Tag Archives: SAR
Promise of Small Satellites for National Security
Author: Rajaram Nagappa
To read the complete report click here
To cite: Nagappa, Rajaram. The Promise of Small Satellites for National Security. NIAS Report No. 33-2015. Bangalore: International Strategic and Security Studies Programme, National Institute of Advanced Studies, December 2015, available at http://isssp.in/promise-of-small-satellites-for-national-security/
India is one of the few spacefaring nations having demonstrated capability in both launch vehicle and satellite domains. The Indian Space Research Organisation (ISRO) functioning under the Department of Space is the responsible agency and has established the capability to plan and implement end-to end missions. The main thrust of ISRO is aimed at carrying out satellite-based applications for societal benefits.
These include satellite missions for communication, earth observation, meteorology and regional navigation. ISRO also carries out scientific missions, deep space missions and offers commercial launch services. Technology improvements have been steadily incorporated and in the earth observation satellites, better than one metre resolution has been achieved. Because of the dual use nature of space applications, the security services in the country have derived information useful their purpose from the ISRO space programmes.
Among the launch vehicles, the Polar Satellite Launch Vehicle (PSLV) is operational and has a good track record. The Geosynchronous Launch Vehicle (GSLV) should also be reaching operational status shortly and while the GSLV Mk-3 is still in the development stage. ISRO is a civilian organisation and very rightly prioritizes its mandated tasks. Consequently, the space services currently do not cater to the needs of military space, which are evolving now. Though ISRO has the technical capability, there are capacity constraints in both satellite building and launch services.
Envisaged military space requirements will include exclusive communication satellites, electronic intelligence satellites (ELINT) and constellation of optical and radar imaging satellites for continuous intelligence, surveillance and reconnaissance (ISR) activities. Small satellites are playing an important role in space applications. They are faster to build, are cost effective and better as they benefit from the use of latest technologies. Small satellite platforms can be adapted for military missions involving optical and radar imaging applications with good resolution as also for ELINT operations. Many examples of international practices bear this out. For increasing the launch frequency, a small satellite launch vehicle can be configured using stages of the Agni missiles and/or ISRO solid rocket stages. Such a launch vehicle would be capable of placing a satellite of mass 350 kg in a nearly circular 500 km polar orbit – quite adequate for military space missions.
The report surveys the small satellite capabilities to meet military space requirement. Use of available standard small satellite buses is suggested to cut down the development time. Major involvement of industry in both satellite and small launch vehicle realization and integration services is suggested to overcome the capacity constraint. It is also suggested that advantage be taken of mobility and different launch locations to carry out the flight missions.
China’s Constellation of Yaogan Satellites & the ASBM
Authors: S. Chandrashekar and Soma Perumal
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With the recent launch of the Yaogan 19 satellite China has in place an advanced space capability to identify, locate and track an Aircraft Carrier Group (ACG) on the high seas. This space capability is an important component of an Anti-Ship Ballistic Missile (ASBM) System that China has set up.
The current 19 satellite constellation consists of ELINT satellites, satellites carrying Synthetic Aperture Radar (SAR) sensors as well as satellites carrying optical imaging sensors. Based on the orbit characteristics, their local time of equatorial crossing and other related parameters, these satellites can be grouped into different categories that perform the various functions for identifying, locating and tracking the ACG.
Yaogan 9 (Yaogan 9A, 9B, 9C), Yaogan (16A, 16B, 16C) and Yaogan 17 (17A, 17B, 17C) are the three clusters that are equipped with ELINT sensors that provide broad area surveillance over the Oceans. With a coverage radius of about 3500 Km, they provide the first coarse fix for identifying and locating an ACG in the Pacific Ocean.
Yaogan 13, Yaogan 10, Yaogan 18 and Yaogan 14 are the satellites carrying a SAR sensor. With Local times of crossing of 02 00, 06 00, 10 00 and 14 00 hours and a resolution of 1 to 3 m , they provide all weather as well as day and night imaging capabilities over the regions of interest.
Yaogan 11, Yaogan 4, Yaogan 2 and Yaogan 7 constitute the high resolution optical satellites in the current constellation. The sensors they carry may have resolutions of between 1 to 3 m. Their local times of crossing of 09 00, 11 00, 13 30, and 15 00 hours respectively ensure favourable illumination conditions for their imaging missions. Yaogan 19 and Yaogan 15 satellites with local times of crossing of 10 30 and 14 30 hours respectively are optical imaging satellites with medium resolution (5 to 10 m) capabilities. They act as a broad area coverage complement for the SAR as well as the high resolution optical imaging satellites.
The Yaogan 12 which replaced the Yaogan5 has the orbital characteristics of a SAR mission but its local time of crossing is 10 30 AM. This is very close to the 10 00 hours crossing time of the Yaogan 18 SAR satellite. Having two satellites spaced so close to each other makes it unlikely that it is a SAR mission. Most probably this is a high resolution optical imaging satellite that complements the broad area coverage provided by the 1200 km orbit of the Yaogan 15 and Yaogan 19 satellites.
Using typical sensor geometries and the two line orbital elements available from public sources the ability of the current constellation to identify, locate and track the Aircraft Carrier Group was simulated.
The three ELINT clusters typically make 18 contacts in a day with the moving target. The maximum period for which the target remains outside the reach of the ELINT satellites is about 90 minutes in a day. The SAR and the optical imaging satellites together typically provide 24 satellite passes over the target. About 16 targeting opportunities, during which the uncertainty in the target’s location is less than 10 km, are available in a day.
The analysis and the simulation results suggest that China has in place an operational ASBM system that can identify, locate, track and destroy an Aircraft Carrier in the Pacific Ocean. This seems to be an important component of a larger Chinese Access and Area Denial Strategy focused around a conflict over Taiwan.
Note: The simulation in the report has been performed using Boeing’s Analysis and Experimentation Centre’s modeling and simulation capability under NIAS-Boeing collaboration
ISSSP Reflections No.1, September 29, 2013
Authors: Professor S. Chandrashekar and Professor Soma Perumal
On September 1, 2013 at 19:16 UTC a Chinese Long March 4 C rocket placed a new ELINT constellation of Yaogan satellites into an 1100 km 63.4 degree inclination orbit.
The three satellites Yaogan 17A, 17 B and 17 C fly in a stable triangular formation. This arrangement of satellites made possible by the inclination of the orbit helps in the location of electronic emission signals over a very large area.
Modern naval ships are constantly emitting electronic signals as part of their regular activities. Capabilities to sense these emissions and then locate the sources of these emissions are critical for anti-access and area denial strategies over the oceans.
The Yaogan 17 triplet joins the Yaogan 9 and Yaogan 16 constellations of ELINT satellites. All of them are launched from the Jiaquan Satellite Launch Centre and fly in similar 1100 km 63.4 degree inclination orbits. The Yaogan 17 constellation would complement the Yaogan 9 constellation (which may be nearing the end of its life) and the more recently launched Yaogan 16 triplet of satellites to provide a near continuous global update on the location of high value naval targets such as aircraft carriers.
Though the Chinese media reported the purpose of new satellites as remote-sensing/scientific applications, land survey, crop yield assessment and disaster monitoring it is clear from the orbit characteristics that this is a part of the operational Anti-Ship Ballistic Missile (ASBM) System that China has put in place as a part of its anti-access and area denial strategy.
In addition to the Yaogan 9, Yaogan 16 and Yaogan 17 ELINT constellations, a number of other Yaogan satellites carry high resolution optical imaging and Synthetic Aperture Radar (SAR) sensors. These work in tandem with the ELINT satellites to provide more precise location information on potential high value targets. The ELINT satellites cover a large area of the sea within which the target is identified and located coarsely.
The orbits and launch times of the SAR and optical imaging satellites are chosen in such a way as to pass over the same areas covered by the earlier ELINT passes.
With the coarse location information provided by the ELINT satellites, the SAR and imaging satellites are commanded to image the target precisely by steering their instruments towards the coarse target position. These can then locate the target position more precisely.
Thus, the Yaogan series of satellites acting as “eyes in the sky” provide the needed C4ISR(Computer, Communication, Control, Command, Intelligence, Surveillance and Reconnaissance) capability for the Chinese to support a missile launch against the enemy target.
According to our assessment, six Yaogan satellites (Yaogan 2,4,7,8,11 and 13) with imaging sensors and four Yaogan satellites (Yaogan 10,12, 13 and 14) with SAR sensors are currently operational.
As mentioned in our detailed study on the ASBM, this architecture of the space segment coupled with on the ground Over-the-Horizon (OTH) radar and missiles with autonomous maneuver capabilities does provide a weapon to target high value targets like aircraft carriers on the high seas.
The latest launch confirms our earlier assessments that the Chinese do have an operational ASBM capability as a part of their larger anti-access and area denial strategy.
One should also keep in mind that the same configuration of satellites, Over-the Horizon (OTH) Radars along with precision weapons can also be used to attack and destroy high value targets on land such as radars, communications centres as well as command and control centres.
Editors Note: The ISSSP had authored a detailed report on the Chinese Anti-Ship Ballistic Missile (ASBM) capabilities. The entire report is can be accessed here
About the Authors
Professor Chandrashekar is JRD Tata Visiting Professor, International Strategic and Security Studies Programme, National Institute of Advanced Studies. He can be reached at chandrashekar.schandra[at]gmail.com.
Professor Soma Perumal is Adjunct Faculty, International Strategic and Security Studies Programme, National Institute of Advanced Studies. He can be reached at som598[at]yahoo.com.