Next objective: a 5,000-km Agni

Interview with Avinash Chander, Director, Advanced Systems Laboratory, and Programme Director, Agni-III mission.

INDIA'S long-range ballistic missile, Agni-III, has been the focus of attention for the past four years. Its launch from Wheeler Island off the Orissa coast on April 12 has been declared a "perfect success". Defence analysts called it "an important milestone on the road to India achieving a credible nuclear deterrent" and said it signalled India "maturing" in a host of missile technologies.

Designed and developed by the Advanced Systems Laboratory (ASL) in Hyderabad, a unit of the Defence Research and Development Organisation (DRDO), Agni-III is the latest in the Agni series of missiles and has two stages, both powered by solid propellants. The ASL was formed on September 28, 2001, with special emphasis on developing large-sized rocket motors and composite products. Its Director, Avinash Chander, was also the Programme Director for the April 12 mission. In an interview to Frontline in his office in Hyderabad on April 16, he called Agni-III not just "a missile but a system for the future with which various configurations can be developed".

Agni-III's success came within nine months of the failure of its maiden flight on July 9, 2006. Said Avinash Chander: "Nine months is a short time to overcome such a failure... . In this case, [if] we could identify, reproduce and recover... within nine months and launch a successful system, it is because of the open, interactive system within the organisation." In his estimate, Agni-III filled a "vital gap in our defence capability."

Avinash Chander, 56, specialises in long-range missile systems. He graduated in Electrical Engineering from the Indian Institute of Technology (IIT) Delhi in 1972 with distinction. He joined the DRDO in August 1972 and pioneered the development of inertial navigation and guidance systems for long-range missiles. He has been associated with the Agni missile programme since its inception, leading the mission design, navigation and guidance, simulation and so on. He became Deputy Project Director, Agni, in 1989 and Project Director for operationalised versions of Agni in 1995.

Excerpts from the interview:

How do you assess the success of the Agni-III missile flight on April 12?

A-3 (Agni-III) has been an important programme for us, primarily because the Agni-I and Agni-II systems were an extension of technologies we were using since the 1970s. They had virtually reached the limit of their capabilities. Agni-I has a 700-km range, which can be extended with minor modifications. Agni-II has a 2,000-km limit. But if you really want to have matching capabilities with respect to your ambience, it is imperative that you must talk of a missile with a range of 3,000 km plus or 3,500 km. That is how the Agni-III programme began.

We thought of Agni-III not as a missile but as a system for the future, with which various configurations can be developed. The project was sanctioned in 1998, but work began only in 2001 because we were busy with the first trial of Agni-II, which took place in 1999 and gave us the confidence for an all-solid system. We had a high-priority programme coming in between, which was Agni-I, whose project director was D.P. Rao. In 2000-01 we were absorbed in making Agni-I feasible for the western sector.

We began real work on Agni-III only in 2001. It was the first time that the DRDO had taken up fabrication of such large rocket motors - two metres in diameter, with about 30 tonnes of solid propellants in the first stage and nine tonnes in the second stage. It had flex [flexible] nozzle control, which no other country had used for the first stage, during the atmospheric phase of the flight. These were the challenges. The [payload] re-entry itself was a challenge because its velocity was five metres a second with a very steep re-entry lasting not more than 20 to 25 seconds, ambient temperatures going to 4,000Celsius, skin temperatures reaching 2,500Celsius and the deceleration going down anywhere between 30 g and 16 g. So, the whole environment was totally different from that of even Agni-II. It required a much more compact, capable vehicle.

We had to set up our own propulsion plant because there was a total separation of activities between DRDO and ISRO [Indian Space Research Organisation] because ISRO was for totally peaceful uses. We had to build the infrastructure for propellant casting, right from raw material to the actual motor realisation and testing. We did all this in five years. For the motor we have flown now, the raw material came from our captive plants, the motor castings were made at our plant in Chhattisgarh, and we did the static test.

What were the reasons for the failure of the first flight in July 2006?

There has been a lot of misconceptions about the failure. When the vehicle is going through a supersonic regime with a flex nozzle, the exhaust jet expands in the higher atmosphere. There is a supersonic aerodynamic jet coming inwards. The hot jet stream expanding outwards and the aerodynamic jet coming inwards at the base of the vehicle started interacting. This is a phenomenon that happens for this class of vehicles. But its severity depends on the size of the nozzle, the gap between the nozzle and the base shroud covering the nozzle, and the time spent in the interactive region because this phenomenon starts only in the higher atmosphere and the supersonic regime.

Was it not anticipated?

Its severity was not anticipated. We had provided a barrier but the barrier was inadequate. Some of the hot gases were entering the base shroud covering the nozzle. In that area, we have some sensitive electronic packages for controlling the nozzle. In this case, the nozzle moves and we have all the control systems housed in that. When the interactive flow started going back into the base shroud and the high-temperature hot gases started entering inside, it caused some of the electronic cables to lose their insulation, leading to short-circuit and damage to the control system. The vehicle lost control at 65 seconds [after lift-off] and tumbled. The stage separation did happen as expected, under the tumbling circumstances.

Did the vehicle break up into bits?

It did not break up into bits. It was structurally sound. Within a day, we could identify that loss of control had happened. We could identify what had failed. But the main issue was what caused it to fail. Was it a random failure of a component, which was an easier theory, or was it some other phenomenon happening? That is why the Prasad Rao Committee was formed. Our teams went into the extreme details, into each and every event, and we could identify the causes of the failure.

The teams struggled for two months to produce the exact signatures of the failure as observed in the flight. We could reproduce each and every signal, which we had telemetered in failed condition, by plotting exactly which wire shorted at what time and that was the strength of the teams, which gave us the confidence, "Yes, we have identified the problem", and we knew how to take care of it.

The solution was relatively simple. We had to put a flexible barrier, a thermal protection system, all round the nozzle, which prevented all interactive hot gases from entering inside. But the barrier should withstand 1,400Celsius and yet allow the nozzle to move freely. That was the challenge that B. Sankara Rao and his team met successfully. That is what we have now flown and we have met all the objectives.

Where does this successful flight place India among the missile powers? We have the Agni family of missiles - Agni, Agni-II, Agni-I and now Agni-III.

Today we have a total gamut of these systems. Agni-I is western-sector specific. It is a single-stage system. It is under induction. Agni-II, which has a dual role, in the western and eastern sectors, is also under induction. Both had certain limitations in covering the total geopolitical threat in our region. Agni-III fills that vital gap in our defence capability.

The most important point is that with minor modifications in this system we can have the capability for a 5,000-km range, which gives you the strategic depth of deployment so that from within your country you can target any potential threat-areas within this region. That is what gives you the strength.

We have the platform, which can be deployed for any role. From central India, you can hit any target, whether [it is] in the east or the west. It has the reach for any target from central India. Your vulnerability becomes that much less.

Another important dimension is that nobody has this 3,000-km-plus range, except Russia, the United States, France and China. That is where we stand.

We are now talking of a quantum jump from 3,000 km to 5,000 km range. It will be totally indigenous.

Do you plan to do it by adding one more stage?

We will be adding one more stage within the same dimensions and practically with the same weight. It will be small. We will be doing some weight-saving and adding some.

Liquid upper stage?No.

So, all the three stages will be powered by solid propellants?

All solid.

Can it be qualified as an Intercontinental Ballistic Missile (ICBM)? An ICBM should have a minimum range of 6,000 km.

They are all variables. Different people have different yardsticks: somebody says 6,000-km-plus or 10,000 km, or continent to continent. But our final range is 5,000 km. That is what matters.

Dr. K. Santhanam, former Chief Adviser to the DRDO, told me that Agni-III gives teeth to our minimum nuclear deterrence capability. Can you expand on that?

The A-3 system is rail-mobile, like A-2. The future 5,000-km-range missile we are planning will be road-mobile. That gives it immunity from vulnerability. The second thing is that it can reach targets that no aircraft can reach.

The missile system [Agni-III] we are making has state-of-the-art inertial guidance, highly accurate sensors with high immunity from jamming. We have no communication with the ground once we take off.

Fire and forget?

Totally fire and forget. Since it is not looking for any data from the ground, no enemy can jam it or divert it or affect its path. Except for an active interception, there is no way one can stop it.

Most of the operations are done in the initial phase except some of the manoeuvres we are planning in the future in order to overcome the interception possibility. Today, once it [Agni-III] is fired, the stages are burnt out and separated, only a small warhead re-enters the atmosphere.

Since there is no communication from the ground, you cannot jam the onboard electronics. We feed the launch-point coordinates from the ground, the system computes the performance of the propulsion system and, based on it, estimates its own path and what will be the best trajectory to take it to the target. All the computations are done on board. There is an inertial guidance system, which measures the position of the missile; the onboard computer with the guidance and algorithm stored computes the path, which is then controlled by the manoeuvring of the nozzle to steer it.

The velocity accuracy we need to achieve at injection is 0.1 metres a second. While the actual velocity of the vehicle is 5,000 metres a second, you should be able to differentiate 5000.1 or 5000.2 metres a second and measure it correctly. That is the type of accuracy required and that is what we have been able to achieve in these systems.

The teeth we are talking of is that it is a totally indigenous system, indigenously designed and indigenously produced, leaving aside some electronic components...

How did you overcome embargoes and technology denial regimes?

The only way to overcome the embargoes is to start our own developmental effort. That is what we did for the inertial navigation system. Software was always our strength. We never went for any consultancy on design. The main issue was hardware, sometimes raw materials. We went in a major way for raw materials from industries such as MIDHANI and for support from laboratories such as DMRL [Defence Metallurgical Research Establishment] for establishing the processing technologies.

We established in-house the fabrication technologies for the re-entry vehicle structures. All the onboard computers, navigation systems and algorithms were developed by our scientists. The advantage is that we have a great strength in software. We have a good availability of engineers and experts. We tried to make the best use of whatever material available and modify the processing technology to overcome the difficulty - whether it was heat-shield, thermal structure, onboard sensors or basic rocket motor casings. That was our main strength. Of course, we received tremendous help from the industry. In Agni-III, I can't think of any component that was made in-house. Every component came from the industry.

Do you plan to have some more trials of Agni-III?

Yes. We will have a couple of more developmental tests and a couple of tests with the user.

China has pushed far ahead of us in missiles. It has ICBMs that have a range of more than 12,000 km.

Today, the Chinese have the whole gamut of missiles. But as far as their capability is concerned, we have equivalent capability. In terms of weights and performances, we are matching.

Not in range?

Range is a question of political requirement. Today, our country is talking of 3,000 km and 5,000 km to meet our... The Chinese have a different need. But as far as our capability is concerned, we have the capability to match the range also.

Can you elaborate on your remark that Agni-III is not a just a missile but a system for the future.

With this two-metre diameter [Agni-III] system, we are flying 3,000 km. With a small stage added, it becomes a 5,000-km system. Even though I do not use the same motors, with certain improvements and using the same technology modules I can generate another system, which can take multiple warheads. I can generate a system with a combination of warheads and decoys. Modules of same technology and sizes can be integrated into a system, which can be launched from different kinds of platforms. That is why I said it is a base that we have created, not just a missile. It makes the entire future open.

The infrastructure is there with us. The technology and industry are there with us. All that is needed is modularising to our requirenments. That has been the major achievement of this programme.