLV-C10 rocket launcher on January 21, 2008. Following RISAT-2 by the year’s end will be the ISRO-built RISAT-1, 1,780kg overhead recce satellite equipped with a C-band active phased-array synthetic aperture radar (SAR) and developed at a cost of Rs4 billion (see: http://directory.eoportal.org/get_announce.php?an_id=12429).
India’s first dedicated operational military reconnaissance satellite was CARTOSAT-2A (see http://directory.eoportal.org/get_announce.php?an_id=10000443), which was launched on board the PSLV-C9 on April 28, 2008. This was preceded on January 21 by the launching of the TecSAR/Polaris at a cost of Rs550 million. Weighing 300kg, both the TecSAR/Polaris and RISAT-2 can take pictures of the earth through cloud and rain, 24 hours of the day utilising electronic beam-steering techniques. The IAI-produced satellite features mesh antennae panels which, once opened, provide high-fidelity reflections of the Earth’s surface. Aside from IAI-subsidiary ELTA Systems, producers of the 100kg SAR payload, program subcontractors include Tadiran Spectralink and RAFAEL Advanced Defense Systems, producers of hydrazine thrusters and other propulsion components. TecSAR was placed into its intended orbit with a perigee (nearest point to earth) of 450km and apogee (farthest point to earth) of 580km with an orbital inclination of 41 degrees with respect to the equator. As the Polaris’ manufacturer—the MBT Space Division of Israel Aerospace Industries (IAI)--wanted a ‘core-alone’ configuration of the PSLV-C10 to put Polaris in orbit, the four-stage rocket launcher did away with the six strap-on booster motors, and weighed only 230 tonnes at liftoff. The Antrix Corp subsidiary of ISRO is now hopeful that it will also bag the follow-on contracts from Israel to launch another two recce satellites of the Polaris family in future.
By February 3 last year, initial streams of TecSAR/Polaris-generated SAR imagery had reached Israel’s highly-secure ground station on the Tel Aviv-based campus of IAI. Once initial imagery was analysed and the satellite’s various operational modes were determined to meet user requirements, the TecSAR/Polaris was certified as operational. Until then, IAI and Israeli Military Intelligence (AMAN) technicians proceeded through an extensive intialisation and calibration testing regime that began about an hour after launch, with first receipt of the satellite’s signals. TecSAR/Polaris and RISAT-2 promise a qualitative upgrade in strategic intelligence not only because of the all-weather, photographic quality imagery they generate, but by their ability to linger longer over targeted areas of interest. Both satellites feature a unique combination of in-orbit agility and electronically-steered beams that allow operators to capture more images over a wider area in each rotational pass. Agility is provided by high-powered, yet low-weight reaction wheels that allow the satellite to alter its orbiting attitude as it travels some 7.5 kilometres per second. In parallel, electronic switching of the radar beam allows operators to back-scan critical target areas and utilise multiple modes of image collection, thereby maximising every second of the typical 8.5-minute overpass of a given area. Both satellites can operate in any inclination and at a wide range of altitudes. The payload is designed to collect imagery in three distinct operating modes: Spot mode for collecting a large number of high-resolution images per orbit; strip mode for capturing many hundreds of medium-resolution imaging swaths; and beam-scanning mosaic mode for very wide coverage at lower, yet ‘extremely valuable’ resolution. The satellites are also inherently capable of detecting and tracking moving targets. During a single pass, due to extraordinary flexibility of the beam and the agility of the satellite itself, the TecSAR/Polaris or RISAT-2 can capture widely spread targets at the same time. The estimated footprint, or area of image collection, is more than 500 square kilometres. If a normal satellite provides a 25km footprint, one can multiply by 20 or even 30 to get the coverage provided by these two satellites in mosaic mode. By activating the reaction wheels, they make a back-scan that allows them to linger more time in a certain area. Their added value thus lies in this unique combination of electronic switching of the beam and the mechanical agility of the satellites that allows one to achieve a phenomenal capability for high-resolution imaging over very large areas. But beyond expected imaging improvements, TecSAR/Polaris and RISAT-2 will provide significantly enhanced revisit time for monitoring ballistic missile launching sites, seaport activities, weapons production facilities, troop movements and other militarily-significant changes. Both these satellites can circle the Earth every 90 minutes.
Almost as anxious as its Israeli counterpart for the TechSAR/Polaris’ success is Northrop Grumman Corp, which hopes to parlay the lightweight, high-resolution SAR-equipped satellite into a new, US niche market for operationally responsive space systems. An exclusive teaming agreement with IAI now allows Northrop Grumman to co-produce slightly-modified TecSAR clones--dubbed Trinidad--to be held in storage for launch by US users at a mere 30-day notice. When the two companies announced their agreement in April 2007, they stressed that implementation of the prospective launch-on-demand initiative was contingent upon the successful launch and operational performance of the Israeli spacecraft. Each Trinidad satellite could be manufactured in about 28 months at a very small fraction of the cost of other US SAR-equipped satellites. Within two years, this satellite will be ready for launch by a very low cost launcher like the Minotaur four-stage Space Launch Vehicle of the Orbital Sciences Corp. The commercial partners still need to wait for IAI to complete all testing, certification and other activities demanded by its Israeli government customer. But following full validation and initial operation of TecSAR/Polaris’ multi-mode, X-band radar-imaging collection capabilities, Northrop Grumman has received the data it needs to convince potential US users of the benefits to be had from the system. According to Northrop Grumman, preliminary plans call for the US firm to invest in a mobile ground station modified to capture, receive, store and process TecSAR/Polaris imagery provided by the IAI ground station. The plan is to actually demonstrate the satellite’s capabilities to prospective customers.
India’s CARTOSAT-2A, which has a spatial resolution of 0.7 metres, will be followed in future by the 2B, 2C and 2D, with these having high-resolution cameras capable of supplying imagery with 0.5-metre spatial resolution. India currently has in orbit four dual-purpose satellites that can be used for military overhead reconnaissance. CARTOSAT-1 (see eoPortal Directory) or IRS P5 (Indian Remote Sensing Satellite) was launched on May 5, 2005 into a 618km-high polar sun synchronous orbit by the PSLV-C6 rocket. It carries two panchromatic (PAN) cameras with 2.5-metre resolution that take black-and-white stereoscopic pictures of the earth in the visible region of the electromagnetic spectrum. The swath covered by these PAN cameras is 30km, and they are mounted in such a way that near-simultaneous imaging of the same area from two different angles is possible. This facilitates the generation of accurate three-dimensional maps. The cameras operate in the 500-750nm wavelength and are tilted +26 degrees and -5 degrees along the track. CARTOSAT-1, weighing 1,560kg, also carries a solid-state recorder with a capacity of 120 Giga Bits to store the images taken by its cameras. The stored images can be transmitted when the satellite comes within the visibility zone of an Earth-based ground station. The 680kg CARTOSAT-2 (see eoPortal Directory), designed for supplying scene-specific spot imagery, was launched into the intended 639km polar orbit by the PSLV-C7 rocket on January 10m 2007. CARTOSAT-2 has a single PAN camera capable of providing scene-specific spot imageries for cartographic applications. The camera is designed to provide imageries with 1-metre spatial resolution and a swath of 10km. The satellite can steer along and across its track up to 45 degrees. It has been placed in a sun-synchronous polar orbit at an altitude of 630km and has a revisit period of four days, but this can be improved to one day with suitable orbit manoeuvres. Several new technologies like two-mirror-on-axis single camera, carbon fabric reinforced plastic-based electro-optic structure, large size mirrors, JPEG-like data compression, solid-state recorder, high-torque reaction wheels and high-performance star sensors are employed on board CARTOSAT-2. The satellite has a revisit interval of four days.
The third overhead recce satellite currently in orbit is the Technology Experiment Satellite or TES (see eoPortal Directory), which weighs 1,108kg and was successfully placed in 568km sun synchronous orbit on October 22, 2001 using the PSLV-C3 rocket. The technologies demonstrated thus far on board TES are attitude and orbit control systems, high-torque reaction wheels, new reaction control systems with optimised thrusters and a single propellant tank, lightweight spacecraft structure, solid-state recorder, X-band active phased-array antenna, improved satellite positioning system, miniaturised power system, and two-mirror-on-axis camera optics. The TES has a PAN camera capable of producing images of 1-metre resolution. In attention to these and the CARTOSAT-2 family of satellites, India will later this year launch the RISAT-1, which will carry a C-band (5.35 GHz) SAR with a spatial resolution of 3 metres to 50 metres and a swath of 10km to 240km. The Earth-facing side of the AESA-SAR antenna is a broadband dual polarised microstrip radiating aperture. The antenna will comprise three deployable panels, each of 2-metre x 2-metre size. Each of the panels is sub-divided into four tiles of size 1-metre x 1-metre, each consisting of 24 x 24 radiating elements. In each tile, all the 24 x 24 radiating elements are grouped into 24 groups, with each group comprising 24 elements spread along azimuth directions, which are fed by two stripline distribution networks feeding for V and H polarisation. Each of these groups of 24 radiating elements is catered to by two separate T/R modules feeding two separate distribution networks for V and H operation with the same radiating patches. Present plans call for deploying up to seven RISAT-type recce satellites by 2015.
Another reconnaissance satellite that will be launched this year by ISRO will be OCEANSAT-2 (see eoPortal Directory), which would study the oceans and the wind surface of oceans. It is more powerful than the OCEANSAT-1 (launched in May 1999), which was nearing the end of its life cycle. The OCEANSAT-2, to be placed into a near-polar sun synchronous orbit of 720km, will carry an ocean-colour monitor and a Ku-band pencil beam scatterometer, which is an active microwave radar and operates at 13.515GHz providing a good resolution cell-size swathe of 50km x 50km. It will also carry a radio occulation sounder for atmospheric studies. The ocean colour monitor payload will be an eight-band multi-spectral camera operating in the visible-near infra-red spectral range. This camera will provide an instantaneous geometric field-of-view of 360 metres covering a swath of 1,420km. The back-scattered beams from the ocean surface would be measured to derive the wind vector. OCEANSAT-2 will be used for sea state forecasting, coastal zone studies, and also provide inputs for weather forecasting and climatic studies of consequence to the movements of both naval surface combatants and submarines. Its orbital path, combined with the wide swathe of both payloads, will provide an observational repetity of two days. For providing the high-accuracy navigation inputs for precision-guided munitions as well as for long-range navigation over land, sea and air, ISRO last year initiated the Indian Regional Navigational Satellite System (IRNSS) project, which calls for the deployment of a constellation of seven low-cost, GPS satellites in geo-stationary orbit over the next five years. Its footprint will be regional, and will include the Indian subcontinent, the Tibetan plateau, Central Asia and Southeast Asia.
DF15
DF21
While the October 1 parade for celebrating 60th anniversary of the People’s Republic of China (PRC) saw the People’s Liberation Army’s (PLA) 2nd Artillery Corps publicly showcasing for the first time its 2,500-km range DF-21C road-mobile ‘cannistered’ medium-range ballistic missile and the road-mobile ChangJiang-10Zai (Long Sword) 2,200km-range land-attack cruise missile (LACM), what was not revealed was how exactly would these missiles be guided to their intended targets. For strategic targetting of both land-based and sea-based targets, the 2nd Artillery Corps has been, since the late 1990s, deployed a mix of overhead recce satellites equipped with both optronic sensors as well as synthetic aperture radars (SAR). Belonging to the ‘Yaogan’ or ‘JianBing’ family, the constellation presently comprises the Yaogan-1 Yaogan-3 and Yaogan-5 satellites equipped with SAR antennae (supplied off-the-shelf by Russia’s NPO Mashinostroneyie), and the Yaogan-2, Yoagan-4 and Yaogan-6 satellites equipped with optronic sensors. All these satellites were designed by the China Aerospace Science and Technology Corp’s (CASC) No5 Research Institute and No8 Research Institute, with final fabrication and systems integration taking place at the CASC’s Shanghai Academy of Spaceflight Technology.
To date, the 2nd Artillery Corps has already implemented the launch-control protocols and ultra-secure SATCOMS-based communications networks required for employing both the land-launched and air-launched variants of the CJ-10A cruise missile against both land-based and seaborne targets. Development of the CJ-10A and its launch platforms (including the Hong 6K bomber) was led by the Hubei-based 9th Academy of the China Aerospace Science and Industry Corp (CASIC), which is also known as the Sanjiang Aerospace Group, or 066 Base. Series-production is now underway at the Beijing-based 3rd Academy, also belonging to CASIC. The navigational and fire-control components of the CJ-10 are produced at the Shanghai-based Xinxin Factory, which was set up in the late 1990s with the help of military-technical assistance from Ukraine and Kyrgyzstan. The CJ-10’s maiden test-flight took place on August 10, 2004. It is widely believed that the CJ-10 is an exact clone of the Korshun LACM (developed in Ukraine) and weighs 1,090kg, has a wingspan of 3.1 metres and diameter of 0.514 metres, and a length of 6.3 metres, 0.26 metres longer than the Kh-55. This slight difference in length comes from placing the Korshun’s R95-300 turbofan within the rear of the missile’s fuselage, with an air intake underneath. The Kh-55’s engine, in contrast, pops out of the rear section after launch, and hangs beneath the missile’s fuselage during cruise flight. By making the Korshun (and the CJ-10) more streamlined, like the Tomahawk cruise missile, Ukrainian designers succeeded in reducing the missile’s overall radar cross-section by eliminating the unwanted right angles of the exposed engine, which reflect telltale radar energy.
Another new-generation nuclear-armed missile deployed since 2007 by the 2nd Artillery Corps is the Dong Feng 21C (NATO reporting name: CSS-5 Mod-3) MBRM, which has a range of 1,700km when carrying a 2,000kg payload. The fully cannistered ballistic missile is carried on a 10 x 10 wheeled WS-2500 transporter-erector-launcher vehicle, which has a maximum load capacity of 28 tonnes. According to the US Defense Intelligence Agency (DIA), the DF-21C can be armed with fuel air explosive-based (FAE) and electromagnetic pulse-based (EMP) warheads, which could typically be employed against high-value strategic land-based targets, or against aircraft carrier-led battle groups. When used as part of a coordinated strike package, both the CJ-10 and DF-21C could significantly up the ante (as force multipliers with strategic reach) against any adversary, while keeping the threshold of hostilities limited to the conventional level. In India’s case, the widespread deployment of these two missile systems by the PLA in either the Tibet Autonomous Region or the Chengdu Military Region could in one stroke neutralise the operational advantages of offensive airpower projection now enjoyed by the Indian Air Force (IAF) in northeastern and northern India, unless India begins a large-scale deployment of theatre-based ballistic missile/cruise missile defence networks that are backed up by a robust constellation of overhead recce satellites for strategic reconnaissance-cum-targetting purposes.
To this end, India’s satellite-based overhead reconnaissance and related strategic targetting capabilities were significantly boosted when the state-owned Indian Space Research Organisation (ISRO) launched India’s second dedicated, military-specific, operational recce satellite—RISAT-2—on board the Polar Satellite Launch Vehicle (PSLV-C12) from the Sriharikota-based Satish Dhawan Space Centre on April 20 this year. The RISAT-2 was bought off-the-shelf from Israel Aerospace Industries (IAI) for India’s Dehra Dun-based National Technical Research Organisation (NTRO) as part of the fast-tracking of procurements of critical hardware required for strategic deterrence, along with related ground receiving stations and imagery interpretation systems. It is virtually identical to the 300kg TecSAR/Polaris synthetic aperture radar-equipped satellite that was launched by ISRO’s subsidiary Antrix Corp for Israel on board the PSLV-C10 rocket launcher on January 21, 2008. Following RISAT-2 by the year’s end will be the ISRO-built RISAT-1, 1,780kg overhead recce satellite equipped with a C-band active phased-array synthetic aperture radar (SAR) and developed at a cost of Rs4 billion (see: http://directory.eoportal.org/get_announce.php?an_id=12429).
India’s first dedicated operational military reconnaissance satellite was CARTOSAT-2A (see http://directory.eoportal.org/get_announce.php?an_id=10000443), which was launched on board the PSLV-C9 on April 28, 2008. This was preceded on January 21 by the launching of the TecSAR/Polaris at a cost of Rs550 million. Weighing 300kg, both the TecSAR/Polaris and RISAT-2 can take pictures of the earth through cloud and rain, 24 hours of the day utilising electronic beam-steering techniques. The IAI-produced satellite features mesh antennae panels which, once opened, provide high-fidelity reflections of the Earth’s surface. Aside from IAI-subsidiary ELTA Systems, producers of the 100kg SAR payload, program subcontractors include Tadiran Spectralink and RAFAEL Advanced Defense Systems, producers of hydrazine thrusters and other propulsion components. TecSAR was placed into its intended orbit with a perigee (nearest point to earth) of 450km and apogee (farthest point to earth) of 580km with an orbital inclination of 41 degrees with respect to the equator. As the Polaris’ manufacturer—the MBT Space Division of Israel Aerospace Industries (IAI)--wanted a ‘core-alone’ configuration of the PSLV-C10 to put Polaris in orbit, the four-stage rocket launcher did away with the six strap-on booster motors, and weighed only 230 tonnes at liftoff. The Antrix Corp subsidiary of ISRO is now hopeful that it will also bag the follow-on contracts from Israel to launch another two recce satellites of the Polaris family in future.
By February 3 last year, initial streams of TecSAR/Polaris-generated SAR imagery had reached Israel’s highly-secure ground station on the Tel Aviv-based campus of IAI. Once initial imagery was analysed and the satellite’s various operational modes were determined to meet user requirements, the TecSAR/Polaris was certified as operational. Until then, IAI and Israeli Military Intelligence (AMAN) technicians proceeded through an extensive intialisation and calibration testing regime that began about an hour after launch, with first receipt of the satellite’s signals. TecSAR/Polaris and RISAT-2 promise a qualitative upgrade in strategic intelligence not only because of the all-weather, photographic quality imagery they generate, but by their ability to linger longer over targeted areas of interest. Both satellites feature a unique combination of in-orbit agility and electronically-steered beams that allow operators to capture more images over a wider area in each rotational pass. Agility is provided by high-powered, yet low-weight reaction wheels that allow the satellite to alter its orbiting attitude as it travels some 7.5 kilometres per second. In parallel, electronic switching of the radar beam allows operators to back-scan critical target areas and utilise multiple modes of image collection, thereby maximising every second of the typical 8.5-minute overpass of a given area. Both satellites can operate in any inclination and at a wide range of altitudes. The payload is designed to collect imagery in three distinct operating modes: Spot mode for collecting a large number of high-resolution images per orbit; strip mode for capturing many hundreds of medium-resolution imaging swaths; and beam-scanning mosaic mode for very wide coverage at lower, yet ‘extremely valuable’ resolution. The satellites are also inherently capable of detecting and tracking moving targets. During a single pass, due to extraordinary flexibility of the beam and the agility of the satellite itself, the TecSAR/Polaris or RISAT-2 can capture widely spread targets at the same time. The estimated footprint, or area of image collection, is more than 500 square kilometres. If a normal satellite provides a 25km footprint, one can multiply by 20 or even 30 to get the coverage provided by these two satellites in mosaic mode. By activating the reaction wheels, they make a back-scan that allows them to linger more time in a certain area. Their added value thus lies in this unique combination of electronic switching of the beam and the mechanical agility of the satellites that allows one to achieve a phenomenal capability for high-resolution imaging over very large areas. But beyond expected imaging improvements, TecSAR/Polaris and RISAT-2 will provide significantly enhanced revisit time for monitoring ballistic missile launching sites, seaport activities, weapons production facilities, troop movements and other militarily-significant changes. Both these satellites can circle the Earth every 90 minutes.
Almost as anxious as its Israeli counterpart for the TechSAR/Polaris’ success is Northrop Grumman Corp, which hopes to parlay the lightweight, high-resolution SAR-equipped satellite into a new, US niche market for operationally responsive space systems. An exclusive teaming agreement with IAI now allows Northrop Grumman to co-produce slightly-modified TecSAR clones--dubbed Trinidad--to be held in storage for launch by US users at a mere 30-day notice. When the two companies announced their agreement in April 2007, they stressed that implementation of the prospective launch-on-demand initiative was contingent upon the successful launch and operational performance of the Israeli spacecraft. Each Trinidad satellite could be manufactured in about 28 months at a very small fraction of the cost of other US SAR-equipped satellites. Within two years, this satellite will be ready for launch by a very low cost launcher like the Minotaur four-stage Space Launch Vehicle of the Orbital Sciences Corp. The commercial partners still need to wait for IAI to complete all testing, certification and other activities demanded by its Israeli government customer. But following full validation and initial operation of TecSAR/Polaris’ multi-mode, X-band radar-imaging collection capabilities, Northrop Grumman has received the data it needs to convince potential US users of the benefits to be had from the system. According to Northrop Grumman, preliminary plans call for the US firm to invest in a mobile ground station modified to capture, receive, store and process TecSAR/Polaris imagery provided by the IAI ground station. The plan is to actually demonstrate the satellite’s capabilities to prospective customers.
India’s CARTOSAT-2A, which has a spatial resolution of 0.7 metres, will be followed in future by the 2B, 2C and 2D, with these having high-resolution cameras capable of supplying imagery with 0.5-metre spatial resolution. India currently has in orbit four dual-purpose satellites that can be used for military overhead reconnaissance. CARTOSAT-1 (see eoPortal Directory) or IRS P5 (Indian Remote Sensing Satellite) was launched on May 5, 2005 into a 618km-high polar sun synchronous orbit by the PSLV-C6 rocket. It carries two panchromatic (PAN) cameras with 2.5-metre resolution that take black-and-white stereoscopic pictures of the earth in the visible region of the electromagnetic spectrum. The swath covered by these PAN cameras is 30km, and they are mounted in such a way that near-simultaneous imaging of the same area from two different angles is possible. This facilitates the generation of accurate three-dimensional maps. The cameras operate in the 500-750nm wavelength and are tilted +26 degrees and -5 degrees along the track. CARTOSAT-1, weighing 1,560kg, also carries a solid-state recorder with a capacity of 120 Giga Bits to store the images taken by its cameras. The stored images can be transmitted when the satellite comes within the visibility zone of an Earth-based ground station. The 680kg CARTOSAT-2 (see eoPortal Directory), designed for supplying scene-specific spot imagery, was launched into the intended 639km polar orbit by the PSLV-C7 rocket on January 10m 2007. CARTOSAT-2 has a single PAN camera capable of providing scene-specific spot imageries for cartographic applications. The camera is designed to provide imageries with 1-metre spatial resolution and a swath of 10km. The satellite can steer along and across its track up to 45 degrees. It has been placed in a sun-synchronous polar orbit at an altitude of 630km and has a revisit period of four days, but this can be improved to one day with suitable orbit manoeuvres. Several new technologies like two-mirror-on-axis single camera, carbon fabric reinforced plastic-based electro-optic structure, large size mirrors, JPEG-like data compression, solid-state recorder, high-torque reaction wheels and high-performance star sensors are employed on board CARTOSAT-2. The satellite has a revisit interval of four days.
The third overhead recce satellite currently in orbit is the Technology Experiment Satellite or TES (see eoPortal Directory), which weighs 1,108kg and was successfully placed in 568km sun synchronous orbit on October 22, 2001 using the PSLV-C3 rocket. The technologies demonstrated thus far on board TES are attitude and orbit control systems, high-torque reaction wheels, new reaction control systems with optimised thrusters and a single propellant tank, lightweight spacecraft structure, solid-state recorder, X-band active phased-array antenna, improved satellite positioning system, miniaturised power system, and two-mirror-on-axis camera optics. The TES has a PAN camera capable of producing images of 1-metre resolution. In attention to these and the CARTOSAT-2 family of satellites, India will later this year launch the RISAT-1, which will carry a C-band (5.35 GHz) SAR with a spatial resolution of 3 metres to 50 metres and a swath of 10km to 240km. The Earth-facing side of the AESA-SAR antenna is a broadband dual polarised microstrip radiating aperture. The antenna will comprise three deployable panels, each of 2-metre x 2-metre size. Each of the panels is sub-divided into four tiles of size 1-metre x 1-metre, each consisting of 24 x 24 radiating elements. In each tile, all the 24 x 24 radiating elements are grouped into 24 groups, with each group comprising 24 elements spread along azimuth directions, which are fed by two stripline distribution networks feeding for V and H polarisation. Each of these groups of 24 radiating elements is catered to by two separate T/R modules feeding two separate distribution networks for V and H operation with the same radiating patches. Present plans call for deploying up to seven RISAT-type recce satellites by 2015.
Another reconnaissance satellite that will be launched this year by ISRO will be OCEANSAT-2 (see eoPortal Directory), which would study the oceans and the wind surface of oceans. It is more powerful than the OCEANSAT-1 (launched in May 1999), which was nearing the end of its life cycle. The OCEANSAT-2, to be placed into a near-polar sun synchronous orbit of 720km, will carry an ocean-colour monitor and a Ku-band pencil beam scatterometer, which is an active microwave radar and operates at 13.515GHz providing a good resolution cell-size swathe of 50km x 50km. It will also carry a radio occulation sounder for atmospheric studies. The ocean colour monitor payload will be an eight-band multi-spectral camera operating in the visible-near infra-red spectral range. This camera will provide an instantaneous geometric field-of-view of 360 metres covering a swath of 1,420km. The back-scattered beams from the ocean surface would be measured to derive the wind vector. OCEANSAT-2 will be used for sea state forecasting, coastal zone studies, and also provide inputs for weather forecasting and climatic studies of consequence to the movements of both naval surface combatants and submarines. Its orbital path, combined with the wide swathe of both payloads, will provide an observational repetity of two days. For providing the high-accuracy navigation inputs for precision-guided munitions as well as for long-range navigation over land, sea and air, ISRO last year initiated the Indian Regional Navigational Satellite System (IRNSS) project, which calls for the deployment of a constellation of seven low-cost, GPS satellites in geo-stationary orbit over the next five years. Its footprint will be regional, and will include the Indian subcontinent, the Tibetan plateau, Central Asia and Southeast Asia.
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