India has a formidable new addition to its armoury — Agni-IV. The missile's first test flight under its earlier name, Agni-II Prime, in December 2010 ended in failure. But those problems have clearly been sorted out. Tuesday's test went without a glitch, and the missile successfully carried a 800-kg warhead to a distance of over 3,000 km. Agni-III missile, which was first successfully tested in 2007, already has a range of over 3,500 km when carrying a 1.5 tonne warhead. With less payload, this missile's range would be considerably greater. The success of Agni-III and Agni-IV reflects the maturing of capabilities in the long-range missile programme. The Agni missile family began with a ‘technology demonstrator' that combined the one-metre, solid-propellant first stage of India's first launch vehicle, the SLV-3, with a liquid-fuelled second stage. When the decision was taken to turn the technology demonstrator into an operational missile, the upper stage too was turned into a solid propellant one. This upper stage was equipped with a ‘flex nozzle' that could be swivelled to control the missile's orientation. Agni-II has a range of more than 2,000 km with a one-tonne payload. A single-stage version, Agni-I, with a range of about 700 km was subsequently developed.

The Defence Research and Development Organisation (DRDO) demonstrated a big leap in its ballistic missile capabilities with the two-stage, all-solid Agni-III. With a diameter double that of the one metre of its predecessors, this was the first Indian missile that can potentially be equipped with multiple warheads. This time the first stage too had a ‘flex nozzle,' a major technological achievement that considerably reduced the weight of the missile's control systems. With the addition of a solid third stage, the missile will be turned into Agni-V, with a range of over 5,000 km. This missile is scheduled to be tested in February. The missile team appears to have used its skills to upgrade Agni-II. Agni-II Prime, now known as Agni-IV, has a diameter of 1.2 metres, allowing a ‘flex nozzle' for the first stage as well. Further weight saving was brought about by having a composite second stage motor casing, instead of the earlier metal one. These weight reductions meant that more propellant could be loaded, thereby increasing the missile's range. Improvements in the missile's navigation systems, which now use laser gyros, as well as better onboard computers and avionics will make it more accurate too. Armed as they are with nuclear warheads, these are capable of causing immense destruction. The hope must be that they will never be put to actual use.

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