'Enemy' ballistic missile to be downed in space next month

Next month, the Defence Research and Development Organisation (DRDO) will attempt to shoot down an incoming “enemy” ballistic missile in outer space, well before it enters the earth’s atmosphere.

DRDO chief V K Saraswat has told Business Standard a newly developed Prithvi Defence Vehicle (PDV) interceptor missile is to be launched from Wheeler Island (off Odisha’s coast, 150 km from Bhubaneswar), travelling 110-150 km into space, where it will destroy an incoming missile, fired earlier from a naval warship in the Bay of Bengal.

This comes on the heels of the DRDO’s successful November 23 test of its Advanced Air Defence (AAD) interceptor missile, which destroyed an incoming target missile at an altitude of 15 km. Together, the AAD and the PDV missiles, with their radars and control centres, will form a two-layered anti-ballistic missile (ABM) defence system to protect strategic targets such as Delhi by 2013-14. While the AAD missile performs endo-atmospheric (inside-the-atmosphere) interceptions of enemy ballistic missiles, the PDV will conduct exo-atmospheric (outside-the-atmosphere) interceptions.

Next month’s test will feature a brand-new target: A two-stage version of the Dhanush missile, launched from a naval vessel 300-350 km from the interceptor location at Wheeler’s, and soaring to about 150 km. This target missile would mimic the trajectory and speed of an enemy ballistic missile fired from 1,500 km away, such as Pakistan’s Gauri and Shaheen projectiles. So far, target missiles, fired from Chandipur, just 70 km away, could only mimic enemy missiles fired from a range of 600 km or less.

“Firing range limitations make developing targets as much a challenge for us as developing interceptors. We have developed a boosted, two-stage version of the ship-launched Dhanush missile, which makes it into quite another system, taking it to a greater altitude that will mimic the actual terminal conditions of a 1,500-km class enemy missile,” explains the DRDO chief.

The brand-new PDV will intercept the incoming target at a 110-150 km altitude, far higher than the 50 km-high interceptions the exo-atmospheric Prithvi Air Defence interceptor has been doing so far. The PDV will carry a new Indian electro-optic seeker, to work in tandem with the radio frequency seeker the PAD has traditionally carried. An electro-optic seeker provides greater accuracy and reliability than a radio frequency seeker in homing the interceptor on to the target.

The PDV will be a solid-fuel missile, to be powered by a sophisticated new “pulse motor”. This will provide surges of propulsion during the missile’s later stage, increasing its manoeuvrability when very close to the target.

Intercepting the target at longer ranges provides several advantages. First, the target is travelling slower — some two km per second at 150 km, compared with 2½ km per second at 50-km altitude. Second, the target missile can be engaged before it enters Indian airspace, so that the debris falls into enemy territory. Finally, a longer flight time gives the interceptor more time for navigation, and the seeker can see better.

The PAD has been test-fired only twice, compared with the four test-firings of the AAD. DRDO insiders say with the PDV under development, there was no incentive to waste effort on the PAD. Now, the PDV could well undergo a phase of intensive testing.

Alongside the actual PDV launch at an actual target missile, the test next month will also feature up to six simulated targets, forcing the radars and command systems to respond. “We can launch six interceptors simultaneously, some endo-atmospheric and some exo-atmospheric, to handle such an attack,” says Saraswat.

Meanwhile, DRDO is working on Phase-II of the anti-ballistic missile defence programme, capable of downing enemy inter-continental ballistic missiles fired from up to 5,000 km away. DRDO says the Phase-II shield would be deployed by 2016.