It is important to have an array of missiles capable of striking deep inside the enemy territory, but it is equally important to have a technology that can block incoming missile attack. A Ballistic Missile Defence (BMD) is a system that is designed to intercept and destroy an incoming ballistic missile on its trajectory much before it approaches the target.
India has been working on a BMD system for quite some time has also carried out several successful trials. India is now planning to deploy by late 2018 the anti-ballistic missile system to protect its metros from hostile aerial attacks.
India's ballistic missile defence system provides a two-layered shield - 'exo' and 'endo'. What this effectively means is that the system provides protection both against ballistic missiles that are outside (exo) as well as inside (endo) the earth's atmosphere.
In the first phase, two-tier interceptor defence system to provide an effective missile shield against incoming hostile projectiles both conventional and nuclear would be developed around New Delhi. The decision to implement the system in other metros and other critical asset locations will be taken this year after a couple of more trials of the system is accomplished in a coordinated manner.
Theory behind BMD systems:
Theoretically, a hostile missile can be intercepted at the launch point, mid-course (flight through space), or terminal phase (during atmospheric descent).
Practically speaking, the first option is almost ruled out as it is would be next to impossible to know where the missile is being launched till the time it is launched. A country needs to have a high level of intelligence gathering capabilities with moles in the top chain of command of the enemy to know exactly when and where a missile launch would take place. This seems highly improbable as the know-how of a missile launch is known only to topmost generals.
Intercepting a missile in next two phases of its flight seem like a plausible option but one needs to bear in mind that the speed of a ballistic missile is just too high for systems to predict its precise location and path. Most of the BMDs and Anti-Ballistic Missile systems in the world aim at blocking the missile in these two phases with the focus more being on intercepting missile's ballistic trajectory outside the atmosphere. Other theories such as confusing the missile's navigation system with jammers have been proposed, but modern ICBM's are equipped with decoys and stealth coatings to counter this. Several countries such as Russia, Israel, China and the US claim to have BDM system in place. India is now only the fourth country after Russia, Israel and the US to have successfully tested a BMD system.
India's BMD program:
India's BMD is a two-layered system. Prithvi Air Defence (PAD) is supposed to tackle incoming missiles at ranges of 80-120 km (exo-atmospheric interception). On the other hand, the advanced air-defence (AAD) mainly consists of Akash Surface-to-Air Missiles (SAM) that can intercept incoming missiles at ranges of 15-30 km (endo-atmospheric interception).
India in December 2017 successfully test-fired its indigenously developed Advanced Air Defence (AAD) supersonic interceptor missile, capable of destroying any incoming ballistic missile in low altitude, from a test range in Odisha. This was the third supersonic interceptor test carried out in 2017 in which an incoming ballistic missile target was successfully intercepted, within 30 km altitude of the earth's atmosphere by an interceptor.
The earlier two tests were conducted on March 1 and February 11, 2017, as part of efforts to have a full-fledged multi-layer Ballistic Missile Defence system.
The target missile-- a Prithvi missile-- was launched from launch complex 3 of the Integrated Test Range (ITR) at Chandipur near here. After getting signals by tracking radars, the interceptor AAD missile, positioned at Abdul Kalam Island --previously known as Wheeler Island -- in the Bay of Bengal, roared through its trajectory to destroy the hostile target missile in mid-air in an endo-atmospheric altitude.
The interceptor is a 7.5-meter long single stage solid rocket-propelled guided missile. It is equipped with a navigation system, a hi-tech computer and an electro-mechanical activator. The interceptor missile has its own mobile launcher, a secure data link for interception, independent tracking and homing capabilities and sophisticated radars.
The DRDO has two phases of the BMD systems. While the phase-I interceptors are now ready for deployment, the phase-II missiles, capable of thwarting threats from enemy missiles with ranges of 5,000 km, are expected to be ready in next couple of years.
Components of India's BMD:
Advanced Air Defence Advanced Air Defence or AAD interceptor is a single-stage, solid-fuelled missile capable of intercepting an incoming missile at around 30 kms.
The interceptors are guided by high accuracy Inertial Navigation System (INS) and supported by a Redundant Micro Navigation System (RMNS). The interceptors zero in on the hostile missile with the help of infrared (IR) seeker and inertial guidance.
Swordfish Long Range Tracking Radar (LRTR) is a long-range tracking radar specifically developed to counter ballistic missile threat. Its main function is target acquisition of incoming missile and provides guidance to interceptors (PAD and AAD) to hit its target in space. This radar has a range of over 800 km and can be used for tracking trajectories. India is upgrading this radar to increase its range to 1500 km.